Promoting Desolvation by Hydrophobic and Zincophilic Adsorption Layer To Achieve Stable Zn Anodes at Low Temperature

Abstract

Aqueous Zn-based energy storage devices have broad prospects in the direction of large-scale energy storage, but the Zn anode still has problems, such as poor reversibility and unsatisfactory performance at low temperature. Due to the influence of thermodynamics at low temperature, the dissolution of the Zn ion becomes more difficult, which will intensify the growth of Zn dendrites. In this study, amphiphilic-ion Betaine (Bet) was introduced into 2 M ZnSO 4 aqueous electrolyte as an antifreeze to improve the stability of Zn anode at different temperatures. It is found that Bet can not only participate in the solvation structure of the Zn ion but also be adsorbed on the Zn anode surface directionally, ensuring good reaction kinetics at low temperature, which can inhibit the growth of Zn dendrites and improve its electrochemical performance at low temperature. The results show that, due to the introduction of Bet, Zn//Zn symmetric cells can cycle stably for more than 2000 h under 25 °C, and they can also cycle stably for more than 1000 h under an extreme condition of −20 °C. This work provides a reasonable method for the design of low-temperature and high-rate Zn-based energy storage devices.