Polysulfone-grafted poly (sodium styrene sulfonate)/polyvinylpyrrolidone amphoteric membranes for vanadium redox flow battery

Amphoteric PSF(polysulfone)-g-NaPSS(sodium p-styrene sulfonate)/PVP (polyvinylpyrrolidone) blended ion exchange membranes were prepared by simple solution casting method with dimethyl sulfoxide (DMSO) as solvent. The effect of the ratio of PSF-g-NaPSS to PVP on the properties of the membranes were studied and compared to that of Nafion 115 (DuPont). The results proved that when the mass ratio of PSF-g-NaPSS to PVP was 3:7 (M 3:7 ), the prepared membrane has exhibited the highest ion selectivity. As a result, the VRB single cell with M 3:7 was superior to that of Nafion 115 under the same condition. Furthermore, after 300 charge-discharge cycles, the efficiency of the M 3:7 membrane has no obvious decrease, and the static chemical stability test reveals that the mass loss ratio and vanadium ion permeability loss ratio of the M 3:7 are only slightly higher than that of N 115 membrane. Consequently, the prepared PSF-g-NaPSS/PVP amphoteric membrane is one of promising candidates for VRB application.