Lattice Boltzmann simulation of oxygen diffusion and electrochemical reaction inside catalyst layer of PEM fuel cells

An in-depth understanding of pore-scale transport process and electrode reaction kinetics is critical to ease the sluggish oxygen reduction reaction of proton exchange membrane fuel cells. In this study, the effects of catalyst layer microstructure on the oxygen diffusion and electrochemical reaction consumption are analyzed, based on the developed 3D single-phase lattice Boltzmann model and optimized stochastic reconstruction algorithm. The results suggest that increasing the ionomer content and platinum loading are beneficial to increasing the active sites, while the oxygen transport along the thickness direction becomes more difficult due to the narrowed pores, so the platinum particles in the back region have less participation in the reaction, which causes the significant catalyst waste and limits the further cost reduction and improvement of power density. Improving the carbon particle diameter ensures the enlarged pores and more effective Pt particles covered by ionomer, thus enhances the oxygen supply and electrochemical reaction rate. (C) 2019 Elsevier Ltd. All rights reserved.