How is a fuel cell different from a battery?
The proton exchange membrane is one of the most advanced fuel cell designs. Hydrogen gas under pressure is forced through a catalyst, typically made of platinum, on the anode (negative) side of the fuel cell. At this catalyst, electrons are stripped from the hydrogen atoms and carried by an external electric circuit to the cathode (positive) side. The positively charged hydrogen ions (protons) then pass through the proton exchange membrane to the catalyst on the cathode side, where they react with oxygen and the electrons from the electric circuit to form water vapour (H2O) and heat. The electric circuit is used to do work, such as power a motor.
While a fuel cell and a battery both convert chemical energy into electrical energy using electrodes and an electrolyte, they differ fundamentally in how they store and consume energy.12
- Fuel Source: A battery contains a limited, internal supply of reactants that are depleted as the device is used. In contrast, a fuel cell is an open system that is continuously supplied with fuel (such as hydrogen) and an oxidizer (such as oxygen) from an external source.21
- Longevity: Because fuel cells are continuously replenished, they can provide electrical energy over a much longer period than a battery, provided the fuel supply is maintained.2
- Design: The electrodes and electrolyte in a fuel cell are designed to remain unchanged by the chemical reaction, whereas the internal components of a battery are consumed or altered during discharge.1
- Complexity: A practical fuel cell is a complex system requiring auxiliary equipment like pumps, blowers, and sensors to manage the continuous flow of reactants, whereas a battery is typically a self-contained unit.13