In Situ Generation of Protective Layer in Aqueous Zinc Batteries to Stabilize the Voltage of Li3V2(PO4)3 Cathode

Aqueous batteries feature high safety, low cost, and environmental friendliness and are considered to be the next generation of large-scale energy storage systems with great potential. Especially an aqueous cell coupling zinc metal anode and polyanion cathode provides high voltage, which renders it a wider range of application prospects. However, the decomposition of polyanion compounds in a conventional aqueous zinc salt electrolyte limits the stability of the system. Herein we introduce a hybrid electrolyte developed by incorporating acetamide (Ace) and water as a cosolvent with Zn(OTf)2 as the salt to stabilize polyanions. In the Zn(OTf)2/H2O-Ace aqueous electrolyte, Ace participates in the solvation structure of Zn2+ to generate an in situ protective layer, wherein the decomposition of Li3V2(PO4)3 (LVP) into vanadium oxide is inhibited and the high voltage is preserved. A good cycling stability is thus realized for the Zn-LVP system. This work provides an effective strategy to enhance the stability of the polyanion compound and a universal approach for other promising aqueous batteries.