Characterizations and selections of electrodes with optimal performance for large-scale vanadium redox flow batteries through lab-scale experiments

Abstract

Conventionally, electrodes for vanadium redox flow batteries (VRFBs) are characterized in lab-scale single cells. However, electrodes selected in such a manner may not provide the best performance in practical large-scale battery stacks, as the flow rates and electrode compression ratios in large stacks are usually much lower than those in single cells. In this work, we study the essential effects of flow rates and electrode compression ratios on the characterizations and selections of electrodes for VRFBs. It is found that the working conditions-induced performance reversal is the reason that leads to the different results in the optimal electrodes between large-scale battery stacks and lab-scale single cells. Hence, the working condition should be considered when evaluating electrodes for VRFBs with lab-scale single cells, especially under low flow rate and compression ratio. This work provides valuable insight and guidance for electrode evaluation with lab-scale single cells, which promotes lab studies to engineering applications.