Preparation, delamination and electrochemical performance of two-dimensional crystal Ti₂CT_x MXene

Herein, exfoliation and delamination of two-dimensional (2D) Ti₂CT_x MXene using etchant of HCl+LiF, in which both etching and intercalation were achieved in exfoliation process, were thoroughly investigated with the focus of reaction temperature. The results suggest that increasing etching temperature promotes the exfoliation process, i.e., the transformation from Ti₂AlC to multilayer Ti₂CT_x MXene, whereas the delamination ratio increases firstly and then decreases with the increasing temperature, and the samples etched at 40℃ show the highest delamination ratio of 18% (corresponding to a suspension concentration of Ti₂CT_x MXene flakes as high as 0.36 mg/mL). The prepared MXene flakes, about 1 nm thick, contained no obvious nanometer sized defects. As anode for lithium ion batteries, the delaminated Ti₂CT_x MXene show high capacity and good cycling behavior, and obtained specific capacities of 352 mAh·g^-1, 245 mAh·g^-1, 169 mAh·g^-1 respectively at the current density of 100 mA·g^-1, 300 mA·g^-1, 1000 mA·g^-1, twice to those of the Ti₂CT_x MXene prepared by conventional HF process.