Cation Defect‐Engineered Boost Fast Kinetics of Two‐Dimensional Topological Bi₂Se₃ Cathode for High‐Performance Aqueous Zn‐Ion Batteries

Abstract

Abstract The challenge with aqueous zinc‐ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two‐dimensional topological Bi 2 Se 3 with acceptable Bi‐vacancies for ZIBs cathode (Cu‐Bi 2−x Se 3 ) is constructed through one‐step hydrothermal process accompanied by Cu heteroatom introduction. The cation‐deficient Cu‐Bi 2−x Se 3 nanosheets (≈4 nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn 2+ migration barrier demonstrated by density‐functional theory (DFT) calculations illustrate the decreased Coulombic ion‐lattice repulsion of Cu‐Bi 2−x Se 3 . Therefore, Cu‐Bi 2−x Se 3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X‐ray diffraction (SXRD). These features endow Cu‐Bi 2−x Se 3 with sufficient specific capacity (320 mA h g −1 at 0.1 A g −1 ), high‐rate performance (97 mA h g −1 at 10 A g −1 ), and reliable cycling stability (70 mA h g −1 at 10 A g −1 after 4000 cycles). Furthermore, quasi‐solid‐state fiber‐shaped ZIBs employing the Cu‐Bi 2−x Se 3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high‐performance battery electrochemistry.