Stainless steel bipolar plates for proton exchange membrane fuel cells: Materials, flow channel design and forming processes

Bipolar plate (BPP) is a key component for proton exchange membrane fuel cell (PEMFC) stack. Stainless steel BPPs possess high electrical and thermal conductivity, good gas impermeability, superior mechanical properties and formability. Furthermore, stainless steel BPPs as thin as 0.1 mm or even thinner can be manufactured by plastic forming methods in mass production with relatively lower cost for PEMFCs, especially for the application of automotive. However, relatively lower corrosion resistance and higher interfacial contact resistance (ICR) may be the two main obstacles hindering full commercialization of stainless steel BPPs. in addition, formability needs to be further improved for higher performance BPPs with fine flow channel geometries while its cost should be reduced to meet the 2020 targets set by the U.S. Department of Energy (DOE). This paper tries to present a comprehensive review of major findings of researches on base and coating materials, channel structure design and forming processes of stainless steel BPPs in recent years. The optimum materials, channel geometries and manufacturing processes currently used or investigated are summarized. In the meanwhile, challenges and future research trends on materials and forming processes of stainless steel BBPs are proposed.