Unlocking the Potential of Aqueous Zinc-Ion Batteries: Hybrid SEI Construction through Bifunctional Regulator-Assisted Electrolyte Engineering

Abstract

Aqueous zinc-ion batteries (AZIBs) represent promising candidates for energy storage devices, because of their inherent high safety and cost efficiency. However, challenges such as uneven zinc ion deposition during electrochemical reduction and anode interface side reactions pose significant obstacles to their advancement and practical deployment. Herein, a medium-concentration aqueous electrolyte combined with a bifunctional regulator (aspartame) is developed to address these issues. Practical validation experiments and theoretical calculations demonstrate that the medium-concentration Zn(OTf)₂ aqueous electrolyte containing Aspartame can form a robust hybrid solid electrolyte interface (SEI) containing ZnF₂ and ZnS by simultaneously modulating the Zn²⁺ solvation structure and optimizing the metal-molecule interface, thereby enabling dense Zn deposition. It achieves dendrite-free Zn plating and stripping and excellent Zn reversibility. Significantly, the Zn||V₂O₅ full cell exhibits an average capacity of 240 mAh g^–1 over 8000 cycles at 5 A g^–1. This work provides new insight into solvation and interface design for high-performance AZIBs.