The Functions and Materials of a Fuel Cell

Introduction:

A fuel cell can be descried as "a plant" because it uses fuel as input and produces electricity as an output. What makes a different between a fuel cell and a battery that fuel cells continue to produce electricity as long as fuel is supplied. Both of them depend greatly on electrochemistry in their function. Engines covert energy of a combustion reaction to a mechanical energy while fuel cells transfer the energy of a chemical reaction to an electrical energy. Fuel cells utilize the movement of electrons in the chemical reaction to create a current flow.

The movement of electrons are caused by oxidation and reduction reaction:

H2(g)→ 2H+(aq) + 2e- (Oxidation )

2H+(aq) + 2e- + 1/2O2(g)→H2O (l) (Reduction)

A fuel cell is a device that uses hydrogen as a reactant and produces electrons and water. The technology of fuel cells is based mainly on the following chemical reaction:

2H2(g) + O2(g)↔ H2O(l) (Net reaction)

Fuel cell produces electricity with high efficiency since it converts the energy resulted from the chemical reaction to electricity directly. Other devices transfer the chemical energy to another form of energy such as mechanical then they convert the mechanical energy to electricity. In each step (conversion of energy) there is loss of energy (friction or heat for instance) so a fuel cell does the desired conversion in one step and that leads to less energy loss.

Fuel cell consists of the electrolyte which keeps the reactants from mixing together (a membrane), two electrodes (cathode and anode) which are usually catalyst. Some cells have in addition to that pi polar plates. They collect the current and cr...

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... chromite due to its high thermal expansion compatibility. In addition, for operating temperature less than 700 oC, stainless steels could be used as a constructed material for interconnects, which is cheap and readily available.

Cathode:

Nowadays, the most commonly used cathode material is lanthanum manganite (LaMnO3) along with basic elements, which is an electronically conducting material. For example, most of the cathode electrodes are made of: strontium-doped lanthanum manganite, lanthanum strontium ferrite, lanthanum strontium cobaltite or lanthanum strontium cobaltite ferrite. In addition, the selection of the cathode material is highly depending on the electrolyte material. To illustrate, for Zirconia electrolyte, Lanthanum strontium manganite (LSM) is the best choice based on yttria stabilized zirconia electrolyte due to its high electrical conductivity.