Regulation of Outer Solvation Shell toward Superior Low-Temperature Aqueous Zinc-Ion Batteries

Aqueous Zn-ion batteries are well regarded among the next-generation energy storage technologies due to their low cost and high safety. However, the unstable stripping/plating process leading to severe dendrite growth under high current density and low temperature impedes their practical application. Herein, we demonstrate that the addition of 2-propanol can regulate the outer solvation shell structure of Zn²⁺ by replacing water molecules to establish a “eutectic solvation shell,” which provides strong affinity with the Zn (101) crystalline plane and fast desolvation kinetics during the plating process, rendering homogeneous Zn deposition without dendrite formation. As a result, the Zn anode exhibits promising cycle stability over 500 hours under an elevated current density of 15 mA cm^-2 and a high depth of discharge of 51.2%. Furthermore, remarkable electrochemical performance was achieved in a 150 mAh Zn|V₂O₅ pouch cell over 1000 cycles at a low temperature of -20 °C. This work offers a new strategy to achieve the excellent performance of aqueous Zn-ion batteries under harsh conditions. It reveals electrolyte structure designs that can be applied in related energy storage and conversion fields.

Keywords: energy storage, solvation structure, aqueous Zn ion batteries, DOD