Lawrence Berkeley National Laboratory

Abstract: Polymer electrolyte membrane fuel cells (PEMFCs) are promising for heavy duty applications due to their unique scalability in terms of both power and energy [1], and the U.S. Department of Energy (DOE) established the Million Mile Fuel Cell Truck (M2FCT) consortium in 2020 to advance fuel cell truck R&D[2, 3]. The 2025 end-of-life (EOL) target of M2FCT is to achieve 2.5 kW/gPGM at 0.7 V after 25, 000 hour-equivalent accelerated durability test. Several novel materials have been developed and integrated into membrane electrode assemblies (MEA) and catalysts that meet the EOL target after 90,000 potential cycles in H2/N2 have been reported. However, these reports do not imply that the M2FCT 2025 target has been met since development of the durability protocol and lifetime prediction models for heavy-duty fuel cells are ongoing efforts. The tentative heavy-duty MEA accelerated stress test (AST) protocol consists of H2/Air potential cycling under elevated temperature (90 °C) [4], which the consortium is still actively refining based on the feedback received from the AST Working Group (ASTWG). In this talk, we will systematically summarize the results from the 500-hour H2/Air testing MEA AST, together with various characterization results from microscopy and X-ray analysis, as well as nondispersive infrared to measure support carbon corrosion and fluoride emission rates to measure membrane degradation. With better understanding of the degradation for each component under different testing conditions, we will illustrate the effect of RH (30%, 50%, 90%, and 100%) on the degradation rates of the membrane and catalyst and explain the rationale behind the proposed MEA AST protocol. The degradation rates from the MEA AST protocol were fit into lifetime prediction models and acceleration factors were calculated based on different RHs and cathode catalyst loadings. Refinement of the protocol based on feedback received will also be briefly introduced. Acknowledgment: We acknowledge the financial support for this work from the U.S. DOE) Hydrogen and Fuel Cell Technologies Office (HFTO) through the M2FCT consortium, technology managers Greg Kleen and Dimitrios Papageoropoulos. References: David A. Cullen, K. C. Neyerlin, Rajesh K. Ahluwalia, Rangachary Mukundan, Karren L. More, Rodney L. Borup, Adam Z. Weber, Deborah J. Myers, and Ahmet Kusoglu, New roads and challenges for fuel cells in heavy-duty transportation. Nat. Energy, 2021. 6(5): 462-474. Million Mile Fuel Cell Truck (M2FCT) Consortium Launched. 2020; Available from: https://millionmilefuelcelltruck.org/news. DOE Launches Two Consortia to Advance Fuel Cell Truck and Electrolyzer R&D. 2020; Available from: https://www.energy.gov/eere/articles/doe-launches-two-consortia-advance-fuel-cell-truck-and-electrolyzer-rd. Accelerated Stress Testing (AST) Protocols for Heavy-Duty Fuel Cells. 2024; Available from: https://millionmilefuelcelltruck.org/ast-protocols.