8 - Applications of Polymer Based Composites: Gas Diffusion Layer of PEM Fuel Cells

Abstract

Carbon papers (CPs) have been widely used as a gas diffusion layer (GDL) for high performance fuel cells. The gas penetration layer in the polymer fuel cell is a porous layer that lays between the catalyst layer and the gas passage channels. This layer is used as an appropriate gas distributor to the catalyst layer and a controller for exiting water at the cathode side of the polymer fuel cell. The gas penetration layer generally plays four important roles: transporting the electrons from catalyst layer to bipolar plates, transporting the reactant gases into the catalyst layer, conducting the heat to bipolar plates, and providing a mechanical support for the electrolyte. Therefore, GDLs should have stability in the fuel cell environment, good electrical and thermal conductivities, high permeability and porosity above 70% for gases and liquids. In this chapter, the different materials and manufacturing methods for GDL have been discussed. Moreover, the manufacturing method of GDL without needing to heat treatment have been described in detail and the results of permeability, interface contact resistance, and other properties have been compared to Toray product.