writer：Junbin Liao, Meizhen Lu, Youqun Chu, Jianli Wang*
keywords：Fluoro-methyl sulfonated poly(arylene ether ketone)，Amphoteric ion-exchange membrane，Ultra-low vanadium permeability，High Coulombic efficiency，Vanadium redox fl ow battery
source：期刊
specific source：Journal of Power Sources
Issue time：2015年

An am photeric ion-exchange membrane (AIEM) from fluoro-methyl sulfonated poly(arylene ether ketone) bearing content-controlled benzimidazole moiety, was firstly fabricated for vanadium redox flow battery ( VRB). The AIEM and its covalently cross-linked membrane ( AIEM-c) behave the highly suppressed vanadium-ion crossover and their tested VO²⁺ permeability are about 638 and 1117 times lower than that of Nafi- on117, respectively. This is further typically verified by the lower VO²⁺ concentration

inside AIEM that is less than half of that inside Nafion117 detected by energy dispersive X-ray spectrometry, in addition of the nearly 3 times longer battery self-di scharge time. The ultra-low vanadium ion diffusion could be ascribed to the narrower ion transporting channel originated from the acid- base interactions and the rebelling effect between the positively-charged benzimidazole structure and VO²⁺ ions. It is found that, VRB assembled with AIEM exhibits the equal or higher Coulombic effi ciency (99.0% vs . 96.4%), voltage efficienc y (90.7% vs . 90 .7%) and energy 

efficiency (89. 8% vs . 87.4%) than that with Nafion117 and keeps continuous 220 chargee-discharge cycles for over 25 days, confirming that the AIEM of this type is a potentially suitable separator for VRB appl ication.© 2015 Elsev ier B.V. Al l rights reserved.