The coupled influence of multiple conditions on the performance and stability characteristics of PEMFCs

Appropriate operating conditions are essential to ensure the stable performance of proton exchange membrane fuel cells (PEMFCs). In this study, the coupled influence of temperature, pressure, and humidity on the performance and stability of a 3-cells stack were investigated through testing under different conditions at a constant current density of 1600 mA/cm². Although increasing temperature accelerates electrochemical reactions, it exacerbates membrane dehydration, increasing internal resistance and reducing performance. For instance, under low-pressure and low-humidity conditions, the voltage drops from 0.540 V to 0.472 V (a 12.6% decrease) as temperature rises from 75 to 84℃. Increasing pressure not only improves cell performance but also enhances stack consistency while mitigating the impacts of temperature and humidity. Under high-temperature and low-humidity conditions, the voltage increases 37.9%, i.e., from 0.472 V(@70/60kPa) to 0.651 V (@170/150kPa). Increasing humidity notably improves performance under low-pressure conditions, but its effect diminishes under high pressure due to the reduced proportion of water vapor partial pressure in the total gas pressure. So, for long-term stable operation of the stack under high-temperature conditions, priority should be given to increasing operating pressure, followed by dynamic adjustment of humidity levels.