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

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.