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

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 Cu 2+ into V 2 O 5 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 + , Cu 2+ , Fe 3+ , Sn 4+ , Nb 5+ , and W 6+ ) pre-embedded in V 2 O 5 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.