The Cracks Effect Analysis on In-Plane Diffusivity in Proton Exchange Membrane Fuel Cell Catalyst Layer by Lattice Boltzmann Method

Crack is always considered as a kind of defect on a catalyst layer in a proton exchange membrane fuel cell (PEMFC), and its enhancement on mass transfer ability has always been ignored. In this work, the crack effect analysis on in-plane (IP) diffusivity on a catalyst layer is numerically evaluated by a D2Q9 lattice Boltzmann method (LBM). The effects on some key parameters like crack length, width, quantity and shape are carried out. The IP concentration distribution of crack CL shows deviation from the theoretical value, and this is because of the tortuosity caused by the CL cracks. The crack shape has almost no effect on the IP effective diffusivity, and the crack length shows a little bit more influence than the crack width and quantity. The crack ratio of the CL is the dominant effect on the IP mass diffusivity enhancement, and the lower the CL porosity is, the higher this enhancement achieve.