Structure and properties of carbon fiber paper with gradient porous structure

It is crucial to develop high porosity and permeability carbon fiber paper for improving the performance of proton exchange membrane fuel cell. Herein, Porous carbon paper with gradient structure (GCP) was prepared by the process of impregnation with a solution of phenolic resin /carbon black composites, overlayer molding, carbonization and graphitization. Specially, conductive carbon black was modified by silane coupling agent (KH-550) and in-situ polymerization with phenolic resin to improve its dispersion uniformity. The microstructure, porosity, gas permeability, electric resistance and mechanic properties of the as-prepared GCP are characterized. The resultant GCP has a gradual transition of porosity from bottom layer to top layer, which constitutes diffusion channels conducive to the transport of gas and liquid. In addition, GCP exhibits superior gas permeability, conductivity, corrosion resistance and tensile strength over commercial carbon paper (CCP). It has potential application prospects for further improving the performance of fuel cells.