Modeling Hydrogen Crossover Through Membrane With And Without Catalyst Layer

Hydrogen crossover in polymer electrolyte fuel cells is a critical factor influencing efficiency and durability. This study models hydrogen permeation through Nafion membranes with and without catalyst layers, quantifying the crossover rate under various operating conditions using gas chromatography. The hydrogen crossover flux is primarily driven by the partial pressure difference of hydrogen across the membrane, while the total pressure difference up to 50 kPa has a negligible effect. A bare Nafion membrane was modeled as a stack of bulk and skin layers. The hydrogen permeability of the bare Nafion membrane and the membrane with catalyst layers was derived based on the moisture content of the membrane and a temperature dependency with an activation energy of 22.8 kJ mol–1. Notably, catalyst-layer integration to the Nafion membrane resulted in the fusion of the membrane’s skin layers, eliminating additional resistance. Therefore, any skin layers of Nafion stacked between catalyst layers were not observed due to the formation of fused layers. These findings offer insight into optimizing membrane design for enhanced fuel cell performance.