Surface-Termination Groups' Tuning to Improve the Lithium-Ion-Storage Performance of Ti3C2Tx MXene

Two-dimensional transition metal carbides/carbonitrides (MXenes) have broad application prospects in the field of energy storage due to their abundant surface functional groups, tunable interlayer spacing, and excellent electrical conductivity. However, the kinetics of Li-ion intercalation/deintercalation between MXene layers is slow, and the stacking between nanosheets due to long cycling reduces the structural stability and battery safety. Herein, we prepare and tune surface-termination groups of Ti3C2Tx MXene by chemical exfoliation and low-temperature annealing methods. The types of functional groups on the surface of the material are optimized by the substitution of oxygen to some -F functional groups on the surface. The optimized Ti3C2Tx MXene material exhibits a reversible lithium-ion-storage specific capacity of 444.1 mAh g(-1) after 200 cycles at a current density of 0.1 A g(-1). The increased of -O functional groups can increase the diffusion rate of Li+, promote the transport of electrons, and accelerate the kinetics of the electrode reaction, thereby improving the performance of lithium-ion storage.