Experimental analysis of reversible degradation of proton exchange membrane fuel cell under dynamic load cycle

Proton exchange membrane fuel cells (PEMFCs) are pivotal for the efficient utilization of renewable hydrogen to decarbonize the transportation sector, yet durability under dynamic conditions remains a primary barrier. To address the lack of quantitative distinction between degradation modes under coupled stresses, this work establishes a temperature-dependent framework to separate reversible voltage losses from irreversible performance decay during Fuel Cell Dynamic Load Cycles (FC-DLC). Accelerated durability tests were conducted at 71 °C and 85 °C. Results demonstrate that elevated temperatures significantly exacerbate irreversible degradation. After 300 F C-DLCs, the voltage degradation rate relative to the initial voltage at 100% load (≈1.28 A/cm2) reached 4.72% at 85 °C, compared to 2.78% at 71 °C. The electrochemical active surface area retention drops to 48.40% at 85 °C, compared to 71.21% at 71 °C.While operation at 85 °C initially enhances reversible voltage recovery (≈0.015 V) due to improved water redistribution, this benefit diminishes as irreversible damage accumulates, with the relative recovery degree dropping below 20% after 300 cycles. Crucially, a novel mechanistic link is established between temperature-enhanced dynamic voltage undershoot and accelerated lifetime degradation, highlighting a strong correlation between transient voltage undershoot and cumulative irreversible damage. Based on these findings, specific actionable strategies are proposed for durability enhancement. Operating temperatures under dynamic loads should be strictly limited to mitigate accelerated ECSA loss; shutdown recovery procedures involving condensation should be scheduled frequently, specifically before 150 cycles, to maximize recovery efficiency before cumulative irreversible degradation becomes dominant. The findings provide specific strategies to enhance the reliability of renewable energy propulsion systems.