Effects of resin type on properties of graphite/polymer composite bipolar plate for proton exchange membrane fuel cell
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The bipolar plate is one of the most important components in proton exchange membrane fuel cell. In this article, the graphite/polymer composite bipolar plates have been developed by compression molding technique. The study on effects of different resin types on the electrical conductivity, mechanical property, and corrosion performance of the composite bipolar plates shows that the properties of graphite/novolac epoxy (NE) plate are all better than those of graphite/phenol formaldehyde resin plate. The triple continuous structure provides graphite polymer blends with high electrical conductivity, high flexural strength, less porosity, and high density. Most of the properties, such as electrical conductivity, flexural strength, water adsorption, porosity, and so on, are affected by the properties of the polymer. The graphite/NE composite bipolar plate when used in the unit fuel cell assembly showed single-cell performance comparable to that of the commercially available graphite bipolar plates.
I. INTRODUCTION
The 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, convenient fuel supply, long life time, etc.1 Despite these advantages, commercialization of PEMFC is delayed mainly due to the high fabrication cost. Bipolar plate is most commonly used among the PEMFC components, and high cost of bipolar plate prevents significantly current economic feasibility of fuel cells. During the successful research and development on low temperature PEMFC, different types of graphite-based separator plates or bipolar plates are used. Bipolar plates must have high electrical conductivity, sufficient mechanical integrity, corrosion resistance, low gas permeability, and low cost as a result of both material selection and processing methodology if they are to be widely used in the automotive industry.2 Historically graphite bipolar plates have been used in PEMFCs for space missions, military, and other special applications. The advantages of graphite plates are excellent corrosion resistance and low bulk density and resistivity. On the other hand, the disadvantages are difficulties in machining and its brittleness,3–5 due to which bipolar plate requires a thickness of the order of several millimeters, and the fuel cell stack will be massive and voluminous.6 Thin metal sheet is also a good material for the bipolar plate. Materials for metallic plates include stainless steel, titanium, a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2011.358 2974
J. Mater. Res., Vol. 26, No. 23, Dec 14, 2011
http://journals.cambridge.org
Downloaded: 15 Mar 2015
and aluminum with stainless steel being considered most promising for commercialization.7 It offers the attributes of good electrical conductivity, low cost, excellent mechanical strength, and ease to fabricate but low corrosion resistance, a conductive and low cost coating mus
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