Unraveling Dual Mechanisms in Quasi‐Layered Bi₂O₂Se via Defect Modulation for High‐Performance Aqueous Zn‐Ion Batteries

Abstract Developing cathode materials for aqueous zinc‐ion batteries (ZIBs) that offer high capacity, rapid charge–discharge rates, and prolonged cycle life remains a significant challenge. This study explores the use of zipper‐type Bi₂O₂Se nanoplates modified by selenium vacancy (V_se) modulation, which reduces electron scattering, enhances carrier mobility in [Bi₂O₂] conducting channels, and decreases coulombic interactions within electrostatic layers. The introduction of Se vacancies facilitates electron transfer from the host to [Bi₂O₂] channels and reduces scattering in the [Bi₂O₂] framework, thus improving carrier mobility. These Se‐poor Bi₂O₂Se nanoplates demonstrate a greater affinity for zinc ions, reduced diffusion barriers, and faster transport kinetics, which enable more efficient Zn‐ion insertion, tripling the electrochemical capacity, improving rate capabilities, and extending cycling life. Enhancements such as reinforced structural integrity and expanded interlayer spaces support a dual Zn‐ion‐driven mechanism involving both insertion and conversion reactions, essential for superior electrochemical storage performance. The results include an impressive discharge/charge capacity of 380.3 mA h g⁻¹ at 0.1 A g⁻¹, a cycle life of up to 10 000 cycles at 5 A g⁻¹, and a current tolerance exceeding 10 A g⁻¹. This research highlights how nano‐ and defect engineering of Bi₂O₂Se can significantly enhance ionic conductivity, expedite electron transfer, and improve Zn‐ion diffusion.