Generic Fuel Cell and Stack

A Anode current collector B Anode flow channels C Anode catalyst layer (CL) D Close-up of anode CL E Electrolyte F Cathode catalyst layer G Cathode flow channels H Cathode current collector 

At the anode elecffode, the electrochemical oxidation of the fuel produces electrons that flow through the bipolar plate (also called cell interconnect) to the external circuit, while the ions generated migrate through the electrolyte to complete the circuit. The electrons in the external circuit drive the load (e.g., electric moter or other device) and return to the cathode catalyst where they recombine with the oxidizer in the cathodic oxidizer reduction reaction (ORR). The products of the fuel cell are thus threefold (1) chemical products, (2) waste heat, and (3) electrical power. 

Other components necessary for fuel cell system operation include subsystems for fuel and oxidizer delivery, voltage regulation and electronic confiol, fuel and possibly oxidizer storage, fuel recirculation/consumption, stack temperature control, and system sensing of control parameters. For the PEFC, separate humidification systems are also needed to ensure optimal performance and stability. A battery is often used 

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