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

This paper presents the fabrication of yolk-shell V₂O ₅ 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 V ₂O₅ 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 V₂O ₅ powders is 201 mA h g^-1. In contrast, spherical V ₂O₅ 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 V ₂O₅ powders, even at high current densities.