Sol–gel synthesis of Li3V2(PO4)3/C cathode materials with high electrical conductivity

• The Li3V2(PO4)3/C composite (LVP) including nanorods and irregular solids.
• Nanorods provide efficient one-dimensional electron transport pathways.
• The LVP2/C synthesized by LiH2PO4 and NH4VO4 precursors has higher conductivity than the LVP1/C prepared by NH4H2PO4, LiOH and NH4VO4 precursors.
• The low polarization of LVP2/C leads to excellent rate performance.
• The discharge capacity of LVP2/C still keeps 96.2 mAh g−1 in the 450th cycle at 20 C discharge rate.

The Li3V2(PO4)3/C composite (LVP) including nanorods and irregular solids were successfully prepared by a sol–gel method. The influences of different precursors on the LVP cathode materials were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size distribution measurement and electrochemical methods. The LVP/C electrodes present good rate capability and excellent cyclic performance when they cycle in the range of 3.0–4.3 V. The LVP1/C composite prepared by NH4H2PO4, LiOH, NH4VO4 and citric acid delivers the initial discharge capacity of 109.6 mAh g−1 at 20 C discharge rate and it still maintains 56.9 mAh g−1 after 450 cycles, with the discharge capacity retention of 51.9%. For the LVP2/C composite synthesized by LiH2PO4, NH4VO4 and citric acid, however, the discharge capacities in the 1st and 450th cycles at 20 C discharge rate are 107.1 and 96.2 mAh g−1, respectively, with only 10.2% loss. The excellent rate capacity is attributed to the pure phases, nanorod structure, small particles and uniform carbon coating.