废石墨化学沉积包覆作锂离子蓄电池负极材料

以大功率石墨电极废品破碎后的微粒为“核”,以中温沥青为包覆原料,经化学沉积包覆形成“核-壳”型锂离子蓄电池负极材料。采用恒电流充放电和循环伏安等方法检测人造石墨包覆前后的充、放电性能和循环性能,以及锂在其中的嵌入脱出反应。结果表明:单颗粒核壳型包覆有效地改善了石墨界面处固体电解质相界面(SEI)膜结构,缓解了电解液在界面发生的强烈还原反应,保护了人造石墨(AG)结构、提高了AG用作锂离子蓄电池负极的充、放电性能。首次放电比容量由包覆改性前的255.5mAh/g增至305.4mAh/g,首次库仑效率则从包覆前的80.8%提高到90.2%;50次循环后放电比容量由改性前的154.1mAh/g提高至302.3mAh/g;同时,改性后的人造石墨提高了对碳酸丙烯酯(PC)系电解液的相容性。

Graphite electrode wastes treated with chemical deposition used as negative materials for Li-ion secondary battery

Particulate of graphite electrode wastes from an electric-carbon materials factory was formed "core-shell" negative materials by chemical deposition coating with medium pitch. Charge-discharge performances and cyclic voltammograns characteristics of the samples were investigated. Experimental results show that the first discharge specific capacity of AG with coating treatment is 305.4 mAh/g, which is higher than 255.5 mAh/g of untreated AG, and its relevant coulombic efficient increases from 80.8% to 90.2%. And the 50th discharge capacity also increases from 154.1 mAh/g to 302.1 mAh/g. Meanwhile, AG with pitch coating treatment can work better than untreated AG with electrolyte dissolved in PC solvent. Charge-discharge curves indicate that irreversible capacity loss is caused by solvent decomposition on AG surface and intercalation into irreversible carbon sites inside the AG. Surface chemical deposition coating process can effectively reduce irreversible capacity loss and can reduce inner lattice limitation.