The impact of bulk electrolysis cycling conditions on the perceived stability of redox active materials

Abstract

Emerging grid storage needs are motivating the discovery and development of new, potentially inexpensive redox couples for use in flow batteries. Long-term stability in electrochemical environments remains a key challenge and charge/discharge cycling in a bulk electrolysis cell is a common initial approach. However, as cycling protocols are not yet standardized, comparison between different materials is difficult. Here, using a well-studied, substituted dialkoxybenzene as a model compound, we examine the impact of cycling conditions on perceived stability. Specifically, we show that cycle time is a better measure of stability than cycle number and, for materials that are unstable in their charged state, the fractional capacity accessed is inversely related to cycle time until failure.