Orthorhombic Cobalt Ditelluride with Te Vacancy Defects Anchoring on Elastic MXene Enables Efficient Potassium‐Ion Storage
Xiaodan Xu, Yelong Zhang, Hongyang Sun, Jianwen Zhou, Zheng Liu, Zhenping Qiu, Da Wang, Chao Yang, Qingguang Zeng, Zhangquan Peng, Shaojun Guo
Abstract
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 CoTe 2 nanowires with Te vacancy defects supported on MXene ( o ‐P‐CoTe 2 /MXene) is designed and prepared, taking advantage of the synergistic effects of the conductive o ‐P‐CoTe 2 arrays with rich Te vacancy defects and the elastic MXene sheets with self‐autoadjustable function. Consequently, the o ‐P‐CoTe 2 /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‐CoTe 2 /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‐CoTe 2 /MXene undergoes reversible evolutions of initially proceeding with the K + ion insertion, followed by the conversion reaction mechanism.