Bipolar plates (BPPs) are a key component in PEMFC with multifunctional characters including distributing reactant gases, conducting current, removing the heat from the acting area, preventing leakage of the gas and coolant, and supporting the cell structure. They account for approximately 70% to 80% of the stack weight, almost all of the stack volume, and approximately 30% to 50% of the stack cost. At present, the base materials widely used for BPPs mainly include graphite materials, metal materials, and composite materials.

Technical targets for BPPs were provided by the United States Department of Energy (DOE) to fulfill the service performance standards, as indicated in table.According to the DOE target, the current density is less than 1 μA cm⁻², and no active peak is required for the anodic corrosion target measured from –0.2 V_SHEto+0.6 V_SHEat 0.1mV/s during potentiodynamic tests with pH = 3, H₂SO₄+0.1ppm HF solution (de-aerated with argon purge) at 80°C. The+1.0 V_SHEpotentiostatic test is performed under the same conditions for more than 24h, and the current density must be less than 1 μA cm⁻². The ICR values (as received and after the cathode corrosion potentiostatic test) are less than 10 mΩ cm²at 1.38MPa contact pressure.

There are four general channel configurations for the flow field of the bipolar plate, including single serpentine, parallel, interdigital flow field, and needle. The parallel design is the simplest of the bipolar plate flow field types, with advantages such as lower pressure drop and uniform gas distribution. The serpentine design has been commercially accepted due to good water management, high cell performance, and all PEMFC active areas will participate in the reaction, but uneven gas reactant distribution and excessive pressure drop are the main disadvantages of the serpentine flow field. Compared with the other three flow fields, the interdigital flow field design has the best performance of the fuel cell because the dead-end channel design causes all gas reactants to enter the catalyst layer for reaction. In addition, the advantages of the interdigital flow field design also include easy water removal, uniform reactant distribution, and effective water management.