Proton exchange membrane fuel cell (PEMFC) is one of the most promising clean energy sources for residential and automotive applications due to its attractive features such as high power density, relatively low operating temperature, convenient fuel supply, longer lifetime, modular in shape etc. [1,2]. Bipolar plate is one of the most important components of low temperature fuel cell, which contributes to about 80% of the total weight of the PEMFC stack [3,4]. Recent cost analysis shows that 38% of the total cost of the PEMFC stack is incurred by the bipolar plate followed by the cost of electrodes, membrane, and catalyst as 32, 12 and 11%, respectively [4]. Different type of materials like metal sheet, polymer coated metal sheet, graphite, flexible graphite, C-C composite, advanced composites etc. are under investigation for the development of low cost and low weight bipolar plates [3-5].
Composite bipolar plates for proton exchange membrane fuel cell were prepared by compression molding technique using novolac type phenol formaldehyde resin as a binder and natural graphite, carbon black and carbon fiber as reinforcements. The effects of different reinforcements on the properties of composite bipolar plate were studied. The bipolar plates were characterized for electrical conductivity, mechanical strength and corrosion resistance. The optimum flexural strength of the composite bipolar plate was 55.28 MPa, with a deflection of 5.2% at mid-span, while the in-plane and through-plane electrical conductivities were 285.54 and 91.79 S·cm-1, respectively. Corrosion analysis of the bipolar plates conducted in simulated fuel cell environment showed significantly high corrosion resistance or low current density, which made it suitable for proton exchange membrane fuel cell. The corrosion current density of the bipolar plate for the optimum composition was 0.245µA∙cm-2 at 0.004V corrosion potential with respect to standard hydrogen electrode. Moreover, corrosion analysis in alkaline solution also showed that the developed bipolar plate had a potential scope for use in alkaline fuel cell.
Keywords: Bipolar plate; Corrosion; Fuel Cell; Phenolic Resin; Reinforcement
