Fengxiang Zhang, Huamin Zhang, and Chao Qu, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, developed a high-performance, inexpensive, composite, anion-exchange membrane (AEM) for an all-vanadium flow battery (VFB) application.

The semi-interpenetrating network anion-exchange membrane is fabricated through dication cross-linking [see picture; PVDF = poly(vinylidene fluoride)], in which the anion conductive groups and cross-links formed simultaneously without the use of trimethylamine (TMA). A VFB using this membrane exhibits high efficiencies: The VFB single cell yielded a Coulombic efficiency of 99 % and an energy efficiency of 84 % at 80 mAcm^–2. Also long-term cycling stability at a high current density is achieved (over 900 charge/discharge cycles).

This is a new possibility of fabricating low-cost, high-performance AEMs in a facile and green way. The membrane obtained has good potential for practical applications in VFBs.

• A Dication Cross-Linked Composite Anion-Exchange Membrane for All-Vanadium Flow Battery Applications,
  Fengxiang Zhang, Huamin Zhang, Chao Qu,
  ChemSusChem 2013.
  DOI: 10.1002/cssc.201300560