Comprehensive review of bipolar plates for proton exchange membrane fuel cells with a focus on materials, processing methods and characteristics

Proton exchange membrane fuel cell (PEMFC) is being developed as a key component of climate change mitigation and post-pandemic economic recovery strategies, especially for the hard to decarbonized sectors like transport. This requires lightweight and highly performing PEMFCs, and bipolar plates (BPs) usually takes around 80% of the weight and volume of the PEMFCs. Bipolar plate provides conducting path for electrons from cell to cell, structural support to cell stack, uniform reactant flow along with removal of biproducts. Fuel cell efficiency, its power density, energy density with water and heat removal are the function of BPs performance, during operation. Whereas the performance or characteristics of BPs i.e., conductivity, gas permeability, hydrophobicity, mechanical and electrochemical durability depends on its quality, which have direct relationship with the material choice, manufacturing method, their parameters and flow field design. Several reviews extensively presented design aspect of flow fields of BPs, whereas a notable comparative analysis of materials, characteristics along with manufacturing processes need to be addressed to encourage better understanding towards efficient PEMFCs and to reduce weight and volume of fuel cell stack. This review aims to provide a comprehensive insight about recent materials (graphite, metallic, and composite materials), processing methods, and characteristics of developed bipolar plates for PEMFC. It highlighted and proposed the various research directions and provide the guidance for the future development of bipolar plates and to obtain optimum combination of required properties, simultaneously.