Preparation And Properties Of Novel Graphite-based Composite Bipolar Plates

Proton exchange membrane fuel cell (PEMFC) is one of the most promising power sources for residential and mobile application due to its attractive features such as high power density, relatively low operating temperature, effectively energy conversion, convenient fuel supply and zero emission. Bipolar plate is an important part of the fuel cell stack and its performance and cost directly affect the popularization of fuel cells. To conquer the problems of high cost, low performance and so on involving present bipolar plate, novel graphite-based composite bipolar plates were prepared. Mesophase pitch (MP) haves rich resource, which electrical conductivity is better than other resins. Polyarylacetylene (PAA) molecular structure contains only C and H. Its prepolymer is liquid or fusible solid-state, which could facilitate process molding. Furthermore, there is no small molecule volatilizing during curing, and it has good heat resistance and mechanical properties when cured. Because of superior performance, both PAA and MP were chosen as binders to prepare bipolar plates with graphite as conducting material in the paper. The composite of resin and graphite after mechanical mixing was shaped by thermal molding technique. The factors including raw material properties, graphite content, the molding temperature, which could affect the density, conductivity, bending strength and H2 permeation rate of the composite were investigated. The results show that the density and electrical conductivity of composite bipolar plate decreased with increasing resin content while the flexural strength increased.70 wt% graphite is an appropriate content for PAA/graphite composite bipolar plate. With the same resin content, the strength of PAA/graphite bipolar plate is better than MP/graphite bipolar plate, while the conductivity of MP/graphite bipolar plate is better than PAA/graphite bipolar plate. The performance of PAA/MP/graphite bipolar plate is between the twos. When the graphite content is 70%, the performance of the composite bipolar plate is the best.