Structure of the fuel cell stack and functions of its parts

The ion exchange membrane is composed of an extremely thin polymer layer (PEM, or proton exchange membrane, which exchanges positive ions). This membrane is sandwiched between two electrodes (the hydrogen electrode and the oxygen electrode), which in turn are sandwiched between separators to compose one cell. These cells are stacked, and when the electricity generated by each cell is combined, a large voltage is produced.
MEA (Membrane Electrode Assembly)
This is the area in the fuel cell where the reaction that generates the electricity takes place. Hydrogen (H2) is separated into hydrogen ions (H+) and electrons (e-) at the hydrogen electrode. Only the hydrogen ions (H+) are permitted to pass through the electrolytic membrane, where they react with the oxygen (O2) at the oxygen electrode to form water (H2O). Meanwhile, the separated electrons (e-) pass through an external circuit, creating electrical energy.
Electrolytic membrane (ion exchange membrane)
The membrane is composed of a polymer layer that is electrolyzed when impregnated with water, making it permeable only to positive ions (H+). It also plays a role in gas separation and electrical insulation.
Electrode layer
This is the layer where the re-oxidization reaction between the hydrogen and oxygen occurs. It incorporates a catalyst to facilitate the reaction.
Diffusion layer
Located between the electrolytic membrane and the separator, this is where the reactive gas is evenly diffused over the electrode layer.
Separator
Inside the fuel cell, paths are required to supply the hydrogen and oxygen to the respective electrodes of the MEA. Also, heat is produced during the reaction that generates the electricity, necessitating a route for the coolant medium. The separator ensures that all these separate elements flow as required without being mixed together. On top of this, the separator also provides a direct path for the electrical current produced in the MEA.
Structure of the fuel cell stack and functions of its parts
 


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1. How electricity is generated
2. Structure and Function
 


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