Application of high‐performance hydrocarbon‐type sulfonated polyethersulfone for vanadium redox‐flow battery

Abstract

Summary The application of hydrocarbon‐based polymer electrolyte membranes as an alternative to Nafion membranes for vanadium redox‐flow batteries (VRFBs) has been investigated. Ionic conductivity measurements and the crossover characteristics of vanadyl ions (VO2+), as well as durability testing against V5+ in H2SO4 solution, were performed to investigate the applicability of sulfonated poly(ethersulfone) (S‐PES) membranes with high molecular weight to VRFB. The diffusion coefficient of V4+ in S‐PES was lower than that in Nafion, and the ionic conductivity was comparable to that of Nafion in S‐PES with an ion‐exchange capacity (IEC) of 1.5 meq/g. A durability evaluation of V5+ with high oxidizing power indicated that it was extremely stable compared to the sulfonated poly(etheretherketone). It was clarified that by setting the IEC to an appropriately high value and reducing the membrane thickness, the membrane characteristics can be made comparable to those of Nafion. Finally, a VRFB test was performed using S‐PES with controlled IEC and membrane thickness, whereby the high molecular weight S‐PES was shown to have relatively good performance comparable to Nafion.

Proton‐Conducting Polymers: Key to Next‐Generation Fuel Cells, Electrolyzers, Batteries, Actuators, and Sensors

“…Ohira et al . demonstrated the effectiveness of sulfonated poly(ethersulfone) (S‐PES) membranes in VRFBs [62] . The S‐PES membranes, compared with traditional Nafion membranes, exhibited lower vanadyl ion crossover and comparable proton conductivity.…”