How does an electrolyte allow a fuel cell to operate?
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.
In a fuel cell, the electrolyte is essential for completing the system's chemical process by conducting ions between the anode and the cathode.1
The electrolyte allows the fuel cell to operate through the following functions:
- Ion Transport: It acts as a medium that facilitates the movement of ions between the two electrodes, which is necessary to complete the internal circuit of the electrochemical system.1
- Separation: It physically separates the anode and cathode while remaining in contact with both, ensuring that the oxidation of fuel at the anode and the reduction of the oxidizer at the cathode can occur in a controlled manner.1
- System Determination: The specific type of electrolyte used is a primary factor in classifying fuel cells, as it dictates the system's operating temperature and influences the types of fuels that can be effectively employed.2
To maintain stable operation, the electrolyte must be carefully managed; if an electrode floods with the electrolyte, the reaction rate slows significantly, and pressure must be controlled to prevent gases from entering the electrolyte compartment.3