气体扩散层压缩对膜电极性能的影响探究

Study on the Influence of Gas Diffusion Layer Compression on the Performance of Membrane Electrode Assembly

质子交换膜燃料电池膜电极中,气体扩散层压缩率同时影响着电荷传导和水、气传输,进而对膜电极性能产生重要影响。本文通过对不同气体扩散层压缩率(17.5%~35.5%)下膜电极欧姆电阻、质子电阻及氧传输阻抗等电化学特性和极化性能的研究,同时基于弛豫时间分布法对不同压缩率下电化学阻抗数据进行拆解分析。结果表明气体扩散层压缩对膜电极性能的影响主要集中在接触电阻和氧扩散阻力两方面。GDL的压缩,使其内部结构趋于致密,孔隙率和孔道尺寸减小,并增强了与催化层的接触,进而使接触电阻减小而氧扩散阻力增大。GDL压缩率设计应兼顾界面接触电阻与气体扩散阻力。

In the membrane electrode of the proton exchange membrane fuel cell,the compression rate of the gas diffusion layer simultaneously affects the charge conduction and the water and gas transmission,and then has an important impact on the membrane electrode assembly performance.In this paper,we studied the electrochemical properties of ohmic resistance,proton resistance and oxygen transmission impedance and polarization properties of different gas diffusion layers(17.5%~35.5%),and analyzed the electrochemical impedance data at different compressive rates based on the relaxation time distribution method.The results show that the influence of gas diffusion layer compression on membrane electrode assembly performance mainly focuses on contact resistance and oxygen diffusion resistance.The compression of GDL makes its internal structure tends to be compact,the porosity and pore size decrease,and enhances the contact with the catalytic layer,so that the contact resistance decreases and the oxygen diffusion resistance increases.The design of GDL compression rate should take into account the interface contact resistance and the gas diffusion resistance.