Ta4C3-Modulated MOF-Derived 3D Crosslinking Network of VO2(B)@Ta4C3 for High-Performance Aqueous Zinc Ion Batteries

A two-dimensional MXene (Ta₄C₃) was innovatively used herein to modulate the space group and electronic properties of vanadium oxides, and the MXene/metal-organic framework (MOF) derivative VO₂(B)@Ta₄C₃ with 3D network cross-linking 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 Ta₄AlC₃ to obtain a large amount of accordion-like Ta₄C₃, and the V-MOF was then hydrothermally grown on the surface of the stripped Ta₄C₃ MXene. During the annealing process of V-MOF@Ta₄C₃, the addition of Ta₄C₃ MXene liberates the V-MOF from agglomerative stacking, allowing it to show additional active sites. More significantly, Ta₄C₃ prevents the V-MOF in the composite structure from converting into V₂O₅ of space group Pmmn but into VO₂(B) of space group C2/m after annealing. A considerable advantage of VO₂(B) for Zn²⁺ 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 nm² along the b axis). According to first-principles calculations, there is a strong interfacial interaction between VO₂(B) and Ta₄C₃, which deliver remarkable electrochemical activity and kinetic performances for the storage of Zn²⁺. Therefore, the ZIBs prepared with the VO₂(B)@Ta₄C₃ cathode material exhibit an ultra-high capacity of 437 mA h·g^-1 at 0.1 A·g^-1 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.