Pore-Scale Investigation of Coupled Two-Phase and Reactive Transport in the Cathode Electrode of Proton Exchange Membrane Fuel Cells

Abstract

A three-dimensional multicomponent multiphase lattice Boltzmann model (LBM) is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells. The gas diffusion layer (GDL) and microporous layer (MPL) are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved, and the catalyst layer is simplified as a superthin layer to address the electrochemical reaction, which provides a clear description of the flooding effect on mass transport and performance. Different kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and performance under the flooding condition. The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under flooding. The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores. Moreover, the MPL helps in the uniform distribution of oxygen for an efficient in-plane transport capacity. Crack and perforation structures can accelerate the water transport in the assembly. The systematic perforation design yields the best performance under flooding by separating the transport of liquid water and oxygen.

Confinement of ionomer for electrocatalytic CO2 reduction reaction via efficient mass transfer pathways

“…The results show that GDE Ag@ionomer reserves the porous structure throughout the CL without significant ionomer aggregation, while the ionomer accumulates at the surface of GDE Ag/ionomer . The optimized ionomer distribution in GDE Ag@ionomer can also be reflected by the pore size distributions of the electrodes [ 48 ]. As revealed by mercury intrusion porosimetry (MIP) experiments ( Supplementary Fig.…”