Temperature-dependent cathode starvation effects on cold start behavior of PEMFC stacks: An experimental investigation

Proton exchange membrane fuel cells (PEMFCs) encounter significant challenges during cold start at subzero temperatures due to water freezing and ice blockage. This study experimentally investigates the impact of cathode air starvation on cold start behavior of a 12-cell PEMFC stack at different subzero ambient temperatures (−10, −20, and −25 °C). Cathode air starvation is induced by reducing the cathode stoichiometric ratio to either 1.2 or 0.9 during startup, monitoring the voltage, temperature, and internal resistance responses. Results demonstrated successful cold starts at −10 and −20 °C, with startup times between 30 and 47 s under both the starvation conditions, facilitated by additional heat generation from exothermic reactions. However, at −25 °C, rapid ice accumulation caused voltage reversals and hence stack failure under both the starvation conditions. The mechanistic observations indicate that the coupled effects of starvation-induced self-heating, localized ice formation, and subsequent melting govern the temperature-dependent voltage divergence and recovery behavior. Post-test analysis showed minimal degradation following successful cold starts, whereas severe cold start failures resulted in slight catalyst-layer damage and increased internal resistance. This study provides experimental evidence supporting controlled cathode air starvation as a promising strategy for improving PEMFC cold start capabilities, while defining its operational limits at extremely low temperatures.