Volume 62

Analysis of PEMFC Degradation at Near-Water-Boiling-Point Temperatures: GDL and CCM Contribution Following Dynamic Load Cycling Yirui Lu, Jiaming Lou, Bo Zhou, Daijun Yang*, Bing Li, Pingwen Ming

Abstract

Although increasing the Proton exchange membrane fuel cells (PEMFCs) operating temperature to near the water-boiling-point enhances mass transport and reaction kinetics for automotive applications, the combined effects of elevated temperature and high current load significantly accelerate the degradation of key PEMFC components. This study performed 1,000 dynamic load cycles (DLC) based on the New European Driving Cycle (NEDC) on single cells (working area: 25 cm²) at operating temperatures of 75 °C and 95 °C. In-situ electrochemical tests—including polarization curves, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV)—were used to evaluate the degradation of PEMFC performance. Additionally, cross-assembling aged and fresh gas diffusion layers (GDLs) with corresponding catalyst coating membranes (CCMs) enabled quantitative separation of their respective contributions to performance degradation. The results show that voltage decays approximately linearly with cycling, with faster degradation at 95 °C than at 75 °C under identical loading conditions. At 2.0 A·cm⁻², the overall degradation rate increases from 17.58% at 75 °C to 28.45% at 95 °C. The electrochemically active surface area (ECSA) decreased by 42.92% at 75 °C and 55.26% at 95 °C, corresponding to a substantial increase in Rmt observed through EIS. Cross-assembly experiments showed that at 2.0 A·cm⁻², replacing only the GDL with an aged one (paired with a fresh CCM) reduced the output voltage to 0.49 V at 75 °C and 0.464 V at 95 °C—corresponding to decreases of 7.37% and 12.29%, respectively, compared to the initial values. In contrast, using aged CCMs with fresh GDLs resulted in greater voltage losses—11.68% at 75 °C and 22.69% at 95 °C—indicating that CCM degradation plays a more significant role in PEMFC performance decline at elevated temperatures.

Keywords proton exchange membrane fuel cell; elevated temperature; gas diffusion layer; catalyst layer; degradation behavior