Maximizing durability of vanadium redox flow battery by evaluating electrolyte-repair-point

Abstract

• Electrolyte repair is a key operation to tackle capacity fade in VRFB. • Estimation of logical timing of electrolyte repair is pivotal for durability of VRFB. • Proposition of ERP Max is vital. • Electrolyte repair before ERP Max imparts durability to VRFB. Repairing of imbalanced electrolytes is a key process, responsible for durable operation of vanadium redox flow battery (VRFB). The scientific community is aware and capable of repairing the imbalanced electrolytes using various remixing techniques. However, till date, no technical rationale is available to know, when the remixing operation should be carried out during operation of the flow battery. This study addresses the issue by assessing degree of imbalance of the vanadium redox flow battery by measuring in-situ state-of-charge of positive and negative electrolytes represented by SoC e+ , and SoC e- , respectively. Interestingly, it is found that during the operation of the flow battery, there is existence of two operational regimes; the first where SoC e+ < SoC e- and the second where SoC e+ > SoC e- . This inflection point is proposed as electrolyte-repair-point (ERP Max ), which is a logical tool to identify right time for the electrolyte repair operation to maximize the efforts of repairing process. Information of ERP Max maximizes the outcome of remixing or repairing process and is instrumental to recognize the regime of battery operation to harness durability of VRFB by designing suitable battery management system.