Approach to high proton/vanadium selectivity in an ionic exchange membrane via a hyperbranching design

Abstract

A series of non-perfluorinated sulfonated polyamide hyperbranched polymers (HBP) were synthesized via a one-step polycondensation reaction for their application as ion exchange membranes for vanadium flow batteries. The homogeneous HBP membranes were manufactured via a solution casting method to exhibit high proton/vanadium (H⁺/V) selectivity up to 14.32 × 10⁴, four times that of commercial Nafion 117 membrane, resulting from their high ion exchange capacity and hyperbranched design. At the same time, their great mechanical and thermal properties indicated that the HBP membranes are highly stable, and such HBP membranes with a hyperbranched structure are promising candidates for application in vanadium redox flow batteries.