Shivani
Fuel cells are devices that convert chemical energy directly into electrical energy through an
electrochemical reaction, not combustion. They typically use hydrogen as fuel and oxygen (from the
air) as the oxidant. The key components are:
1. Anode: Where hydrogen molecules are split into protons and electrons.
2. Cathode: Where oxygen reacts with the protons and electrons to form water.
3. Electrolyte: Allows only protons to pass through, forcing electrons to take an external circuit,
creating an electric current.
The overall reaction is:
2H2+O2→2H2O+Electricity + Heat2H_2 + O_2 \rightarrow 2H_2O + \text{Electricity + Heat}2H2+O2
→2H2O+Electricity + Heat
Fuel cells are efficient and clean, producing water as the only byproduct, making them a promising
alternative energy source for applications like vehicles, power plants, and portable electronics.
This is a schematic diagram of a fuel cell, showing its components and how it operates. Here's an
explanation of the key parts:
1. Fuel Inlet (Left Side):
o Hydrogen gas (H₂) is supplied here as the fuel.
2. Anode (Yellow Layer):
o At the anode, hydrogen molecules (H₂) split into protons (H⁺) and electrons (e⁻)
through a reaction with a platinum catalyst.
o Reaction: H2→2H++2e−H_2 \rightarrow 2H^+ + 2e^-.
3. Electrolyte (Middle Layer):
o The electrolyte only allows protons (H⁺) to pass through to the cathode.
o Electrons (e⁻) cannot pass through the electrolyte and are forced to travel through
an external circuit.
4. External Circuit:
o The electrons flow through the external circuit, creating an electric current (useful
electricity), which can power devices. The resistance RLR_L shown here represents
the load (e.g., a motor or lightbulb).
5. Cathode (Red Layer):
o At the cathode, oxygen gas (O₂) from the air combines with the incoming protons
(H⁺) and electrons (e⁻) to form water (H₂O).
o Reaction: 2H++2e−+12O2→H2O2H^+ + 2e^- + \frac{1}{2}O_2 \rightarrow H_2O.
6. Air Inlet (Right Side):
o Oxygen (O₂) is supplied here for the reaction at the cathode.
7. Excess Fuel Outlet (Left Bottom):
o Any unused hydrogen fuel is released here.
8. Unused Gases Outlet + Water (Right Bottom):
o Water, the byproduct of the reaction, exits here along with any unused oxygen or
other gases.
Key Takeaways:
Input: Hydrogen and oxygen.
Output: Electricity, water, and heat.
Working Principle: Chemical energy of hydrogen is converted directly into electrical energy
through an electrochemical process. This makes fuel cells efficient and environmentally
friendly, as they emit only water as a byproduct.
