Pore-scale investigation of water-gas transport in reconstructed gas diffusion layers with binder and polytetrafluoroethylene coating

The microstructure of the gas diffusion layer (GDL) influences the fuel cell performance significantly. A deeper understanding of the transport processes within the GDL is crucial for its optimisation. In this study, a porous microstructure of the gas diffusion layer is reconstructed stochastically, and the impact of the anisotropy parameter on transport properties is examined and determined by comparing it to experimental data. Subsequently, a series of GDLs with different binder and polytetrafluoroethylene (PTFE) volume fractions are reconstructed. A pore-scale model (PSM) simulation is employed to compute the anisotropic transport properties of the reconstructed model. The PSM result indicates that, as the binder and PTFE percentages increase, the in-plane and through-plane diffusivities decrease, while the electrical and thermal conductivities show non-monotonic evolution. The water distribution and the invasion process of liquid water into the reconstructed GDL is investigated using the multiple-relaxation-time lattice Boltzmann method (LBM). The result demonstrates the effect of binder and PTFE, on water penetration in the GDL with constant and reduced porosity. Furthermore, the optimal volume fractions of binder and PTFE are determined based on the PSM and LBM results. This comprehensive analysis contributes to a better understanding of the interplay between microstructure, transport properties, and water behaviour in GDLs, offering insights for optimisation of mass transport and water management of fuel cells.