真空-液相法制备沥青炭包覆人造石墨负极材料的研究

以两种煤沥青的四氢呋喃溶液作包覆剂,采用真空-液相法对人造石墨进行沥青炭包覆改性处理,将得到的样品与人造石墨分别进行扫描电子显微镜(SEM)、X射线衍射(XRD)分析测试,并组装电池进行电化学性能测试.结果表明:沥青炭不仅包覆在人造石墨颗粒的表面,而且会填充到其孔隙中使平均孔径减小;沥青炭包覆导致人造石墨近表面区域的无序度增大,但不会改变人造石墨的晶体结构;改质沥青炭包覆人造石墨样品的比表面积从4.27m~2/g降至1.65m~2/g,首次库伦效率提高3.5%,不可逆容量降低10.9mAh/g,循环性能也有所改善.

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

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.