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 1.8-1.90g/cm(3), electrical resistivity between 0.002 and 0.007 Omega cm, shore hardness similar to 65, flexural strength similar to 45 MPa and flexural modulus similar to 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 similar to 500 mW/cm(2) was achieved at 1400 mA/cm(2) current density when the above composite plate was used as a bipolar plate in a unit fuel cell (C) 2007 Elsevier B.V. All rights reserved.