Interfacial Gradient Engineering Synergized with Self-Adaptive Cathodic Defense for Durable Zn-Ion Batteries

Abstract

The undesirable electrode/electrolyte interfaces, resulting in the 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 fluctuation, effectively suppressing water activity and 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 vanadium-based cathode is alleviated, and the desolvation process is promoted by the DP-rich cathode electrolyte interphase. 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.