不同沥青包覆球形天然石墨负极材料结构和性能研究

Study on the structure and properties of spherical natural graphite with different pitch-coating

通过选用3种不同软化点及组分含量的石油沥青,采用固相包覆法对球形天然石墨进行包覆,考察了软化点不同的沥青对包覆后球形天然石墨负极材料的结构和电化学性能的影响。结果表明:高软化点及高TI和QI组分含量的沥青,炭化过程中分子分解聚合反应更为平缓,挥发分气体逸出少,具有更高残炭率,包覆炭化后能在球形天然石墨表面形成致密无定形碳层,改性后的石墨负极材料具有更高的可逆容量和更好的循环性能,经过高软化点沥青包覆后的球形天然石墨样品,常温1 C下循环200次容量保持率由55.8%提升至96%以上。

The pitch-coating spherical natural graphite was prepared by solid phase coating method. Three kinds of petroleum pitches with different softening points and component contents were selected. The effects of softening points of the pitches on the structure and electrochemical properties of graphite anode materials were investigated. The results show that the petroleum pitch with high softening point and high TI and QI contents has higher fixing carbon content, and can form dense carbon layer on the surface of spherical natural graphite after coating-carbonization. The capacity retention ratio of the modified spherical natural graphite anode material increased from 55.8% to above 96%,which possesses higher reversible capacity and better cycle performance.