Analysis of operating condition parameters induced gas crossover phenomenon in proton exchange membrane fuel cells: A review

Proton exchange membrane fuel cells are widely adopted in transportation due to their high energy density and low emissions. While thinner membranes reduce ohmic losses, they exacerbate gas crossover, thereby compromising cell performance and safety. This review traces the complete causal chain: “external parameter perturbations - component structural degradation - intensified gas crossover - deteriorated performance and safety.” It analyzes how operating parameters, including temperature, humidity, and gas flow rate, induce thermal, chemical, and mechanical degradation in the proton exchange membrane, catalyst layer, and gas diffusion layer. These changes indirectly promote gas crossover while also directly regulating crossover behavior. Gas crossover reduces open-circuit voltage and wastes fuel. It also forms a vicious cycle with component degradation, accelerating membrane damage and gas permeation. Based on these insights, this paper summarizes key suppression strategies, including mitigating membrane degradation and optimizing membrane electrode assembly structures. Finally, it outlines future research directions, such as developing multi-parameter coupled dynamic models and designing high-performance anti-crossover membrane materials. This review provides a reference for overcoming gas crossover constraints on fuel cell lifespan and performance, thereby advancing their large-scale commercial application.