Ultra-wide temperature range aqueous electrolyte through local aggregation anchoring active water towards practical aqueous zinc metal battery

Abstract

The key to realizing the application of aqueous electrolytes to extreme environments lies in rational constraints on active water. Herein, a strategy for local aggregation electrolyte (LA-Zn(OTf)2) with dynamic anchoring of active H2O is proposed and achieved by precisely regulating the molecular weight and addition amount of organic long chains enriched with hydrogen-bond acceptors. The results show that the saturated vapor pressure of LA-Zn(OTf)2 is reduced by 16 % at 90 °C and it does not freeze at -30 °C, achieving a wide operating temperature range of 120 °C. In LA-Zn(OTf)2, the local aggregation of Zn2+, solvent water, and ether bonding groups form a contact ion pair (CIP) structure, which enables rapid and stable deposition of Zn metal. Moreover, a stable organic-inorganic solid electrolyte interface (SEI) is formed to suppress corrosion and hydrogen evolution. At room temperature, the Zn|LA-Zn(OTf)2|Zn symmetric cell is stably cycled for over 4000 h at 1 mA cm-2. At the extreme temperatures of 90 and -30 °C, the Zn|LA-Zn(OTf)2|NVO full cells achieve stable cycling more than 1400 and 2000 cycles at 0.5 A g-1, respectively, and the capacity retention rates are 70.1 % and 80.5 %, respectively.