Solvothermal preparation of Co-doped Co_xV_(6-x)O_(13) of cathode materials for lithium-ion batteries

摘要

V_6O_(13) cathode materials have received great attention owing to its high theoretical specific capacity and energy density; however, the poor cycle stability and rate performance have constrained their development. In this experiment, the nanorod-like Co-doped V_6O_(13) with a theoretical equation of Co_xV_(6-x)O_(13) was synthesized for the first time by one-step solvothermal method, and investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tests of electrochemical performances. When x = 0.03, the material shows the best electrochemical performance, the sample has the best discharge specific capacity of 377.3 mAh/g at the beginning, and the capacity retention is 54.4% after 100 cycles at 0.1 C (42 mA/g), comparing with those of the pure V_6O_(13) only 279.4 mAh/g and 37.6% in the same condition. The increase in specific surface area and structural stability promoted the kinetics of the chemical reaction and improved the electrochemical properties of the material. The applicability of this method was further examined through a series of tests and analysis of disassembled batteries after cycle, and the evidences that proper Co doping can stable the structure of materials are provided.