Review

Sustainable Extraction of Critical Minerals from Waste Batteries:

A Green Solvent Approach in Resource Recovery
Afzal Ahmed Dar 1 , Zhi Chen 1,2, *, Gaixia Zhang 3 , Jinguang Hu 4 , Karim Zaghib 5 , Sixu Deng 5 ,
Xiaolei Wang 6 , Fariborz Haghighat 1,2 , Catherine N. Mulligan 1,2 , Chunjiang An 1,2 ,
Antonio Avalos Ramirez 7 and Shuhui Sun 8

1 Department of Building, Civil, and Environmental Engineering, Concordia University, 1455 De Maisonneuve
Blvd. W., Montreal, QC H3G 1M8, Canada; afzalahmed.dar@concordia.ca (A.A.D.)
2 Concordia Institute of Water, Energy and Sustainable Systems, Concordia University, 1455 De Maisonneuve
Blvd., Montreal, QC H3G 1M8, Canada
3 Department of Electrical Engineering, École de Technologie Supérieure (ÉTS), Montreal, QC H3C 1K3, Canada
4 Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW,
Calgary, AB T2N 1N4, Canada
5 Department of Chemical and Materials Engineering, Concordia University, 1455 De Maisonneuve Blvd. W.,
Montreal, QC H3G 1M8, Canada
6 Department of Chemical and Materials Engineering, University of Alberta, 9211-116 Street NW,
Edmonton, AB T6G 1H9, Canada
7 Centre National en Électrochimie et en Technologies Environnementales, 2263 Av. du Collège,
Shawinigan, QC G9N 6V8, Canada; aaramirez@cnete.qc.ca
8 Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications,
Varennes, QC J3X 1S2, Canada
* Correspondence: zhi.chen@concordia.ca

Abstract: This strategic review examines the pivotal role of sustainable methodologies in
battery recycling and the recovery of critical minerals from waste batteries, emphasizing
the need to address existing technical and environmental challenges. Through a system-
atic analysis, it explores the application of green organic solvents in mineral processing,
advocating for establishing eco-friendly techniques aimed at clipping waste and boosting
resource utilization. The escalating demand for and shortage of essential minerals including
Academic Editor: George Zheng Chen
copper, cobalt, lithium, and nickel are comprehensively analyzed and forecasted for 2023,
2030, and 2040. Traditional extraction techniques, including hydrometallurgical, pyrometal-
Received: 7 December 2024
Revised: 21 January 2025
lurgical, and bio-metallurgical processes, are efficient but pose substantial environmental
Accepted: 22 January 2025 hazards and contribute to resource scarcity. The concept of green extraction arises as a
Published: 28 January 2025 crucial step towards ecological conservation, integrating sustainable practices to lessen the
Citation: Dar, A.A.; Chen, Z.; Zhang, environmental footprint of mineral extraction. The advancement of green organic solvents,
G.; Hu, J.; Zaghib, K.; Deng, S.; Wang, notably ionic liquids and deep eutectic solvents, is examined, highlighting their attributes
X.; Haghighat, F.; Mulligan, C.N.; An, of minimal toxicity, biodegradability, and superior efficacy, thus presenting great potential
C.; et al. Sustainable Extraction of
in transforming the sector. The emergence of organic solvents such as palm oil, 1-octanol,
Critical Minerals from Waste Batteries:
and Span 80 is recognized, with advantageous low solubility and adaptability to varying
A Green Solvent Approach in
Resource Recovery. Batteries 2025, 11,
temperatures. Kinetic (mainly temperature) data of different deep eutectic solvents are
51. https://doi.org/10.3390/ extracted from previous studies and computed with machine learning techniques. The
batteries11020051 coefficient of determination and mean squared error reveal the accuracy of experimental
Copyright: © 2025 by the authors.
and computed data. In essence, this study seeks to inspire ongoing efforts to navigate
Licensee MDPI, Basel, Switzerland. impediments, embrace technological advancements including artificial intelligence, and
This article is an open access article foster an ethos of environmental stewardship in the sustainable extraction and recycling of
distributed under the terms and critical metals from waste batteries.
conditions of the Creative Commons
Attribution (CC BY) license
(https://creativecommons.org/
licenses/by/4.0/).

Batteries 2025, 11, 51 https://doi.org/10.3390/batteries11020051

Batteries 2025, 11, 51 2 of 36

Keywords: mineral extraction; battery; recycling; green organic solvents; DES; ma-
chine learning

1. Introduction
Sustainable development and the environment are intrinsically interconnected, serv-
ing as the cornerstone of global initiatives aimed at fostering a harmonious coexistence
between industry and nature [1,2]. Notably, the investigation of sustainable methods in
battery recycling and mineral extraction is of utmost importance. Both are essential com-
ponents of contemporary technology, but their traditional approaches are often tainted by
environmental deterioration and the exhaustion of resources [3]. The practice of recycling
batteries is becoming more popular due to the growing demand for electric vehicles (EVs)
and portable electronic gadgets [4]. The battery industry had significant growth from USD
62.00 billion in 2014 to USD 120.00 billion in 2019 [5]. The estimated size of the worldwide
rechargeable battery market in 2022 was USD 110.44 billion [6]. It is projected to reach
around USD 195.55 billion by 2032, with a compound annual growth rate of 5.88% over
the forecast period from 2023 to 2032, as shown in Figure 1A. The expansion of Pb-acid
batteries is expected to be driven by their cost-effectiveness and dependable performance,
as shown in Figure 1B [7].
However, conventional recycling techniques, which depend on strong chemicals
and energy-intensive procedures, cause notable environmental hazards [8]. In addition,
recycling technologies for rechargeable batteries cannot only contaminate (in the event of
their leakage) the environment with heavy metals but also with organic compounds and
highly acidic or alkaline electrolytes [9].
The U.S. Geological Survey (USGS) defines key minerals as those that are vital to
national security and the economy yet susceptible to supply chain disruptions because
of limited domestic production and geopolitical considerations. These are essential for
electronics, defense applications, and renewable energy technologies [10]. The process of
extracting minerals from ores is often demanding in terms of energy. It is necessary to
employ high temperatures during the smelting or leaching process, as well as significant
amounts of strong acids or bases, both of which demand energy to create. It is necessary
to treat the gas, liquid, or solid waste that is typically generated by these processes before
it can be properly disposed of. Extra energy is needed for this waste treatment process
as well. The traditional reagents used in these approaches often exhibit potential risks to
human health, the environment, and safety, and the cause other associated concerns [11].
To enhance the safety and cleanliness of these approaches, it is essential to investigate the
use of green and more eco-friendly reagents. It is estimated that around 20 million metric
tons (MT) of organic solvents are produced annually at the industrial scale [12]. Overuse
of hazardous, non-renewable solvents is a prime example of unsustainable behavior and
unhygienic for the environment [13].
Solvation offers several significant benefits, including enhanced handling and safety,
by acting as a heat sink that absorbs excess heat generated during chemical reactions,
thereby preventing overheating, protecting solvents from thermal degradation, and main-
taining optimal conditions for selective recovery. For example, green solvents such as
choline chloride–urea effectively serve as heat sinks in battery-recycling processes [14].
Over the past two decades, researchers have introduced and investigated a new class of
solvents known as “master solvents”, which include ionic liquids, supercritical carbon
dioxide, deep eutectic solvents (DESs), thermomorphic solvents, and fluorous solvents.
These solvents, often referred to as green or designer solvents, have the potential to expand
 Batteries 2025, 11, 51 3 of 36

the capabilities of conventional solvents by enhancing solubility, stability of excited states,

1, x FOR PEER REVIEW and overall process efficiency [15]. For a solvent to be considered green, it3 should
of 39 be
non-volatile, non-toxic, recyclable, and biodegradable and require minimal energy for its
synthesis [16,17].

Figure 1. (A) Rechargeable batteries by market size, 2022–2023 (billion USD), and (B) rechargeable
Figure 1. (A) Rechargeable batteries by market size, 2022–2023 (billion USD), and (B) rechargeable
batteries by battery type, 2022.
batteries by battery type, 2022.
Ionic liquids, supercritical CO2 , DESs, thermosmorphic, and fluorous solvents
However, conventional recycling
comprise majority of the techniques,
components. which
These depend
solvents on
andstrong chemicals and
their applications are well-
documented and widely appreciated [18]. Utilizing ionic liquids
energy-intensive procedures, cause notable environmental hazards [8]. In addition, (ILs) and DESs as agents
recycling technologies for rechargeable batteries cannot only contaminate (in the event of
their leakage) the environment with heavy metals but also with organic compounds and
highly acidic or alkaline electrolytes [9].
The U.S. Geological Survey (USGS) defines key minerals as those that are vital to
Batteries 2025, 11, 51 4 of 36

in mineral flotation and extraction of important metals offers innovative alternatives to con-
ventional technologies, enabling environmentally friendly and sustainable production [19].
A number of minerals, including carbonate asphalt, quartz, quartz hematite, and rare earth
minerals, have been successfully floated in DESs and ILs in recent years [20].
The scalability of existing recycling technologies remains limited due to technical
and economic constraints, presenting a significant challenge, particularly in the case of
direct positive-electrode recycling. To enable scaling, it will be crucial to recover feedstock
directly from end-of-life (EoL) LIBs to verify its feasibility at scale [21]. While direct positive-
electrode recycling is recognized for its potential to recover valuable materials with a lower
environmental impact compared to conventional methods, several challenges must be
addressed before it can be adopted on an industrial scale. For example, the handling
of fluorine impurities generates toxic byproducts, hindering the recycling process [21].
Additionally, the precise chemical selection of waste LIBs is essential, further increasing the
complexity and cost of recycling.
The rapid advancement of positive-electrode chemistries suggests that older recycling
techniques may not be compatible with the cutting-edge materials used in next-generation
batteries. This disparity necessitates continuous adaptation of recycling methods to align
with ongoing developments in battery design, potentially hindering the widespread adop-
tion of direct positive-electrode recycling [22]. To address these challenges and enhance
the environmental sustainability of LIB production and recycling, the development of
eco-friendly methods is critical. New binders can replace traditional polymeric binders
like PVDF, which rely on solvents such as N-methyl-2-pyrrolidone (NMP), known for its
environmental drawbacks.
Considering the present challenges, it is essential to develop sustainable strategies to
address future challenges and opportunities in battery recycling and mineral extraction. The
novelty of this study lies in the comprehensive determination of the gaps and limitations
in current recycling methods, such as, for example, massive cross contamination of black
mass and traditional inefficiencies of hydrometallurgical and pyrometallurgical methods.
This study highlights the urgent need to develop green organic solvents, binders, and more
efficient recycling methods.
Additionally, it also explores the radical potential of ILs and DESs to overcome the
challenges faced, as innovative solutions that could markedly lower environmental impacts
and raise the viability of large-scale battery recycling. The emerging role of machine learn-
ing and its application may be useful in this industry. A focus on sustainable, green solvents
allows this study to make a significant contribution toward advancing environmentally
responsible and economically feasible recycling technologies.

2. Critical Minerals in Batteries

2.1. The Role of Critical Minerals in Battery Technology
The most crucial minerals in rechargeable batteries are cobalt (Co), lithium (Li), nickel
(Ni), copper (Cu), and lead (Pb) [21]. Further details are given in Table 1. A key element is
a valuable component of a mineral commodity, based on the state of demand, which faces
the risk of supply disruption [22].
Batteries 2025, 11, 51 5 of 36

Table 1. Critical minerals in battery chemistry.

Critical Mineral Main Global Producer Uses Global Demand References

It is forecast that in 2030,
e-mobility batteries alone
will account for an
Batteries (50%), super estimated 176,000 metric
Republic of Congo alloys (17%), hard tons of cobalt demand
Cobalt (73%), Russia (4.3%) metals (8%), magnets worldwide. In contrast, [23,24]
and Australia (4%) (3%), catalysts (5%), and non-battery applications of
ceramics/pigments (4%) cobalt are only expected to
amount to 65,000 metric
tons of cobalt demand
globally by that year.
Lithium-ion batteries
In 2030, the global demand
(LIBs) (59%), ceramics
for lithium is expected to be
and glass (9%),
more than quadruple the
Australia (53%), lubricating greases (8%),
demand in 2022, having
Lithium Chile (32%), casting and alloy [25,26]
increased from
and China (13%) industries (3%), air
720,000 metric tons to a
conditioning (3%), and
forecasted 3.1 million
primary aluminum
metric tons.
manufacturing (1%)
Global graphite
Almost 90% of the consumption by LIBs is
spherical negative- anticipated to grow to just
Graphite China (62%) [27,28]
electrode-grade graphite below 447,000 metric tons
used in LIBs in 2021 and increase
four-fold thereafter by 2030.
According to smart new
energy (SNE) research, the
global demand for nickel
batteries is predicted to
Stainless steel (69%), double from 385,000 tons in
batteries (11%), 2022 to 841,000 tons in 2025
Nickel Indonesia (40.2%) nonferrous alloy (7%), and increase six-fold to [29]
plating (6%), alloy steel 2.37 million tons in 2030.
(3%), and foundry (1%) The market will rise from
USD 7.7 billion in 2022 to
USD 18.511 billion in 2025
and USD 71.088 billion
in 2030.
Recently, Co has been
projected to increase to
44.4 Mt in 2050 compared to
24.3 Mt in 2015. The need
for copper in transportation
Transport (36%), infrastructure and
Copper Chile (27%) infrastructure (18%), automobiles will increase [30]
and appliances (20%) fourfold. A higher
collection rate can reduce
the primary copper output
(from copper ore) by 2.2
and 2.3 Mt, respectively,
by 2050.
Batteries 2025, 11, 51 6 of 36

Table 1. Cont.

Critical Mineral Main Global Producer Uses Global Demand References

The global market for Mn
Solar, wind power,
Manganese South Africa (36%) will be increased to USD [31,32]
and LIB
3.9 billion in 2038.
Electrolysis, positive
By 2050, the demand for
electrode
Guinea, Australia, aluminum products is
Aluminum manufacturing, alumina [33]
Vietnam expected to increase
smelting, and bauxite
by 81%.
mining and Al scrap
By 2028, the titanium
market is expected to
Titanium dioxide (TiO2 ), expand by USD 8.78 billion
a white pigment in at a compound annual
Titanium China (30%) [34,35]
paints, paper, and growth rate (CAGR) of
plastics 5.89% due to its use in the
automotive, aerospace, and
medical sectors.
In 2024, the worldwide iron
ore market was estimated to
be worth USD 297.82 billion.
Iron Australia (37.6%) Metallurgical industry It is anticipated to increase [36,37]
at a CAGR of 2.7% from
2024 to 2032, reaching USD
392.11 billion.

2.2. Challenges and Limitations in Traditional Extraction Methods

The ubiquitous demand for critical minerals is supported by the growing need for
renewable energy and low-carbon technology, which are prerequisites for a future energy
system that uses less carbon [38]. Important minerals for low-carbon technology include
Co, Ni, Ag, Mn, Cu, Li, and rare earth elements. Numerous products that benefit the
environment make use of these eco-friendly minerals. Those include solar photovoltaic
panels, wind turbines, electrical vehicle (EVs), and energy storage devices. A considerable
portion of the world’s supply of different minerals is processed in China [39]. Extraction
corporations persist in extracting minerals at a rate that is not sustainable, resulting in the
depletion of resources.

2.2.1. Extraction Practices and Environmental Deterioration

Environmental deterioration is a significant problem that is strongly connected to the
exhaustion of both natural and mineral resources [40]. Annually, a significant amount of
mine waste, amounting to several gigatons, is generated worldwide. The rapidly growing
worldwide demand for natural resources is driving an increase in the extraction of larger-
scale and lower-grade deposits [41]. Mine waste is typically kept on-site indefinitely
when there is no technical or financial means to recycle or otherwise increase its value.
Even with proper management in designed storage facilities, extraction waste may still
have far-reaching consequences. Among them are climatic, environmental, hydrological,
geotechnical, and ecological factors pertaining to the state of the natural environment,
including air, water, and soil [42].
Excavation activities have a significant impact on the environment by altering land
usage, causing deforestation, generating waste [43] ,and resulting in other disturbances in
the ecological system, such as air and water contamination [44]. The release of greenhouse
Batteries 2025, 11, 51 7 of 36

gases resulting from extraction and beneficiation operations, as well as fuel and electricity
use, contributes to climate change [45]. The adverse effects on population displacement,
human health, and safety and the creation of conflicts over land usage are also widely
recognized [46]. Excavation and extraction activities can affect regions extending up to
50 km from mine sites [47]. Because of their detrimental effects on biodiversity, extraction-
related activities close to or inside protected areas have occasionally been prohibited [48].
The necessity of extraction will persistently rise in the future due to the significant
contribution of mineral resources in fostering socio-economic progress and facilitating the
shift towards a more environmentally friendly future [49]. The World Bank has determined
that the output of some minerals may see roughly a 500% rise by the year 2050 in order to
satisfy the rising need for renewable energy technology [50].

2.2.2. Environmentally Friendly Extraction Practices

Due to the substantial dependence of sustainable development on minerals, it is
essential to participate in meticulous planning and decision-making procedures to ensure
that extraction operations provide advantages for all stakeholders. Eco-friendly and climate-
smart extraction are novel methodologies that effectively address the environmental and
sustainability concerns linked to mineral extraction activities, while also mitigating the
impacts of climate change [46].
Implementing recycling technologies and procedures is the optimal and primary
approach to ensuring the preservation of mineral waste [51]. An increasing number of
nations recognize the significance of metal recovery in parallel with the exploitation of
natural resources and have implemented a governance framework for the metal-recycling
sector [52]. For example, European mineral extraction companies prioritize the utilization
of valuable secondary minerals by using the circular economy concept. This approach has
significant potential to address the scarcity of minerals, generate profit, and simultaneously
reduce energy consumption, environmental risks, and overall environmental impact [53].
In South Africa, these forms of mineral waste are commonly deposited in landfills, resulting
in significant environmental and health issues for local people. The adverse impacts of
excavation and metallurgical and metal production processes are being addressed by
implementing recycling techniques [54]. A general illustration of the mineral extraction
impact is given in Figure 2.

2.3. Potential of Using Recycled Critical Minerals in Battery Production

Critical minerals are the fundamental aspects of battery technology. Li and Co, in
particular, are critical and primary pillars of major economies including China, the US,
Japan, and the EU. Because of their geopolitical supply chain risk, better understanding
and importance of energy evolution [55].
In this study, we performed a comprehensive analysis of recent reports and statistics,
as mentioned in Figure 3 [56]. According to the analysis and reports, Cu is high in demand,
with its extraction reaching 31,131 KT in 2023, and mining is not enough to fulfill the
demand. This scenario will worsen by 2040 with a 60% shortage of Cu, Co (50.37%), Li
(69.11%), and Ni (31.74%), as described in Figure 3b. Therefore, it is necessary to unlock
the potential of critical recycled minerals (Figure 3c) for battery production, to achieve a
low-carbon and green sustainable future.
 deposited in landfills, resulting in significant environmental and health issues for local
people. The adverse impacts of excavation and metallurgical and metal production
Batteries 2025, 11, 51 processes are being addressed by implementing recycling techniques [54]. A general 8 of 36
illustration of the mineral extraction impact is given in Figure 2.

Batteries 2025, 11, x FOR PEER REVIEW 8 of 39

demand. This scenario will worsen by 2040 with a 60% shortage of Cu, Co (50.37%), Li
(69.11%), and Ni (31.74%), as described in Figure 3b. Therefore, it is necessary to unlock
the potential of critical recycled minerals (Figure 3c) for battery production, to achieve a
Figure
Figure Impact
2.2.Impact
low-carbon ofgreen
andof mineral extractionfuture.
sustainable
mineral extraction and environmental
and environmentaldeterioration,
deterioration,emission
emissionof
ofgases
gasesduring
during
mining and battery production, and ubiquitous consumption of electronic appliances.
mining and battery production, and ubiquitous consumption of electronic appliances.

2.3. Potential of Using Recycled Critical Minerals in Battery Production

Critical minerals are the fundamental aspects of battery technology. Li and Co, in
particular, are critical and primary pillars of major economies including China, the US,
Japan, and the EU. Because of their geopolitical supply chain risk, better understanding
and importance of energy evolution [55].
In this study, we performed a comprehensive analysis of recent reports and statistics,
as mentioned in Figure 3 [56]. According to the analysis and reports, Cu is high in demand,
with its extraction reaching 31,131 KT in 2023, and mining is not enough to fulfill the

Figure3.3.(a)
Figure (a)Critical
Criticalminerals
mineralsinindifferent
differentaspects
aspectsincluding
includingdemand,
demand,mining,
mining,and
andrefining
refiningminerals
mineralsin
in 2023,
2023, 2030,2030, and 2040,
and 2040, (b) shortage
(b) shortage of minerals,
of minerals, which iswhich is calculated
calculated by demandby and
demand
mining and mining
parameters,
and (c) refinery
parameters, andaddition of minerals
(c) refinery additionto
offulfill the demand.
minerals to fulfill the demand.

Developments
Developmentsininbattery recycling
battery and and
recycling battery-manufacturing
battery-manufacturing technology are directly
technology are
linked
directly and poorly
linked anddiscussed in the previous
poorly discussed literature
in the previous [57]. For
literature instance,
[57]. the stress
For instance, in the
the stress
DRC
in themining industry
DRC mining was reflected
industry in a threefold
was reflected increaseincrease
in a threefold in Co pricesin Co between 2016 and
prices between
2018.
2016 Because these
and 2018. resources
Because are essential
these resourcesforaresatisfying thefor
essential expanding worldwide
satisfying demand
the expanding
brought on by advancements in the battery-manufacturing industry,
worldwide demand brought on by advancements in the battery-manufacturing industry, it is imperative that
DR
it isCongo industrializes
imperative and diversifies
that DR Congo its Co and
industrializes production [58,59].
diversifies its Co If production
we examine[58,59].
Figure If
3c,
then we can see that recycling facilities are increasing and this is combating
we examine Figure 3c, then we can see that recycling facilities are increasing and this is the total
combating the total need for minerals (2023), but if we further look at the recycling
facilities, we can see that production will not be enough to fulfill mineral demand; for
instance, in the case of Li, the recycling facilities will offer −39% the demand. This scenario
reveals a need to develop novel methods to improve the efficiency of recycling facilities.
Batteries 2025, 11, 51 9 of 36

need for minerals (2023), but if we further look at the recycling facilities, we can see that
production will not be enough to fulfill mineral demand; for instance, in the case of Li, the
recycling facilities will offer −39% the demand. This scenario reveals a need to develop
novel methods to improve the efficiency of recycling facilities.
Moreover, another analysis indicates that by recycling end-of-life batteries efficiently,
the global EV material demand may be reduced by 55% for freshly mined Cu, 25% for Li,
and 35% for Co and Ni by 2040. Recent analysis reflects that there is significant potential
in recycling minerals, for example, recycling lithium cobalt oxide (LCO, 43%) and nickel
manganese cobalt (NMC: NMC333 27%, NMC811 16%), hydro-recycling them (LCO 41%;
NMC333 13%, and pyro-recycling them (LCO 38%; NMC333 6%, NMC811 5%). Further-
more, it is projected that by 2050, positive electrodes will reach 22 million metric tons
(MMT) with an 80% recovery efficiency, cobalt will reach 2.7 MMT with an 80% recovery
rate, and nickel will reach 8 MMT with 6.5 MMT recovery [60]. This presents a substantial
potential to minimize the requirement for new mineral extraction industries to achieve
sustainable development goals. It will also be crucial to explore additional methods for
recycling, such as regulations that discourage private automobile ownership and increase
accessibility to public and active transportation options, given the rate at which the demand
for EVs is growing.

3. Current Recycling Techniques

The use of rechargeable batteries is increasing in direct proportion to the substantial
expansion in the worldwide demand for these batteries. In light of the current situation, the
remaining capacity of end-of-life rechargeable batteries presents a compelling possibility
for new enterprises via battery reuse and remanufacturing for second-life applications [61].
Recycling used batteries to reduce energy consumption and CO2 emissions conserves
natural resources by removing the need to extract new materials and arrange imports,
mitigates environmental damage, provides economic advantages, minimizes waste, and
addresses safety issues [62]. An earlier investigation reported that metal recycling might
produce a 13% reduction in the cost of LIBs per kilowatt-hour. However, at present, the
worldwide recycling rate for LIBs is at less than 3%, which is alarming [63].

3.1. Metallurgical Processes and Study Gaps

3.1.1. Hydrometallurgy
The hydrometallurgical process has gained substantial attention in both research cir-
cles and industry due to its remarkable recovery rates of Co, Ni, and Li, exceeding 98%,
along with its low energy requirements, excellent selectivity, minimal pollutant generation,
and relatively low cost, particularly at lower production volumes [64]. This approach
involves a systematic sequence of four phases, preceded by pretreatment. During pretreat-
ment, the sophisticated recycling process typically comprises five steps [65,66]. Initially, a
sorting process eliminates non-battery waste and categorizes battery chemistries, sizes, and
conditions according to recycling facility standards [67]. Stabilization follows to mitigate
thermal runaway risks and potential product losses from fires, before disassembly and
comminution facilitate outer shell removal, enabling potential future advancements [68].
Subsequent separation yields highly concentrated materials for further reclamation pro-
cessing, with resulting byproducts including various components like metals, plastics, and
separators [69]. After implementing all this preprocessing, the primary recycling technolo-
gies of pyrometallurgy and hydrometallurgy are used to recover essential components, as
shown in Figure 4.
Batteries 2025, 11,
Batteries 2025, 11, 51
x FOR PEER REVIEW 10
10 of 39
of 36

Figure 4.4.Hydrometallurgical
Figure Hydrometallurgicalprocess comprising
process the pretreatment
comprising of negative-electrode
the pretreatment and positive-
of negative-electrode and
electrode materials followed by potential leaching and mineral extraction.
positive-electrode materials followed by potential leaching and mineral extraction.

Leaching serves as the subsequent stage in hydrometallurgy post-pretreatment. Here,

Leaching serves as the subsequent stage in hydrometallurgy post-pretreatment.
the objective is to convert metals from the positive-electrode material into ionic solutions
Here, the objective is to convert metals from the positive-electrode material into ionic
crucial for metal recovery [64]. Leaching techniques encompass acid (inorganic) [70] or
solutions crucial for metal recovery [64]. Leaching techniques encompass acid (inorganic)
organic [71]), ammonia [72], electrochemical [73], and bioleaching methods [74], often
[70] or organic [71]), ammonia [72], electrochemical [73], and bioleaching methods [74],
supplemented with reductants to optimize effectiveness [73,75]. Acid leaching has partic-
often supplemented with reductants to optimize effectiveness [73,75]. Acid leaching has
ularly proven efficient in extracting Li, Ni, Co, and Mn in the solution, with impurities
particularly proven efficient in extracting Li, Ni, Co, and Mn in the solution, with
subsequently extracted [76]. This necessitates purification and separation procedures for
impurities subsequently extracted [76]. This necessitates purification and separation
successful recovery. Separation becomes critical due to the complex composition of leach-
procedures for successful recovery. Separation becomes critical due to the complex
ing solutions [77], aiming to recover targeted minerals effectively and selectively while
composition of leaching solutions [77], aiming to recover targeted minerals effectively and
preventing the leaching of unwanted elements like Cu and Al [78], such as MeSO4 (where
selectively while preventing the leaching of unwanted elements like Cu and Al [78], such
Me represents Ni, Co, or Mn) [79], Co3 O4 [76], MnO2 , Li2 CO3 , or Li3 PO4 [80].
as MeSO4 (where Me represents Ni, Co, or Mn) [79], Co3O4 [76], MnO2, Li2CO3, or Li3PO4
Solvent extraction, chemical precipitation, and electrochemical deposition are em-
[80].
ployed to retrieve metals from unpolluted solutions. Extracting different minerals from
Solvent extraction, chemical precipitation, and electrochemical deposition are
heterogeneous solutions can be complicated, even though it is simple for some components
employed to retrieve metals from unpolluted solutions. Extracting different minerals from
like Li and transition minerals [80]. Techniques for isolation range from progressive seg-
heterogeneous solutions can be complicated, even though it is simple for some
regation to systematic categorization followed by gradual separation. With the new EU
components like Li and transition minerals [80]. Techniques for isolation range from
battery directive emphasizing high standards for precursor materials and circular economy
progressive segregation to systematic categorization followed by gradual separation.
goals, hydrometallurgy emerges as a favorable approach [81]. Its ability to produce high-
With the new EU battery directive emphasizing high standards for precursor materials
purity metal salts and recover greater amounts of battery ingredients aligns with these
and circular economy goals, hydrometallurgy emerges as a favorable approach [81]. Its
requirements [82].
ability to produce high-purity metal salts and recover greater amounts of battery
However, challenges persist, including cross-contamination during mechanical pre-
ingredients aligns with these requirements [82].
treatment, control of manganese’s oxidative state, fluorine recovery from electrolytes, and
However, challenges persist, including cross-contamination during mechanical pre-
commercially viable extraction of Li, Ni, Co, and graphite [83]. Additionally, ensuring
treatment, control of manganese’s oxidative state, fluorine recovery from electrolytes, and
the recovery of suitable battery salt remains a hurdle, with only half of the overall battery
commercially viable extraction of Li, Ni, Co, and graphite [83]. Additionally, ensuring the
material, including crucial constituents like graphite, being recovered. Resolving these
recovery of suitable battery salt remains a hurdle, with only half of the overall battery
technological issues is imperative to advance hydrometallurgical recycling operations,
material, including crucial constituents like graphite, being recovered. Resolving these
enhancing their sustainability and competitiveness in the transition towards a circular
technological issues is imperative to advance hydrometallurgical recycling operations,
economy approach to LIB recycling [64].
enhancing their sustainability and competitiveness in the transition towards a circular
One significant limitation of hydrometallurgical recycling is the reliance on physi-
economy approach to LIB recycling [64].
cal disassembly and separation methods, which often lead to cross-contamination of the
Batteries 2025, 11, 51 11 of 36

black mass with organic materials, such as the fluorine-containing polyvinylidene fluoride
(PVDF) binder, as well as impurities like Al, Cu, and Ti [63]. Moreover, hydrometallurgical
processes face technological challenges, including controlling the oxidative state of Mn,
recovering fluorine from electrolytes, and efficiently extracting Li, Ni, Co, and graphite
in a commercially viable form suitable for battery reuse [59,73]. Subsequently, it is diffi-
cult to guarantee the recovery of Li, Ni, and Co salts suitable for batteries in a way that
satisfies market requirements. Merely 50% of the overall battery material is comprised
of the positive-electrode materials that have been recovered [59]. Important constituents
are lost, including graphite, which accounts for 12.5% (0.978 kg kW−1 h−1 ) of the total
energy in an nickel manganese cobalt (NMC) 111 battery, as well as Cu and Al, which make
up 3.11 kg kW−1 h−1 and 0.677 kg kW−1 h−1 , respectively [64]. To advance hydrometal-
lurgical recycling operations and improve their sustainability and competitiveness as we
move toward a circular economic approach to LIB recycling, it is imperative that these
technological issues be resolved.

3.1.2. Pyrometallurgy
A conventional method for recycling rechargeable batteries typically involves the
steps in Figure 5 [84]. The process begins with adding the batteries and reductants, such as
charcoal, to the smelter. To roast the mixture, the furnace is then brought to a temperature
of more than 1400 ◦ C. Notably, the organic electrolyte, Al current collector, and negative-
electrode graphite may be used as fuel or reductant on the spot, which can lead to savings in
both money and energy [85]. Subsequently, the smelter is supplemented with slag-forming
agents such as (CaO) and SiO2 to separate the non-reducible components such as Li, Mn,
and Al from the alloy portion. Mostly pyrometallurgical techniques are often used for the
industrial recycling of LIBs [52]. The recovery of transition metals such as Ni, Co, and
Cu is efficient, but elements like Li and Al are lost in the slag [86]. From an ecological
Batteries 2025, 11, x FOR PEER REVIEW 12 of 39
perspective, this procedure is not favorable since it requires a significant amount of energy
and specialized equipment.

Figure5.5.Pyrometallurgical
Figure Pyrometallurgicalrecycling
recyclinglayout
layouttotorecover
recoverthe
theminerals.
minerals.

One significant disadvantage of pyrolysis operations, which are carried out at

temperatures ranging from 300 °C to 900 °C in inert atmospheres, is the absence of
selective recovery. Although pyrolysis can break down organic materials, it is unable to
selectively extract high-value metals from LIBs, leaving behind a blend of low-value
elements [91]. In addition, pyrolysis is not an environmentally or economically viable
process because expensive equipment is required, processes are energy-intensive, and
Batteries 2025, 11, 51 12 of 36

Hydrometallurgical procedures such as leaching, solvent extraction, and precipitation

are used for metal extraction [87]. Pyrometallurgical methods have limited flexibility since
they demand significant economic expenditures and include complicated procedures for
extracting metals [88]. Additional drawbacks of these methods include restricted storage
capabilities, massive energy consumption, and suboptimal recycling efficiency [89]. One
benefit of these methods is their resilience, as they need very little preprocessing and
conditioning of the input material, while avoiding several possible issues such as gas
emission and loss of minerals in slag formation, etc. [89,90].
One significant disadvantage of pyrolysis operations, which are carried out at tem-
peratures ranging from 300 ◦ C to 900 ◦ C in inert atmospheres, is the absence of selective
recovery. Although pyrolysis can break down organic materials, it is unable to selectively
extract high-value metals from LIBs, leaving behind a blend of low-value elements [91].
In addition, pyrolysis is not an environmentally or economically viable process because
expensive equipment is required, processes are energy-intensive, and dangerous gases
are produced.
Pyrolysis is ineffective in the initial stages and raises operating costs as treatment
times are extended. Li recovery presents similar difficulties during smelting, which takes
place in air atmospheres at temperatures ranging from 1400 ◦ C to 1700 ◦ C. Even though Li
can reach high temperatures that are favorable for metal extraction, smelting procedures
frequently result in low Li recovery rates, requiring the inclusion of metal alloys to speed
up the recovery process [91]. The smelting and roasting process is made more difficult and
expensive by this additional step, which reduces its overall viability for large-scale metal
recovery from LIBs and Li2 CO3 as a common compound. The advancement of the effective
and sustainable recycling of valuable metals from electronic waste streams, such as wasted
LIBs, depends on pyrometallurgical processes overcoming these limitations [92].

3.1.3. Bio-Metallurgy
Electrode materials may be bio-metallurgically extracted by utilizing the oxidative
and reductive capabilities of microbes [85]. In the past decades, microbial leaching as a
method for removing metal-rich sulfides or low-grade ores has gained a lot of traction [93].
Bioleaching is an innovative technique used to extract metals from various solid materi-
als. The capacity of certain microbes to transform solid elements into metals that can be
extracted is a determining factor in this process [94]. The most common types of microbes
that may dissolve metals include fungi, as well as bacteria like Aspergillus, Thiobacillus
ferrooxidans, and T. thiooxidans, and yeasts like Penicillium and Thiobacillus [85]. In contrast
to bacterial leaching, fungal leaching is more resistant to potentially dangerous chemicals.
Recently, research was conducted into the bioleaching of Aspergillus niger from spent LIBs
in a variety of settings. The aim was to recycle metals, and the findings demonstrated
that Ni (38%), Co (45%), Al (65%), Mn (70%), Li (95%), and Cu (100%) were successfully
retrieved [95,96]. Bioleaching techniques that use microorganisms as leaching agents have
several benefits. For example, bioleaching demonstrates high extraction efficiency and low
operating expenses, and it is particularly successful in extracting low amounts of Li from
used batteries [97].
The management of environmental risks and regulatory compliance are two major
obstacles that bio-metallurgy faces, despite its potential benefits. Concerns over the release
of genetically modified organisms (GMOs) into the environment and the possible ecological
effects of introducing non-native microbial species into natural ecosystems are raised on
the topic of using microorganisms in bioleaching procedures. If waste and byproducts from
bioleaching processes are not adequately managed, they may spread infections or harmful
compounds that endanger human health and the environment [98]. Bio-metallurgical
Batteries 2025, 11, 51 13 of 36

processes are also difficult to adopt commercially because different regions have different
regulatory frameworks for the use of GMOs and the disposal of bioleaching waste. To
guarantee the sustainable and ethical application of bioleaching technology, it is imperative
to tackle these environmental and regulatory obstacles.

4. Green Organic Solvents: A Paradigm Shift in Mineral Extraction

Environmentally friendly solvents are sometimes referred to as “green organic sol-
vents” due to their exceptional biodegradability, renewability, and recyclability [13]. Ac-
cording to several studies, these solvents are very stable, easily soluble, non-flammable, and
non-toxic [99]. Green organic sorbents often originate from renewable sources like biomass,
bio-based feedstock, or agricultural waste. As a result, we rely less on fossil fuels and may
utilize solvents in a more environmentally friendly way [100]. Furthermore, green solvents
have lower vapor pressures and cause fewer air pollutants, which lower ground-level air
pollution and ozone depletion [101]. Table 2 provides the physiochemical characteristics of
certain green organic solvents.

Table 2. Properties of green organic solvents including chemical formulas, molecular weights,
densities, melting points, and levels of solubility in water.

Properties of Some Green Organic Solvents

Chemical Molecular Density at 20 ◦ C Melting Point Solubility in
Green Organic Solvent
Formula Weight (g/mol) (g/cm3 ) at 1 atm (◦ C) Water (g/L)
Palm Oil C16 H32 O2 846.1 0.892 (50 ◦ C) 35 0.23
PFAD C12 H24 O2 265.5 0.861 (60 ◦ C) 43 0.104
1-Octanol C8 H18 O 130.23 0.827 −15 0.096
Span 80 C24 H44 O6 428.61 1.068 11 Insoluble
1:10
Ethyl Acetate C4 H8 O2 88.10 0.902 −83
Less soluble
d-Limonene C10 H16 136.24 0.856 −74 Insoluble
Methyl Oleate C19 H36 O2 296.49 0.880 −3 0.01
Ethylene Glycol C2 H6 O2 62.07 1.113 −13 Miscible
N-Methyl-2-Pyrrolidone C5 H9 NO 99.1 1.02 −2 Miscible
Source: [99,102,103].

Green solvents are highly valued for their environmental friendliness and sustain-
ability, encompassing a range of materials, such as water, bio-based solvents, DESs, and
supercritical fluids, and their combinations [99]. DESs have emerged as promising al-
ternatives to conventional solvents due to their low vapor pressure, non-flammability,
superior chemical and thermal stability, tunability, ease of preparation, cost-effectiveness,
and potential for applications like metal recovery [102].
However, some DES formulations have raised concerns regarding poor biodegrad-
ability and potential toxicity, attributed to specific cationic groups, side-chain lengths, and
anions [100,101]. To overcome these limitations, ongoing research is focused on developing
new DES formulations that enhance biodegradability and minimize toxicity while retaining
their beneficial properties. These advancements aim to improve DES safety and sustainabil-
ity, particularly for applications in metal recovery, supporting green chemistry and circular
economy initiatives.
Incorporating environmentally acceptable solvents in mineral extraction provides a
sustainable and eco-friendly approach to obtaining critical minerals from natural sources.
Green solvents can enhance the efficiency of critical mineral recovery while reducing
Batteries 2025, 11, 51 14 of 36

reliance on hazardous chemicals, fostering a circular economy for these essential re-
sources [103]. For example, DESs containing iodine have proven effective for dissolving
sulfide minerals [104]. Ethylene glycol (EG) is considered a preferred environmentally
friendly solvent, as noted in the CHEM21 selection guide and the Global Harmonized Sys-
tem (GHS) [105]. Additionally, in a green solvometallurgical process for extracting copper
from sulfidic ores, FeCl3 combined with ethyl glycerol has been identified as an effective
oxidizing agent [106]. DESs have also demonstrated significant potential in recycling LIBs,
offering a more environmentally friendly alternative to traditional mineral acids [107,108].
Although there are different types of green solvents, here, we focus on acids, functional
ionic solvents, and DESs for mineral extraction. Table 3 demonstrates different types of
green solvents and their properties and applications.

Table 3. Classification of green solvents based on their properties, applications, and roles in min-
eral extraction.

Role in Mineral
Green Solvents Description Properties Other Applications References
Extraction
Non-toxic, biodegradable,
Applications in various
Derived from and with a low VOC
Extraction of critical industries, including
renewable biomass content. They offer
minerals from spent extraction processes,
Bio-based Solvents sources, such as plants, favorable health and [104]
batteries through cleaning agents, coatings,
algae, or environmental profiles
bioleaching and personal care
microorganisms compared to
products
petroleum-based solvents
Non-toxic,
Water as the primary Extensively used in
non-flammable, and have
component, often Extraction of mineral industries such as paints,
low VOC emissions. They
Water-based Solvents supplemented with matter from organic coatings, adhesives, [105,106]
are readily available,
other solvents or compounds cleaning products, and
inexpensive, and have
additives textile manufacturing
high heat capacity
Direct extraction of
Combination of copper from copper
Applications across
hydrogen bond donor Low toxicity, low sulfide minerals,
various industries and
(HBD) and a hydrogen volatility, and high recovery of mineral
processes such as
Deep Eutectic bond acceptor (HBA); thermal stability. Specific from spent batteries
catalysis and [107,108]
Solvents these can be either characteristics (tunable and e-waste, and
electrochemistry, and as
bio-based or polarity, viscosity, and green leaching of
reaction media for
non-bio-based solubility) chalcopyrite, sulfide
organic synthesis
compounds ore, gold, and
silver ore
Typical thermophysical
properties of SCFs are
low viscosity, high Many applications in
Pressure and Mineral recovery
diffusivity, and density various fields, including
temperature are above from spirulina
Supercritical Fluids and a dielectric constant pharmaceuticals, food [109,110]
their respective microalgae and rare
that can easily be processing, and
critical values earth elements
changed by varying the materials science
operating pressure
and/or temperature
Green leaching of
Organic or inorganic
chalcopyrite, sulfide
cations (like ILs can be used in various
ore, gold, and silver
imidazolium or Low vapor pressure, high areas from chemistry to
ore. Extractions of
Ionic Liquids pyridinium) and anions thermal stability, and engineering through the [111,112]
gold (Au (III)), silver
(e.g., nitrate, acetate) tunable polarity medical and the
(Ag (I)), palladium
that are liquid at or pharmaceutical fields
(Pd (II)), and
below 100 ◦ C
platinum (Pt (IV))

4.1. Harnessing Organic Acids for Sustainable Extraction Practices

Acids play a crucial role in extracting minerals from different substances, and most
of the environmentally conscious research on sustainable mineral recovery methods cen-
ters around leaching agents. The acid utilized for leaching can consist of either organic
Batteries 2025, 11, 51 15 of 36

acid (such as citric acid or succinic acid) or inorganic acid (such as sulfuric acid or nitric
acid) [113]. Inorganic sulfuric acid is a commonly used chemical reagent for leaching
different minerals, including non-ferrous metals from polymetallic tailings [114].
Organic acids, such as oxalic acid, combined with sulfuric acid solutions have been
used to extract manganese from low-grade ores. These organic acids have shown ef-
fectiveness in selectively extracting calcareous elements from low-grade phosphate ores,
suggesting potential for increasing ore value [115]. The choice of acid significantly impacts
the leaching process. For example, the dissolution kinetics of smithsonite were examined in
sulfamic acid solution, highlighting the importance of the specific acid used in the leaching
process. Different acids, including sulfuric, acetic, and oxalic acids, have varying effects on
iron mobilization from dust source materials, emphasizing the importance of acid selection
in mineral extraction processes [116].
While inorganic acids are effective in facilitating metal recovery, their usage has signifi-
cant environmental consequences. This is mostly due to the substantial water consumption,
emission of gases such as Cl2 , SO3 , and NOx, and generation of secondary pollutants during
the treatment process. Their utilization further involves corrosion-resistant equipment, as
well as expenditure of financial resources and energy [117]. On the other hand, microorgan-
isms synthesize organic acids, which pose a lower risk to operators and equipment. These
acids also enable the targeted extraction of metals. Additionally, they are easily broken
down in both aerobic and anaerobic conditions and do not produce gases, making their use
in leaching processes environmentally sustainable. Although their use is more expensive, it
is cost-effective since it circumvents the issues and constraints associated with inorganic
acids [118]. In this review, our emphasis lies solely on organic acids for mineral extraction
due to their superior eco-friendliness compared to inorganic acids.

4.1.1. Organic Acids and Mineral Extraction

Organic acid is an organic compound exhibiting an acidic pH due to the presence of
functional groups, including carboxyl (-COOH) and hydroxyl (-OH), which determines
the strength of its effects. The four main features that categorize organic acids are their
carbon chain type (aromatic, aliphatic, alicyclic, or heterocyclic), saturation level (high,
low, or unsaturated), substitution status, and number of functional groups (mono-, di-, or
tri-carboxylic) [119]. One advantage of organic acids is that they break down naturally,
leading to less run-off in the environment. In addition, they are recyclable and show
excellent metal selectivity [120]. In contrast, organic molecules have shown remarkable
reductive capabilities, especially in the processing of ores, and they are renewable, cheap,
and ecologically benign [121].
Leaching, chelating, and precipitation are all roles they may play due to their capacity
to contribute hydrogen ions and form metal complexes. When it comes to binding lan-
thanides from different sources including coal ash, neodymium magnets, and red mud,
citric acid has been shown to be the most successful of the known acids. This is because
its structure has three carboxylic acid groups and one hydroxyl group [122]. The use of
organic acids, such as leachates, in mineral and metal recovery is on the rise. These acids
include citric, tartaric, succinic, and malic acids [123,124]. Some examples of waste products
that may be used to recover valuable minerals include used catalysts, old batteries, and
low-grade mineral ores. Oxalic acid has been shown to be effective in this regard [125].
Using a solution containing 30 g/L of oxalic acid in a 0.75 molar (M) sulfuric acid (H2 SO4 )
medium has been shown to achieve a leaching efficiency of around 90.49% for Mn and
6.78% for iron (Fe) when leaching manganic-ferrous ore [126].
Similarly, a study indicated that 65% of light rare earth elements (LREEs) and 19% of
heavy rare earth elements (HREEs) could be extracted in a single stage using a 5% tartaric
Batteries 2025, 11, 51 16 of 36

acid concentration, all without the use of mineral acids. The most effective method for
extracting rare earth element (REE) minerals from phosphor-gypsum is to use organic acids
generated from A. niger [127]. These acids include citric acid, gluconic acid, and oxalic
acid. Under perfect leaching circumstances, they may attain a maximum leaching rate of
74% [128]. One typical chemical leaching method is the extraction of low-grade rare earth
minerals via the use of inorganic acids such as sulfuric acid. However, an environmentally
friendly alternative to this method is available, which involves little investment and low
energy usage [129]. Table 4 shows the different organic acids and their efficiency in the
leaching process.

Table 4. Organic acids and their efficiency in leaching mineral resources.

Material Inorganic Acids Side Effects of Inorganic Acids Alternative Organic Acid Leaching Efficiency References

- Residues in the soil of mining areas

(ranging from 200 to 1000 mg/L).
Ion-adsorption-type - Groundwater contamination.
((NH4 )2 SO4 ),
Rare Earth Ores - Soil acidification. Citric acid 96% [27,130]
(MgSO4 )
(IAREOs) - MgSO4 lead to soil salinization,
compaction, and Mg2+
accumulation.

- High acid consumption.

Saprolitic Ores H2 SO4 , HNO3 , HCl Citric acid 72% [131]
- Leaching toxicity.

- Release toxic gases (Cl2 , SO3 , Ni (89.63%),

Lateritic Nickel Ore H3 PO4 and NOx). Oxalic acid Co (82.89%), [132]
- Waste acid solution. Fe (69.63%)

- Release toxic gases like Cl2 , SO3 ,

Spent Lithium-Ion and NOx. Malic acid, citric acid,
H2 SO4 , HCl, HNO3 Co and Li (99%) [133]
Batteries - Waste acid solutions are harmful to tartaric acid, succinic acid
the environment.

4.1.2. Organic Acid Leaching Mechanisms

Organic acid–mineral resource interactions may be understood via acid hydrolysis,
organic acid chelation, and the participation of other organic ligands [134]. Various pro-
cesses may lead to the dissolution of mineral resources, including complex-lysis, acidolysis,
and redox reactions, among others [135]. The protonation of organic acid oxygen atoms is
the primary mechanism by which acids undergo acidolysis. When the acid dissociates, the
oxygen in the metal complex may be protonated with relative ease. Extraction of metal ions
from metal ore surfaces is made possible when protons connect to and react with the ore’s
surface, weakening the bonds and demonstrating this phenomenon. The trace mineral
separates from the solid’s surface as a result of the reaction between water and the protons
and oxygen [136].
In organic acid chelation, elements that have been leached in the past are complexed
with organic acids to produce soluble metal complexes [137]. Instead of metal chelates,
organic acids may dissolve the bond between surface metals and the leached material [138].
Furthermore, organic acids can supply protons during the process of leaching and decrease
the concentration of ore in a solution by engaging in ligand reactions. Over time, additional
minerals are discharged into the solution and then retrieved by diverse techniques [139].

4.2. Advancements in Functional Ionic Solvents for Eco-Friendly Extraction

The use of ILs as diluents and/or extractants instead of volatile organic compounds is
a new and fast-growing technique for separation [69]. A class of organic salts known as
ILs contain both inorganic and organic anions, as well as organic cations like tetraalkylam-
monium and tetra-alkyl-phosphonium, along with inorganic or organic tetrafluoroborate,
trifluoromethyl sulphonate, acetate, nitrate, and halide. The melting points of these com-
pounds are lower than 100 ◦ C [140]. Since ILs do not release acid, traditional extractants
would have to be neutralized afterward since the raffinate would include hydrogen ions
Batteries 2025, 11, 51 17 of 36

(H+). This is why ILs are better [141]. As a result of their low vapor pressure, wide range
of operating temperatures in the liquid state, high solubility of both inorganic and organic
substances, and high chemical, thermal, and electrochemical stability, which reduces po-
tential health risks, ILs have long been categorized as environmentally friendly solvents.
They can also be mixed with water to the desired levels [142]. Recent studies have clearly
reported that certain ILs have significant harmful effects on various organisms and stages
of the food chain [143].

Extraction of Minerals with Ionic Liquids

Several operations in the mineral- and metal-processing industry have been exploring
the use of ILs, including solvent extraction, froth flotation, and mineral leaching [144]. A
new approach of collecting quartz from hematite via froth flotation has been investigated;
it involves the use of ILs comprising ammonium, imidazolium, and pyridinium [145]. ILs
demonstrated a significant ability to selectively dissolve metals and metal oxides, which
can create novel possibilities for ion metallurgy and mineral processing [146]. Minerals
and metal oxides may be dissolved in ILs due to their coordinating-ion functionalities or
oxide-binding species [144]. Ore and waste mineral processing has also made use of ionic
liquids as leaching agents to extract certain metals from their native matrix [147].
It is worth mentioning that bifunctional ILs have been shown to be more effective than
conventional extractants and other ILs. This is because the extraction process employs both
cations and anions from the ILs [148].
(A) Mineral flotation with ionic liquids
Flotation of minerals is an important and extensively utilized process in the mineral-
processing industry. The advent of this technique has greatly improved mineral resource
exploitation and productivity, leading to a dramatic decrease in the minimum grade needed
for mineral resource development. As a result, the world’s economy is better able to rely
on the availability of natural resources [149]. An essential aspect of achieving successful
mineral flotation is the careful selection of highly effective and discriminating flotation
reagents [150].
Over the past few years, numerous effective flotation chemicals have been created and
advanced for various mineral-processing purposes. Activators, foaming agents, collectors,
inhibitors, dispersants, and modifiers are some of the reagents used in the process of extract-
ing valuable minerals from ores [151]. Significant progress has been made in the processing
of minerals that are difficult to float by using ILs, a class of green solvents characterized by a
variable structure, lack of flammability, low vapor pressure, and almost nonvolatile charac-
teristics [152]. One can utilize 1-butyl-3-methyl imidazolium bis (trifluoromethyl-sulfonyl)-
imide ([Bmim]Ntf2) and acidic N-dimethylacetamide bis(trifluoromethyl-sulfonyl)imide
([DMAH]Ntf2) ILs for the process of separating the most concentrated material and produc-
ing minerals similar to Bast (RECO3 F) as well as RE2 O3 and RE2 (CO3 )3 compounds [153].
In an aqueous solution, the tetrabutyl bis(2-ethylhexyl)ammonium phosphate
([N4444][DEHP]) ionic liquid was used to test the flotation behavior of model monazite
and bastnäsite minerals. The collectors used in the experiments were Aero-6493 (containing
6–10 carbon alkyl chains) and Aero-9849 (containing 10–18 carbon alkyl chains) [154]. A
combination of micro-flotation methods, zeta potential measurements, Fourier-transform
infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) was used to
analyze the flotation test findings. The micro-flotation tests on the two minerals reveal that
[N4444][DEHP] exhibits a superior ability to collect minerals compared to the typical hy-
droxamic acid collector. Similarly, 1-propyl-3-methylimidazolium bromide (propyIMIMBr)
ionic liquid shows efficiency in the recovery of barite minerals. Therefore, the propyIMIMBr
 Batteries 2025, 11, 51 18 of 36

ionic liquid can enhance the recovery of valuable materials from drilling waste and has the
1, x FOR PEER REVIEW potential for reuse in other applications [26,155]. 19 of 39
In addition to earlier research, there is an emerging polymerization trend of ionic
acid monomers, for example, imidazolium-SO3 H− heteropolyanion, poly-4-vinlpyridine,
divinylbenzene, and resorcinol formaldehyde, as given in Figure 6a. Then, Figure 6b
prepared via polymerization of a zwitterionic
presents the general monomer
synthesis method, where [156].
-SO3 H Grafting the imidazolium
functionalized heteropolyanion is
polysulfonic acid—Brönsted acidic, ionic liquids (BAILs)—on a silica top surface
prepared via polymerization of a zwitterionic monomer [156]. Grafting the imidazolium using
chlorophyll silicapolysulfonic
also makesacid—Brönsted
it easier to access the ionic
acidic, acidic function
liquids [157], as agiven
(BAILs)—on silicain two
top stepsusing
surface
in Figure 6c. In chlorophyll
the precedingsilicaresearch
also makes it easier
works, to access
the use oftheILsacidic function
in the [157],ofasvarious
flotation given in two
steps in Figure 6c. In the preceding research works, the
minerals has also been researched, and outstanding results have been achieved. use of ILs in the flotation of various
minerals has also been researched, and outstanding results have been achieved.

Figure 6. Innovations in6.ionic

Figure liquid: in(a)ionic
Innovations common
liquid: polymeric, acidic, ionic
(a) common polymeric, liquids,
acidic, (b) polymeric,
ionic liquids, (b) polymeric,
acidic, ionic liquidacidic, ionic liquid
synthesis synthesis
process [156], process
and (c)[156], and (c) sulfonic-acid-functionalized
sulfonic-acid-functionalized acidic,liquid
acidic, ionic ionic liquid
synthesis by grafting [157,158]. Reprinted with permission from reference [158]. Copyright 2016,
synthesis by grafting [157,158]. Reprinted with permission from reference [158]. Copyright 2016,
American Chemical Society.
American Chemical Society.
(B) Mineral leaching with Ionic Liquids
(B) Mineral leaching witheco-friendly
These Ionic Liquids
chemicals are being used in pretreatment and leaching, which are
the primary
These eco-friendly steps of processing
chemicals are being mineral
used inore. The significant
pretreatment andacidifying
leaching,properties
which are of some
inorganic compounds (including ILs) have prompted an investigation into leaching [159].
the primary steps of processing mineral ore. The significant acidifying properties of some
Mineral leaching has emerged as a significant technique for separating and extracting
inorganic compounds
several(including ILs) have
precious elements dueprompted
to its benefitsanof
investigation into leaching
being environmentally [159].
friendly, easy to
Mineral leaching has emerged as a significant technique for separating and extracting
perform, energy-efficient, and cost-effective [20]. The utilization of ILs in the process of
several preciousleaching
elements due
offers to its benefits
numerous benefits inofcomparison
being environmentally friendly, easyleaching
to traditional hydrometallurgical to
methods. ILs
perform, energy-efficient, andcan be used instead
cost-effective [20]. of The
mineral acids to of
utilization dissolve
ILs inmetals, offering
the process ofmore
leaching offers numerous benefits in comparison to traditional hydrometallurgical solid
selectivity for the desired metals compared to the secondary impurities present in the
materials. This typically enables a decrease in the requirements for future separation and
leaching methods. ILs can be used instead of mineral acids to dissolve metals, offering
purification processes, resulting in reduced consumption of reagents [160].
more selectivity for Chalcopyrite
the desired is metals compared to the secondary impurities present in
a prevalent kind of copper sulfide ore, known for being particularly
the solid materials. This typically
challenging enables
to extract Cu a decrease
from, details in the
are given requirements
in Table 5. The adventforoffuture
ILs offers a
separation and purification processes, resulting in reduced consumption of reagents [160].
Chalcopyrite is a prevalent kind of copper sulfide ore, known for being particularly
challenging to extract Cu from, details are given in Table 5. The advent of ILs offers a
novel potential approach to accomplish this objective [161]. Using two acidic ILs based on
Batteries 2025, 11, 51 19 of 36

novel potential approach to accomplish this objective [161]. Using two acidic ILs based
on imidazoles, namely [Bmim]HSO4 and [Hmim]HSO4 (1-hexyl-3-methyl-imidazolium
hydrogen sulphate), speeds up the leaching of chalcopyrite. After 60 ◦ C, the Cu recovery
rate may reach 70%, which is a significant improvement [142].
Similarly, industrial brass ash was leached using the ionic liquid [Bmim]HSO4 to
recover Cu and Zn. With the temperature maintained at 70 ◦ C, the Cu dissolution reached
25% and the zinc dissolution reached nearly 99% [162,163]. The synthesized imidazolyl
cyanate ionic liquids exhibited a notable capacity to dissolve gold, with [C2 MIM][OCN]
demonstrating a superior efficacy in extracting gold from mineral deposits due to its low
viscosity and minimal steric hindrance [164].

Table 5. Leaching with ILs for critical minerals.

Conditions
Material Used IL Leaching Yields (%) References
Temperature Time (h) L/S (L/kg)
[Hbet]+ [NTf2 ]− with 40–100% HREE and
Bastnasite ore 50–90 ◦ C 24 5–20 [165]
30–50 v% water 65–100% LREE
[C4 MIM]+ [HSO4 ]− with
Thiourea (as complexant,
Pyrite ore 20 g/kg ore) and ferric 25 ◦ C 48 4 85% Au and 60% Ag [166]
sulfate (as oxidant,
0.5 g/kg ore)
([HMIm]HSO4 ) with
Chalcopyrite 45 ◦ C 2 10 98.3% [167]
20% H2 O2
[C2 MIM]+ [HSO4 ]−
100% Zn
Brass waste 20–80 v% in water with 40–80 ◦ C 2 10 [168]
40–50% Cu
H2 O2 (as oxidant) 20 v%

4.3. Deep Eutectic Solvents, Kinetics, Mechanism, and Machine Learning Intrusion
A new class of eco-friendly solvents called DESs was introduced by Abbott in
2003 [169]. Along with ILs, they have remarkable attributes, such as cost-effectiveness, an
environmentally friendly nature, low volatility, biodegradability, and ease of synthesis [170].
Metal electrodeposition, metal recovery, extraction, biocatalytic activity, organic synthesis,
and related uses are among their primary applications [171]. More recently, DESs have
shown potential as replacements for inorganic and organic acids and as a leaching agent
to remove metals from old batteries. They find widespread use in metal separation and
recovery processes because of their high solubility in various metal materials [172].
Mineral recovery with DESs is driven by their capacity to improve separation and
extraction efficiency as well as environmental issues. Strong coordination with metal ions
and dissolution of metal–oxygen connections are made possible by the fact that DESs have
a separate hydrogen bond donor and acceptor. This allows for the complete dissolution of
a number of metal oxides that are poorly soluble in water. Altering the system’s acidity and
alkalinity may improve its solubility. In addition, DESs have unique reducibility, which
means that additional reducing agents are not needed during leaching. The addition of
oxidants enables the catalytic dissolution of metals in DESs. An important advantage of
utilizing DESs in this research field is avoiding the need for an additional step, such as a
lowering agent [173].

4.3.1. Types of Deep Eutectic Solvents

There are several types of DESs, such as Cat+, which may be any cation of the am-
monium, phosphonium, or sulphonium type; X, which is a Lewis base, and Y, which is
 Batteries 2025, 11, 51 20 of 36

a Lewis acid; this is the conventional way of representing the DES composition. X and Y
form a complex, with z being the number of Y molecules interacting with an anion [174]. A
wide variety of DESs based on complex chemicals have been created.
Figure 7 shows the five types separated into their component parts. Similar to compos-
ites of metal halides and imidazolium salts, Type I DESs are produced by mixing quaternary
ammonium salts with metal chlorides [175]. Metal chloride hydrates and quaternary ammo-
nium salts make up the second category of DESs. Choline chloride (ChCl) with hydrogen
Batteries 2025, 11, x FOR PEER REVIEW HBDs including alcohols, amides, polysaccharides, and others makes up Type III 21 DESs.
of 39
Because of their adaptability and capacity to dissolve transition metal species, these sol-
vents have attracted a lot of interest from researchers. Depending on the HBD used in
the combination,
HBD the physical
and metal chlorides properties
are the building of theseofDESs
blocks Typemay be altered.
IV DESs. HBD HBD and metal
and HBA, which
chlorides are the building blocks of Type IV DESs. HBD and HBA, which are non-ionic
are non-ionic molecular entities, are forming a new class of DES called Type V. This family
ofmolecular entities, are forming
DESs is characterized a new classofofhydrogen
by the abundance DES called Type[176,177].
bonds V. This family of DESs is
characterized by the abundance of hydrogen bonds [176,177].

Deepeutectic
Figure7.7.Deep
Figure eutecticsolvents
solvents with
with their
their five
five different
different types.
types.
4.3.2. Preparation of Deep Eutectic Solvents and Mechanism of Mineral Recovery
4.3.2. Preparation of Deep Eutectic Solvents and Mechanism of Mineral Recovery
In many cases, DES synthesis is straightforward, whereby HBDs and HBAs are com-
In at
bined many cases, DES
temperatures synthesis
usually betweenis straightforward,
50 and 100 ◦ C duringwhereby HBDs and
the synthesis HBAs
of these are
com-
combined
pounds. Afterat temperatures
allowing enoughusually
timebetween 50 and 100
for the hydrogen °C during
bonds the synthesis
to develop, of these
the temperature
compounds. After allowing enough time for the hydrogen bonds
is lowered. Two distinct approaches to combining the parts have been considered. To to develop, the
temperature is lowered.
melt the component with Two distinct
the lowest approaches
melting toand
point first combining
then add the parts havewith
the component been
considered. To melt the component with the lowest melting point first and
the highest melting point is one way to work it. Alternatively, the mixing and initiating then add the
component
processes ofwithtwothe highest melting
substances pointhigh
with similar is one way to
melting workoccur
points it. Alternatively,
concurrentlythe mixing
[178].
and initiating processeshasofbeen
Recently, research twoconducted
substances on with similar high
the mechanics melting
involved in thepoints occur
separation
concurrently [178].
of minerals using DESs. DESs interact with the mineral surface through a combination of
Recently,
physical research processes
and chemical has been conducted
via hydrogen onbonding
the mechanics involved
[179]. When DESsininteract
the separation
with a
ofmineral
mineralssurface, the process of dissolving the metal oxide of the minerals can be consideredof
using DESs. DESs interact with the mineral surface through a combination
physical and [180].
as two steps chemical processes
First, via hydrogen
the carboxyl and hydroxyl bonding
groups[179]. Whenacids
of organic DESs interact
and with
alcohols, as a
well as the protons from HBDs, react with the active OH sites on the
mineral surface, the process of dissolving the metal oxide of the minerals can be hydrated metal oxide.
considered as two steps [180]. First, the carboxyl and hydroxyl groups of organic acids
and alcohols, as well as the protons from HBDs, react with the active OH sites on the
hydrated metal oxide. Protonated oxide-containing intermediate species are formed
because of this reaction. The following chemical equations (Equations (1) and (2)) describe
Batteries 2025, 11, 51 21 of 36

Protonated oxide-containing intermediate species are formed because of this reaction. The
following chemical equations (Equations (1) and (2)) describe this procedure:

Bulk ≡ Me − OH + HX ↔ bulk ≡ Me − OH2 + · · · Xn− (1)

where “Bulk ≡ Me − OH” stands for the hydrated metal oxide with active OH sites, and
HX stands for the HBDs of DESs.
In the second step, protons will break the bonds between the metal and oxide if the
complexes with ligands are more stable than the ones with OH. The OH active sites will be
replaced by the deprotonated HBD ligand via metal–ligand complexation. After that, in
the bulk DESs, the ligand will be swapped out for an anion, such as chloride, Cl− :

Bulk ≡ Me − OH2 + · · ·Xn− ↔ Me − X(DES)n− + · · · H2 O (2)

4.3.3. Mineral Extraction with Deep-Eutectic-Solvent-Based Leaching

In leaching, a powdered material is subjected to acid or basic solutions in order to dis-
solve the metals, while some impurities remain insoluble. Two new subfields of hydromet-
allurgy, solvo-metallurgy and iono-metallurgy, have emerged due to DESs. Non-aqueous
solutions combining Lewis and Bronsted acids and bases are used in solvo-metallurgy,
which is different from hydrometallurgy. These mixtures are ideal for processing ores of
lower grades and provide novel opportunities for natural resource extraction. Processing
lower-quality ores is very necessary due to the depletion of high-quality raw materials
that contain greater quantities of minerals [141]. DES-based leaching has eco-friendly fea-
tures that make it safer for the environment and ensure that natural resources are handled
responsibly [181].
The mining ores are put through DES leaching to recover minerals. The solvent is
usually a mixture of an HBD and a hydrogen bond acceptor (HBA) [173]. The raw material
is crushed and ground into mineral grains to a precise size appropriate for leaching, a
process known as comminution. The leaching procedure may not have extracted enough
of the critical mineral (antimony) from the source material if the grains were too big. It was
also undesirable for the grains to be too small since this would have increased viscosity.
Therefore, the ideal grain size was very important during leaching [83]. The crushed ores
are then mixed with the DES solution, allowing the solvent to penetrate the mineral matrix
and initiate the solvation process.
During the reaction of a DES, the HBD component solvates metal ions from the
mineral surface, forming metal complexes, while the HBA component may also participate
in complexation through coordination with the metal ions. This contact facilitates the
release of metal ions from the mineral surface into the DES phase [182]. DES’s special
qualities, namely, its low volatility and high viscosity, help with mass transfer processes.
The sample was filtered after the leaching procedures and then rinsed with distilled water
at a particular ratio to the liquid eutectic mixture, as given in Figure 8 [183].

4.3.4. Machine Learning and Intrusion with Kinetics of Deep Eutectic Solvents
DESs have been used to extract a variety of minerals, such as bastnasite, lead, Cu, zinc
sulfide, telluride, iron sulfide, and arsenide [184,185]. Recent studies explored the different
types of DESs fabricated with ChCl, urea, EG, and a combination of those to recover Li, Ni,
Mn, and Co at different temperatures. Li was efficiently recovered at 100 ◦ C with ChCl and
urea. The kinetics of chemical reactions are regulated by a thin ash/product layer when
ChCl:EG and ChCl:urea are present. Conversely, kinetics highlight the leaching efficiency
increase as temperature rises. Thus, the ChCl:EG DES reaction is under the influence of
a mixed control effect. Additionally, NiO production on the surface is likely indicated by
 participate in complexation through coordination with the metal ions. This con
facilitates the release of metal ions from the mineral surface into the DES phase [1
Batteries 2025, 11, 51 DES’s special qualities, namely, its low volatility and high viscosity, help 22 of 36
with m
transfer processes. The sample was filtered after the leaching procedures and then rin
with distilled water at a particular ratio to the liquid eutectic mixture, as given in Fig
8Ni peaks in the EDS analysis, as in Figure 9. The particle surface is coated by NiO, which
[183].
stops reagent diffusion across the surface.

Figure 8. Mineral extraction with DES-based leaching, initiating with choline chloride as the hydrogen
bond acceptor and urea as the hydrogen bond donor.

In addition, DESs were applied for metal recovery and reclamation from various
sources [172]. For example, using saprolite ore as an example, the direct mineral refining
method first used a hydrophobic DES. By lowering the leaching of Mn, the DES proved to
be more efficient than traditional sulfuric acid leaching in recovering Mn, Ni, and Co [186].
DESs were utilized for the extraction of gold-bearing ores and other minerals. By applying
electrolysis to the DES, scientists have shown that selective dissolving is possible. The
achieved dissolution rates met expectations, and the method was much less harmful to the
environment than the cyanidation methods previously used [83].
In recent studies, it was reported that quantum and machine learning techniques
were employed to estimate the phase diagrams of deep eutectic solvents (DESs) across
an extensive chemical space. By pinpointing the eutectic point coordinates, one study
highlighted the impact of melting properties and mole fractions on eutectic temperature
(ET) [187]. Furthermore, molecular dynamics simulations at the eutectic points emphasized
the role of hydrogen bonding in elucidating the contributions of individual components
within the mixture. The findings underscore that computer-aided estimation of eutectic
diagrams for novel extraction systems deserves special attention, offering a promising
pathway for designing efficient and sustainable solvent systems [187].
In addition, three distinct DES types were tested using a sample taken from extraction
waste produced during antimonite ore flotation. The leaching process was optimized
by changing the quantities of the solid and liquid components and increased oxidized
efficiency [63].
Temperature is crucial element that can influence the leaching percentage concentra-
tion of metals. In a recent study, different types of DESs with a combination of ChCl were
used. The results revealed that, in most cases, a maximum concentration was observed
at 100 ◦ C and that ChCl with a combination of urea and EG was best for Li, Ni, and Mn
concentration, as given in Figure 10.
Batteries 2025, 11, x FOR PEER REVIEW 24 of 39
Batteries 2025, 11, 51 23 of 36

Figure
Figure 9. EDS
9. EDS analysis
analysis andand SEMimages
SEM imagesfrom
from before
before (A)
(A)and
andafter
after(B–D) thethe
(B–D) leaching process:
leaching process: (A
ChCl(A)+ ChCl
urea,+ (B)
urea, (B) ChCl + EG, (C) ChCl + urea + EG, (D) DES: (ChCl:urea 1:2, ChCl:EG 1:2, and
ChCl + EG, ◦
(C) ChCl + urea + EG, (D) DES: (ChCl:urea 1:2, ChCl:EG 1:2, and
ChCl:urea:EG 1:2:1 at 100 C) [188]. Reprinted with permission from reference [188], Copyright
ChCl:urea:EG 1:2:1 at 100 °C) [188]. Reprinted with permission from reference [188], Copyright 2022
2022, Elsevier.
Elsevier.
The graphs in Figure 11 show the actual concentration data for different metals at
various temperatures,
In addition, three which wereDES
distinct extracted
types from previous
were studies
tested using [92,189], along with
a sample taken from
predictions from linear and quadratic regression models. Each subplot represents a different
extraction waste produced during antimonite ore flotation. The leaching process was
metal (Li, Co, Ni, Mn), and within each subplot, the actual data points and the predictions
optimized by changing the quantities of the solid and liquid components and increased
from both regression models are plotted.
oxidizedToefficiency [63].
enhance the credibility of the extracted data, a machine learning model was em-
ployed. The coefficientcrucial
Temperature is element(R2that
of determination can squared
) and mean influenceerrorthe
wereleaching
determinedpercentage
by
concentration
the followingofequation:
metals. In a recent study, different types of DESs with a combination of
n
ChCl were used. The results revealed MSE =that,
1/n ∑ in Ymost
i − Ŷi

cases,
2 a maximum concentration (3) was
observed at 100 °C and that ChCl with a combination
i =1 of urea and EG was best for Li, Ni
and Mn concentration, as given in Figure 10.
Batteries 2025, 11, 51 24 of 36

where n is the number of data points, Yi is the observed value, and Y is the predicted value.
According to the data, most of the DESs have an R2 near 1, which highlights the accuracy
of data, and similarly, the MSE, which is the average square difference between calculated
and estimated values, elucidates the variability in different leaching extraction efficiencies.
After predictions are made from the linear, quadratic model, the quantifying measures
Batteries 2025, 11, x FOR PEER REVIEW 25 ofare
39
calculated, i.e., MSE and R2 . This assesses the performance of the model for each respective
metal, as given in Table 6.

Figure 10. Effect of leaching temperature on mineral efficiency of three different types of DESs—ChCl,
Figure 10. Effect of leaching temperature on mineral efficiency of three different types of DESs—
urea, and EG—and combination of urea and EG. (A) Percentage Li recovery, (B) percentage Co
ChCl, urea, and EG—and combination of urea and EG. (A) Percentage Li recovery, (B) percentage
recovery, (C) percentage Ni recovery, and (D) percentage manganese recovery. Source: [99,102,103].
Co recovery, (C) percentage Ni recovery, and (D) percentage manganese recovery. Source:
[99,102,103].
Table 6. Coefficients of determination and mean squared errors of DESs with their respective metals.

DESThe graphs in Figure 11 show

Metal MSE
the actual concentration R2
data for different metals at
various
ChCl + temperatures,
Urea + EG which wereLi extracted from previous
2.00 studies [92,189],
0.99 along with
predictions from
ChCl + Urea + EG linear and quadratic
Mn regression models.
4.5 Each subplot
0.955 represents a
different metal (Li, Co, Ni, Mn), and
ChCl + Urea Li within each subplot,
8.00 the actual data
0.95points and the
predictions from both regression models are plotted.
ChCl + Urea Co 3.566 0.923
ChCl + Urea Ni 0.22 0.99
ChCl + Urea Mn 0.88 0.96
ChCl + EG Li 3.55 0.98
ChCl + EG Co 2.00 0.97
ChCl + EG Ni 0.22 0.99
ChCl + EG Mn 5.55 0.88
ChCl + PSTA Li 4.50 0.97
ChCl + PSTA Co 5.55 0.97
ChCl + Mal Li 14.22 0.95
ChCl + Mal Co 16.05 0.94
Batteries 2025, 11, x FOR PEER REVIEW 26 of 39
Batteries 2025, 11, 51 25 of 36

Percentage concentrations
Figure 11. Percentage concentrations of
of respective
respective metal
metal combinations
combinations of DESs with fluctuating
temperature (50, ◦ C), where black, blue, and red represent actual, linear fit, and quadratic
temperature (50, 75,
75, and 100 °C),
and 100 where black, blue, and red represent actual, linear fit, and quadratic
fit values,
fit values, respectively.
respectively.

5. Innovations and Future Directions in Sustainable Mineral Extraction

To enhance the credibility of the extracted data, a machine learning model was
5.1. Sustainable
employed. The Development
coefficient ofin Mineral Extraction
determination (R2) and mean squared error were determined
by theThe contemporary
following world cannot function without sustainable development, which
equation:
takes a comprehensive view of the interconnected problems of social, economic, and envi-
ronmental welfare [190]. As a major 𝑀𝑆𝐸 = 1/n
factor impacting 𝑌 −development,
𝑌 the mineral extraction
(3)
industry is vital in the fight for sustainable development goals [191]. Given the mineral
extraction
where n isindustry’s
the number interconnectedness
of data points, Yi with
is theglobal supply
observed networks
value, and Y and resource
is the ex-
predicted
ploitation, its practices
value. According to the greatly impact
data, most environmental
of the DESs have an preservation, socialhighlights
R2 near 1, which welfare, and
the
economic progress.
accuracy of data, and similarly, the MSE, which is the average square difference between
Sustainable
calculated mineral values,
and estimated extraction refers to
elucidates thethe implementation
variability of practices
in different leaching during ex-
extraction
cavation operations that lead to positive environmental and social outcomes
efficiencies. After predictions are made from the linear, quadratic model, the quantifying compared
to conventional
measures resourcei.e.,
are calculated, development
MSE and R2methods. It also
. This assesses theprioritizes
performancethe of
well-being
the modelandfor
safety of workers, as well as the concerns
each respective metal, as given in Table 6. of stakeholders and affected communities [192].
Environmental education has a significant role in promoting broad change in the quest
for sustainability. By integrating ecological education into curricula across all levels of
Batteries 2025, 11, 51 26 of 36

education, ranging from elementary to higher education, society may cultivate a cohort
of ecologically aware individuals who possess the requisite knowledge and abilities to
address complex issues [193].

5.2. Technological Innovations in Extraction Efficiency

Currently, research is responsible for promoting the creative growth of the mineral
extraction industry in nations that possess abundant natural resources [194]. Technology
enables the use of Geographic Information System (GIS) operations to provide guidance
to miners during exploratory activities and to assist in the assessment of the value of a
specific ore. Moreover, the use of automated procedures, such as the utilization of trucks,
ventilation systems, and site monitoring, has resulted in enhanced efficiency within the
enterprise [195].
The mineral extraction sector has historically used technology to tackle challenges
related to workplace efficiency and environmental difficulties [196]. The implementation
and use of innovative extraction technologies have significantly augmented productivity,
leading to an overall improvement in working conditions within the extraction and recy-
cling sector. Technological advancements play a crucial role in driving the expansion of the
recycling sector [197].

5.3. Advancements in Battery Recycling with Artificial Intelligence

The field of AI offers remarkable methods for accomplishing intelligent assembly to
disassembly. AI is reviving and growing quickly with recent advancements in computer
technology and algorithms, especially in machine learning (ML) tools [198,199]. Numerous
intelligence techniques inspired by nature, including evolutionary computation and neural
networks, endow machines with improved learning capabilities to handle complicated
and nonlinear situations. AI is starting to show promise as a sustainability booster for
two reasons.
The mineral extraction and battery industry has greatly benefited from artificial in-
telligence. To enable a sustainable closed-loop supply chain, recovery operations can be
optimized with the use of intelligent robotics tools and equipment, networking, cloud
services, and learning-based decision support systems [200,201].
In recent work, researchers computed a dataset of 1510 groups that can elicit symbolic
visual and functional expressions using the genetic programming model (GPM). The find-
ings showed that, because of various initial applied stresses, the GPM can be associated with
better fitting (accuracy) for capacity prediction as a function of real-time stress. As a result,
this GPM can be used to classify battery waste according to its residual energy [202,203].
To determine the solubility of Co ions, fourteen parameters and properties were analyzed,
including viscosity, water content, molecular weight, and the hydrogen bond acceptor
to hydrogen bond donor (HBA:HBD) ratio. The dissolution of the positive electrode can
be facilitated and coordinated with an organic acid ion and Cl− . In addition, the acidity
of the solution, reducibility, and strength of coordination are directly correlated with the
reaction potential and solubility of Co. Therefore, the predictive performance with Shapley
additive explanation (SHAP) of different models is represented as R2 XGBoost > R2 others,
and MSEXGBoost < MSEothers, revealing the effectiveness of XGBOOST [204].
Battery technology and mineral extraction are parallel processes. Recently, the Pa-
cific Northwest National Laboratory (PNNL) and Microsoft Azure Quantum Elements
developed a methodology and system where 32.6 million electrolytes are used in battery
processing into eighteen usable electrolytes in just nine months. This paradigm shift con-
verts 20 years of work into a short period [205,206]. Similarly, AI facilitates the process
of material design; sixteen solid-state electrolytes with ionic conductivity greater than
Batteries 2025, 11, 51 27 of 36

10−4 S cm−1 were identified by ML training from 3000 compounds [207]. The study further
used an artificial neural network model to estimate and predict the dielectric constant
of complex and complicated electrolytes and concluded that there is a specific volcano
pattern with an increasing Li ion content. These findings attest to the remarkable innova-
tion in electrochemical and battery technology [208]. AI not only assists in the recovery
of minerals from waste batteries but also aids in exploring and identifying new mineral
resources. Based on its integration and AI projections, KoBold Metals has found and
claimed 800 km of metal reserves in North Quebec, Canada, including Ni and Co [204].
Increased equipment utilization via continuous operation; automation, prediction, and
precision; and exploration of new resources are positive aspects for the mineral extraction
industry [209]. In addition, deep generative models can be developed on large, verifiable
datasets to incorporate physics-driven restrictions in materials structures at both the atomic
and continuum capacities by analyzing the underlying probability distributions in the
input space [210]. Then, novel and creative yet still feasible designs can be created by
employing trained models as potential battery materials [211].

6. Concluding Remarks
To summarize, this research emphasizes the need to switch from conventional to
synergistic methods for mineral extraction, as well as the noteworthy developments and
new trends in the creation of green organic solvents. Effective resource management and
environmental problems can only be addressed by incorporating sustainable approaches
into mineral extraction and battery recycling. Critical minerals like Ni, Cu, and Co play
crucial roles in battery technology, and their extraction and recycling provide inherent
obstacles that are highlighted in this manuscript. Global demand for cobalt is anticipated to
reach 176,000 metric tons by 2030; in comparison, it is only anticipated that cobalt demand
for non-battery uses will reach 65,000 metric tons worldwide by that year. Meanwhile, it is
projected that LIB battery production will reach slightly less than 447,000 metric tons in
2021 and then quadruple by 2030. In a recent projection of 2050, the positive electrode, Co,
and Ni are forecast to reach 22 MMT, 2.7 MMT, and 6.5 MMT, respectively, with an 80%
recovery efficiency.
Conventional techniques, such as hydrometallurgy, pyrometallurgy, and bio-metallurgy
cause substantial environmental hazards and have technological constraints despite their
relative effectiveness. For example, hydrometallurgy typically involves a physical disas-
sembly and separation approach that often results in black mass cross-contamination with
organics such as the fluorine-containing PVDF binder and impure metals such as Al, Cu,
and Ti. Meanwhile, in pyrometallurgy, Li has the capacity to achieve high temperatures
that are advantageous for the extraction of metals; however, smelting processes usually
lead to low rates of Li recovery, necessitating the addition of metal alloys to accelerate the
recovery process. This extra stage increases the complexity and cost of the smelting process,
decreasing its overall feasibility for large-scale metal recovery from LIBs.
The use of green solvents, like DESs and ionic liquids (ILs), is changing the paradigm
and offering viable environmentally acceptable substitutes. Emerging organic solvents
include palm oil, PFAD, 1-Octanol, and Span 80 due to their low solubility and temperature
flexibility. The combination of different solvents such as 30 g/L of oxalic acid in 0.75 molar
(M) sulfuric acid (H2 SO4 ) can achieve the maximum leaching efficiency (approx. 91% for
Mn). Organic acid obtained from A. niger can be used to extract rare earth minerals from
phosphorus–gypsum ores. Recent studies confirm that reaction kinetics can influence the
extraction and leaching process, e.g., four hours of leaching at 100 ◦ C can achieve almost
100% iodine removal or uptake, which cannot be achieved with a low temperature and
less time. Thus, the entry of machine learning into the mining industry may revolutionize
Batteries 2025, 11, 51 28 of 36

mineral recovery, as demonstrated by data extracted from previous studies and computed
values, which have coherence and significant R2 and MSE results.
Sustainable extraction methods can benefit from these solvents’ low toxicity, biodegrad-
ability, and minimal environmental impact. Essentially, the use of green organic solvents
in mineral extraction not only helps the industry become more robust and ecologically
sensitive but also supports global sustainability goals. Research is not just limited to
rechargeable batteries; this method can also facilitate mineral extraction from other energy
wastes. By moving forward with this, we can pave the way for a future that is resilient and
equitable for coming generations. That hinges on us cooperating, encouraging creativity,
and exhibiting a commitment to environmental stewardship.

Author Contributions: Conceptualization: A.A.D., Z.C., G.Z., J.H., S.D. and X.W. Methodology:
G.Z., Z.C., J.H., S.D. and X.W. Software: A.A.D. Validation: Z.C., G.Z. and J.H. Resources: K.Z.
Writing—original draft preparation: A.A.D. Writing—review and editing: G.Z., J.H., K.Z., S.D., X.W.,
F.H., C.N.M., C.A., A.A.R. and S.S., Supervision: Z.C. Funding acquisition: Z.C. All authors have
read and agreed to the published version of the manuscript.

Funding: This research received no external funding.

Acknowledgments: This study was supported by a research grant from the Volt-Age Electrification
Research Program at Concordia University.

Conflicts of Interest: Authors declare no conflicts of interest.

References
1. Schroeder, P.; Anggraeni, K.; Weber, U. The Relevance of Circular Economy Practices to the Sustainable Development Goals.
J. Ind. Ecol. 2019, 23, 77–95. [CrossRef]
2. Vanderbruggen, A.; Hayagan, N.; Bachmann, K.; Ferreira, A.; Werner, D.; Horn, D.; Peuker, U.; Serna-Guerrero, R.; Rudolph, M.
Lithium-Ion Battery Recycling—Influence of Recycling Processes on Component Liberation and Flotation Separation Efficiency.
ACS EST Eng. 2022, 2, 2130–2141. [CrossRef]
3. Mudd, G.M.; Jowitt, S.M. The new century for nickel resources, reserves, and mining: Reassessing the sustainability of the devil’s
metal. Econ. Geol. 2022, 117, 1961–1983. [CrossRef]
4. Zeng, X.; Gong, R.; Chen, W.-Q.; Li, J. Uncovering the recycling potential of “new” WEEE in China. Environ. Sci. Technol. 2016, 50,
1347–1358. [CrossRef]
5. Zhao, Y.; Pohl, O.; Bhatt, A.I.; Collis, G.E.; Mahon, P.J.; Rüther, T.; Hollenkamp, A.F. A review on battery market trends, second-life
reuse, and recycling. Sustain. Chem. 2021, 2, 167–205. [CrossRef]
6. Hao, J.; Hao, J.; Liu, D.; He, L.; Liu, X.; Zhao, Z.; Zhao, T.; Xu, W. Maximizing resource recovery: A green and economic strategy
for lithium extraction from spent ternary batteries. J. Hazard. Mater. 2024, 472, 134472. [CrossRef]
7. Precedence Research. Rechargeable Batteries Market—Global Industry Analysis, Size, Share, Growth, Trends, Regional Outlook, and
Forecast 2023–2032; FBI101350; Fortune Business Insights: Maharashtra, India, 2023; p. 150.
8. Asadi Dalini, E.; Karimi, G.; Zandevakili, S.; Goodarzi, M. A review on environmental, economic and hydrometallurgical
processes of recycling spent lithium-ion batteries. Miner. Process. Extr. Metall. Rev. 2021, 42, 451–472. [CrossRef]
9. Chagnes, A.; Pospiech, B. A brief review on hydrometallurgical technologies for recycling spent lithium-ion batteries. J. Chem.
Technol. Biotechnol. 2013, 88, 1191–1199. [CrossRef]
10. Schulz, K.J. Critical Mineral Resources of the United States: Economic and Environmental Geology and Prospects for Future Supply;
Geological Survey: Reston, VA, USA, 2017.
11. Viñas-Ospino, A.; López-Malo, D.; Esteve, M.J.; Frígola, A.; Blesa, J. Green solvents: Emerging alternatives for carotenoid
extraction from fruit and vegetable by-products. Foods 2023, 12, 863. [CrossRef] [PubMed]
12. Singh, A.; Singh, K.; Singh, S. Green Solvents for Sustainable Organic Synthesis: An Overview. In Green Chemistry for the
Development of Eco-Friendly Products; Chahal, K.S., Solanki, T., Eds.; IGI Global: Hershey, PA, USA, 2022; pp. 104–128.
13. Clark, J.H.; Farmer, T.J.; Hunt, A.J.; Sherwood, J. Opportunities for bio-based solvents created as petrochemical and fuel products
transition towards renewable resources. Int. J. Mol. Sci. 2015, 16, 17101–17159. [CrossRef] [PubMed]
14. Clarke, C.J.; Tu, W.-C.; Levers, O.; Brohl, A.; Hallett, J.P. Green and sustainable solvents in chemical processes. Chem. Rev. 2018,
118, 747–800. [CrossRef] [PubMed]
Batteries 2025, 11, 51 29 of 36

15. Hessel, V.; Tran, N.N.; Asrami, M.R.; Tran, Q.D.; Long, N.V.D.; Escribà-Gelonch, M.; Tejada, J.O.; Linke, S.; Sundmacher, K.
Sustainability of green solvents–review and perspective. Green Chem. 2022, 24, 410–437. [CrossRef]
16. Das, S.; Mondal, A.; Balasubramanian, S. Recent advances in modeling green solvents. Curr. Opin. Green Sustain. Chem. 2017,
5, 37–43. [CrossRef]
17. Flieger, J.; Feder-Kubis, J.; Tatarczak-Michalewska, M. Chiral ionic liquids: Structural diversity, properties and applications in
selected separation techniques. Int. J. Mol. Sci. 2020, 21, 4253. [CrossRef] [PubMed]
18. Winterton, N. The green solvent: A critical perspective. Clean Technol. Environ. Policy 2021, 23, 2499–2522. [CrossRef]
19. Bidari, E.; Winardhi, C.W.; Godinho, J.R.d.A.; Frisch, G. Role of oxidants in metal extraction from sulfide minerals in a deep
eutectic solvent. ACS Omega 2024, 9, 14592–14603. [CrossRef]
20. Tian, G.; Liu, H. Review on the mineral processing in ionic liquids and deep eutectic solvents. Miner. Process. Extr. Metall. Rev.
2024, 45, 130–153. [CrossRef]
21. Hund, K.L.; Arrobas, D.L.P.; Fabregas Masllovet, T.P.; Laing, T.J.; Drexhage, J.R. Minerals for Climate Action:The Mineral Intensity of
the Clean Energy Transition; World Bank Group: Washington, DC, USA, 2020.
22. Hayes, S.M.; McCullough, E.A. Critical minerals: A review of elemental trends in comprehensive criticality studies. Resour. Policy
2018, 59, 192–199. [CrossRef]
23. Cheyns, K.; Nkulu, C.B.L.; Ngombe, L.K.; Asosa, J.N.; Haufroid, V.; De Putter, T.; Nawrot, T.; Kimpanga, C.M.; Numbi, O.L.;
Ilunga, B.K. Pathways of human exposure to cobalt in Katanga, a mining area of the DR Congo. Sci. Total Environ. 2014, 490,
313–321. [CrossRef]
24. Maisel, F.; Neef, C.; Marscheider-Weidemann, F.; Nissen, N.F. A forecast on future raw material demand and recycling potential
of lithium-ion batteries in electric vehicles. Resour. Conserv. Recycl. 2023, 192, 106920. [CrossRef]
25. Altiparmak, S.O. China and lithium geopolitics in a changing global market. Chin. Political Sci. Rev. 2023, 8, 487–506. [CrossRef]
26. Meng, F.; McNeice, J.; Zadeh, S.S.; Ghahreman, A. Review of lithium production and recovery from minerals, brines, and
lithium-ion batteries. Miner. Process. Extr. Metall. Rev. 2021, 42, 123–141. [CrossRef]
27. Abdollahifar, M.; Doose, S.; Cavers, H.; Kwade, A. Graphite Recycling from End-of-Life Lithium-Ion Batteries: Processes and
Applications. Adv. Mater. Technol. 2023, 8, 2200368. [CrossRef]
28. Natarajan, S.; Divya, M.L.; Aravindan, V. Should we recycle the graphite from spent lithium-ion batteries? The untold story of
graphite with the importance of recycling. J. Energy Chem. 2022, 71, 351–369. [CrossRef]
29. Choi, H.H.; Hwang, Y.W.; Kim, J.; Kang, H.Y.; Kim, D.H. Material flow and domestic demand analysis for nickel in South Korea.
J. Clean. Prod. 2024, 449, 141711. [CrossRef]
30. Klose, S.; Pauliuk, S. Sector-level estimates for global future copper demand and the potential for resource efficiency. Resour.
Conserv. Recycl. 2023, 193, 106941. [CrossRef]
31. Ritchie, H.; Rosado, P. Which Countries Have the Critical Minerals Needed for the Energy Transition? Our World in Data: Oxford,
UK, 2024.
32. Shafique, M.; Akbar, A.; Rafiq, M.; Azam, A.; Luo, X. Global material flow analysis of end-of-life of lithium nickel manganese
cobalt oxide batteries from battery electric vehicles. Waste Manag. Res. 2023, 41, 376–388. [CrossRef] [PubMed]
33. Yi, X.; Lu, Y.; He, G. Aluminum demand and low carbon development scenarios for major countries by 2050. J. Clean. Prod. 2024,
475, 143647. [CrossRef]
34. Bothare, V. Molybdenum Market Size & Share Analysis—Growth Trends & Forecasts (2025–2030); Mordor Intelligence: Hyderabad,
India, 2024.
35. Sverdrup, H.U.; Sverdrup, A.E. An assessment of the global supply, recycling, stocks in use and market price for titanium using
the WORLD7 model. Sustain. Horiz. 2023, 7, 100067. [CrossRef]
36. Liu, M.; Mao, J.; Zhang, Z.; Li, L.; Long, T.; Chao, W. Current supply status, demand trends and security measures of chromium
resources in China. Green Smart Min. Eng. 2024, 1, 53–57. [CrossRef]
37. Straits Research. Iron Ore Market Size, Growth & Share, Forecast-2032; Fortune Business Insights: Maharashtra, India, 2024.
38. Sovacool, B.K.; Ali, S.H.; Bazilian, M.; Radley, B.; Nemery, B.; Okatz, J.; Mulvaney, D. Sustainable minerals and metals for a
low-carbon future. Science 2020, 367, 30–33. [CrossRef] [PubMed]
39. Agusdinata, D.; Liu, W. Global sustainability of electric vehicles minerals: A critical review of news media. Extr. Ind. Soc. 2023,
13, 101231. [CrossRef]
40. Zakari, A.; Khan, I.; Alvarado, R. The impact of environmental technology innovation and energy credit rebate on carbon
emissions: A comparative analysis. J. Int. Dev. 2023, 35, 2609–2625. [CrossRef]
41. Hudson-Edwards, K.A.; Jamieson, H.E.; Lottermoser, B.G. Mine wastes: Past, present, future. Elements 2011, 7, 375–380. [CrossRef]
42. Dino, G.A.; Cavallo, A.; Rossetti, P.; Garamvölgyi, E.; Sándor, R.; Coulon, F. Towards sustainable mining: Exploiting raw materials
from extractive waste facilities. Sustainability 2020, 12, 2383. [CrossRef]
Batteries 2025, 11, 51 30 of 36

43. Haddaway, N.R.; Cooke, S.J.; Lesser, P.; Macura, B.; Nilsson, A.E.; Taylor, J.J.; Raito, K. Evidence of the impacts of metal mining
and the effectiveness of mining mitigation measures on social–ecological systems in Arctic and boreal regions: A systematic map
protocol. Environ. Evid. 2019, 8, 9. [CrossRef]
44. Ruokonen, E.; Temmes, A. The approaches of strategic environmental management used by mining companies in Finland.
J. Clean. Prod. 2019, 210, 466–476. [CrossRef]
45. Azadi, M.; Northey, S.A.; Ali, S.H.; Edraki, M. Transparency on greenhouse gas emissions from mining to enable climate change
mitigation. Nat. Geosci. 2020, 13, 100–104. [CrossRef]
46. Jiskani, I.M.; Cai, Q.; Zhou, W.; Shah, S.A.A. Green and climate-smart mining: A framework to analyze open-pit mines for cleaner
mineral production. Resour. Policy 2021, 71, 102007. [CrossRef]
47. Sonter, L.J.; Dade, M.C.; Watson, J.E.; Valenta, R.K. Renewable energy production will exacerbate mining threats to biodiversity.
Nat. Commun. 2020, 11, 4174. [CrossRef] [PubMed]
48. Luckeneder, S.; Giljum, S.; Schaffartzik, A.; Maus, V.; Tost, M. Surge in global metal mining threatens vulnerable ecosystems. Glob.
Environ. Chang. 2021, 69, 102303. [CrossRef]
49. Drexhage, J.; La Porta, D.; Hund, K.; McCormick, M.; Ningthoujam, J. The Growing Role of Minerals and Metals for a Low Carbon
Future; World Bank: Washington, DC, USA, 2017.
50. Hund, K.; La Porta, D.; Fabregas, T.P.; Laing, T.; Drexhage, J. Minerals for Climate Action: The Mineral Intensity of the Clean Energy
Transition; World Bank: Washington, DC, USA, 2023.
51. Chung, K.W. Proposal on how to activate recycling of critical minerals. J. Korean Soc. Miner. Energy Resour. Eng. 2022, 59, 489–497.
[CrossRef]
52. Zheng, X.; Zhu, Z.; Lin, X.; Zhang, Y.; He, Y.; Cao, H.; Sun, Z. A mini-review on metal recycling from spent lithium ion batteries.
Engineering 2018, 4, 361–370. [CrossRef]
53. Ivic, A.; Saviolidis, N.M.; Johannsdottir, L. Drivers of sustainability practices and contributions to sustainable development
evident in sustainability reports of European mining companies. Discov. Sustain. 2021, 2, 17. [CrossRef]
54. Matinde, E.; Simate, G.S.; Ndlovu, S. Mining and metallurgical wastes: A review of recycling and re-use practices. J. South. Afr.
Inst. Min. Metall. 2018, 118, 825–844. [CrossRef]
55. Ali, A.; Li, W.; Hussain, R.; He, X.; Williams, B.W.; Hameed Memon, A. Overview of current microgrid policies, incentives and
barriers in the European Union, United States and China. Sustainability 2017, 9, 1146. [CrossRef]
56. USGS. Mineral Commodity Summaries; USGS: Reston, VA, USA, 2024.
57. Thompson, D.L.; Hartley, J.M.; Lambert, S.M.; Shiref, M.; Harper, G.D.; Kendrick, E.; Anderson, P.; Ryder, K.S.; Gaines, L.;
Abbott, A.P. The importance of design in lithium ion battery recycling–a critical review. Green Chem. 2020, 22, 7585–7603.
[CrossRef]
58. Zeng, A.; Chen, W.; Rasmussen, K.D.; Zhu, X.; Lundhaug, M.; Müller, D.B.; Tan, J.; Keiding, J.K.; Liu, L.; Dai, T.; et al. Battery
technology and recycling alone will not save the electric mobility transition from future cobalt shortages. Nat. Commun. 2022,
13, 1341. [CrossRef] [PubMed]
59. Banza Lubaba Nkulu, C.; Casas, L.; Haufroid, V.; De Putter, T.; Saenen, N.D.; Kayembe-Kitenge, T.; Musa Obadia, P.; Kyanika Wa
Mukoma, D.; Lunda Ilunga, J.-M.; Nawrot, T.S. Sustainability of artisanal mining of cobalt in DR Congo. Nat. Sustain. 2018, 1,
495–504. [CrossRef] [PubMed]
60. Dixit, M.; Witherspoon, B.; Muralidharan, N.; Mench, M.M.; Kweon, C.-B.M.; Sun, Y.-K.; Belharouak, I. Insights into the Critical
Materials Supply Chain of the Battery Market for Enhanced Energy Security. ACS Energy Lett. 2024, 9, 3780–3789. [CrossRef]
[PubMed]
61. Saju, D.; Ebenezer, J.; Chandran, N.; Chandrasekaran, N. Recycling of lithium iron phosphate cathode materials from spent
lithium-ion batteries: A mini-review. Ind. Eng. Chem. Res. 2023, 62, 11768–11783. [CrossRef]
62. Bankole, O.E.; Gong, C.; Lei, L. Battery recycling technologies: Recycling waste lithium ion batteries with the impact on the
environment in-view. J. Environ. Ecol. 2013, 4, 14–28. [CrossRef]
63. Li, G.; Chen, Y.; Wu, M.; Xu, Y.; Li, X.; Tian, M. High-efficiency leaching process for selective leaching of lithium from spent
lithium iron phosphate. Waste Manag. 2024, 190, 141–148. [CrossRef]
64. Yao, Y.; Zhu, M.; Zhao, Z.; Tong, B.; Fan, Y.; Hua, Z. Hydrometallurgical Processes for Recycling Spent Lithium-Ion Batteries:
A Critical Review. ACS Sustain. Chem. Eng. 2018, 6, 13611–13627. [CrossRef]
65. Xu, P.; Tan, D.H.S.; Chen, Z. Emerging trends in sustainable battery chemistries. Trends Chem. 2021, 3, 620–630. [CrossRef]
66. Ortega-Tong, P.; Jamieson, J.; Kuhar, L.; Faulkner, L.; Prommer, H. In Situ Recovery of Copper: Identifying Mineralogical Controls
via Model-Based Analysis of Multistage Column Leach Experiments. ACS EST Eng. 2023, 3, 773–786. [CrossRef]
67. Feng, X.; Ren, D.; He, X.; Ouyang, M. Mitigating thermal runaway of lithium-ion batteries. Joule 2020, 4, 743–770. [CrossRef]
68. Sommerville, R.; Shaw-Stewart, J.; Goodship, V.; Rowson, N.; Kendrick, E. A review of physical processes used in the safe
recycling of lithium ion batteries. Sustain. Mater. Technol. 2020, 25, e00197. [CrossRef]
Batteries 2025, 11, 51 31 of 36

69. Sun, X.; Luo, H.; Dai, S. Ionic liquids-based extraction: A promising strategy for the advanced nuclear fuel cycle. Chem. Rev. 2012,
112, 2100–2128. [CrossRef] [PubMed]
70. Xuan, W.; Otsuki, A.; Chagnes, A. Investigation of the leaching mechanism of NMC 811 (LiNi0.8 Mn0.1 Co0.1 O2 ) by hydrochloric
acid for recycling lithium ion battery cathodes. RSC Adv. 2019, 9, 38612–38618. [CrossRef] [PubMed]
71. Meng, F.; Liu, Q.; Kim, R.; Wang, J.; Liu, G.; Ghahreman, A. Selective recovery of valuable metals from industrial waste lithium-
ion batteries using citric acid under reductive conditions: Leaching optimization and kinetic analysis. Hydrometallurgy 2020,
191, 105160. [CrossRef]
72. Qi, Y.; Meng, F.; Yi, X.; Shu, J.; Chen, M.; Sun, Z.; Sun, S.; Xiu, F.-R. A novel and efficient ammonia leaching method for recycling
waste lithium ion batteries. J. Clean. Prod. 2020, 251, 119665. [CrossRef]
73. Meng, Q.; Zhang, Y.; Dong, P. Use of glucose as reductant to recover Co from spent lithium ions batteries. Waste Manag. 2017, 64,
214–218. [CrossRef]
74. Biswal, B.K.; Jadhav, U.U.; Madhaiyan, M.; Ji, L.; Yang, E.-H.; Cao, B. Biological leaching and chemical precipitation methods for
recovery of Co and Li from spent lithium-ion batteries. ACS Sustain. Chem. Eng. 2018, 6, 12343–12352. [CrossRef]
75. Chen, X.; Luo, C.; Zhang, J.; Kong, J.; Zhou, T. Sustainable recovery of metals from spent lithium-ion batteries: A green process.
ACS Sustain. Chem. Eng. 2015, 3, 3104–3113. [CrossRef]
76. Joulié, M.; Laucournet, R.; Billy, E. Hydrometallurgical process for the recovery of high value metals from spent lithium nickel
cobalt aluminum oxide based lithium-ion batteries. J. Power Sources 2014, 247, 551–555. [CrossRef]
77. Al-Thyabat, S.; Nakamura, T.; Shibata, E.; Iizuka, A. Adaptation of minerals processing operations for lithium-ion (LiBs) and
nickel metal hydride (NiMH) batteries recycling: Critical review. Miner. Eng. 2013, 45, 4–17. [CrossRef]
78. Nasser, O.A.; Petranikova, M. Review of achieved purities after li-ion batteries hydrometallurgical treatment and impurities
effects on the cathode performance. Batteries 2021, 7, 60. [CrossRef]
79. Idris, J.; Musa, M.; Yin, C.-Y.; Hamid, K.H.K. Recovery of nickel from spent catalyst from palm oil hydrogenation process using
acidic solutions. J. Ind. Eng. Chem. 2010, 16, 251–255. [CrossRef]
80. Chen, X.; Xu, B.; Zhou, T.; Liu, D.; Hu, H.; Fan, S. Separation and recovery of metal values from leaching liquor of mixed-type of
spent lithium-ion batteries. Sep. Purif. Technol. 2015, 144, 197–205. [CrossRef]
81. Islam, M.T.; Iyer-Raniga, U. Lithium-Ion Battery Recycling in the Circular Economy: A Review. Recycling 2022, 7, 33. [CrossRef]
82. Neumann, J.; Petranikova, M.; Meeus, M.; Gamarra, J.D.; Younesi, R.; Winter, M.; Nowak, S. Recycling of lithium-ion batteries-
current state of the art, circular economy, and next generation recycling. Adv. Energy Mater. 2022, 12, 2102917. [CrossRef]
83. Zheng, C.; Jiang, K.; Cao, Z.; Northwood, D.O.; Waters, K.E.; Wang, H.; Liu, S.; Zhu, K.e.; Ma, H. Agitation Leaching Behavior of
Copper–Cobalt Oxide Ores from the Democratic Republic of the Congo. Minerals 2023, 13, 743. [CrossRef]
84. Lee, J.; Park, K.W.; Sohn, I.; Lee, S. Pyrometallurgical recycling of end-of-life lithium-ion batteries. Int. J. Miner. Metall. Mater.
2024, 31, 1554–1571. [CrossRef]
85. Fan, E.; Li, L.; Wang, Z.; Lin, J.; Huang, Y.; Yao, Y.; Chen, R.; Wu, F. Sustainable recycling technology for Li-ion batteries and
beyond: Challenges and future prospects. Chem. Rev. 2020, 120, 7020–7063. [CrossRef] [PubMed]
86. Georgi-Maschler, T.; Friedrich, B.; Weyhe, R.; Heegn, H.; Rutz, M. Development of a recycling process for Li-ion batteries. J. Power
Sources 2012, 207, 173–182. [CrossRef]
87. Pradhan, S.; Nayak, R.; Mishra, S. A review on the recovery of metal values from spent nickel metal hydride and lithium-ion
batteries. Int. J. Environ. Sci. Technol. 2022, 19, 4537–4554. [CrossRef]
88. Gao, W.; Zhang, X.; Zheng, X.; Lin, X.; Cao, H.; Zhang, Y.; Sun, Z. Lithium carbonate recovery from cathode scrap of spent
lithium-ion battery: A closed-loop process. Environ. Sci. Technol. 2017, 51, 1662–1669. [CrossRef]
89. Harper, G.; Sommerville, R.; Kendrick, E.; Driscoll, L.; Slater, P.; Stolkin, R.; Walton, A.; Christensen, P.; Heidrich, O.; Lambert, S.
Recycling lithium-ion batteries from electric vehicles. Nature 2019, 575, 75–86. [CrossRef]
90. Ellis, T.W.; Howes, J.A. Roadmap for the lifecycle of advanced battery chemistries. In Rewas 2016: Towards Materials Resource
Sustainability; Springer: Berlin/Heidelberg, Germany, 2016; pp. 51–56. [CrossRef]
91. Zhou, M.; Li, B.; Li, J.; Xu, Z. Pyrometallurgical Technology in the Recycling of a Spent Lithium Ion Battery: Evolution and the
Challenge. ACS EST Eng. 2021, 1, 1369–1382. [CrossRef]
92. Cornelio, A.; Zanoletti, A.; Bontempi, E. Recent progress in pyrometallurgy for the recovery of spent lithium-ion batteries:
A review of state-of-the-art developments. Curr. Opin. Green Sustain. Chem. 2024, 46, 100881. [CrossRef]
93. Rodriguez Rodriguez, N.; Machiels, L.; Binnemans, K. p-Toluenesulfonic acid-based deep-eutectic solvents for solubilizing metal
oxides. ACS Sustain. Chem. Eng. 2019, 7, 3940–3948. [CrossRef]
94. Yun, L.; Linh, D.; Shui, L.; Peng, X.; Garg, A.; Le, M.L.P.; Asghari, S.; Sandoval, J. Metallurgical and mechanical methods for
recycling of lithium-ion battery pack for electric vehicles. Resour. Conserv. Recycl. 2018, 136, 198–208. [CrossRef]
95. Horeh, N.B.; Mousavi, S.M.; Shojaosadati, S.A. Bioleaching of valuable metals from spent lithium-ion mobile phone batteries
using Aspergillus niger. J. Power Sources 2016, 320, 257–266. [CrossRef]
Batteries 2025, 11, 51 32 of 36

96. Boxall, N.J.; Cheng, K.Y.; Bruckard, W.; Kaksonen, A.H. Application of indirect non-contact bioleaching for extracting metals from
waste lithium-ion batteries. J. Hazard. Mater. 2018, 360, 504–511. [CrossRef] [PubMed]
97. Garole, D.J.; Hossain, R.; Garole, V.J.; Sahajwalla, V.; Nerkar, J.; Dubal, D.P. Recycle, recover and repurpose strategy of spent
Li-ion batteries and catalysts: Current status and future opportunities. ChemSusChem 2020, 13, 3079–3100. [CrossRef]
98. Chen, J.; Liu, Y.; Mahadevan, R. Genetic Engineering of Acidithiobacillus ferridurans Using CRISPR Systems To Mitigate Toxic
Release in Biomining. Environ. Sci. Technol. 2023, 57, 12315–12324. [CrossRef] [PubMed]
99. Chang, S.H. Utilization of green organic solvents in solvent extraction and liquid membrane for sustainable wastewater treatment
and resource recovery—A review. Environ. Sci. Pollut. Res. 2020, 27, 32371–32388. [CrossRef]
100. Novisi, K.O.; Leah, C.M.; Banothile, C.E.M. Bio-Solvents: Synthesis, Industrial Production and Applications. In Solvents, Ionic
Liquids and Solvent Effects; Daniel, G.-M., Magdalena, M., Eds.; IntechOpen: Rijeka, Croatia, 2019. [CrossRef]
101. Usman, M.; Cheng, S.; Boonyubol, S.; Cross, J.S. Evaluating Green Solvents for Bio-Oil Extraction: Advancements, Challenges,
and Future Perspectives. Energies 2023, 16, 5852. [CrossRef]
102. Jumaah, M.A.; Yusoff, M.F.; Salimon, J.; Bahadi, M. Physical characteristics of palm fatty acid distillate. J. Chem. Pharm. Sci. 2019,
12, 1–5. [CrossRef]
103. Halim, S.F.A.; Chang, S.H.; Morad, N. Extraction of Cu (II) ions from aqueous solutions by free fatty acid-rich oils as green
extractants. J. Water Process Eng. 2020, 33, 100997. [CrossRef]
104. Moosakazemi, F.; Ghassa, S.; Jafari, M.; Chelgani, S.C. Bioleaching for recovery of metals from spent batteries—A review. Miner.
Process. Extr. Metall. Rev. 2023, 44, 511–521. [CrossRef]
105. Kumar, S.; Jain, S.; Nehra, M.; Dilbaghi, N.; Marrazza, G.; Kim, K.-H. Green synthesis of metal–organic frameworks: A state-of-
the-art review of potential environmental and medical applications. Coord. Chem. Rev. 2020, 420, 213407. [CrossRef]
106. Hartonen, K.; Riekkola, M.-L. Water as the first choice green solvent. In The Application of Green Solvents in Separation Processes;
Pena-Pereira, F., Tobiszewski, M., Eds.; Elsevier: Amsterdam, The Netherlands, 2017; pp. 19–55. [CrossRef]
107. Liu, Y.; Friesen, J.B.; McAlpine, J.B.; Lankin, D.C.; Chen, S.-N.; Pauli, G.F. Natural deep eutectic solvents: Properties, applications,
and perspectives. J. Nat. Prod. 2018, 81, 679–690. [CrossRef] [PubMed]
108. Guo, M.; Deng, R.; Gao, M.; Xu, C.; Zhang, Q. Sustainable recovery of metals from e-waste using deep eutectic solvents: Advances,
challenges, and perspectives. Curr. Opin. Green Sustain. Chem. 2024, 47, 100913. [CrossRef]
109. Knez, Ž.; Pantić, M.; Cör, D.; Novak, Z.; Hrnčič, M.K. Are supercritical fluids solvents for the future? Chem. Eng. Process.-Process
Intensif. 2019, 141, 107532. [CrossRef]
110. Hrnčič, M.K.; Cör, D.; Verboten, M.T.; Knez, Ž. Application of supercritical and subcritical fluids in food processing. Food Qual.
Saf. 2018, 2, 59–67. [CrossRef]
111. Marrucho, I.; Branco, L.; Rebelo, L. Ionic liquids in pharmaceutical applications. Annu. Rev. Chem. Biomol. Eng. 2014, 5, 527–546.
[CrossRef]
112. Makertihartha, I.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. Solvent Extraction of Gold Using Ionic Liquid Based Process; AIP Conference
Proceedings; AIP Publishing: New York, NY, USA, 2017.
113. Das, D.; Mukherjee, S.; Chaudhuri, M.G. Studies on leaching characteristics of electronic waste for metal recovery using inorganic
and organic acids and base. Waste Manag. Res. 2021, 39, 242–249. [CrossRef] [PubMed]
114. Javanshir, S.; Arasteh, A.; Mohebbi, M.; Gorgij, M. A comprehensive evaluation on leaching of non-ferrous metals from
polymetallic tailings. Environ. Sci. Mater. Sci. 2023. [CrossRef]
115. Xie, F.; Zhang, J.; Chen, J.; Wang, J.; Wu, L. Research on enrichment of P2 O5 from low-grade carbonaceous phosphate ore via
organic acid solution. J. Anal. Methods Chem. 2019, 2019, 9859580. [CrossRef] [PubMed]
116. Chen, H.; Grassian, V.H. Iron dissolution of dust source materials during simulated acidic processing: The effect of sulfuric,
acetic, and oxalic acids. Environ. Sci. Technol. 2013, 47, 10312–10321. [CrossRef] [PubMed]
117. Golmohammadzadeh, R.; Faraji, F.; Rashchi, F. Recovery of lithium and cobalt from spent lithium ion batteries (LIBs) using
organic acids as leaching reagents: A review. Resour. Conserv. Recycl. 2018, 136, 418–435. [CrossRef]
118. Urias, P.M.; dos Reis Menêzes, L.H.; Cardoso, V.L.; de Resende, M.M.; de Souza Ferreira, J. Leaching with mixed organic acids
and sulfuric acid to recover cobalt and lithium from lithium ion batteries. Environ. Technol. 2021, 42, 4027–4037. [CrossRef]
119. Chahardoli, A.; Jalilian, F.; Memariani, Z.; Farzaei, M.H.; Shokoohinia, Y. Analysis of organic acids. In Recent Advances in
Natural Products Analysis; Silva, A.S., Nabavi, S.F., Saeedi, M., Nabavi, S.M., Eds.; Elsevier: Amsterdam, The Netherlands, 2020;
pp. 767–823. [CrossRef]
120. Golmohammadzadeh, R.; Rashchi, F.; Vahidi, E. Recovery of lithium and cobalt from spent lithium-ion batteries using organic
acids: Process optimization and kinetic aspects. Waste Manag. 2017, 64, 244–254. [CrossRef]
121. Sinha, M.K.; Purcell, W. Reducing agents in the leaching of manganese ores: A comprehensive review. Hydrometallurgy 2019, 187,
168–186. [CrossRef]
122. Banerjee, R.; Chakladar, S.; Mohanty, A.; Chakravarty, S.; Chattopadhyay, S.K.; Jha, M. Review on the environment friendly
leaching of rare earth elements from the secondary resources using organic acids. Geosyst. Eng. 2022, 25, 95–115. [CrossRef]
Batteries 2025, 11, 51 33 of 36

123. Chen, X.; Kang, D.; Cao, L.; Li, J.; Zhou, T.; Ma, H. Separation and recovery of valuable metals from spent lithium ion batteries:
Simultaneous recovery of Li and Co in a single step. Sep. Purif. Technol. 2019, 210, 690–697. [CrossRef]
124. Hamelin, E.; Swaim, L.; Thomas, J.; Kobelski, R.; Johnson, R.C. Quantitation of tetramethylene disulfotetramine in human urine
using isotope dilution gas chromatography mass spectrometry (GC/MS and GC/MS/MS). J. Chromatogr. B 2010, 878, 2541–2547.
[CrossRef] [PubMed]
125. Verma, A.; Kore, R.; Corbin, D.R.; Shiflett, M.B. Metal recovery using oxalate chemistry: A technical review. Ind. Eng. Chem. Res.
2019, 58, 15381–15393. [CrossRef]
126. Top, S. Separation of Fe and Mn from manganiferous iron ores via reductive acid leaching followed by magnetic separation. Min.
Metall. Explor. 2020, 37, 297–309. [CrossRef]
127. Banerjee, R.; Mohanty, A.; Chakravarty, S.; Chakladar, S.; Biswas, P. A single-step process to leach out rare earth elements from
coal ash using organic carboxylic acids. Hydrometallurgy 2021, 201, 105575. [CrossRef]
128. Zhang, J.; Zhang, X.; Su, X.; Du, H.; Lu, Y.; Zhang, Q. Rare Earth Extraction from Phosphogypsum by Aspergillus niger Culture
Broth. Molecules 2024, 29, 1266. [CrossRef] [PubMed]
129. Yu, S.; Liao, R.; Yang, B.; Fang, C.; Wang, Z.; Liu, Y.; Wu, B.; Wang, J.; Qiu, G. Chalcocite (bio) hydrometallurgy-current state,
mechanism, and future directions: A review. Chin. J. Chem. Eng. 2022, 41, 109–120. [CrossRef]
130. Zhao, M.; Teng, Z.; Ma, X.; Jiang, X.; Zhang, H.; Yang, Y.; Li, T. Insight into leaching rare earth from ion-adsorption type rare earth
ores with citric acid: Performance, kinetic analysis and differentiation leaching. J. Rare Earths 2024, in press. [CrossRef]
131. Astuti, W.; Hirajima, T.; Sasaki, K.; Okibe, N. Comparison of effectiveness of citric acid and other acids in leaching of low-grade
Indonesian saprolitic ores. Miner. Eng. 2016, 85, 1–16. [CrossRef]
132. Kursunoglu, S.; Kaya, M. Dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching
method. Int. J. Miner. Metall. Mater. 2015, 22, 1131–1140. [CrossRef]
133. Li, L.; Dunn, J.B.; Zhang, X.X.; Gaines, L.; Chen, R.J.; Wu, F.; Amine, K. Recovery of metals from spent lithium-ion batteries with
organic acids as leaching reagents and environmental assessment. J. Power Sources 2013, 233, 180–189. [CrossRef]
134. Abhilash; Hedrich, S.; Meshram, P.; Schippers, A.; Gupta, A.; Sen, S. Extraction of REEs from blast furnace slag by Gluconobacter
oxydans. Minerals 2022, 12, 701. [CrossRef]
135. Rasoulnia, P.; Barthen, R.; Lakaniemi, A.-M. A critical review of bioleaching of rare earth elements: The mechanisms and effect of
process parameters. Crit. Rev. Environ. Sci. Technol. 2021, 51, 378–427. [CrossRef]
136. Dong, Y.; Zan, J.; Lin, H. Bioleaching of heavy metals from metal tailings utilizing bacteria and fungi: Mechanisms, strengthen
measures, and development prospect. J. Environ. Manag. 2023, 344, 118511. [CrossRef] [PubMed]
137. Pathak, A.; Vinoba, M.; Kothari, R. Emerging role of organic acids in leaching of valuable metals from refinery-spent hydroprocess-
ing catalysts, and potential techno-economic challenges: A review. Crit. Rev. Environ. Sci. Technol. 2021, 51, 1–43. [CrossRef]
138. Mouna, H.; Baral, S.S. A bio-hydrometallurgical approach towards leaching of lanthanum from the spent fluid catalytic cracking
catalyst using Aspergillus niger. Hydrometallurgy 2019, 184, 175–182. [CrossRef]
139. Fathollahzadeh, H.; Eksteen, J.J.; Kaksonen, A.H.; Watkin, E.L. Role of microorganisms in bioleaching of rare earth elements from
primary and secondary resources. Appl. Microbiol. Biotechnol. 2019, 103, 1043–1057. [CrossRef] [PubMed]
140. Dhiman, S.; Agarwal, S.; Gupta, H. Application of phosphonium ionic liquids to separate Ga, Ge and In utilizing solvent
extraction: A review. J. Ion. Liq. 2024, 4, 100080. [CrossRef]
141. Binnemans, K.; Jones, P.T. Solvometallurgy: An emerging branch of extractive metallurgy. J. Sustain. Metall. 2017, 3, 570–600.
[CrossRef]
142. Carlesi, C.; Cortes, E.; Dibernardi, G.; Morales, J.; Muñoz, E. Ionic liquids as additives for acid leaching of copper from sulfidic
ores. Hydrometallurgy 2016, 161, 29–33. [CrossRef]
143. Makanyire, T.; Sanchez-Segado, S.; Jha, A. Separation and recovery of critical metal ions using ionic liquids. Adv. Manuf. 2016,
4, 33–46. [CrossRef]
144. Wellens, S. Ionic Liquid Technology in Metal Refining: Dissolution of Metal Oxides and Separation by Solvent Extraction. 2014.
Available online: https://api.semanticscholar.org/CorpusID:99532665 (accessed on 6 December 2024).
145. Sahoo, H.; Rath, S.S.; Das, B. A review on the application of quaternary ammonium-based ionic liquids in mineral flotation. Miner.
Process. Extr. Metall. Rev. 2020, 41, 405–416. [CrossRef]
146. Rodríguez, M.; Ayala, L.; Robles, P.; Sepúlveda, R.; Torres, D.; Carrillo-Pedroza, F.R.; Jeldres, R.I.; Toro, N. Leaching chalcopyrite
with an imidazolium-based ionic liquid and bromide. Metals 2020, 10, 183. [CrossRef]
147. Freiderich, J.W.; Stankovich, J.J.; Luo, H.; Dai, S.; Moyer, B.A. Dissolution of the rare-earth mineral bastnaesite by acidic amide
ionic liquid for recovery of critical materials. Eur. J. Inorg. Chem. 2015, 2015, 4354–4361. [CrossRef]
148. Liu, Y.; Chen, J.; Li, D. Application and perspective of ionic liquids on rare earths green separation. Sep. Sci. Technol. 2012, 47,
223–232. [CrossRef]
149. Ejtemaei, M.; Gharabaghi, M.; Irannajad, M. A review of zinc oxide mineral beneficiation using flotation method. Adv. Colloid
Interface Sci. 2014, 206, 68–78. [CrossRef] [PubMed]
Batteries 2025, 11, 51 34 of 36

150. Araujo, A.C.; Viana, P.R.M.; Peres, A.E.C. Reagents in iron ores flotation. Miner. Eng. 2005, 18, 219–224. [CrossRef]
151. Wang, D. Flotation Reagents: Applied Surface Chemistry on Minerals Flotation and Energy Resources Beneficiation; Springer: Singapore,
2016; Volume 2. [CrossRef]
152. Kowalczuk, P.B.; Siedlarz, M.; Szczerkowska, S.; Wojcik, M. Facile determination of foamability index of non-ionic and cationic
frothers and its effect on flotation of quartz. Sep. Sci. Technol. 2018, 53, 1198–1206. [CrossRef]
153. Eney de Matos, V.; Nogueira, S.d.C.S.; Kowalczuk, P.B.; Silva, G.R.d.; Peres, A.E.C. Differences in etheramines froth properties
and the effects on iron ore flotation. Part I: Two-phase Systems. Miner. Process. Extr. Metall. Rev. 2022, 43, 209–216. [CrossRef]
154. Azizi, D.; Larachi, F.; Latifi, M. Ionic-liquid collectors for rare-earth minerals flotation Case of tetrabutylammonium bis(2-
ethylhexyl)-phosphate for monazite and bastnäsite recovery. Colloids Surf. A Physicochem. Eng. Asp. 2016, 506, 74–86. [CrossRef]
155. Ovejero-Pérez, A.; Nakasu, P.Y.S.; Hopson, C.; Costa, J.M.; Hallett, J.P. Challenges and opportunities on the utilisation of ionic
liquid for biomass pretreatment and valorisation. npj Mater. Sustain. 2024, 2, 7. [CrossRef]
156. Leng, Y.; Jiang, P.; Wang, J. A novel Brønsted acidic heteropolyanion-based polymeric hybrid catalyst for esterification. Catal.
Commun. 2012, 25, 41–44. [CrossRef]
157. Amarasekara, A.S.; Owereh, O.S. Synthesis of a sulfonic acid functionalized acidic ionic liquid modified silica catalyst and
applications in the hydrolysis of cellulose. Catal. Commun. 2010, 11, 1072–1075. [CrossRef]
158. Amarasekara, A.S. Acidic Ionic Liquids. Chem. Rev. 2016, 116, 6133–6183. [CrossRef] [PubMed]
159. Quijada-Maldonado, E.; Olea, F.; Sepúlveda, R.; Castillo, J.; Cabezas, R.; Merlet, G.; Romero, J. Possibilities and challenges for
ionic liquids in hydrometallurgy. Sep. Purif. Technol. 2020, 251, 117289. [CrossRef]
160. Paiva, A.; Nogueira, C. Ionic liquids in the extraction and recycling of critical metals from urban mines. Waste Biomass Valorization
2021, 12, 1725–1747. [CrossRef]
161. Hu, J.; Zi, F.; Tian, G. Extraction of copper from chalcopyrite with potassium dichromate in 1-ethyl-3-methylimidazolium
hydrogen sulfate ionic liquid aqueous solution. Miner. Eng. 2021, 172, 107179. [CrossRef]
162. Bhuiyan, M.S.I.; Rahman, A.; Kim, G.W.; Das, S.; Kim, P.J. Eco-friendly yield-scaled global warming potential assists to determine
the right rate of nitrogen in rice system: A systematic literature review. Environ. Pollut. 2021, 271, 116386. [CrossRef]
163. Hu, X.; Robles, A.; Vikström, T.; Väänänen, P.; Zackrisson, M.; Ye, G. A novel process on the recovery of zinc and manganese from
spent alkaline and zinc-carbon batteries. J. Hazard. Mater. 2021, 411, 124928. [CrossRef]
164. Zhang, N.; Zhang, Y.; Liu, Z.; Liu, Z.; Sun, C.; Altun, N.E.; Kou, J. Investigation on Gold Dissolution Performance and Mechanism
in Imidazolium Cyanate Ionic Liquids. Molecules 2024, 29, 897. [CrossRef] [PubMed]
165. Davris, P.; Marinos, D.; Balomenos, E.; Alexandri, A.; Gregou, M.; Panias, D.; Paspaliaris, I.J.H. Leaching of rare earth elements
from ‘Rödberg’ore of Fen carbonatite complex deposit, using the ionic liquid HbetTf2N. Hydrometallurgy 2018, 175, 20–27.
[CrossRef]
166. Whitehead, J.A.; Lawrance, G.A.; McCluskey, A. Green leaching: Recyclable and selective leaching of gold-bearing ore in an ionic
liquid. Green Chem. 2004, 6, 313–315. [CrossRef]
167. Hu, J.; Tian, G.; Zi, F.; Hu, X. Leaching of chalcopyrite with hydrogen peroxide in 1-hexyl-3-methyl-imidazolium hydrogen sulfate
ionic liquid aqueous solution. Hydrometallurgy 2017, 169, 1–8. [CrossRef]
168. Kilicarslan, A.; Saridede, M. Leaching performance of imidazolium based ionic liquids in the presence of hydrogen peroxide for
recovery of metals from brass waste. Rev. Metal. 2016, 52. [CrossRef]
169. Abbott, A.P.; Capper, G.; Davies, D.L.; Rasheed, R.K.; Tambyrajah, V. Novel solvent properties of choline chloride/urea mixtures.
Chem. Commun. 2003, 70–71. [CrossRef] [PubMed]
170. Chen, Y.; Han, X.; Liu, Z.; Yu, D.; Guo, W.; Mu, T. Capture of toxic gases by deep eutectic solvents. ACS Sustain. Chem. Eng. 2020,
8, 5410–5430. [CrossRef]
171. Hooshmand, S.E.; Afshari, R.; Ramón, D.J.; Varma, R.S. Deep eutectic solvents: Cutting-edge applications in cross-coupling
reactions. Green Chem. 2020, 22, 3668–3692. [CrossRef]
172. Yuan, Z.; Liu, H.; Yong, W.F.; She, Q.; Esteban, J. Status and advances of deep eutectic solvents for metal separation and recovery.
Green Chem. 2022, 24, 1895–1929. [CrossRef]
173. Zante, G.; Boltoeva, M. Review on Hydrometallurgical Recovery of Metals with Deep Eutectic Solvents. Sustain. Chem. 2020, 1,
238–255. [CrossRef]
174. Velez, C.; Acevedo, O. Simulation of deep eutectic solvents: Progress to promises. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2022,
12, e1598. [CrossRef]
175. Lu, X.; Hansen, E.J.; He, G.; Liu, J. Eutectic electrolytes chemistry for rechargeable Zn batteries. Small 2022, 18, 2200550. [CrossRef]
[PubMed]
176. Abranches, D.O.; Coutinho, J.A. Type V deep eutectic solvents: Design and applications. Curr. Opin. Green Sustain. Chem. 2022,
35, 100612. [CrossRef]
177. Abranches, D.O.; Martins, M.A.; Silva, L.P.; Schaeffer, N.; Pinho, S.P.; Coutinho, J.A. Phenolic hydrogen bond donors in the
formation of non-ionic deep eutectic solvents: The quest for type V DES. Chem. Commun. 2019, 55, 10253–10256. [CrossRef]
Batteries 2025, 11, 51 35 of 36

178. Tomé, L.I.; Baião, V.; da Silva, W.; Brett, C.M. Deep eutectic solvents for the production and application of new materials. Appl.
Mater. Today 2018, 10, 30–50. [CrossRef]
179. Hartley, J.M.; Al-Bassam, A.Z.; Harris, R.C.; Frisch, G.; Jenkin, G.R.; Abbott, A.P. Investigating the dissolution of iron sulfide and
arsenide minerals in deep eutectic solvents. Hydrometallurgy 2020, 198, 105511. [CrossRef]
180. Singh, M.K.; Kumar, S.; Ratha, D. Physiochemical and leaching characteristics of fly and bottom ash. Energy Sources Part A
Recovery Util. Environ. Eff. 2016, 38, 2377–2382. [CrossRef]
181. Smith, E.L.; Abbott, A.P.; Ryder, K.S. Deep eutectic solvents (DESs) and their applications. Chem. Rev. 2014, 114, 11060–11082.
[CrossRef]
182. Richter, J.; Ruck, M. Synthesis and dissolution of metal oxides in ionic liquids and deep eutectic solvents. Molecules 2019, 25, 78.
[CrossRef] [PubMed]
183. Sudová, M.; Sisol, M.; Kanuchova, M.; Marcin, M.; Kurty, J. Environmentally Friendly Leaching of Antimony from Mining
Residues Using Deep Eutectic Solvents: Optimization and Sustainable Extraction Strategies. Processes 2024, 12, 555. [CrossRef]
184. Abbott, A.P.; Al-Bassam, A.Z.; Goddard, A.; Harris, R.C.; Jenkin, G.R.; Nisbet, F.J.; Wieland, M. Dissolution of pyrite and other
Fe–S–As minerals using deep eutectic solvents. Green Chem. 2017, 19, 2225–2233. [CrossRef]
185. Jenkin, G.R.; Al-Bassam, A.Z.; Harris, R.C.; Abbott, A.P.; Smith, D.J.; Holwell, D.A.; Chapman, R.J.; Stanley, C. The application of
deep eutectic solvent ionic liquids for environmentally-friendly dissolution and recovery of precious metals. Miner. Eng. 2016,
87, 18–24. [CrossRef]
186. Sakamoto, T.; Hanada, T.; Sato, H.; Kamisono, M.; Goto, M. Hydrophobic deep eutectic solvents for the direct leaching of nickel
laterite ores: Selectivity and reusability investigations. Sep. Purif. Technol. 2024, 331, 125619. [CrossRef]
187. Fajar, A.T.N.; Hanada, T.; Hartono, A.D.; Goto, M. Estimating the phase diagrams of deep eutectic solvents within an extensive
chemical space. Commun. Chem. 2024, 7, 27. [CrossRef]
188. Jafari, M.; Shafaie, S.Z.; Abdollahi, H.; Entezari-Zarandi, A. Green recycling of spent Li-ion batteries by deep eutectic solvents
(DESs): Leaching mechanism and effect of ternary DES. J. Environ. Chem. Eng. 2022, 10, 109014. [CrossRef]
189. Lu, B.; Du, R.; Wang, G.; Wang, Y.; Dong, S.; Zhou, D.; Wang, S.; Li, C. High-efficiency leaching of valuable metals from waste
Li-ion batteries using deep eutectic solvents. Environ. Res. 2022, 212, 113286. [CrossRef]
190. Henderson, K.; Loreau, M. A model of Sustainable Development Goals: Challenges and opportunities in promoting human
well-being and environmental sustainability. Ecol. Model. 2023, 475, 110164. [CrossRef]
191. Li, H.; Qiu, H.; Schirmer, T.; Goldmann, D.; Fischlschweiger, M. Tailoring Lithium Aluminate Phases Based on Thermodynamics
for an Increased Recycling Efficiency of Li-Ion Batteries. ACS EST Eng. 2022, 2, 1883–1895. [CrossRef]
192. Hu, D.; Ma, B.; Lv, Y.; Zhao, Q.; Wang, C.; Chen, Y. A Sustainable Process for Efficient Extraction of Lithium, Aluminum, and
Phosphorus from Montebrasite. ACS Sustain. Chem. Eng. 2024, 12, 3439–3449. [CrossRef]
193. Yousefian, M.; Bascompta, M.; Sanmiquel, L.; Vintró, C. Corporate social responsibility and economic growth in the mining
industry. Extr. Ind. Soc. 2023, 13, 101226. [CrossRef]
194. Lu, Q.; Chen, L.; Li, X.; Chao, Y.; Sun, J.; Ji, H.; Zhu, W. Sustainable and Convenient Recovery of Valuable Metals from Spent
Li-Ion Batteries by a One-Pot Extraction Process. ACS Sustain. Chem. Eng. 2021, 9, 13851–13861. [CrossRef]
195. Onifade, M.; Adebisi, J.A.; Shivute, A.P.; Genc, B. Challenges and applications of digital technology in the mineral industry.
Resour. Policy 2023, 85, 103978. [CrossRef]
196. Lööw, J.; Nygren, M. Initiatives for increased safety in the Swedish mining industry: Studying 30 years of improved accident
rates. Saf. Sci. 2019, 117, 437–446. [CrossRef]
197. Ganthavee, V.; Trzcinski, A.P. Artificial intelligence and machine learning for the optimization of pharmaceutical wastewater
treatment systems: A review. Environ. Chem. Lett. 2024, 22, 2293–2318. [CrossRef]
198. Shen, S.C.; Khare, E.; Lee, N.A.; Saad, M.K.; Kaplan, D.L.; Buehler, M.J. Computational Design and Manufacturing of Sustainable
Materials through First-Principles and Materiomics. Chem. Rev. 2023, 123, 2242–2275. [CrossRef] [PubMed]
199. Rene, E.R.; Sethurajan, M.; Kumar Ponnusamy, V.; Kumar, G.; Bao Dung, T.N.; Brindhadevi, K.; Pugazhendhi, A. Electronic waste
generation, recycling and resource recovery: Technological perspectives and trends. J. Hazard. Mater. 2021, 416, 125664. [CrossRef]
200. Meng, K.; Xu, G.; Peng, X.; Youcef-Toumi, K.; Li, J. Intelligent disassembly of electric-vehicle batteries: A forward-looking
overview. Resour. Conserv. Recycl. 2022, 182, 106207. [CrossRef]
201. Ni, D.; Xiao, Z.; Lim, M.K. Machine learning in recycling business: An investigation of its practicality, benefits and future trends.
Soft Comput. 2021, 25, 7907–7927. [CrossRef]
202. Microsoft. Accelerating the Discovery of Battery Materials with AI 2024; Science/AAAS Custom Publishing Office: Washington, DC,
USA, 2024.
203. Goodfellow, I.; Pouget-Abadie, J.; Mirza, M.; Xu, B.; Warde-Farley, D.; Ozair, S.; Courville, A.; Bengio, Y. Generative adversarial
networks. Commun. ACM 2020, 63, 139–144. [CrossRef]
204. Goldman, J.; House, K. AI Hunts for Hidden Minerals: Machine Learning is Uncovering Hoards of Vital EV Battery Metals. IEEE
Spectr. 2023, 60, 22–27. [CrossRef]
Batteries 2025, 11, 51 36 of 36

205. Conover, E. Artificial intelligence helped scientists create a new type of battery. Science News, 16 January 2024.
206. Chen, C.; Nguyen, D.T.; Lee, S.J.; Baker, N.A.; Karakoti, A.S.; Lauw, L.; Owen, C.; Mueller, K.T.; Bilodeau, B.A.; Murugesan, V.
Accelerating computational materials discovery with artificial intelligence and cloud high-performance computing: From
large-scale screening to experimental validation. arXiv 2024, arXiv:2401.04070. [CrossRef]
207. Hargreaves, C.J.; Gaultois, M.W.; Daniels, L.M.; Watts, E.J.; Kurlin, V.A.; Moran, M.; Dang, Y.; Morris, R.; Morscher, A.;
Thompson, K.; et al. A database of experimentally measured lithium solid electrolyte conductivities evaluated with machine
learning. npj Comput. Mater. 2023, 9, 9. [CrossRef]
208. Shimano, Y.; Kutana, A.; Asahi, R. Machine learning and atomistic origin of high dielectric permittivity in oxides. Sci. Rep. 2023,
13, 22236. [CrossRef] [PubMed]
209. Bhowmik, A.; Berecibar, M.; Casas-Cabanas, M.; Csanyi, G.; Dominko, R.; Hermansson, K.; Palacin, M.R.; Stein, H.S.; Vegge, T.
Implications of the BATTERY 2030+ AI-Assisted Toolkit on Future Low-TRL Battery Discoveries and Chemistries. Adv. Energy
Mater. 2022, 12, 2102698. [CrossRef]
210. Eguchi, M.; Han, M.; Asakura, Y.; Hill, J.P.; Henzie, J.; Ariga, K.; Rowan, A.E.; Chaikittisilp, W.; Yamauchi, Y. Materials Space-
Tectonics: Atomic-level Compositional and Spatial Control Methodologies for Synthesis of Future Materials. Angew. Chem. Int. Ed.
2023, 62, e202307615. [CrossRef] [PubMed]
211. Zhang, Y.; He, X.; Chen, Z.; Bai, Q.; Nolan, A.M.; Roberts, C.A.; Banerjee, D.; Matsunaga, T.; Mo, Y.; Ling, C. Unsupervised
discovery of solid-state lithium ion conductors. Nat. Commun. 2019, 10, 5260. [CrossRef] [PubMed]

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual
author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to
people or property resulting from any ideas, methods, instructions or products referred to in the content.