Assessing Durability in Automotive Fuel Cells:Understanding the Degradation Patterns of PEM Fuel Cells Under Variable Loads, Temperature, Humidity, and Defective Stack Conditions

This paper embarks on an analytical exploration of the degradation mechanisms affecting the proton exchange membrane (PEM) fuel cell with 3.2 kW capacity, pivotal in hybrid systems of Toyota vehicles and electric scooters. Through rigorous experimentation, we quantitatively dissect the impact of varying operational conditions–humidity (25% to 100% RH), temperature (45°C to 75°C), and load (half-load to over-load)—on fuel cell efficiency and longevity. Notably, our findings reveal that humidity levels above 75% RH precipitate a stark efficiency decline at higher current densities due to exacerbated internal resistance, with a degradation rate peaking at -0.019%/day under optimal conditions and escalating significantly under adverse conditions. Temperature variations further illuminate the critical balance between performance and durability, with the highest stability observed at 55°C, manifesting in a moderated degradation rate of -0.024%/day, contrasting sharply with the -0.124%/day observed under over-load scenarios. Structural integrity analysis, facilitated by scanning electron microscope (SEM) imaging, identified two distinct defect types, directly correlating to degradation rates of -0.0384%/day and -0.0552%/day, respectively. This comprehensive study provides pivotal insights into fuel cell operational efficiency, unveiling specific degradation rates and operational thresholds that demarcate resilience from rapid decline, thereby guiding the future of sustainable fuel cell technology in transportation.