Electrochemical intercalation of anions in graphite for high-voltage aqueous zinc battery

Rechargeable aqueous zinc batteries are ideal for large-scale energy storage due to their low cost and high safety. Here we demonstrate the reversible anion intercalation chemistry in graphite cathode for aqueous zinc battery, thus operating as a high-voltage dual-ion battery system. The use of a hybrid “water-in-salt” electrolyte with zinc and lithium bi-salts can maximize the ionic content, expand the anodic stability, promote dendrite-free zinc plating/stripping, and bring the reversible anion intercalation in graphite cathode. This cell configuration offers a high operating voltage and unprecedented cycling stability with comparable Coulombic efficiency to the organic dual-ion battery, opening new opportunities for the development of high-voltage rechargeable aqueous batteries. [Display omitted] •Hybrid “water-in-salt” electrolyte for zinc batteries.•Highly reversible Zn stripping/plating reaction.•Graphite cathode for anion intercalation in aqueous electrolyte.•A novel concept of aqueous dual-ion battery with high operating voltage.