Synthesis and performance of carbon-coated Li 3V 2(PO 4) 3 cathode materials by a low temperature solid-state reaction

Abstract

The carbon-coated monoclinic Li 3V 2(PO 4) 3 (LVP) cathode materials can be synthesized by a low temperature solid-state reaction route. The influences of different heat treatments on the LVP have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. In the range of 3.0–4.3 V, both LVP/C electrodes present good rate capability and excellent cyclic performance. It is found that the sample (LVP1/C) prepared by the two-step heat treatment with pre-sintering at 350 °C delivers the initial discharge capacity of 99.8 mAh g −1 at 10 C charge–discharge rate and still retains 95.8 mAh g −1 after 300 cycles. For the sample (LVP2/C) synthesized by the one-step heat treatment, 95.9 and 90.0 mAh g −1 are obtained in the 1st and 300th cycles at 10 C rate, respectively. Our results based on the XRD patterns and the SEM images suggest that the good rate capability and cyclic performance may be owing to the pure phases, small particles, large specific surface areas and residual carbon. In the range of 3.0–4.8 V, compared with the LVP2/C, the LVP1/C also exhibits better performance.