Development and evaluation of a novel two-stage exponential current ramping strategy for low-temperature self-cold start of PEM fuel cells

Proton exchange membrane fuel cells (PEMFCs) are promising clean energy technologies for mobile and stationary applications. However, achieving rapid and reliable self-cold start at subzero temperatures remains a critical bottleneck for PEMFC commercialization due to ice formation and irreversible performance degradation. This study addresses a key gap in cold-start research: the lack of systematic analysis on how the shape of current ramping profiles affects the coupled thermal, electrochemical, and phase-change dynamics. To address this knowledge gap, a transient three-dimensional multi-physics model is developed that incorporates electrochemical reactions, mass and heat transfer, and water–ice phase change. Three ramping strategies-linear, exponential, and a novel two-stage exponential-are evaluated under equivalent charge input to explore their impact on voltage stability, thermal response, and ice formation dynamics. The simulation results reveal that exponential ramping causes a rapid voltage drop of 0.2 V within 15 s due to premature ice accumulation, while the two-stage exponential strategy delays voltage decay by approximately 20 s and maintains a final voltage of 0.73 V, 4.3 % higher than that of the linear strategy. Additionally, the two-stage profile reduces the final average ice volume fraction in the cathode catalyst layer by approximately 9.3 %, improves temperature uniformity, and suppresses vertical ice propagation into gas diffusion layer. These improvements stem from the sequential coordination of heat generation and water management across both stages of ramping. This work provides theoretical guidance for optimizing current ramping strategies and offers insights into the design of intelligent control algorithms for PEMFC cold start under extreme conditions.