Reduced graphene oxide supported highly porous V ₂O ₅ spheres as a high-power cathode material for lithium ion batteries

Reduced graphene oxide (rGO) supported highly porous polycrystalline V ₂O ₅ spheres (V ₂O ₅/rGO) were prepared by using a solvothermal approach followed by an annealing process. Initially, reduced vanadium oxide (rVO) nanoparticles with sizes in the range of 10-50 nm were formed through heterogeneous nucleation on rGO sheets during the solvothermal process. These rVO nanoparticles were oxidized to V ₂O ₅ after the annealing process in air at 350 °C and assembled into polycrystalline porous spheres with sizes of 200-800 nm. The weight ratio between the rGO and V ₂O ₅ is tunable by changing the weight ratio of the precursors, which in turn affects the morphology of V ₂O ₅/rGO composites. The V ₂O ₅/rGO composites display superior cathode performances with highly reversible specific capacities, good cycling stabilities and excellent rate capabilities (e.g. 102 mA h g ^-1 at 19 C).