Manipulating Size of Li3V2(PO4)3 with Reduced Graphene Oxide: towards High-Performance Composite Cathode for Lithium Ion Batteries

Lithium vanadium phosphate (Li3V2(PO4)(3), LVP)/reduced graphene oxide (rGO) composite is prepared with a rheological method followed by heat treatment. The size and interface of LVP particles, two important merits for a cathode material, can be effectively tuned by the rGO in the composite, which plays as surfactant to assist sol-gelation and simultaneously as conductive carbon coating. As a consequence, the composite with 7.0 +/- 0.4 wt.% rGO shows a capacity of 141.6 mAh g(-1) at 0.075 C, and a rate capacity of 119.0 mAh g(-1) at 15 C with respect to the mass of LVP/rGO composite, and an excellent cycling stability that retains 98.7% of the initial discharge capacity after 50 cycles. The improved electrochemical performance is attributed to the well-controlled rGO content that yields synergic effects between LVP and rGO. Not only do the rGO sheets reduce the size of LVP particles that favor the Li+ ion migration and the electron transfer during charging and discharging, but also contribute to the reversible lithium ions storage.