High-density quaternized polymer ionic liquid/polybenzimidazole cross-linked membrane achieves excellent acid stability

Abstract

High-temperature proton exchange membranes (HT-PEMs) were created by incorporating quaternate polymeric ionic liquids (PILs) with a triazine structure into polybenzimidazole (OPBI). The membranes that were developed demonstrate excellent proton transport and retention capabilities for phosphoric acid (PA). It was found that the best overall performance of the cross-linked membranes was achieved at the ideal ratio of 30 wt% PIL. The proton conductivity of OPBI-PIL-30 % membranes at 180 °C was 126.71 mS cm−1. The PA retention was 69.37 % after 240 h of testing at 80 °C and 40 % RH. The PA retention was 91.61 % at 160 °C, indicating its superior acid retention ability. The OPBI-PIL-30 % membrane was assembled into a single cell with a peak power density of 448.99 mW cm−2 at a current density of 1490 mA cm−2. These excellent performances suggest that cross-linked composite membranes containing bulky structures and quaternary ammonium groups are one of the potential materials for HT-PEMs.