A water/sulfolane/γ-valerolactone ternary hybrid electrolyte enables highly stable zinc metal anodes at 60 °C.

Abstract

The practical application of aqueous zinc metal batteries (AZMBs) is plagued by notorious zinc dendrite growth and water-caused side reactions (hydrogen evolution, Zn corrosion, etc.), especially at high temperatures. Rising temperatures will increase water activity and water-related side reactions, significantly undermining the reversibility and lifespan of AZMBs at high temperatures. Herein, sulfolane (SL) and γ-valerolactone (VA) are synergistically introduced as cosolvents to remarkably suppress water activity and water-involving side reactions at a high temperature of 60 °C by disturbing the H-bond network between water molecules and restructuring the Zn²⁺ solvation sheath. The optimized 5SL-4VA-1H₂O ternary hybrid electrolyte enables reversible and dendrite-free Zn deposition at 60 °C with a coulombic efficiency of up to 99.5% in a Zn∥Cu cell and unprecedentedly long-term stability in a Zn∥Zn cell (4772 h). Furthermore, the assembled zinc metal full cell exhibits excellent cycling stability with no capacity decay after 5163 cycles along with an impressive duration of 1060 h at 60 °C. This work provides a new perspective on electrolyte design for high-temperature AZMBs.