Development of bipolar plates for fuel cells from graphite filled wet-lay material and a thermoplastic laminate skin layer

In this paper, a method with the potential to rapidly produce thermoplastic polymer composite bipolar plates with improved formability and through-plane conductivity is described. In our earlier work, it was reported that composite bipolar plates made with graphite filled wet-lay materials exhibited excellent mechanical properties and in-plane electrical conductivity. However, the through-plane conductivity and formability of the materials needed improvement. In this work, laminate polymer composite plates consisting of a wet-lay based core and a fluoropolymer/graphite skin layer are manufactured in an effort to improve formability and through-plane conductivity. These plates are characterized by their through-plane and in-plane conductivity, half-cell resistance, and mechanical properties at ambient and elevated temperatures. The laminate plates with PPS based wet-lay core exhibited bulk conductivities of above 300 S cm(-1), tensile strength of up to 34 MPa, and flexural strength of up to 54 MPa. Compared to the bipolar plates consisting of wet-lay material only, the bipolar plates with laminate structure exhibited an increase in through-plane conductivity of 25-35%, as well as a decrease in half-cell resistance by a factor of up to 5. The laminate bipolar plates can be manufactured in several ways with two of them being discussed in detail in the paper. (c) 2006 Elsevier B.V. All rights reserved.