A new 2,3-dimethoxy-1,4-naphthoquinone redox anolyte for non-aqueous organic static redox battery

Abstract

Redox flow batteries (RFB) are the choice for grid-level large-scale energy storage applications. Especially, the non-aqueous variant of RFB is considered for its unique advantages such as low cost, diverse engineering possibility of redox molecules, and broad voltage window of organic solvents. However, non-aqueous RFB systems suffer from a lack of well-established ion-conducting separator, redox-active material crossover, limited solubility, and low material utilization of active material. Here, we propose 2,3-dimethoxy-1,4-naphthoquinone (2,3-DMNQ) with a solubility of 0.39 M in acetonitrile as novel anode material for organic RFB. A modified Daramic-390® membrane, commonly used for reverse osmosis application was used as a separator to reduce the analyte crossover. Coupled with 2,5-di‑tert‑butyl‑1,4-dimethoxybenzene (DTDMB) catholyte a static cell was formed as proof of concept. The DTDMB/2,3-DMNQ cell provides cell potentials of 1.85 V for the first electron transfer reactions and operates at the highest current density of 18 mA cm−2.