Joint cationic and anionic redox chemistry in a vanadium oxide cathode for zinc batteries achieving high energy density

Rechargeable aqueous zinc batteries are promising for large-scale energy storage due to their low cost and high safety; however, their energy density has reached the ceiling based on conventional cathodes with a single cationic redox reaction mechanism. Herein, a highly reversible cathode of typical layered vanadium oxide is reported, which operates on both the cationic redox couple of V5+/V3+ accompanied by the Zn2+ storage and the anionic O-/O2- redox couple by anion hosting in an aqueous deep eutectic solvent electrolyte. The reversible oxygen redox delivers an additional capacity of similar to 100 mAh g-1 at an operating voltage of similar to 1.80 V, which increases the energy density of the cathode by similar to 36%, endowing the cathode system a record high energy density of similar to 506 Wh kg-1. The findings highlight new opportunities for the design of high-energy zinc batteries with both Zn2+ and anions as charge carriers. A zinc battery operating on joint cationic and anionic redox chemistry of a vanadium oxide cathode in an aqueous deep eutectic solvent electrolyte is presented, where the reversible anionic O-/O2- by anion hosting delivers an excess capacity of similar to 100 mAh g-1 with an voltage of similar to 1.80 V, endowing the cathode a record high energy density of similar to 506 Wh kg-1. image