Laser engraving of embossing plates
At the anode side of the fuel cell, hydrogen is supplied as fuel gas. The protons pass through the proton exchange membrane while the electrons pass through an external circuit to generate electric energy.
At the cathode side of the fuel cell, oxygen (out of the air) is supplied. The oxygen molecules react with the protons, transported through the membrane, and the electrons from the anode side to form water.
Directly next to the anode and cathode is the gas distribution system. This layer provides an even distribution of the fuel gas (hydrogen) on the anode side and oxygen on the cathode side over the complete surface of the electrodes. Efficient gas distribution is necessary for an even reaction and to avoid hotspots.
The diffusion layer lies between the gas distribution layer and the electrode. Its task is to optimize the gas exchange by transporting the fuel gas and oxygen evenly to the reaction layers.
Directly next to the diffusion layer is the reaction layer. Fuel gas (hydrogen) and oxygen meet with the protons that diffuse through the membrane on this layer. At this point, the electric reaction takes place, which releases electrons and protons.
You can find the proton exchange membrane (PEM) in the middle of the fuel cell. This membrane is one of the central components of the PEM-fuel cell as it conducts the protons but is electrically insulating so that electrons cannot pass through it. The PEM makes the separation of fuel gas (hydrogen) and oxygen and makes the proton transport between the electrodes possible.
The interaction of the components – anode, cathode, gas distribution, diffusion layer, reaction layer, and membrane – makes it possible for the PEM-fuel cell to generate environmentally friendly electricity without producing harmful emissions.