Influence of the Heating Temperature on the Electrochemical Performance of Coal-Based Needle Coke Anode for Lithium Ion Batteries

In this study, the effect of the heating temperature on the initial coulombic efficiency, capacity and cycle stability of the coal-based needle coke was examined. The needle cokes were heated to different temperatures, and their microstructures were characterized by the scanning electron microscope, the X-ray diffraction and Raman spectroscope. The results indicated that the defect and the degree of disorder were reduced with increasing the heating temperature. Moreover, the electrochemical properties of these needle cokes were tested. A decrease of the capacity from 368.3 to 257.3 mAh/g, while an increase of the initial coulombic efficiency was observed, when the heating temperature was improved to 1100 oC. This is because fewer defects and more ordered crystal structures reduce active sites for the storage of Li ions and decrease the irreversible consumption of Li ions, as the heating temperature was higher.