Review of material research and development for vanadium redox flow battery applications

The vanadium redox flow battery (VRB) is one of the most promising electrochemical energy storage systems deemed suitable for a wide range of renewable energy applications that are emerging rapidly to reduce the carbon footprint of electricity generation. Though the Generation 1 Vanadium redox flow battery (G1 VRB) has been successfully implemented in a number of field trials and demonstration projects around the world, it suffers from low energy density that limits its use to stationary applications. Extensive research is thus being carried out to improve its energy density and enhance its performance to enable mobile applications while simultaneously trying to minimize the cost by employing cost effective stack materials and effectively controlling the current operating procedures. The vast bulk of this research was conducted at the University of New South Wales (UNSW) in Sydney during the period 1985–2005, with a large number of other research groups contributing to novel membrane and electrode material development since then. This paper presents a historical overview of materials research and development for the VRB at UNSW, highlighting some of the significant findings that have contributed to improving the battery's performance over the years. Relevant work in this field by other research groups in recent times has also been reviewed and discussed.