Novel carbon fiber/aramid fiber composite carbon paper for improved performance in proton exchange membrane fuel cells

A novel carbon paper (CP) composite was fabricated using dopamine hydrochloride-modified carbon fibers (CFs) and aramid fibers (AFs) as raw materials though wet paper forming process. The effects of AF addition ratios on the surface morphology, tensile strength, flexural strength, electrical resistivity, air permeability, and pore size distribution of raw carbon paper (RCP), hot-pressed carbon paper (HPCP), and CP were systematically evaluated. Additionally, the influence of AF composition on the polarization curves, power density, and material transport impedance of proton exchange membrane fuel cells (PEMFCs) was also investigated. The results revealed that dopamine hydrochloride modification introduced abundant –NH 2 and –OH functional groups onto CF surfaces, considerably enhancing the surface hydrophilicity of CF. As the AF addition ratio increased from 0 % to 14 %, the tensile strength, flexural strength, and air permeability of CF/AF composite CPs initially increased and then decreased. AF-CP-6 sample exhibited optimal values for tensile strength, flexural strength, and air permeability, reaching 7.38 MPa, 119.05 MPa, and 1965 L/m 2 /s, respectively. Furthermore, the PEMFCs assembled with AF-CP-6 exhibited the highest limiting current density (1522.50 mA/cm 2 ) and power density (480.58 mW/cm 2 ), and the lowest mass transport impedance, indicating superior water management capability and gas transfer performance. • Dopamine hydrochloride modification enhanced the hydrophilicity and dispersibility of carbon fiber. • The addition of aramid fiber helps to improve the mechanical properties of carbon paper. • The addition of aramid fiber is 6 %, and the tensile strength, air permeability of carbon paper reach the highest value. • The PEMFC assembled by aramid fiber composite carbon paper is excellent.