Abstract:

The impact of doping different proportions （0， 5%， 10%， 25%， and 50%） of pitch-based carbon fiber on the properties of polyacrylonitrile （PAN）-based carbon paper is implored in this study. The microstructure， mechanical， electrical， gas transport， and electrochemical properties of the carbon paper are systematically characterized using scanning electron microscopy （SEM）， tensile strength measurements， in-plane resistivity measurements， air permeability tests， pore size distribution analysis， polarization curves， power density measurements， and electrochemical impedance spectroscopy （EIS）. The results show that doping pitch-based carbon fiber can significantly reduce the in-plane resistivity of the carbon paper， decreasing from 7.2 mΩ·cm to 2.0 mΩ·cm at a doping ratio of 50%. The tensile strength exhibits a trend of increasing followed by decreasing with increasing doping ratio， reaching the peak of 18.5 MPa at a 10% doping ratio， an approximately 176% increase compared to the undoped sample. The air permeability shows a trend of decreasing followed by increasing with increasing doping ratio， and the pore size distribution changes accordingly. Membrane electrode assembly （MEA） and single-cell tests indicate that the carbon paper doped with 5% pitch-based carbon fiber exhibits the best electrochemical performance， including lower electrochemical impedance and higher power density， attributed to its excellent water management capability. The findings reveal the regulatory effect of pitch-based carbon fiber doping on the properties of PAN-based carbon paper， providing a reference for optimizing the performance of gas diffusion layers of fuel cells.

Key words: carbon paper, polyacrylonitrile carbon fiber, pitch-based carbon fiber, in-plane resistivity, tensile strength, air permeability, power density