Preparation and optimization of carbon fiber paper for fuel cell applications: Effect of dispersants, pulp and hot-pressing parameters

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As a critical component in proton exchange membrane fuel cells (PEMFCs), carbon fiber paper (CFP) functions as the gas diffusion layer (GDL) backing, providing mechanical support, electrical conductivity, and effective gas–liquid transport. This work introduces a controllable wet papermaking fabrication route that integrates a dual dispersant regulation, refined pulp reinforcement and orthogonal optimization of hot-pressing parameters. The approach effectively addresses the long-standing issues of uneven fiber dispersion and suboptimal resin infiltration in conventional CFPs. The combination of polyethylene oxide (PEO) and anionic polyacrylamide (APAM) at a total concentration of 0.15 wt% (1:1 by mass) effectively stabilized the dispersion of 6 mm chopped carbon fibers (CFs), reducing large floc (>10 mm 2 ) coverage to 3.0 % and improving sheet uniformity. Furthermore, incorporating 20 wt% softwood pulp (45 °SR) provided sufficient structural integrity for green sheets to withstand subsequent resin impregnation and hot-pressing processes. The result identified 15 wt% phenolic resin, 6 MPa compaction pressure, and 300 °C curing temperature as the optimal combination. The resulting CFP exhibited a uniformly impregnated and homogeneously compressed structure, showing an average pore size of 19.60 μm, 142 % higher tensile strength than the lowest-performing sample, conductivity of 31 mΩ cm, thermal diffusivity of 8.18 mm 2 /s and permeability of 1.56 Darcy.