Bill Fleming

Automotive Electronics Senior Editor

Electric Vehicle Collaboration—

Toyota Motor Corporation and Tesla Motors

T wo years ago, Toyota Motor

Corporation (Gardena, Califor-
nia) and Tesla Motors (Palo Alto,
in Cambridge, Ontario,
Canada. The electric
powertrain for the
California) announced that they had RAV4 EV is manufac­
entered into a collaborative partner- tured by Tesla Motors
ship. Toyota wanted to come out in Fremont, California,
with an electric vehicle (EV), and and shipped to Toyota’s
they wanted to do so sooner rather plant in ­ Canada for
than later [1]. In the meantime, Tesla installation. All RAV4
Motors was developing their Model EVs will be monospec,
S, an all-electric roadster [2]. Their which means that they Figure 1  The 2012 Toyota RAV4 EV is basically a normal
collaboration produced the 2012 will only have one RAV4 but with an electric powertrain [1]. (Photo courtesy
RAV4 EV—an all-electric-powered, stan­dard trim pack- of Toyota Motor Corp., Gardena, California.)
five-passenger, cross-over sport age. RAV4 EVs are
utility vehicle (SUV). available in select dealerships solely had good range and, on the other
As the name implies, the RAV4 in California (to meet California man- hand, could provide “spirited” driv-
EV, shown in Figure 1, is basicially dates requiring a minimum number ing. So they developed a system
a normal RAV4 vehicle but with of zero-emission vehicles sold during that has both normal and sport
an electric powertrain. Tesla Mo- 2012–2014). modes, with the latter providing a
tors contributed all of the RAV4’s A liquid-cooled battery pack of more aggressive accelerator feel
electric powertrain components, the RAV4 EV consists of some 4,500 as well as boosting the maximum
including the motor and lithium- cells and is rated at 41.8 kWh. The speed. In sport mode, the claimed
ion (Li-ion) battery pack. Toyota battery is capable of providing at 0–to–60-mi/h time drops from 8.6
provided the RAV4 chassis and the least 129 kW of instant power dur- to 7.0 s, and the top speed climbs
body. The RAV4 electric motor out- ing 30 s of wide-open throttle accel- to 160 from 135 km/h (100 from
put is routed through a single-speed eration. The nominal motor output 85 mi/h) [3].
transmission to its front wheels is 115 kW (154 hp). The charge time They also designed the EV charg-
[3]. The single-speed transmission for the battery, using a 240-V 40-A ing to have two modes: standard and
takes advantage of the electric mo- ac charger, is 5–6 h. There is also a extended. In standard mode, the bat-
tor’s flat torque curve from zero to 120-V 12-A charging cable provided tery charges to 35 kWh. This provides
mid-operating-range engine speeds. with the vehicle for use when 240-V enough power to drive a U.S. Environ-
This is a decidedly low-volume charging is not available. This op- mental Protection Agency–estimated
vehicle—approximately 2,600 RAV4 tion is used when there is a lot of range of 92 mi (148 km)—the stan-
EVs will be produced during a three- time available because in this case dard charging mode helps maximize
model-year period (2012–2014) at the battery takes approximately 44 h battery life. On the other hand, the
Toyota’s Motor Manufacturing plant to recharge [1]. extended range mode allows the
One of the things that Toyota and battery to charge to its full capacity
Digital Object Identifier 10.1109/MVT.2012.2233933 Tesla Motors worked on was creat- of 41.8 kWh, which provides an esti-
Date of publication: 26 February 2013 ing a vehicle that, on the one hand, mated range of 113 mi (182 km) [1].

4 ||| 1556-6072/13/$31.00©2013ieee IEEE vehicular technology magazine | march 2013

 The RAV4 EV includes remote
climate control, which allows pre-
heating or precooling the cabin via a
smartphone. It can control the heat-
ing, ventilation, and air conditioning
system while the vehicle is plugged
in, so that the draw on the battery is
reduced once the SUV is unplugged
and driving on the road. The RAV4
EV’s infotainment system, in navi-
gation display mode, is shown in
Figure 2.

EV Technology Forecast
In 2012, three zero-emission all-
electric vehicles (pure EVs) were
available to consumers. They were
the Ford Focus Electric, Mitsubishi
MiEV, and Nissan Leaf. By 2020, it is Figure 2  The RAV4 EV navigation display provides information on the vehicle’s range
and the location of charging stations. The concentric shaded circles on the display show
forecasted that every major vehicle differences in range that can be achieved by shutting the climate system off versus
manufacturer will likely be offering having it on [1]. (Photo courtesy of Toyota Motor Corp., Gardena, California.)
at least one all-electric EV [4].
According to the study, “Automo-
tive 2020: Clarity Beyond the Cha-
os,” by Gartner Industry Advisory
Services (Stamford, Connecticut),
most vehicles will have some form
of electric hybridization by 2020.
EV powertrains will range from
regenerative brake-powered mild
hybrids that merely boost gas mile-
age to plug-in hybrids like the Chevy
Volt (Figure 3) that seldom use their
gasoline engine [4].
The internal combustion engine
is expected to be dominant for the
next 15 years and maybe even lon-
ger. By 2020, only 5–8% of vehicles Figure 3  The Chevy Volt runs in all-electric EV mode for about 35 mi and has most of its
are expected to be at least partly recharging electronics onboard. Its recharging connect ports are shown [4]. (Photo courte-
powered by electric motor, with all- sy of Chevrolet, Detroit, Michigan.)

electric models only accounting for

2–3% of vehicle sales.
An important EV market factor the EV market share could exceed the that could stimulate quicker consum-
could be a breakthrough in battery current forecasts. For now, efforts like er acceptance of EVs.”
technology. Many of today’s EV man- IBM’s Battery 500 Project (see the sec- Current EV model vehicles are
ufacturers continue to use nickel- tion “IBM Li-Air Battery 500 Project”), limited to under 100-mi ranges due
metal hydride (NiMH) or lead–acid which are focusing on Li-air technol- to the extra cost (US$10,000) and
batteries in their first-generation ogy, will not hit the market until 2025. weight [600 lb (270 kg)] of Li-ion bat-
hybrids. However, most new EV “Despite the huge investments tery packs. With cheaper, lightweight
designs are presently transition- currently being made in Li-ion manu- Li-air batteries, EVs might ultimately
ing to Li-ion batteries that provide facturing capacity, NiMH may still be achieve a 500-mi range at the same
over three times more usable energy the dominant battery for the next weight as gasoline vehicles, allow-
density, typically 160 kWh/kg [4]. seven years,” said Rick Doherty of ing EVs to match or exceed the range
And if a breakthrough battery tech- Envisioneering Group (Seaford, New of the internal combustion engine.
nology like Li-air is commercialized, York). “And Li-air is the wild card Doherty said, “In the long run, pure

MARCH 2013 | IEEE vehicular technology magazine ||| 5

EVs will win because their EV Li-Ion Battery Pack
range will keep extending as In mild-hybrid EVs, a vehicle’s
their fuel efficiency and per- internal combustion engine is
formance will get better and controlled by a stop/start con-
better” [4]. trol system. Such vehicles are
equipped with electric motor/
EV Recharging Infrastructure generators that allow their
An electric recharging infra- engines to be turned off when-
structure similar to today’s ever the car is coasting, is brak-
nationwide network of gas ing, or has stopped, and yet
stations is slowly falling into restart quickly. Most mild
place in the United States. In Figure 4  Nissan’s Leaf all-electric EV includes two ports to hybrids utilize regenerative
an attempt to solve the support both 240-V ac recharging (red, right) and fast 480-V braking to recharge the battery.
dc charging (black, left) [4]. (Photo courtesy of Nissan North
“chicken-or-egg” problem that America Inc., Smyrna, Tennessee.) Although mild-hybrid EVs only
buyers need to see charging provide modest improvements
stations before they will buy in fuel efficiency of 10–15%,
EVs, charging stations are beginning with precharged battery packs in less they are increasing in popularity
to sprout up in larger cities and time than it takes to fill up at the gas because they are considerably cheap-
along some U.S. interstate high- pump. As part of a pilot project, Better er than full-hybrid systems [5].
ways. Currently, a US$230 million Place is installing battery-switching In a bid to further increase the
U.S. Energy Department EV project stations in the Bay Area, San Fran- fuel efficiency of mild-hybrid EVs,
is installing recharging infrastruc- cisco, California, to support a fleet of DENSO International America Inc.
ture in six states. In addition, a West EV taxis with switchable battery. (Southfield, Michigan) has devel-
Coast Green Highway initiative is Ford Motor’s EV, Focus, is being oped a new Li-ion battery pack. The
installing public, fast-charging sta- marketed as a direct competitor battery pack allows the stop/start
tions along Interstate I-5 between to Nissan’s Leaf. Eric Kuehn, Ford system to store more regenerative
Vancouver and San Diego [4]. Motor’s chief engineer for hybrids power than current conventional
Three basic types of EV recharg- and EVs, said their EV, Focus, has systems, which typically use a sin-
ers are currently available: more horsepower and a lighter bat- gle lead-acid battery [6]. DENSO’s
■■ The first type uses a standard tery providing 107 kW. “The Focus battery pack is shown in Figure 5.
120-V, 15-A ac outlet to recharge a has 23% more power than the Leaf, This battery pack stores regen-
battery to as much as 3 kW in and if you purchase the 240-V charg- erated power and then supplies
about 10 h. ing station you’ll also be able to fully the stored power to electrical and
■■ The second type costs about charge it in about half the time,” electronic components, such as car
US$1,500 and delivers 240-V ac Kuehn claimed. Nissan counters navigation and audio systems. This
power, which is converted to dc to that, unlike the Focus, the Leaf has reduces the power generation re-
recharge EV batteries to as much a fast-recharge port that can fill its quired by the alternator, which re-
as 7 kW in between 4 and 8 h. battery pack to 80% of capacity in sults in an overall load reduction on
■■ A high-end EV recharger, which about 30 min [4]. the engine and improves the vehicle’s
costs about US$15,000, converts fuel economy.
480 V of ac power to high-current DENSO’s battery pack is naturally
dc for recharging to up to 100 kW air cooled and therefore does not
in under 1 h. require a dedicated battery cooling
EVs with a fast-charge connect system. There is no need for auxiliary
port, like the one used in Mitsubishi’s cooling components, allowing the bat-
MiEV vehicle and Nissan’s Leaf tery pack to be lighter and more com-
(Figure 4), permit recharge in under 1 pact. This provides automakers more
h. Despite the convenience, consum- design flexibility, which is important
ers continue to balk at spending more for vehicles with limited space.
time at a charging station than at a The battery pack has three main
gas pump, relegating most of their re- Figure 5  DENSO’s battery pack consists of components [6]:
charging to evenings [4]. a battery management unit, a power sup- ■■ a battery management unit that
A 1-min recharge is the goal of Bet- ply control switch, and battery cells (which monitors and controls the voltage
are supplied by third-party sources) [6].
ter Place (Palo Alto, California), which (Photo courtesy of DENSO International of the Li-ion battery cells to main-
switches out depleted battery packs America Inc., Southfield, Michigan.) tain the proper charge level to

6 ||| IEEE vehicular technology magazine | MARCH 2013

 protect them from overcharge Researchers at IBM-Almaden, San than current systems. “Our battery
and overdischarge Jose, California, have success­ fully would be great for pure-electric
■■ a power supply control switch demonstrated the fundamental chem- types of EVs,” she stated.
that regulates the charging pro- istry of the charge-and-recharge Her idea is to build a dry electro-
cess of the battery cells by regu- process for Li-air batteries (see the lyte Li-ion battery that
lating the energy captured during section “IBM Li-Air Battery 500 Proj- ■■ has a very high power density
vehicle deceleration and braking ect”). Winfried Wilcke, senior manager ■■ would charge and discharge very
(it also controls the amount of for nanoscale science and technology, quickly
power supplied to the car naviga- Energy Storage, IBM-Almaden says, ■■ would still be very safe.
tion, audio, and other systems “We have found that the choice of She says, “If things go well, the
during driving) electrolyte is the key. We’re still in the result will be a cheaper, scalable,
■■ rechargeable Li-ion battery cells science phase of the project; we’re not manufacturable battery” [7].
that have a higher energy density, yet in the engineering phase.” The tar- Traditional Li-ion batteries are ba-
charge more quickly than lead– get dates for a product are 2020–2025. sically two dimensional, with many
acid batteries, and efficiently The findings to date leave Wilcke op- stacked layers limiting the speed of
store more regenerated power timistic that automotive-scale charge/ the power-producing reactions. Pri-
quickly to vehicle’s electronic and recharge cycles—1,000 cycles—are eto and her colleagues plan to use
electrical components. achievable. In addition, recharge cy- electrodeposition to make a three-
cle‐life is further extended because dimensional (3-D) battery wherein
Next-Generation large‐capacity Li‐air batteries do the active components—electrodes
EV Lithium Batteries not typically have to cycle as often and electrolyte—are brought to-
EV batteries today can typically as smaller batteries like those used, gether on a small, intimate scale. As
power electric cars for a maximum for instance, in a present‐day hybrid illustrated in Figures 6 and 7, their
useful distance of about 100 mi (161 EV [7]. design relies on
km). Future EVs will at least need to However, any commercialization ■■ creating a porous foam electrode
go beyond a 300-mi (480-km) driving of Li-air batteries will most likely ■■ conformally coating the porous
range, so a transformational shift is not come until the outcome of cur- electrode with an ultrathin poly-
needed. New types of Li‐air batteries rent efforts to develop advanced mer electrolyte
have the potential to provide this solid-state Li-ion batteries become ■■ surrounding the electrolyte coat-
operating range [7]. clear. A promising Li-ion battery ing with a cathode matrix [7].
In theory, future Li-air batteries R&D project is the Prieto Battery, in- The use of copper antimonide
could offer performance that is ten vented by Amy Prieto, an assistant (Cu2Sb) nanowires, especially elec-
times better than the current state- chemistry professor at Colorado trodeposited onto the porous cop-
of-the-art Li-ion batteries. A fully de- State University, Fort Collins. Pri- per foam, provides much improved
veloped Li-air cell would have high eto hopes to exploit her expertise anode stability. “We plan to prove
specific energy densities (per unit in electrodeposition (a process that out the technology with portable
mass), as much as 100–200 Wh/kg, uses electricity to coat materials on electronics applications and build up
while being lighter and lasting lon- surfaces) to create a battery with to electric and hybrid EV vehicles,”
ger than current batteries. significantly greater power density said Prieto [7].

Negative
Copper Foam Interdigitated
Cathode and Anode

Separator
Positive

1 2 3
Copper-Foam Anode (–) Electrolyte/Separator, Cathode (+),
4
Substrate Electrodeposition Electropolymerization Slurry Coating

Figure 6  The manufacturing process used to fabricate the electrode core of the Prieto Li-ion battery cell is based on electrodeposition. The
high surface area of a porous copper foam substrate first receives an anode coating, then a solid electrolyte/separator coating, and finally a
cathode slurry fills the spaces, leaving a thin coating of solid electrolyte [7]. (Illustration courtesy of Colorado State University, Fort Collins.)

MARCH 2013 | IEEE vehicular technology magazine ||| 7

 to approach the usable specific en-
ergy density of gasoline (Figure 8).
One
Negative Their energy density would be over
Single-Piece Design,
3-D Foam Interdigitated ten times that of the Li-ion batteries
Positive currently used in the Chevrolet Volt,
H2O Nissan Leaf, and Mitsubishi MiEV
and over 30 times that of the NiMH
Water-Based Process
batteries used in Toyota Prius.
3-D
Multidirectional “IBM Li-Air Battery 500 Project
Ion Flow
Copper remains a scientifically very chal-
Electroplated
Foam lenging project, but we have made
significant progress in the last three
Figure 7  The Prieto Li-ion battery, unlike a conventional battery, uses no liquid electrolyte. years,” said Wilcke. “Our goal now is
The cell is actually a single, integrated system that enables lithium ions to flow in three to have major laboratory prototypes
dimensions and in very short distances, which boosts the overall electrochemical reaction. ready by 2014 and achieve commer-
The battery components are made using a green manufacturing process [7]. (Illustration
courtesy of Colorado State University, Fort Collins.) cialization by the middle of the next
decade” [8].
IBM reports that although its
IBM Li-Air Battery 500 Project working on IBM’s Battery 500 Proj- goal to create practical Li-air bat-
IBM-Almaden and its partners Asahi ect, is to use oxygen from air teries remains challenging, so much
Kasei and Central Glass (companies instead of the intercalation (electro- scientific progress has been made
with expertise in membranes and lyte conduction) heavy metal during the first three years that the
electrolyte chemistries) are devel- oxides used in present conventional project should enter the engineering
oping Li-air battery technology Li-ion batteries [8]. phase by 2015. Key to the project’s
aimed at extending the range of EVs By breathing air the same way progress so far has been the use of
up to 500 mi on a single charge. that internal combustion engines do, supercomputer simulations of un-
The concept, according to those lightweight Li-air batteries promise paralleled magnitude to identify the

Strea
m of A
ir

Carbon
Oxygen
Molecules
Cathode Oxygen Molecules Are Absorbed
Connector Through the Carbon Layer
Oxygen and Lithium-Ions React
Anode Chemically, Generating Electrical
Connector Energy and Forming Lithium Peroxide
Li-Ions Dissolved in Electrolyte 1
Electrolyte 1 Impregnate the Carbon Layer
Lithium-Ion The Transport Membrane Prevents
Transport Membrane Contamination of the Different Layers
Electrolyte 2 Lithium Metal Releases Li-Ions in
Lithium Metal Electrolyte 2

Figure 8  During discharge, while powering a vehicle, oxygen from the air reacts with lithium, forming lithium peroxide on a carbon matrix.
Upon recharge, the oxygen is given back to the atmosphere and the lithium ions go back onto the anode [8]. (Illustration courtesy of IBM.)

8 ||| IEEE vehicular technology magazine | MARCH 2013

Figure 9  A vehicle equipped with a V2V and V2I communication Figure 10  The status of upcoming traffic signals and collision
device [9]. The test area consists of about 75 lane-mi (121 km) of warnings will be communicated to drivers [9]. (Photo courtesy of
public roadway in the greater Ann Arbor, Michigan, area. (Photo the U.S. DOT.)
courtesy of the U.S. DOT.)

materials and processes necessary system operability and its effective- level of V2V integrated equipment.
to perfect a practical Li-air battery. ness in reducing crashes. The project data will be used not only
“We are using some of the largest Vehicle awareness devices (VADs) by the DOT but also by participants
supercomputers in the world, built were installed in some of the other for their own internal research
by IBM and owned by the U.S. De- vehicles. VADs only have the capac- and development purposes. “This
partment of Energy, to advance in ity to send speed, location, and head- program will help GM determine a
parallel both our theoretical under- ing data, but they cannot receive or timeline for introducing V2V tech-
standing of the mechanisms at work process incoming messages. nology on our vehicles, globally, in
inside a Li-air battery and the ex- All systems and devices emit a the second half of this decade,” said
perimental results we achieve in the basic safety message ten times/s, Hariharan Krishnan, GM R&D tech­
lab,” said Wilcke. “We are also using which forms a data stream that is nical fellow for perception and ve-
computer models to predict the mo- used by other in-vehicle devices to hicle control systems [9].
lecular composition of materials we determine a potential traffic hazard.
will need, thereby accelerating the Combined with the vehicle’s own References
[1] G. Vasilash. (2012, Aug. 22). “Creating
development process” [8]. data, this information (Figure 10) the RAV4 EV,” Auto. Des. Prod. [Online].
provides highly accurate data that Available: www.autofieldguide.com/articles/
creating-the-rav4-ev
Largest-Ever On-Road are used by the crash-avoidance [2] Tesla Motors. (2012, Sept. 25). Tesla Model
Intelligent Transportations safety-capability systems integrated S: Motor Trend’s 2013 Car of the Year.
[Online]. Available: www.teslamotors.com/
Systems Test Project or installed in vehicles [9]. [3] A . Stoklosa. (2012, May). “The 2012 Toyota
A major real-life demonstration of Information collected from the RAV4 EV,” Car Driver. [Online]. Available:
www.caranddriver.com/news/2012-toyota-
intelligent transportation systems demonstration will be used by rav4-ev-photos-and-info-news
(ITSs) vehicle-to-vehicle (V2V) and the U.S. Department of Transpor- [4] R . Johnson, “Bumpy road to EV 2020,”
Electron. Eng. Times, no. 1629, pp. 24–29,
vehicle-to-infrastructure (V2I) tech- tation’s (DOT) National Highway Oct. 2012.
nologies was launched in Ann Arbor, Traffic Safety Administration unit [5] J. Olvera. (2008, May 12). “Mild hybrid
facts,” GreenCar.com. [Online]. Available:
Michigan, in August 2012. The U.S. to determine whether it should pro- www.greencar.com/articles/5-mild-hybrid-
government, via several of its trans- ceed with additional V2V communi- facts.php
[6] DENSO International America Inc. (2012,
portation-related agencies, is spon- cation activities, including possible Oct. 9). “DENSO develops lithium-ion bat-
soring the demonstration, which it future regulations. tery pack for stop/start systems,” Design-
Fax. [Online]. Available: www.designfax.
claims is the largest-ever road test of A large number of companies and net/cms/dfx/opens/article-view-dfx.php?ni
connected-vehicle crash-avoidance institutions are involved in the proj- d=4&bid=183&et=electrical&pn=01
[7] S. Ashley, “Next-generation lithium bat-
technologies [9]. ect. The University of Michigan’s teries step forward,” AEI-Online, vol. 120,
Roughly 3,000 cars, trucks, and Transportation Research Institute is no. 6, pp. 34–38, Sept. 2012.
[8] R . Johnson, “IBM’s Battery 500 Project:
transit buses are involved in the running the project for the DOT (the Lithium-air batteries could level playing
one-year project. Most of the vehi- DOT is funding 80% of the project’s field for EVs,” Electron. Eng. Times, no. 1629,
p. 26, Oct. 2012.
cles are being provided by volunteer US$25 million cost). [9] P. Ponticel, “Cars converse in largest-
participants. As shown in Figure 9, General Motors (GM) is one of the ever on-road ITS test project,” AEI-Online,
vol. 120, no. 7, pp. 8–10, Oct. 2012.
some vehicles are equipped with automakers involved in the project.
V2V and V2I communication devic- It will run eight Buick and Cadillac
es that gather extensive data about models that will include the highest 

MARCH 2013 | IEEE vehicular technology magazine ||| 9