Ti-enhanced exfoliation of V2AlC into V2C MXene for lithium-ion battery anodes

Two-dimensional V2C (MXene) derived from layered V2AlC phase attracts increasing interest due to its various promising applications such as lithium-ion batteries. Yet it is a great challenge to obtain completely exfoliated V2C MXene by etching Al from V2AlC. Here, in this work, we highlight that alloying Ti can significantly enhance the exfoliation of (V1-xTix)2C MXene from (V1-xTix)2AlC based on our systematic studies of experiments and first-principles calculations. Furthermore, the exfoliated (V1-xTix)2C MXene shows better multilayered morphology characterized by X-ray diffraction and scanning electron microscopy. Meanwhile, by analyzing the exfoliation process and electron localization functions, we have demonstrated that the micro-origin of Ti enhancement effect on the exfoliation of (V1-xTix)2AlC is due to the significantly weakened interlayer bonding between the VC and Al layers in (V1-xTix)2AlC induced by alloying Ti. Finally, we have shown that the performance of (V1-xTix)2C as anode materials for Li-ion batteries is improved with the increase of Ti content. Our results provide a useful way to improve the synthesis of V-based MXenes and are beneficial to the applications as well.