St John s All-Vanadium Flow Battery

In the 1980s, the University of New South Wales in Australia started to develop vanadium flow batteries (VFBs). Soon after, Zn-based RFBs were widely reported to be in use due to the high adaptability of Zn-metal anodes to aqueous systems, with Zn/Br2 systems being among the first to be reported.

Vanadium redox flow batteries are one of the most promising chemistries, because of vanadium's ability to maintain different states of charge as a standalone element, unlike other chemistries like zinc-bromine or iron-chromium.

The membranes employed in vanadium flow batteries can be grouped into ion exchange membranes and physical separators; however, this topic will only focus on ion exchange membranes .

All-vanadium redox flow batteries use V (II), V (III), V (IV), and V (V) species in acidic media. This formulation was pioneered in the late eighties by the research group of Dr Maria Skyllas-Kazacos as an alternative to the Fe/Cr chemistry originally proposed by NASA.

Skyllas-Kazacos et al. developed the all-vanadium redox flow batteries (VRFBs) concept in the 1980s . Over the years, the team has conducted in-depth research and experiments on the reaction mechanism and electrode materials of VRFB, which contributed significantly to the development of VRFB going forward, , .

Innovative membranes are needed for vanadium redox flow batteries, in order to achieve the required criteria; i) cost reduction, ii) long cycle life, iii) high discharge rates and iv) high current densities. To achieve this, variety of materials were tested and reported in literature. 7.1. Zeolite membranes