Mxene Ti3C2 generated TiO2 nanoparticles in situ and uniformly embedded in rGO sheets as high stable anodes for potassium ion batteries

Ti 3 C 2 /TiO 2 /rGO nanosheets were synthesized as anode materials for potassium ion batteries (KIBs) using modified Hummers, freeze drying, and thermal reduction in this paper. Layered Ti 3 C 2 /TiO 2 /rGO nanosheets were synthesized by in-situ formation of rGO and TiO 2 nanoparticles between Ti 3 C 2 layers. As one of the most important members of MXenes family, Ti 3 C 2 exhibits unique electronic characteristics, high specific surface area, strong electrical conductivity and chemically active surface, which can enhance electrode capacity. There are three ways to increase electrode conductivity and capacity: Firstly, rGO is applied as the substrate for the inlaying of TiO 2 and Ti 3 C 2 nanoparticles and nanosheets. Secondly, rGO may also buffer electrode volume changes during charging and discharging processes. In addition, the enormous surface area of rGO makes Ti 3 C 2 and TiO 2 nanoparticles dispersion well, and Ti 3 C 2 and TiO 2 nanoparticles can well separate rGO nanoparticles and prevent them from stacking up again. The synergistic effect of the three can efficiently relieve the stress and provide a rapid transport pathway between electrons and ions. The flake structure of Ti 3 C 2 /TiO 2 /rGO is advantageous to the stability of SEI film, which makes the material maintain good activity during charge and discharge process, and significantly increases its electrochemical performance. Therefore, Ti 3 C 2 /TiO 2 /rGO electrode has a high reversible capacity of 349.2 mAhg −1 after 200 cycles of 100 mAg −1 current, and a high stable capacity of 229.3 mAhg −1 after 500 cycles of 500 mAg −1 current, and has exceptional rate performance. The structure of Ti 3 C 2 /TiO 2 /rGO composite remains stable after 500 cycles, and no agglomeration occurs. The detailed reaction mechanism of Ti 3 C 2 /TiO 2 /rGO electrode as KIBs anode was analyzed by SEM, XRD , Raman, TGA , FT-IR, BET, TEM, XPS , EDS , CV, EX-situ XRD, ex-situ TEM, and so on. Therefore, it can be concluded that the Ti 3 C 2 /TiO 2 /rGO composite is an appropriate anode material for KIBs.