Controllable Preparation of V2O5/Graphene Nanocomposites as Cathode Materials for Lithium-Ion Batteries

Transition metal oxides and graphene composites have been widely reported in energy storage and conversion systems. However, the controllable synthesis of graphene-based nanocomposites with tunable morphologies is far less reported. In this work, we report the fabrication of V2O5 and reduced graphene oxide composites with nanosheet or nanoparticle-assembled subunits by adjusting the solvothermal solution. As cathode materials for lithium-ion batteries, the nanosheet-assembled V2O5/graphene composite exhibits better rate capability and long-term cycling stability. The V2O5/graphene composites can deliver discharge capacities of 133, 131, and 122 mAh g-1 at 16 C, 32 C, and 64 C, respectively, in the voltage range of 2.5-4.0 V vs. Li/Li+. Moreover, the electrodes can retain 85% of their original capacity at 1C rate after 500 cycles. The superior electrochemical performances are attributed to the porous structures created by the connected V2O5 nanosheets and the electron conductivity improvement by graphene.