ABSTRACT This study employs an integrated approach combining three‐dimensional multiphase numerical simulations with experimental validation. A refined single‐channel proton exchange membrane fuel cell (PEMFC) model, verified for grid independence, was developed. User‐defined functions (UDFs) were implemented to accurately describe key processes, including electrochemical reactions, water phase change (liquid/ice), and transport phenomena. A systematic simulation analysis was conducted to elucidate the influence of operating temperature (50–70°C), anode/cathode inlet humidity (50–100% relative humidity), and gas diffusion layer (GDL) porosity (0.4–0.8) on cell output characteristics (polarization curves, power density) and internal mass transport dynamics. Concurrently, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) experiments were performed to deeply investigate the electrochemical performance degradation and microstructural evolution of electrodes with varying water contents under freeze–thaw cycling. The results demonstrate that elevating the operating temperature to 60–70°C significantly enhances cell performance, primarily attributable to increased membrane conductivity and optimized water management. A synergistic optimization effect was identified between reactant gas humidity and GDL porosity. At 60°C, a combination of 75% anode humidity and 100% cathode humidity achieved an optimal balance between output performance and operational stability. Increasing GDL porosity to 0.6–0.8 effectively enhanced reactant gas transport and liquid water removal, reducing current density decay during cold start (−10°C) by approximately 50% and significantly mitigating mass transport blockage and performance degradation caused by ice formation. Freeze–thaw cycling experiments further revealed that electrode water content is a critical factor determining its durability. Flooded conditions exacerbated structural damage from freezing, leading to persistent performance decay, whereas lower water content conditions effectively preserved electrode structural integrity and catalytic activity. This research elucidates the interactive mechanisms of water–thermal–mass transport under multiphysics coupling, providing a theoretical foundation and practical design guidelines for optimizing performance and enhancing the durability of PEMFCs under complex operating conditions.
Li et al. (2025) studied this question.