New high-performance bulky N-heterocyclic group functionalized poly(terphenyl piperidinium) membranes for HT-PEMFC applications

The development of high-performance high temperature proton exchange membranes (HT-PEMs) is a huge challenge that impedes the application of HT-PEM fuel cell (HT-PEMFC). Herein, novel bulky basic group grafted ether-free poly(terphenyl piperidinium) membranes are proposed for HT-PEMFC. Through a simple one-step polymerization, the poly(terphenyl piperidine) (PTP) polymer is synthesized. In order to improve the phosphoric acid (PA) uptake and solubility of PTP in organic solvents, both benzimidazole and pyridine side chains are functionalized into the PTP backbone. Comparing with methyl and methylene pyridine grafted PTP membranes (PTP-Me and PTP-Py), the methylene benzimidazole side chain grafted membrane (PTP-BeIm) exhibits an excellent PA doping content of 215 wt% and a high conductivity of 0.088 S cm−1 at 180 °C under anhydrous condition. The H2–O2 fuel cell based on PTP-41%BeIm/215%PA displays a high peak power density of around 1 W cm−2 at 180 °C without any backpressure, which is about 1.5 times higher than that of PBI/342 wt%PA based cell. Thus, this work develops a facile and low-cost approach on the preparation of high-performance HT-PEMs.