Novel fabrication process for carbon fiber composite bipolar plates using sol gel and the double percolation effect for PEMFC

Bipolar plates are a key component of polymer electrolyte membrane fuel cells (PEMFCs) in terms of cost and weight. Recently, bipolar plates based on carbon fiber-reinforced composites have been the main focus of development activities by researchers because they provide high strength and stiffness as well as excellent corrosion resistance. Although carbon composite bipolar plates have these advantages, they also have low electrical properties that compromise the efficiency of PEMFCs. In this study, a bipolar plate for PEMFCs was developed with a carbon fiber/polypropylene (PP)/polyethylene (PE) composite filled with multiwall carbon nanotubes (MWCNTs) by compression molding. Carbon fiber/PP/PE composite sheets filled with MWCNTs were made by using the sol impregnation method to enhance the degree of impregnation and dispersion of MWCNTs. In addition, the double percolation effect was introduced to improve the electrical conductivity. The electrical resistance, flexural strength, and gas permeability were investigated via the four-point probe method, three-point bending test, and unsteady-state permeability measurement method, respectively. The results were also compared with the technical target from the Department of Energy (DOE). (C) 2015 Elsevier Ltd. All rights reserved.