Co3(PO4)2-Coated LiV3O8 as positive materials for rechargeable lithium batteries

Co3(PO4)2-coated LiV3O8 has been successfully synthesized and used as positive material for rechargeable lithium batteries by a facile liquid phase method. The as-prepared powders were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and the galvanostatic discharge/charge experiments. As-prepared Co3(PO4)2-coated LiV3O8 forms a good layered structure with a poor cyrstallinity. SEM reveals that Co3(PO4)2-coated LiV3O8 has uniform particle distribution and reduced particle size when compared with bare one. The Co3(PO4)2 coating layer is about 33–59 nm forming a continuous lumps attached to LiV3O8 particle surface. Co3(PO4)2-coated LiV3O8 electrode shows increased capacity and more stable cycling. The first and 35th discharge capacities of the Co3(PO4)2-coated LiV3O8 electrode are 322.8 mAh g−1 and 235.7 mAh g−1 in the range of 4.0–1.8 V at a current rate of 30 mA g−1, respectively. The improved electrochemical performance is assigned to the greatly reduced LiV3O8 particle with uniform morphology. Co3(PO4)2-coating further benefits the phase transitions of LiV3O8 during discharge/ charge while preventing parasite reactions between electrode surface and electrolyte.