炭化过程施压对气体扩散层用碳纸结构与性能的影响

Effect of applying pressure during carbonization process on structure and properties of carbon paper for gas diffusion layer

碳纸作为一种最常用的质子交换膜燃料电池气体扩散层的基底材料,其良好的性能是保证电池稳定运行的前提。为改善碳纸的结构与性能,使其更好地满足燃料电池的性能要求,本研究通过在炭化阶段压制不同数量的石墨板来调控施加的压力,分析不同压力下碳纸微观结构的演变规律及其作用机制,同时研究施加压力对碳纸的平面电阻率、孔径分布、表面粗糙度及力学性能的影响。结果表明:施加压力有利于抑制树脂炭的开裂,减少裂纹的产生,并可在一定程度上提高碳纸的石墨化程度。此外,随着施加压力的增加,碳纸的表面粗糙度逐渐降低,平均孔径和最大孔径逐渐减小。当施加压力为3600 Pa时,与未施加压力相比,碳纸的平面电阻率从17.15 mΩ·cm下降到12.79 mΩ·cm,同时拉伸强度和弯曲强度分别提高150%和82.9%。

Carbon paper is one of the most commonly used materials for the gas diffusion layer of proton exchange membrane fuel cell,and its performance is the premise to ensure the stable operation of the cell.In order to improve the structure and properties of carbon paper and make it better meet the performance requirements of fuel cell,this study was conducted to press different amounts of graphite plates in the carbonization process to control the applied pressure and analyze the microstructure evolution and mechanism of carbon paper under different pressure.In addition,the effects of applied pressure on the in-plane resistivity,pore size distribution,surface roughness and mechanical properties of carbon paper were also studied.The results show that applying pressure helps to restrain the cracking of resin carbon,reduce the generation of cracks and improve graphitization degree of carbon paper to a certain extent.Furthermore,with the increase of applied pressure,the surface roughness of carbon paper is reduced gradually,while the average and maximum apertures also decrease.When the applied pressure reaches 3600 Pa,compared with the samples without pressure,the in-plane resistivity of carbon paper decreases from 17.15 mΩ·cm to 12.79 mΩ·cm,the tensile strength and flexural strength are improved by 150%and 82.9%respectively.