Synthesis and characterization of carbon-coated LiNi1/3Co1/3Mn1/3O2 cathode material prepared by polyvinyl alcohol pyrolysis route

Carbon-coated LiNi1/3Mn1/3Co1/3O2 cathode materials for lithium ion battery were synthesized by the pyrolysis of polyvinyl alcohol (PVA) to improve the electrochemical performance of LiNi1/3Mn1/3Co1/3O2 and the carbon content was optimized. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the crystal structure of LiNi1/3Co1/3Mn1/3O2 was not destroyed during the carbon coating process. Transmission electron microscope (TEM) images confirmed that amorphous carbon existed on the surface of LiNi1/3Co1/3Mn1/3O2 particles. Charge and discharge tests showed that the cycle performance and the rate capability of LiNi1/3Co1/3Mn1/3O2 were improved by carbon coating. The LiNi1/3Co1/3Mn1/3O2 composite with the optimal carbon content of 1.0wt.% showed the highest capacity retention of 96.3% after 40 cycles at the current density of 20 mA g(-1) (C/8), and the highest initial discharge capacity of 150 mAh g(-1) at 160 mA g(-1) (1C). The electrochemical impedance spectroscopy (EIS) results showed that the improved electrochemical performance caused by carbon coating was mainly attributed to the decrease of the charge transfer resistance. (C) 2008 Elsevier B.V. All rights reserved.