Pretty Porous

Explanation of the Cathode and Anode

Explanation of the Cathode and Anode

The hydrogen is fed into the cell on the anode side and transported through the GDL and MPL. Hydrogen molecules are split into protons and electrons in the CL, the catalyst layer. This is the anode reaction in the fuel cell. The electrons are transported via the MPL, GDL and the anode gas distributor into the electrical circuit and to the consumer (e.g. electric motor). The protons reach the cathode side of the fuel cell by passing the proton permeable PEM layer. On the cathode side there is a mirrored stack of the porous layers. Oxygen is transported into the cell by the air via the gas distributor and distributed homogeneously on the catalyst layer via the GDL and MPL. There, the oxygen molecules react with the protons which have passed through the membrane into the cathode catalyst layer. During this cathode reaction, electrons are consumed, which enter the cathode from the electrical circuit.

The reaction of protons, electrons and oxygen molecules produces water and heat. Both must be transported out of the cell via the porous layers on the cathode side.

If the water cannot be removed, too many water molecules accumulate in the fuel cell. This leads to a high condensation rate. If there is too much liquid water on the cathode side, the paths through which the oxygen can reach the catalyst layer are blocked. This can lead to a reduction in performance.

If the heat cannot be dissipated, this leads to fuel cell damage. At elevated temperatures, reactions take place in the catalyst layers, which should not take place there and which damage the material. The oxidation processes lead to premature “ageing” of the fuel cell.