Phenolic triamine dangling poly(VDF-co-HFP) anion exchange membrane for all aqueous organic redox flow battery

High ion conductivity ion exchange membrane with good chemical and thermal stability is a basic requirement in any redox flow battery system. Anion exchange membrane have positively charge matrix that allow only anions to pass through it and repel cations and neutral molecules. However, they are prone to physical degradation while operating for long time in a highly oxidative environment of redox flow battery system. Herein we are reporting a new anion exchange membrane with high chemical and thermal stable fluorinated backbone. The membrane is synthesized from a phenol derivative 2,4,6-Tris(dimethylaminomethyl)phenol and its docking to poly(vinylidene fluoride-co-hexafluoropropylene) followed by quaternization with methyl iodide. The in-depth study of electrochemical and physiochemical properties of the membrane are reported with its applicability in electrochemical energy storage system. The synthesized membrane is incorporated in an indigenously constructed redox flow battery with 4-OH-Tempo as catholyte and sulphonated vilogen as anolyte. We achieve 88% coulombic efficiency, 70% voltage efficiency and 62% energy efficiency when battery is operated over 50 charge/discharge cycles. The performance of the battery is comparable with literature that employs commercial ion exchange membranes and Tempo/Vilogen or its derivatives as electrolyte. We conclude this is an alternative membrane material for electrochemical device applications.

Automated summary

A new anion exchange membrane with high chemical and thermal stable fluorinated backbone has been developed, showing promising electrochemical and physiochemical properties for energy storage system applications.