Semi-empirical modeling of electrical conductivity for composite bipolar plate with multiple reinforcements B.K. Kakati a , D. Sathiyamoorthy b , A. Verma a, * a Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India b Powder Metallurgy Division, BARC, Mumbai 400705, Maharashtra, India a r t i c l e i n f o Article history: Received 5 August 2010 Received in revised form 27 December 2010 Accepted 27 February 2011 Available online 30 March 2011 Keywords: Bipolar plate Composite Electrical conductivity Fuel cell Percolation a b s t r a c t Carbon composite bipolar plates were developed by compression molding of novolac type phenol formaldehyde resin with natural graphite, carbon black, and carbon fiber. The General Effective Media equation was adapted to model the electrical conductivity of the bipolar plate. The experimental values of the electrical conductivity of the composites with different reinforcements were well predicted by the model. For resinegraphite system (2- component), the most effective in-plane and through-plane electrical conductivities for 70% graphite content were found to be 201.26 and 40.91 S cm 1 , respectively. Similarly, for optimum resinegraphiteecarbon black system (3-component), these values were found as 269.55 and 82.77 S cm 1 , respectively. The most effective in-plane and through-plane electrical conductivities were found to be 285.54 and 91.79 S cm 1 , respectively, for the composite with resinegraphiteecarbon blackecarbon fiber system (4-component). The predicted electrical conductivities for all the three systems were found to be in well agreement with the experimental values. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Fuel cells have emerged as one of the most promising new technologies for energy needs in the 21st century. Different types of fuel cells have been used for decades, especially in spacecraft, and they are currently in use for power generation at a variety of commercial and industrial sites [1]. Use of fuel cells in domestic power application has so far been limited by the cost considerations. However, due to the decreasing trend of fuel cell cost, it is expected that it will emerge as a viable power source in near future [2]. Researchers and developers have shown interest toward the proton exchange membrane fuel cell (PEMFC) due to its high power density, relatively low operating temperature, convenient fuel supply, longer life- time and modularity [3]. Bipolar plate is a vital component of PEMFC, which supplies fuel and oxidant to the reactive sites, removes reaction products, collects the electrons and provides mechanical support for the individual cell in the stack [4,5].Bipolar plate may consume upto 80% of the total weight of the PEMFC stack [6e8]. Whereas, 38% of the total cost of PEMFC stack is incurred by the bipolar plate followed by the costs for the electrodes, membrane, and catalyst as 32, 12 and 11%, respectively [8e10].Currently, several types of materials like metal sheets, coated metal sheets, electro- graphite, flexible graphite, carbonecarbon composites, graphiteepolymer composites, and so forth, are being used for the development of bipolar plates for PEMFC application [11]. Sheet metal and coated metal sheets are potentially low cost materials and in principle suitable for mass production due to the reduction in thickness and easy processibility of flow field design on the bipolar plate [13]. However, corrosion of the metal plate and uneven expansion of coated metal at the fuel * Corresponding author. Tel.: þ91 (0) 361 2582255; fax: þ91 (0) 361 2582291. E-mail address: anil.verma@iitg.ernet.in (A. Verma). A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / h e i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 6 ( 2 0 1 1 ) 1 4 8 5 1 e1 4 8 5 7 0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2011.02.136