Mass transport and performance of proton exchange membrane fuel cell considering the influence of porosity distribution of gas diffusion layer

As a key component of proton exchange membrane (PEM) fuel cell, gas diffusion layer (GDL) plays an important role in mass transport process. In this study, the layered setting method is used to cut the GDL along the thickness direction, and the porosity of different layers is set to make it have porosity distribution along the thickness direction. The influence of five porosity distributions of GDL on the internal mass transport process and performance of fuel cell is studied. It is found that the porosity gradient and distribution shape of the GDL affects the effective diffusion coefficient of the reactant gas, and larger porosity gradient leads to poorer uniformity of the gas diffusion coefficient distribution, which is not conducive to the internal mass transport of fuel cell. When the porosity gradient of the GDL is smaller, the gas diffusion process occurs more uniformly, the electrochemical reaction rate is higher, and the performance of the fuel cell is better. In addition, the inverted "V" shaped porosity distribution along the thickness direction of the GDL is more conducive to the reactant gas transport and fuel cell performance than the "V" shaped porosity distribution.