Systematic refinement of experimental practices to improve repeatability in flow battery cycling

Flow batteries represent one of the leading options for large-scale, long-duration energy storage. In recent years, research into this technology has accelerated, with numerous innovative studies focusing on electrolytes, membranes, and electrode materials. Despite this, there is presently no clear set of testing protocols followed during full-cell testing of flow batteries and the experimental techniques detailed in published literature are often insufficient to reproduce results. Furthermore, testing to quantify the repeatability of experiments is not often reported. In this work, various aspects of an experimental procedure developed from the peer-reviewed literature are refined, with voltage efficiency, coulombic efficiency, energy efficiency, and electrolyte utilization used as indicators of repeatability. A set of improved testing protocols are presented for researchers to consider when conducting charge-discharge testing, and additional factors to be reported and studied in the context of repeatability are suggested.