Preparation and properties of graphite/phenolic resin composite bipolar plate

Bipolar plate is an important part of proton exchange membrane fuel cell. The composite bipolar plate of graphite and polymer is the main direction of research. With phenolic resin as binder, natural flake graphite as conductive aggregate, carbon black as additive, the composite bipolar plate for proton exchange membrane fuel cell was prepared by using the molding and thermosetting two-step method. The effects of graphite species on conductive properties and flexural strength of graphite/phenolic resin composites were investigated and analyzed systematically. The results show that there will be the best performance when the natural flake graphite is used as conductive raw material. The electrical conductivity of the graphite/phenolic resin composites can be effectively improved if conductive carbon black is added. By adding 4wt% carbon fiber into composites, the flexural strength of the carbon fiber-graphite/phenolic resin composites is improved by 29%. The liquid phase oxidation processing of carbon fiber surface can effectively improve the bonding strength between the fibers and matrix. With the extending of processing time and elevating of processing temperature, electrical conductivity and flexural strength of carbon fiber-graphite/phenolic resin composites are greatly improved. The final curing temperature mainly affects the cross-linking degree of phenolic resins. With the increase of final curing temperature, the crosslinking degree of phenolic resin gets increased, and the electrical conductivity increases while flexural strength decreases to a certain extent.