A Na3V2(PO4)2O1.6F1.4 Cathode of Zn‐Ion Battery Enabled by a Water‐in‐Bisalt Electrolyte

Abstract Aqueous zinc‐ion batteries are receiving increasing attention; however, the development of high‐voltage cathodes is limited by the narrow voltage window of conventional aqueous electrolytes. Herein, it is reported that Na 3 V 2 (PO 4 ) 2 O 1.6 F 1.4 exhibits the excellent performance, optimal to date, among polyanion cathode materials in a novel neutral water‐in‐bisalts electrolyte of 25 m ZnCl 2 + 5 m NH 4 Cl. It delivers a reversible capacity of 155 mAh g −1 at 50 mA g −1 , a high average operating potential of ≈1.46 V, and stable cyclability of 7000 cycles at 2 A g −1 .