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Principle of a Fuel Cell
A fuel cell converts the fuel‘s chemical energy (e. g. hydrogen) directly to electricity by a highly efficient catalytic reaction. In contrast to the electrodynamic principle (dynamo), no motion is necessary for the generation of electricity. Each hydrogen molecule (H2) reacts to two H+ ions by splitting off two electrons on one side of an electrically non-conductive, gastight but proton-conducting membrane (PEM = Proton Exchange Membrane), at the presence of a noble metal catalyst (e. g. homogeneously distributed small platinum particles). The hydrogen protons are transported to the other side through the membrane, where another catalytic reaction with an oxygen ion (O2-, e. g. out of air) to water vapor (H2O) occurs. In order to enable this reaction, the electrons are transferred through the bipolar plates to an external circuit at the oxygen side of the membrane. A direct current is generated which may be used to operate an electrical consumer. Besides water vapor, heat is generated in this process. This heat must be dissipated and may also be used. Bipolar plates have the following tasks:- Electrical conduction of the electrons
- Feeding of the reaction media (H2 and O2) to the reactive surface
- Removal of the reaction products (with H2 pure water vapor at operation)
- Dissipation of the generated heat into a cooling medium
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