Ti–Cl bonds decorated Ti<sub>2</sub>NT<i> <sub>x</sub> </i> MXene towards high-performance lithium-ion batteries
Yuyang Cao, Shiqiang Wei, Quan Zhou, Pengjun Zhang, Changda Wang, Kefu Zhu, Wenjie Xu, Xin Guo, Xiya Yang, Yixiu Wang, Xiaojun Wu, Shuangming Chen, Li Song
Abstract
Abstract Transition metal carbides or nitrides, collectively known as MXenes, are burgeoning two-dimensional materials for energy conversion and storage. The surface chemistry of MXenes could be specially tuned by the modified surface terminations, which directly influences their physicochemical properties. However, the in-depth study and understanding of the specific microstructure and the influence on the electrochemical performance of these terminations remain lacking. Herein, we present an accordion layered Ti 2 NT x MXene with –Cl and –O terminations obtained from copper chloride molten salt etching at a relatively low temperature. X-ray absorption fine structure and x-ray photoelectron spectroscopy analyses reveal the formation of Ti–Cl and Ti–O bonds on the surface of Ti 2 NT x MXene. Density functional theory calculations further suggest that the surface terminations tend to be replaced by –O terminations after Ti–Cl decoration, which implies promising lithium-ion storage performance due to the high lithium affinity of –O terminations. As a result, the Ti 2 NT x MXene based electrode delivers a high reversible capacity (303.4 mAh g −1 at 100 mA g −1 ), stable cycling capability (1200 cycles without capacity attenuation), and fast Li + storage (52% capacity retention at 32 C). This work provides a new vision for MXene surface chemistry and an effective avenue to prepare high-performance nitride electrodes, expanding the diversity and controllability of the MXenes family.