Analysis of coupled electron and mass transport in the gas diffusion layer of a PEM fuel cell

A numerical investigation of the coupled electrical conduction and mass diffusion in the cathodic GDL of a PEMFC is performed using 2D simulations. The current density on the GDL/catalyst layer interface, which constitutes one of the boundary conditions for the GDL domain and reflects the activation overpotential in the catalyst layer and the ohmic loss in the membrane, is solved iteratively using a novel numerical algorithm. A parametric study is performed to investigate the effects on current density distribution of various operating conditions such as oxygen concentration and membrane resistance, and of design factors such as GDL geometry, anisotropic transport properties, and deformation under the land area due to compression. The results show that the current density distribution under the land area can be dominated by either electron transport or mass transport, depending on the operating regime. The analysis of the in-plane current density gradients shows the contributions due to electrical conduction, oxygen diffusion and membrane resistance in an explicit form. The analysis also provides guidance for the scaling of the coupled transport problem.