Enhancing cold self-start of a PEM fuel cell stack using adaptive voltage, stoichiometry and oxygen enrichment strategies

Proton exchange membrane fuel cells (PEMFCs) are essential for transport decarbonization, requiring long-term durability, reliable operation in extreme cold weather, and rapid cold starts at −30 °C. To meet these targets, this study investigates an oxygen-enrichment approach. Tests down to −20 °C were performed using a 4-kW PEMFC stack to evaluate start-up parameters: voltage, cathode stoichiometry, cathode oxygen content, and temperature. Increasing oxygen content significantly accelerates cold self-starts: at −20 °C, start-up time decreases from 21 s with air to 6 s and 3 s at 35 % and 100 % oxygen, while reducing ice formation and potentially enabling self-starts at lower temperatures. The improvement is non-linear, with 35 % oxygen providing the greatest benefit per oxygen increase. Adaptive voltage and stoichiometry strategies enhance efficiency and cold start performance and may mitigate degradation. These results support cold-start strategies that improve start-up time, reliability, efficiency, and durability of next-generation PEMFC systems. • Cold self-start of a 4-kW PEMFC stack is systematically investigated down to −20 °C. • Adaptive voltage avoids current plateaus and accelerates ice melting. • Adaptive cathode stoichiometry outperforms high constant airflow. • Moderate O 2 enrichment (35 %) provides the highest cold-start gain per O 2 increment. • Ultra-fast self-starts (3 s, 6 s) at −20 °C are achieved using 100 % and 35 % O 2 .