Theoretical study on lithium storage performance of V-doped Ti₂CO₂ 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. Ti₂CO₂ 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 Ti₂CO₂ 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 Ti₂CO₂ 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 TiVCO₂ and Ti₂CO₂ MXene indicated the transition of their conductive types from semiconductors to conductors. In addition, we observed that TiVCO₂ has higher electrical conductivity and ion transport speed than the original Ti₂CO₂ 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, TiVCO₂ is expected to become the anode material for the next generation of lithium-ion batteries and has good lithium storage performance.