An innovative accelerated stress test representative of automotive PEMFC degradation mechanisms validated on 1000 hours real-world operation

Abstract

Automotive Polymer Electrolyte Membrane Fuel Cells (PEMFC) must improve durability to increase competitiveness. Single cell accelerated stress tests (ASTs) were standardized over the years aiming at accelerating the progress of durable materials at reduced cost and time. However, state-of-the-art ASTs are effective to selectively enhance the degradation of each component, but are difficult to correlate to real-world aging. To overcome this issue, this study presents a novel hydrogen/air AST, which mimics in a comprehensive and representative way the driving functioning. The AST includes operational modes as low power, high power, stop protocols and reproduces stressors that reflect parameters and mitigation strategies adopted in the application. The aging results of three state-of-the-art PEMFC are successfully correlated to 1000 operating hours of single cell realistic load cycling [Colombo E. et al., J. Power Sources, 553 (2023) 232246]. Decays of cell voltage, mass transport resistance, electrocatalyst nanoparticles distribution and efficiency were correlated, identifying a 10-fold acceleration in time. Cathode catalyst active surface area reduced to 61–65% of the initial value and the promoted transport loss was mainly related to the cathode thin-film resistance. Performance indicators mostly changed within the first 400 cycles, while predictions highlighted a progressive slowing down of rates of decay.