Accelerating Zn²⁺ Desolvation and Diffusion via Interfacial Engineering in MXene/Amorphous VOx Composites for High-Stable Zn-Ion Batteries.

Abstract

As cathode materials for aqueous zinc-ion batteries (AZIBs), amorphous materials emerge as promising cathodes due to their isotropic ion diffusion pathways and abundant active sites. However, their intrinsically low electronic conductivity and irreversible crystallization during cycling exacerbate structural degradation, which severely degrades the cycling stability. To address this, we designed a novel cathode by integrating amorphous VOx nanospheres into a porous V₂CT_<i>x</i> MXene skeleton, creating ion/electron conduction highways that overcome the sluggish ion kinetics in crystalline cathodes and restricted interlayer electron transport in MXenes. <i>In situ</i> X-ray diffraction verifies that oxygen/fluorine-terminated MXene surfaces accelerate Zn²⁺ desolvation via hydrophobic F-group-mediated water repulsion. Composite electrode achieves 401 mAh g^-1 (0.2 A g^-1) and retains 140 mAh g^-1 after 6500 cycles at 4 A g^-1. A quasi-solid-state device with poly(vinyl alcohol) gel electrolyte achieves 97% capacity retention over 1200 cycles. This interface-bulk synergy guides AZIB cathode design, combining interfacial desolvation acceleration (MXene) with bulk-phase ion confinement (amorphous VOx).