Abstract: In this paper, water-soluble phenolic resin is used as the sizing agent and precursor of carbon paper, and graphene oxide (GO) is used as a functional filler to prepare carbon paper for high-performance proton exchange membrane fuel cells. Differential scanning calorimeter and thermos-gravimetric analyzer were used to characterize the water-soluble phenolic resin and GO. It was found that as the GO content increased, the carbon residual rate of the resin increased significantly, from 57.36%to 66.23%. The micromorphology of the modified carbon paper was observed with a scanning electron microscope and it was found that as the GO content increased, the interface bonding between the resin carbon and the carbon fiber was significantly improved. In addition, a universal testing machine, a four-probe tester and a mercury injection tester were used to explore the effects of resin concentration and graphene oxide on the mechanical properties, electrical properties and porosity of carbon fiber paper. The results show that with the increase of resin concentration and GO content, the conductivity and mechanical properties of carbon paper are significantly enhanced. In order to ensure that the fuel cell has good water vapor transmission capacity, electrical conductivity and mechanical properties, the carbon paper needs to have appropriate pore and pore size distribution, high electrical conductivity and good mechanical strength. When the resin concentration is 30wt%, the carbon paper modified with 0.6wt% GO has the best performance, with a tensile strength of 25.56 MPa, a porosity of 65.27%, and a surface resistivity of 1.365 Ω·sq^-1.

Key words: water-soluble phenolic resin, graphene oxide, carbon fiber paper, gas diffusion layer, PEM fuel
cells