In Situ Vanadium-Deficient Engineering of V 2 C MXene: A Pathway to Enhanced Zinc-Ion Batteries.

This research examines vanadium-deficient V 2 C MXene, a two-dimensional (2D) vanadium carbide with exceptional electrochemical properties for rechargeable zinc-ion batteries. Through a meticulous etching process, a V-deficient, porous architecture with an expansive surface area is achieved, fostering three-dimensional (3D) diffusion channels and boosting zinc ion storage. Analytical techniques like scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and X-ray diffraction confirm the formation of V 2 C MXene and its defective porous structure. X-ray photoelectron spectroscopy further verifies its transformation from the MAX phase to MXene, noting an increase in V 3+ and V 4+ states with etching. Cyclic voltammetry reveals superior de-zincation kinetics, evidenced by consistent V 3+ /V 4+ oxidation peaks at varied scanning rates. Overall, this V-deficient MXene outperforms raw MXenes in capacity and rate, although its capacity diminishes over extended cycling due to structural flaws. Theoretical analyses suggest conductivity rises with vacancies, enhancing 3D ionic diffusion as vacancy size grows. This work sheds light on enhancing V-based MXene structures for optimized zinc-ion storage.