A fuel cell consists of a hydrogen electrode (fuel electrode) on the negative side (hydrogen electrode) and an oxygen electrode (air or oxygen electrode) on the positive side (oxidation electrode). An electrolyte separates the two electrodes. Different types of fuel cells use different electrolytes, including acidic, alkaline, molten salt, or solid electrolytes. In a fuel cell, fuel and oxidant react electrochemically through a catalyst to produce electricity and water (H2O) during energy conversion. Therefore, it does not produce nitrogen oxides (NOx) or hydrocarbons (HC) that pollute the atmosphere.
The difference between fuel cells and ordinary batteries is:
1. A fuel cell is an energy conversion device that requires an input of energy (fuel) to produce electrical energy. A regular battery is an energy storage device that requires electrical energy to be stored in the battery first. When it is working, it can only output electrical energy and does not require an input of energy or produce electrical energy. This is the essential difference between fuel cells and regular batteries.
2. Once the technical performance of a fuel cell is determined, the electrical energy it can generate depends solely on the fuel supply. As long as fuel is supplied, electrical energy can be generated, and its discharge characteristic is continuous. In contrast, once the technical performance of a conventional battery is determined, it can only output electrical energy within its rated range, and it can only be reused after repeated charging. Its discharge characteristic is intermittent.
3. While the fuel cell itself is relatively small in mass and volume, it requires a fuel storage or fuel conversion device and auxiliary equipment to obtain hydrogen. The mass and volume of these devices far exceed that of the fuel cell itself. During operation, fuel is gradually consumed as the fuel cell generates electricity, causing its mass to gradually decrease (referring to the limited onboard fuel). Ordinary batteries, on the other hand, lack other auxiliary equipment. Once their technical performance is determined, their mass and volume remain essentially unchanged regardless of whether they are fully charged or fully discharged.
4. Fuel cells convert chemical energy into electrical energy, as do ordinary batteries; this is their commonality. However, when fuel cells generate electricity, the reactants involved in the reaction are continuously consumed and not reused, thus requiring a constant input of reactants. In contrast, the active materials in ordinary batteries change with charging and discharging. These active materials undergo repeated reversible chemical changes and are not consumed; only electrolytes and other substances need to be added.
