Anion Endowed High Dielectric Water-Deficient Interface towards Ultrastable Zn Metal Battery

Abstract

Towards reversible metallic Zn anode for aqueous rechargeable zinc battery, regulating electrolyte-Zn interface serves as the key to address the side reactions on Zn. Besides possessing water-deficiency, design rules for constructing the highly efficient electrochemical interface is still vague. As primary electrolyte constituents, not only the roles of anions on solvation structure are being perceived, but also their influence on electrolyte-Zn interface. Here, the characteristics of representative anions are surveyed across current aqueous zinc electrolytes. The candidate reconciling polarizability, H-bond tuning ability and high solubility, is proposed to construct high dielectric water-deficient electrolyte-Zn interface, regulating the interfacial chemistry on Zn. The anion-dominated electrochemical interface promotes Zn deposition kinetics and achieves uniform Zn deposition with high stability, which further renders the in situ formation of SEI towards highly stable Zn stripping/plating, e.g. at 20 mA cm-2 and 20 mAh cm-2. Further, this built-in interface exhibits its function on stabilizing V2O5 cathode, empowering the V2O5/Zn cell with ultra-stable long-term cycling, e.g. 10000 cycles at 10 A g-1 with a high retention rate of 89.7%. Our design offers insight into guidelines for the development of novel electrolytes towards rationalizing electrochemical interface.