Template-free synthesis of porous V2O5 yolk-shell microspheres as cathode materials for lithium ion batteries

The porous V2O5 yolk-shell microspheres have been synthesized via hydro/solvothermal method with subsequent annealing treatment. Due to the volume contraction of the solid microspheres prepared by hydro/solvothermal reaction and the decomposition and combustion of the organics in air, the porous yolk-shell microspheres were prepared. Derived from the unique structure, the porous V2O5 yolk-shell microspheres show a better electrochemical performance than the pristine V2O5 powder. The electrochemical performance of yolk-shell microspheres is tested between 2.0 and 4.0 V, the V2O5 microspheres can deliver a high initial capacity of 287.2 mA h g−1, and a good capacity of 225.7 mA h−1 can be reached at a current density of 50 mA g−1 after 50 cycles. Moreover, the microspheres electrode possess a higher capacity than the pristine V2O5 powder under the same rate, for example, 159.5 mA h g−1 of V2O5 yolk-shell microspheres vs. 144.6 mA h g−1 of pristine V2O5 powder at a current density of 2000 mA g−1. Even at 1000 mA g−1 in the voltage range of 2.5–4.0 V, the yolk-shell microspheres can also deliver a good discharge capacity of 117.5 mA h g−1 after 1000 cycles.