Cathode Electrochemical Performance of PEMFCs with Compressed Gas Diffusion Layer: A Pore-Scale Investigation

Abstract

Proton exchange membrane fuel cells (PEMFCs) are one of the most promising power sources in the fields of vehicle and ship power. Compression caused by assembly pressure, freeze-thaw cycles, and mechanical vibration can cause changes in the microstructure of the gas diffusion layer (GDL), thereby affecting the mass transfer and electrochemical reaction processes inside the PEMFC. In this paper, a three-dimensional single-phase multi-component lattice Boltzmann (LB) model is established to investigate the effects of binder volume fraction and compression on the cathode electrochemical performance. The stochastic reconstruction method is employed to generate 20 GDLs with different binder volume fractions and compression ratios. Afterward, the reactive gas flow within the 20 GDLs is simulated, and the distribution of oxygen mole fraction, water vapor mole fraction, and the current density are analyzed. The simulation results demonstrate that the mean current density decreases with the increase of the compression ratio, and the optimal binder volume fraction of 20% resulted in the highest current density. This paper enriches the research on the cathode electrochemical performance of PEMFCs at the pore scale and provides a guideline for optimizing the GDL design.