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

Abstract

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 /H 2 O-Ace aqueous electrolyte, Ace participates in the solvation structure of Zn 2+ to generate an in situ protective layer, wherein the decomposition of Li 3 V 2 (PO 4 ) 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. KEYWORDS: aqueous zinc batteries, high voltage, Li 3 V 2 (PO 4 ) 3 , acetamide, protective layer