TaC-Modulated MOF-Derived 3D Crosslinking Network of VO(B)@TaC for High-Performance Aqueous Zinc Ion Batteries.

A twodimensional MXene (TaC) was innovatively used herein to modulate the space group and electronic properties of vanadium oxides, and the MXene/metal-organic framework (MOF) derivative VO(B)@TaC with 3D network crosslinking was prepared, which was then employed as a cathode to improve the performance of aqueous zinc ion batteries (ZIBs). A novel method combining HCl/LiF and hydrothermal treatments was used to etch TaAlC to obtain a large amount of accordion-like TaC, and the V-MOF was then hydrothermally grown on the surface of the stripped TaC MXene. During the annealing process of V-MOF@TaC, the addition of TaC MXene liberates the V-MOF from agglomerative stacking, allowing it to show additional active sites. More significantly, TaC prevents the V-MOF in the composite structure from converting into VO of space group but into VO(B) of space group 2/ after annealing. A considerable advantage of VO(B) for Zn intercalation is provided by the negligible structural transformation during the intercalation process and the special tunnel transport channels, which have an enormous area (0.82 nm along the axis). According to first-principles calculations, there is a strong interfacial interaction between VO(B) and TaC, which deliver remarkable electrochemical activity and kinetic performances for the storage of Zn. Therefore, the ZIBs prepared with the VO(B)@TaC cathode material exhibit an ultra-high capacity of 437 mA h·g at 0.1 A·g while showing good cycle performance and dynamic performance. This study will offer a fresh approach and a reference for creating metal oxide/MXene composite structures.