Low Vanadium Permeability Membranes Based on Flexible Hydrophilic Side Chain Grafted Polybenzimidazole/Polymeric Ionic Liquid for VRFBs

Based on amino polybenzimidazoles with flexible hydrophilic side chains (AmPBI-MOE) and polymeric ionic liquid (PIL), a series of composite membranes (AmPBI-MOE-PIL-X) were fabricated for vanadium redox flow battery applications. Here, 1-Bromo-2-(2-methoxyethoxy)ethane was grafted onto polybenzimidazole (AmPBI) by the method halogenated hydrocarbons, PIL synthesized from liquids in situ radical polymerization to build hydrogen-bonded cross-linked network within film. The chain improves proton conductivity. With increase liquids, transmittance conductivity increase. AmPBI-MOE-PIL-5 membrane not only exhibits ions permeability 0.88 × 10−9 cm2 min−1, which is much lower than Nafion117 (6.07 10−8 min−1), but also shows very excellent blocking ability ion. performances at 60 mA cm−2, VE 87.93% EE 82.87%, both higher that VRFB.