Engineering VOx structure by integrating oxygen vacancies for improved zinc-ion storage based on cation-doping regulation with electric density

Abstract

Aqueous zinc-ion batteries (ZIBs) have attracted enormous attention for future energy-storage devices owing to their high theoretical capacity and environmental friendliness. However, obtaining cathodes with a high specific capacity and fast reaction kinetics remains a huge challenge. Herein, Cu-VO_x material with a thin sheet microsphere structure composed of nanoparticles was prepared by a simple hydrothermal reaction, which improved reaction kinetics and specific capacity. Pre-embedding Cu²⁺ into V₂O₅ to introduce abundant oxygen vacancies extended the interlayer distance to 1.16 nm, weakened the effect of the V–O bonds, and improved the electrical conductivity and structural stability. At the same time, the influence of different valence metal ions (M = K⁺, Cu²⁺, Fe³⁺, Sn⁴⁺, Nb⁵⁺, and W⁶⁺) pre-embedded in V₂O₅ was studied. Benefiting from a large interlayer spacing, high electrical conductivity, and excellent structural stability, the Cu-VO_x electrode demonstrated a high specific capacity of 455.9 mA h g⁻¹ at 0.1 A g⁻¹. Importantly, when the current density was increased to 6 A g⁻¹, the Cu-VO_x electrode still achieved a high specific capacity of 178.8 mA h g⁻¹ and maintained a high capacity retention of 76.5% over 2000 cycles.