Fuel Cell

A fuel cell is an electrochemical device that directly converts the chemical energy of a reaction into electrical energy. The main structure of a fuel cell consists of an electrolyte, an anode electrode, and a cathode electrode. A typical fuel cell includes the reactant gases, product gases, and the path of ion movement, as illustrated.

Theoretically, a fuel cell can continuously generate electricity as long as the oxidizing agent and fuel are supplied to the electrodes. In practice, however, wear, corrosion, and poor performance of components reduce the fuel cell’s lifespan. In a fuel cell, fuel is continuously supplied to the anode and oxygen to the cathode, where electrochemical reactions occur, generating electric potential and allowing current flow.

Although a fuel cell shares some components and features with a battery, it differs significantly in operation. A battery is an energy storage device whose energy output depends on the chemical reactants stored within it. Once the reactants are consumed, the battery stops generating electricity. Rechargeable batteries restore reactants through an external energy supply, but the energy is still limited by the stored chemicals.

In a fuel cell, an oxidizing gas, such as oxygen from the air, flows through the cathode and reacts electrochemically with the fuel—typically hydrogen—at the anode. This converts the chemical energy of the reactants into electrical energy.

Any chemically oxidizable substance that can be continuously supplied (as a fluid) can serve as fuel at the anode, while a suitable reducible substance can act as the oxidant at the cathode. Hydrogen is ideal as a fuel due to its high reactivity and energy density. It can be produced from hydrocarbons via catalytic reactions or from water through electrolysis and stored in various forms. Oxygen is typically obtained directly from the air.

At the anode and cathode, oxidation and reduction reactions occur in the three-phase region (or two-phase if the electrolyte is solid) near the interface of reactants, catalyst, and electrolyte. This region