Orthorhombic Cobalt Ditelluride with Te Vacancy Defects Anchoring on Elastic MXene Enables Efficient Potassium‐Ion Storage. Issue 31 (24th June 2021) - Xu, Xiaodan
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. Abstract : P‐doping‐induced orthorhombic CoTe2 nanowires supported on MXene ( o ‐P‐CoTe2 /MXene) are successfully fabricated to enhance performance in potassium storage. The o ‐P‐CoTe2 /MXene anode displays extraordinary structural stability, superior reversible capacity, exceptional rate capability, and long‐term cycling stability, as well as reliable operation in flexible advanced potassium‐ion full batteries.