Enhancing the stability of zinc-ion batteries with titanium-doped VO2 cathode materials

Abstract

Vanadium-based oxides, due to their large specific capacity and relatively stable crystal structures, are one of the promising candidates as cathode materials for aqueous zinc-ion batteries (ZIBs). However, their low electronic conductivity and sluggish kinetics of electrochemical reactions severely hinder their practical applications. Herein, Ti⁴⁺-doped VO₂(B) materials have been synthesized by a hydrothermal method and utilized as cathode materials for aqueous ZIBs. The incorporation of Ti⁴⁺ alters the crystal nucleation mechanism, substantially enlarges the material's specific surface area, and concurrently improves its conductivity and the diffusion coefficient of Zn²⁺. Ti–VO₂ demonstrates a specific capacity of 443.7 mA h g⁻¹ at 0.1 A g⁻¹ and retains a reversible capacity of 161.5 mA h g⁻¹ after 1000 charge per discharge cycles beyond 10 A g⁻¹. The utilization of ex situ characterization techniques confirms the Zn²⁺/H⁺ co-intercalation mechanism and elucidates the irreversible structural alterations occurring in Ti–VO₂ during charge and discharge processes. This study provides new ideas for the application of vanadium-based materials and can provide a reference for future research and development work in the field of vanadium-based ZIBs.