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 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 m(2) 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.