Enhancing PA-PBI Composite Membrane with Metal Oxides Incorporation for HT-PEMFC Operating Above 200 oc

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are renowned for their excellent CO tolerance and rapid reaction kinetics [1]. Among the various membrane types, phosphoric acid doped polybenzimidazole (PA-PBI) membranes, phosphoric acd (PA) acts as a proton conductor, facilitating proton transfer through hydrogen bond rearrangement between PA molecules and the PBI backbone [2]. However, the operating temperature of PA-PBI membrane-based HT-PEMFC is constrained by the condensation of PA, limiting their use to below 180 o C and posing a significant challenge for achieving efficient operation above 200 o C. Recent research endeavors have focused on enhancing PA-PBI membranes by incorporating metal oxides to extend their operational temperature range beyond 180 o C. The addition of metal oxides into PA solution leads to the formation of metal hydrogen phosphate, effectively preventing PA evaporation at elevated temperatures ( > 180 o C) and maintaining membrane performance without degradation. Furthermore, the presence of metal oxides facilitates proton transfer to the metal hydrogen phosphate surface, thereby improving ionic conductivity even at temperatures exceeding 200 o C. In this study, we present the synthesis of poly(2,2’-(1,4-phenylene)-5,5’ bibenzimidaozle) (pPBI) composite membranes through an in-situ method, where various metal oxides (SnO 2 , TiO 2 , ZrO 2 ) are introduced into the synthesis solution. Through systematic investigation, we evaluate the impact of these metal compounds on fuel cell performance and durability at high temperatures exceeding 200 o C. Our findings shed light on the potential of metal oxide-modified PA-PBI composite membranes for advancing the performance and reliability of HT-PEMFCs in demanding operating conditions. References [1] J. M. L. e Canut, R. M. Abouatallah, D. A. Harrington, J. Electrochem. Soc , Sci, 153 ( 2006 ) A857. [2] Z. Wang, J. Zhang, S. Lu, Y. Xiang, Z. Shao, S. P. Jiang, Adv. Sustainable Syst , 7, ( 2023 ) 2200432.