A new strategy for synthesizing yolk–shell V2O5 powders with low melting temperature for high performance Li-ion batteries

Abstract

This paper presents the fabrication of yolk–shell V₂O₅ powders with a low melting temperature of 690 °C by using a simplified two-step process. The spherical V₂O₃–C composite obtained by spray pyrolysis transforms into yolk–shell V₂O₅ powder by a simple combustion process at 400 °C. The yolk–shell V₂O₅ powders are composed of nanoplate crystals several tens of nanometers in size, and have a BET surface area of 15 m² g⁻¹. The powders exhibit initial discharge and charge capacities of 271 and 264 mA h g⁻¹ at a current density of 1000 mA g⁻¹, respectively, and a corresponding Coulombic efficiency of 97.4%. After 100 cycles, the discharge capacity of the yolk–shell V₂O₅ powders is 201 mA h g⁻¹. In contrast, spherical V₂O₅ powders with a dense structure exhibit low initial discharge and charge capacities of 160 and 145 mA h g⁻¹, respectively. The structural stability of the yolk–shell during Li-ion insertion and extraction improves the electrochemical properties of the V₂O₅ powders, even at high current densities.