Orthorhombic Cobalt Ditelluride with Te Vacancy Defects Anchoring on Elastic MXene Enables Efficient Potassium‐Ion Storage

Abstract The fast and reversible potassiation/depotassiation of anode materials remains an elusive yet intriguing goal. Herein, a class of the P‐doping‐induced orthorhombic CoTe₂ nanowires with Te vacancy defects supported on MXene (o‐P‐CoTe₂/MXene) is designed and prepared, taking advantage of the synergistic effects of the conductive o‐P‐CoTe₂ arrays with rich Te vacancy defects and the elastic MXene sheets with self‐autoadjustable function. Consequently, the o‐P‐CoTe₂/MXene superstructure exhibits boosted potassium‐storage performance, in terms of high reversible capacity (373.7 mAh g⁻¹ at 0.2 A g⁻¹ after 200 cycles), remarkable rate capability (168.2 mAh g⁻¹ at 20 A g⁻¹), and outstanding long‐term cyclability (0.011% capacity decay per cycle over 2000 cycles at 2 A g⁻¹), representing the best performance in transition‐metal‐dichalcogenides‐based anodes to date. Impressively, the flexible full battery with o‐P‐CoTe₂/MXene anode achieves a satisfying energy density of 275 Wh kg⁻¹ and high bending stability. The kinetics analysis and first‐principles calculations reveal superior pseudocapacitive property, high electronic conductivity, and favorable K⁺ ion adsorption and diffusion capability, corroborating fast K⁺ ion storage. Especially, ex situ characterizations confirm o‐P‐CoTe₂/MXene undergoes reversible evolutions of initially proceeding with the K⁺ ion insertion, followed by the conversion reaction mechanism.