Enhancing MEA Performance of PEFCs with Ionic Liquid Impregnated ORR Catalysts

Abstract

For polymer electrode fuel cells (PEFCs) vehicles, low precious metal (PGM) loading is desired to reduce the cost of stacks for future mass applications. In order to improve catalyst activity and reduce PGM loading, intensive research activities were conducted on the development of novel electrocatalysts. Among them, bimetallic alloy catalysts such as PtCo and PtNi received great attention.1 Along with alloy catalysts, surface modifications were also studied to promote catalyst activity.2 Among them, ionic liquids have been used and studied to promote activity of oxygen reduction (ORR) catalysts.3 We recently developed two unique ionic liquids aiming to improve ORR catalyst activity by mitigating anion poisoning on platinum surface. The effects of the ionic liquids were studied in membrane electrode assembly (MEA) on catalyst activity and durability with PtCo alloy catalyst. Polarization curves at different relative humidity, electrochemical active surface area (ECSA), mass activity (MA), electrochemical impedance spectroscopy and gas transport resistance were compared with in-house catalyst to confirm the advantages and study the mechanism of the improvements. Accelerated durability test with potential cycling on cathode was performed to study the catalyst durability after impregnation of ionic liquids. The enhanced activity and durability in MEAs provide opportunity to reduce PGM loading while maintaining high performance.References Kodama, T. Nagai, A. Kuwaki et al., Nat. Nanotechnology, 2021 , 16, 140–147.Gui-Rong, W. Thomas, J.S. Daniel. et al., ACS Catalysis, 2018, 8 (9), 8244-8254.Huang, T. Song, O. Morales-Collazo, H. Jia, J.F. Brennecke, 16TJ. Electrochem. Soc., 2017, 16T 164, F1448-F1459. Figure 1