Novel synthesis of LiCoPO4–Li3V2(PO4)3 composite cathode material for Li-ion batteries

Abstract LiCoPO4–Li3V2(PO4)3 composite cathode material is synthesized by a chemical lithiation method, with Co3V2O8 as the precursor and oxalic acid as the reductant. XRD result indicates that the composite is composed of olivine-type LiCoPO4 and monoclinic Li3V2(PO4)3. TEM, HRTEM and FFT results show that the LiCoPO4–Li3V2(PO4)3 particles are wrapped with nano-carbon webs, and the crystal particles contain the lattice fringes and diffraction spots of LiCoPO4 and Li3V2(PO4)3. The composite shows the stepped charge–discharge platforms which contain the potential plateaus of LiCoPO4 (~4.8 V) and Li3V2(PO4)3 (~3.6, 3.7, 4.1 and 4.5 V). During the potential range of 3.0–5.0 V, the composite delivers the specific capacities of 163.7, 133.6 and 93.8 mA h g−1 at 0.05, 0.5 and 2 C rates, respectively, and shows good cycling performance.