Synthesis and characterization of various V2O5 microsphere structures and their electrochemical performance

The solid, yolk-shell and hollow V2O5 microspheres are successfully synthesized via a facile solvothermal method with a subsequent annealing treatment. As the cathode materials, the V2O5 hollow microspheres display good cycling performance and excellent rate capability, e.g., the discharge specific capacity of 217.1 mA h g-1 can be reached after 100 cycles in the potential range 2.0 to 4.0 V at 100 mA g−1; the high rate capacity of 178.5 mA h g-1 at 5000 mA g−1 can be delivered, which is higher than 122.1 mA h g-1 of V2O5 yolk-shell microspheres and 89.3 mA h g-1 of V2O5 solid microspheres. In the 5000 mA g−1, the Li ions diffusion distance of the HM-V2O5, YS-V2O5 and SM-V2O5 is about 396.6 nm, 220.6 nm and 186.8 nm, respectively. The capacitive contribution of V2O5 hollow microspheres is up to 48.5% for the total capacity at 0.2 mV s−1 due to high specific surface area arising from considerable amounts of pores. The excellent electrochemical performance of hollow microspheres can be attributed to the fact that the thin porous shell and hollow interior allow the easy penetration of electrolyte and rapid diffusion of ions, and ensure make full use of the V2O5 active materials during Li+ insertion/extraction process.