Investigation on performance recovery and consistency of proton exchange membrane fuel cell stack under automotive accelerated stress test

Part of the performance loss of proton exchange membrane fuel cell (PEMFC) can be recovered in time by stopping or changing operating conditions, and is defined as reversible loss. Under the increasingly stringent lifespan requirements and the imperative to reduce PGM loading in fuel cells, accurate identification and recovery of reversible losses are key technologies to enhance the durability of current PEMFC stacks. However, there are few reports on the recovery characteristics of reversible losses in full-scale and high-power stacks. The differences in reversible loss recovery and consistency across various typical automotive operating conditions for high-power stacks have not been thoroughly investigated. In this paper, a 100 kW fuel cell stack was tested under four typical vehicle conditions: Idle, Rated, Dynamic and startup-shutdown (SUSD) conditions. The reversible loss recovery and consistency difference of the stack under different accelerated stress test (AST) conditions are investigated. The results indicate that both prolonged downtime and adjustments in operating parameters can facilitate the recovery of reversible losses, but altering operating temperatures and gas humidity proved to be more convenient and efficient. Under constant conditions such as Idle and Rated, the degradation and recovery of individual cells were relatively uniform. Under Dynamic and SUSD conditions, the recovery of cells was more significantly influenced by their positions, closely related to current and operating parameters. The findings of this study provide important references for the online recovery of reversible degradation in high-power fuel cell stacks.