Interfacial gradient engineering synergized with self-adaptive cathodic defense for durable Zn-ion batteries

Abstract

The undesirable electrode/electrolyte interfaces, resulting in severe parasitic reactions and uncontrolled dendrite growth at the Zn anode, as well as cathode dissolution, significantly hinder the practical application of aqueous zinc-ion batteries. Herein, a diethyl phosphoramidate (DP) additive was proposed to regulate the interfacial chemistry at both anode and cathode. DP molecules disrupt the hydrogen bond network and suppress interfacial pH fluctuations, effectively reducing water activity and inhibiting side reactions. DP molecules preferentially adsorb onto the Zn surface, facilitating the formation of a robust crystalline–amorphous hybrid solid electrolyte interphase (SEI) composed of ZnS, Zn₃N₂, and Zn₃(PO₄)₂, which not only enhances Zn²⁺ transport kinetics but also homogenizes the zinc ions deposition. The dissolution of a vanadium-based cathode is alleviated, and the DP-rich cathode electrolyte interphase promotes the ion desolvation. As a result, Zn||Zn symmetric cells achieve extended cycling life, while Zn||Cu asymmetric cells exhibit high coulombic efficiencies. Additionally, both Zn||NH₄V₄O₁₀ full cells and pouch cells demonstrate improved cycling stability.