Theoretical study on lithium storage performance of V-doped TiCO MXene.

With the increasing application of lithium-ion batteries, the demand for high energy density, high-rate performance and high stability lithium-ion batteries is becoming more and more urgent. TiCO MXene, as a two-dimensional material with multilayer atomic structure and multiple active sites, has great advantages in lithium-ion battery electrode materials. However, the original TiCO MXene has been unable to meet the requirements of lithium-ion batteries due to its semiconductor properties. Doping is an effective means to regulate the conductivity and electrochemical properties of TiCO and improve the capacity of lithium-ion batteries and other energy storage devices. Hence, we use first-principles calculations to study the effect of V atom doping on the adsorption and diffusion of Li on the MXene surface. The density of states (DOS) and partial density of states (PDOS) of TiVCO and TiCO MXene indicated the transition of their conductive types from semiconductors to conductors. In addition, we observed that TiVCO has higher electrical conductivity and ion transport speed than the original TiCO MXene, and at the same time, Li atoms can be adsorbed well on the surface of MXene and show a lower diffusion energy barrier. Therefore, TiVCO is expected to become the anode material for the next generation of lithium-ion batteries and has good lithium storage performance.