Unveiling Ion Pairing Reorganization Mechanism of Oxygen Vacancy‐Rich Amorphous Molybdenum Oxide‐Based Solid‐Electrolyte Interphase for Fast Zn 2+ Desolvation

Abstract Constructing metal oxide‐based solid‐electrolyte interphase (SEI) on the metallic Zn anode is a prevailing strategy for stable Zn‐based aqueous batteries. However, the underlying mechanism of the interfacial process, especially Zn 2+ desolvation behavior, is still unclear to date. Herein, it is disclosed that the low‐solvent‐coordination Zn 2+ solvation structure can be induced near the inner Helmholtz plane via “ion pairing reorganization” at the oxygen vacancy‐rich amorphous unsaturated molybdenum (Mo) oxide‐based SEI on the Zn anode (AMO@Zn). As a result, oxygen vacancies can enable a low Zn 2+ desolvation barrier and fast Zn 2+ diffusion capability across the SEI of AMO@Zn. The symmetric batteries using AMO@Zn exhibit reversible cycles over 4000 h under a high current density of 5 mA cm −2 . Moreover, the AMO@Zn//NaV 3 O 8 full batteries with high mass loading of cathode materials and low N/P ratio of 3 reach the capacity retention of 85.8% after 2000 cycles at 5 A g −1 . This work provides a new perspective into the role of oxygen vacancy in SEI for fast Zn 2+ desolvation.