乳液法制备中间相炭微球的微观结构及其电化学性能

分别以石油渣油中间相沥青(FCC-MP)和萘系中间相沥青(AR-MP)为原料,采用乳液法制备出两种粒径分布窄、球形圆整的中间相沥青微球(MPMB-1和MPMB-2,粒径约25μm),再经预氧化、碳化、石墨化处理后得到中间相石墨微球(MGMB-1和MGMB-2);采用偏光显微镜、扫描电镜(SEM)、X射线衍射(XRD)等表征了乳液法微球的微观结构,结果显示MPMB-1和MPMB-2的内部稠环芳烃大分子片层排列复杂无规则;经2800℃石墨化处理后,MGMB-1和MGMB-2的石墨片层间距d002大于热缩聚法石墨微球(MGMB-3)的d002。对MGMB-1、MGMB-2和MGMB-3进行锂离子二次电池负极性能测试,发现乳液法石墨微球循环性能和库伦效率优于热缩聚法制备的石墨微球,MGMB-1和MGMB-2的首次放电容量分别为305mAh/g和302mAh/g。

Micro-structure and anodic performance of mesocarbon microbeads prepared by emulsion method

Two kinds of mesophase pitch microbeads (MPMB-1 and MPMB-2,about 25μm in diameter) with narrow size distribution and perfect spherical shape were prepared by emulsion method from mesophase pitches based on FCC-decant oil (FCC-MP) and naphtha-tar pitch (AR-MP),respectively.After Oxidation,carbonization and graphitization,mesophase graphite microbeads (MGMB-1 and MGMB-2) were obtained.The prepared microbeads were characterized by using polarizing microscope,scanning electron microscope (SEM) and X-ray diffraction (XRD).Results showed that MPMB-1 and MPMB-2 have an irregular and distorted lamellar structure of oriented aromatic hydrocarbons.After graphitization at 2800 ℃,interlayer spacing (d_(002)) of MGMB-1 and MGMB-2 were a little larger than that of MGMB-3 which was prepared by polycondensation of FCC-decant oil.Electrochemical measurements showed that MGMB-land MGMB-2 have better cyclability and cycle efficiency than those of MGMB-3 as an anode of a Li-ion battery.The first discharge capacities of MGMB-1 and MGMB-2 were measured as 305 mAh/g and 302 mAh/g,respectively.