High-Capacity Zinc Anode with 96 % Utilization Rate Enabled by Solvation Structure Design

Abstract

Aqueous zinc-ion batteries (AZBs) show promises for large-scale energy storage. However, the zinc utilization rate (ZUR) is generally low due to side reactions in the aqueous electrolyte caused by the active water molecules. Here, we design a novel solvation structure in the electrolyte by introduction of sulfolane (SL). Theoretical calculations, molecular dynamics simulations and experimental tests show that SL remodels the primary solvation shell of Zn²⁺ , which significantly reduces the side reactions of Zn anode and achieves high ZUR under large capacities. Specifically, the symmetric and asymmetric cells could achieve a maximum of ∼96 % ZUR at an areal capacity of 24 mAh cm^-2 . In a ZUR of ∼67 %, the developed Zn-V₂ O₅ full cell can be stably cycled for 500 cycles with an energy density of 180 Wh kg^-1 and Zn-AC capacitor is stable for 5000 cycles. This electrolyte structural engineering strategy provides new insight into achieving high ZUR of Zn anodes for high performance AZBs.

Keywords: Aqueous Zn Batteries; Electrolyte Solvation Structure; High Zn Utilization Rate; Large-Scale Energy Storage; Zn Anode.