Vanadium-MOF derivatives/MXene heterostructures for kinetics-enhanced zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZICs) are promising for wearable and automotive applications, yet their development is challenged by the kinetic mismatch between the carbon cathode and the zinc anode, causing performance decay. In this work, we fabricate a 3D open nanoarchitecture (Ti₃C₂T _z -MC) featuring MIL-88B(V) derivatives and Ti₃C₂T _z , prepared by solvothermal synthesis followed by thermal annealing. The resulting nanocomposite comprises spindle-shaped V₂O₃@C nanospikes uniformly distributed on Ti₃C₂T _z nanosheets, suppressing MXene self-stacking and creating abundant active interfaces. Its heterostructure, comprising crystalline Ti₃C₂T_z and V₂O₃ embedded in an amorphous carbon matrix, enhances conductivity and Zn²⁺ diffusion, while in-situ electrochemical induction further converts V₂O₃@C to amorphous V₂O₅@C, unlocking additional active sites and accelerating ion transport. Consequently, the Ti₃C₂T _z -MC electrode delivers a superior gravimetric capacity of 610.1 mAh g⁻¹ at 0.05 A g⁻¹ that is almost 10 times that of pristine Ti₃C₂T _z , along with noteworthy rate capability and ultralong cycling stability (98.2% capacity retention after 20,000 cycles). Density functional theory calculations attribute the enhanced kinetics to a built-in electric field at the heterointerface for efficient electron transfer and optimal Zn²⁺ adsorption energy for facile ion transport, collectively boosting the capacitance and rate capability. Furthermore, a flexible ZIC achieves an outstanding energy density of 564.0 Wh kg⁻¹, retains 97% of its capacity at a bending angle of 135°, and can power a red LED. This work offers a generalized heterointerface engineering strategy, featuring intertwined crystalline-amorphous phases, which provides fundamental insights into ion transport and a practical solution to reconcile kinetic mismatch in ZICs.