Polybenzimidazole-Based Semi-Interpenetrating Proton Exchange Membrane with Enhanced Stability and Excellent Performance for High-Temperature Proton Exchange Membrane Fuel Cells
Junqiao Jiang, Xunyuan Jiang, Min Xiao, Dongmei Han, Shuanjin Wang, Yuezhong Meng
Abstract
It is of great significance to explore an approach for developing high-strength and enhanced stability materials for high-temperature proton exchange membranes (HT-PEMs) due to their high temperature and strong acid working environment. In this work, proton exchange membranes with semi-interpenetrating (semi-IPN) network structure are constructed by a simple in situ cross-linking method, from linear poly(4,4′-(diphenyl ether)-5,5′-bibenzimidazole) (OPBI) and a cross-linkable poly(arylene ether ketone) with a grafted carboxyl group (c-PAEK), using amino-terminated polybenzimidazole (PBI-4NH2) as a cross-linker. The chemical reaction between the diamine functional group of PBI-4NH2 and the carboxyl group of c-PAEK results in the double anchoring of the molecules. The semi-IPN-1.0/0.7OPBI membrane shows the maximum proton conductivity of 59.6 mS cm–1 at 160 °C under anhydrous conditions. Remarkably, the title membranes (semi-IPN-x/yOPBI) with semi-IPN structure exhibit both excellent chemical stability and highly mechanical properties compared to pristine OPBI. Single cells with semi-IPN-x/yOPBI are successfully operated with dry hydrogen and oxygen at 160 °C, where one using the semi-IPN-1.0/0.7OPBI membrane achieves the maximum power density of 608 mW cm–2, which is 30% higher compared with the OPBI membrane (469 mW cm–2).