A dication cross-linked composite anion-exchange membrane for all-vanadium flow battery applications

Abstract

We report the fabrication and properties of a high-performance, inexpensive, composite, anion-exchange membrane (AEM) for an all-vanadium flow battery (VFB) application. The AEM was fabricated by dication cross-linking without the involvement of trimethylamine, and shows well-balanced anion conductivity and robustness due to imidazolium and imidazolium-ammonium functionalities, as well as a concomitantly achieved semi-interpenetrating network structure. The VFB single cell yielded a Coulombic efficiency of 99 % and an energy efficiency of 84 % at 80 mA cm(-2) , and operated for over 900 charge/discharge cycles. This work demonstrates the combined use of several favorable AEM design rationales, such as incorporating abundant and efficient anion-exchange groups, constructing a swelling- and oxidation-resistant structure, and facile fabrication; it provides an effective way of developing high-performance, low-cost AEMs for VFB applications.

Keywords: anion exchange; electrochemistry; membranes; synthesis design; vanadium batteries.