Dual-anion chemistry synchronously regulating the solvation structure and electric double layer for durable Zn metal anodes

Abstract

The zinc (Zn) metal electrode suffers from poor stability especially at high currents and large capacities due to insufficient Zn²⁺ supply and intricate side reactions. Despite significant progress, the fundamental understanding of the correlation between anions and the induced electrode/electrolyte interface remains elusive. Here, a comparative framework based on anion-polarity hybridization is constructed, generating variations of regulation in the bulk solvation and interfacial structure. Herein, a dual-anion electrolyte towards the durable Zn electrode is modulated by incorporating the strong-polarity acetate anion (Ac⁻) together with the trifluoromethanesulfonate anion (OTf⁻), which synchronously prompts anion enrichment in the solvation structure and abundant Zn²⁺ aggregation in the Helmholtz layer. Remarkably, a cumulative plating capacity of 15.25 A h cm⁻² (3050 h) is harvested in the Zn‖Zn symmetric cell at 10 mA cm⁻² and 10 mA h cm⁻². Moreover, the designed electrolyte demonstrates superior adaptability to varying low temperatures and high temperature (60 °C). Zn-ion hybrid capacitors and Zn–air batteries also manifest enhanced electrochemical performance, demonstrating the feasibility of dual-anion chemistry in various electrochemical devices. This study provides the fundamental principle to construct advanced electrolytes via anion chemistry for high-performance Zn-based electrochemical devices.