Reversible Chlorite/Chlorine Dioxide Anion Redox Couple for Low-Cost Energy Storage

The ClO2-/ClO2 electrochemical reaction is shown to be highly reversible in acidic, near-neutral, and alkaline electrolytes while using low-cost carbon electrodes. Its equilibrium potential (0.954 V vs SHE) is pH-independent and enables high aqueous cell voltages of 1.38-2.15 V when used as a positive electrode with negative electrodes such as Zn, Fe, or S. This anion redox couple may enable low-cost aqueous rechargeable batteries free of resource-constrained metals, here demonstrated in prototype Zn-NaClO2 full cells. The rapid reaction kinetics and stability of the ClO2 phase at low temperatures also suggests that chlorite-based batteries may be favorable for applications in cold environments.