Preparation and properties of composite flexible graphite bipolar plates for proton exchange membrane fuel cells
The preparation of high performance bipolar plates is the key to achieve high performance of proton exchange membrane fuel cells.Graphite based bipolar plates are considered as potential bipolar plates due to their high electrical and thermal conductivities and chemical corrosion resistance.The expanded graphite/acrylic resin composite flexible graphite bipolar plate was prepared by using ex-panded graphite substrate and acrylic resin as raw materials through vacuum molding and continuous impregnation and cleaning process.The results show that the graphite plate exits excellent physical and chemical properties.The dissimilar runner on both sides is well formed,and the dimensional accuracy is good,the runner cycle can reach 1.6 mm,and the runner depth can reach 0.37 mm.And the graphite sheet layer is packed together after molding,and the acrylic resin and expanded graphite are well combined.Therefore,the graphite plate shows high performance:the gas permeability is 0.62×10-6cm3·s-1·cm-2,contact resistance is less than 2.25 mΩ·cm2,e-lectrical conductivity reaches332 S·cm-1,and bending strength reaches28 MPa.At the same time,the corrosion current density is0.85 μA·cm-2,and after 4 500 s of constant potential(1.2 V)corrosion,the corrosion current density is still less than 1 μA·cm-2.It can be seen that the expanded graphite/acrylic composite flexible graphite bipolar plate has the characteristics of simple preparation process and excellent performance,and has a good application prospect.
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