石墨烯用作锂离子电池负极材料的电化学性能研究

High quality graphene sheets with a curled morphology consisting of a thin wrinkled paper-like structure and fewer layers (1~4 layers) has been prepared from natural graphite by oxidation, hydrogen reduction at 400 ?C and ultrasonic treatment. Graphene sheets were investigated as anode materials for lithium ion batteries by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and a variety of electrochemical testing techniques. The electrochemical performance testing results showed that the first reversible specific capacity of the graphene sheet electrode was as high as 1005 mAh/g at a current density of 0.2 mA/cm2. After 30 cycles the reversible specific capacity was still maintained at 609 mAh/g. Even at a high current density of 1 mA/cm2, the reversible specific capacity remained at 576 mAh/g after 30 cycles. These results indicate that the prepared high quality graphene sheets possess excellent electrochemical performances for lithium storage.