Effect of different carbon fillers on the properties of graphite composite bipolar plate

A bipolar plate is one of the key components of a proton exchange membrane fuel cell. Development of a suitable material for use as bipolar plate is scientifically and technically important due to the need to maintain high-electrical conductivity, better mechanical properties and low-manufacturing cost. A replacement of the conventional graphite bipolar plate is reported which is twice as strong as the conventional monolithic graphite plate. These plates have been produced by compression molding technique using natural graphite, synthetic graphite, carbon fiber and carbon black as reinforcing constituents and phenolic resin as a binder matrix. A judicious combination and their respective proportions, could produce a composite plate with bulk density 1.8–1.90 g/cm3, electrical resistivity between 0.002 and 0.007 Ω cm, shore hardness ∼65, flexural strength ∼45 MPa and flexural modulus ∼12 GPa. The characteristics and the performance of the composite plate developed by us are compared with the commercially available bipolar plates. A power density of ∼500 mW/cm2 was achieved at 1400 mA/cm2 current density when the above composite plate was used as a bipolar plate in a unit fuel cell.