Water–alcohol solution as a diluent for phenolic resin to improve the toughness and pore size distribution of carbon paper

Carbon paper is the preferred material for proton exchange membrane fuel cell gas-diffusion layers. Enhancing the toughness of carbon paper and improving the uniformity of its pore structure are crucial for cost reduction and performance optimization in fuel cells. In this study, carbon papers were prepared using a water-alcohol solution as a diluent of phenolic resin . The evolution of the resin impregnation solution and its influence on the toughness and pore size distribution of the carbon paper were systematically investigated. The results indicated that the resin impregnation solution initially formed a liquid film within the pore structure of the preforms, with higher anhydrous ethanol content enhancing the stability of the liquid film . Compared to pure ethanol, the water–alcohol solution improved the viscosity and surface tension of the resin impregnation solution, resulting in 78.9 % of the pore sizes being distributed within the 20–40 μm range, thereby enhancing the uniformity of pore structure of carbon paper. Using a water-alcohol solution as a diluent enhances the toughness of the carbon paper by 148.67 %. The improvement is attributed to the formation of a structure resembling “beaded fibers”, which promotes crack deflection and branching, thereby increasing energy dissipation during fracture propagation . The fuel cells achieved a maximum power density of 673.96 mW/cm 2 and a current density of 1.68 A/cm 2 respectively, demonstrating significant improvements in both toughness and fuel cell performance .