Uniform Decoration of Vanadium Oxide Nanocrystals on Reduced Graphene-Oxide Balls by an Aerosol Process for Lithium-Ion Battery Cathode Material

VO2-decorated reduced graphene balls were prepared by a one-pot spray-pyrolysis process from a colloidal spray solution of well-dispersed graphene oxide and ammonium vanadate. The graphene-VO2 composite powders prepared directly by spray pyrolysis had poor electrochemical properties. Therefore, the graphene-VO2 composite powders were transformed into a reduced graphene ball (RGB)-V2O5 (RGB) composite by post-treatment at 300 degrees C in an air atmosphere. The TEM and dot-mapping images showed a uniform distribution of V and C components, originating from V2O5 and graphene, consisting the composite. The graphene content of the RGB-V2O5 composite, measured by thermogravimetric analysis, was approximately 5wt%. The initial discharge and charge capacities of RGB-V2O5 composite were 282 and 280mAhg(-1), respectively, and the corresponding Coulombic efficiency was approximately 100%. On the other hand, the initial discharge and charge capacities of macroporous V2O5 powders were 205 and 221mAhg(-1), respectively, and the corresponding Coulombic efficiency was approximately 93%. The RGB-V2O5 composite showed a better rate performance than the macroporous V2O5 powders.