Research progress in carbon-based composite molded bipolar plates

Bipolar plates are significant components in proton exchange membrane fuel cells (PEMFCs), thus playing a decisive role in the weight, volume, efficiency, durability, and cost of battery stacks. At present, the preparation technologies of metal and graphite plate stacks have become relatively mature, and have been widely used in the fields of commercial and passenger vehicles. However, production of composite material bipolar plates has not been marketed on a large scale in China due to the incomplete localization of raw material formulation, absence of mass production lines and high production cost. Therefore, it is of great significance to find low-cost raw materials, screen raw material compositions and ratios, optimize processing conditions including molding temperature, pressure and time, and shorten the processing cycle for the industrialization of composite bipolar plates. In this review, the characteristics of metal bipolar plates, graphite bipolar plates and composite material bipolar plates were compared. Moreover, the molding process and its advantages in composite bipolar plate production were introduced. Subsequently, recent progress in research of carbon-based composite molded bipolar plates was summarized. This includes resin/graphite composite bipolar plates using thermosetting resins such as phenol formaldehyde resin, epoxy resin and vinyl ester resin as the binder, and carbon black, carbon fiber and carbon nanotube reinforced composite bipolar plates. The effects of the types and ratios of raw materials and molding process conditions on the performance of bipolar plates were emphasized. Finally, the industrialization status of composite bipolar plates was discussed, and the problems faced by major composite bipolar plate manufacturers at home and abroad were pointed out. Prospects in the development of composite bipolar plates were also explored. Additionally, unified performance test standards for composite bipolar plates were recommended to make the performance of products developed by different enterprises comparable.