Mastering cathode and anode electrolyte interphases for vanadium-based zinc batteries via solvation structure control

Abstract

Metallic zinc-based anodes often encounter challenges such as dendrite growth, side reactions, and by-product generation, leading to diminished reversibility. This study introduces a novel approach by introducing methyl acetate as a cosolvent into an aqueous electrolyte based on Zn(OTf)2 through a salting-in effect. Regulating the solvation sheath structure of Zn2+ enables the formation of cathode electrolyte interphase and anode electrolyte interphase, enhancing the stability of the vanadium-base cathode and zinc metal anode, respectively. The incorporation of this cosolvent allows for prolonged operation of Zn//Cu half-cells for over 1500 cycles with the average columbic efficiency of 99.82 % under a current density of 1 mA cm−2. When zinc anodes are paired with NaV3O8·1.5 H2O cathodes, a remarkable 80 % of the capacity can be maintained after 1500 cycles under a current density of 1 A/g. Furthermore, even under conditions of a 6 mg cm−2 mass loading and a negative to positive ratio of 3, the full battery demonstrates 77 % capacity retention after 300 cycles. This dual-interphase strategy provides valuable insights into advancing the stability of vanadium-based zinc metal batteries.