The performance of a proton exchange membrane fuel cell exhibits strong association with liquid transport in a gas diffusion layer. The content and distribution of Polytetrafluoroethylene are key factors that determine liquid transport behaviors in a gas diffusion layer. In this study, by employing a stochastic algorithm, a two-dimensional microstructure of a representative carbon paper type gas diffusion layer was reconstructed. Subsequently, the influence of Polytetrafluoroethylene content and various proposed gradient distributions of Polytetrafluoroethylene in the reconstructed gas diffusion layer on liquid transport behaviors was examined by implementing a two-phase Lattice Boltz-mann method. The results supported the findings that an increased content of Polytetrafluoroethylene in gas diffusion layer favored liquid removal, but an extremely high one could cause a remark decrease of the cor-responding porosity of the gas diffusion layer, hence weakening mass diffusion. An optimal gradient design of Polytetrafluoroethylene could enhance water removal performance of a gas diffusion layer reflected by a reduced liquid water saturation and liquid phase steady-state time, meanwhile could ensure an excellent mass diffusion with a relatively high effective porosity of gas diffusion layer, thereby benefitting fuel cell per-formance. The study here could provide guideline for the design of high performance of a fuel cell with a gradient gas diffusion layer.
Keywords proton exchange membrane fuel cell, gradient distributions of Polytetrafluoroethylene, liquid transport in gas diffusion layer, Lattice Boltzmann method, fuel cell performance.