Fuel Cells Tutorial
- A fuel cell is a galvanic (voltaic) cell in which the reactants are continuously fed into the cell as the cell produces electricity.
- Fuel cells are more efficient at converting the chemical energy of fuels into electrical energy compared to the combustion of the same fuel in air.
- In general, a fuel cell produces about 0.7 volts.
- A generalised fuel cell is shown below:
e- →electrolytefuel →← oxidant← excess fuelexcess oxidant →waste
- At the anode:
The fuel is the reductant (reducing agent).
The fuel is the substance that will be oxidised.
The oxidation of the fuel produces electrons.
The anode is negative.
Oxidation occurs at the anode.
Electrons flow from the anode (-) to the cathode (+)
- At the cathode:
The oxidant (oxidizing agent) is the substance that will be reduced.
The reduction of the oxidant consumes electrons.
The cathode is positive.
Reduction occurs at the cathode.
- The porous electrodes:
(a) conduct electrons
(b) physically separate the fuel and the oxidant
(c) allow contact between the reactants and the electrolyte
(d) act as catalysts for the oxidation and reduction reactions
- Maximum voltage that can be delivered by the cell during discharge is equal to the electrode potential for the spontaneous redox reaction.
Under standard conditions, maximum voltage during discharge = Eo(redox)