Study on the Pitch Carbon-coated Artificial Graphite Anode Materials by Vacuum-liquid Phase Method

LIU Hong-bo, LI Fu-ying, HE Yue-de, CHEN Yu-xi

Abstract

Two types of pitch carbon-coated artificial graphite were prepared in the vacuum liquid impregnation method, while the coating agents were medium pitch and modified pitch dissolved in THF solutions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the structure of the carbon-coated graphite and artificial graphite. Li-lion batteries were assembled and their electrochemistry performances were evaluated. The results have shown that the pitch carbon has been coated on the surface of the artificial graphite particles. Meanwhile, the average pore diameter decreases due to the carbon coating. The carbon coating increases the disorder degree on the surface of the artificial graphite. However, the crystal structure of the artificial graphite remains the same. The BET specific surface area of the carbon-coated artificial graphite derived from the modified pitch decreases from 4.27 m2/g to 1.65 m2/g. Its initial coulombic efficiency increases by 3.5%, and its irreversible capacity decreases by 10.9 mAh/g. Meanwhile, the cyclic performance has been enhanced.

 

 

Keywords: anode materials,  artificial graphite,  pitch,  coating


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