Novel ether-free sulfonated poly(biphenyl) tethered with tertiary amine groups as highly stable amphoteric ionic exchange membranes for vanadium redox flow battery

The development of cost-effective, ion-selective and highly stable non-fluorinated hydrocarbon membranes is crucial to the vanadium redox flow battery (VRFB). Herein, we report a facile approach to designing a novel ether-free amphoteric ionic exchange membrane (AiEM) grafted with long flexible alkyl side chains with zwitterionic groups, prepared by superacid-catalyzed polycondensation with post-modification. Both FTIR and H1NMR spectra confirm...