含菱形相的天然石墨用做锂离子电池负极材料  

Electrochemical Performances of Natural Graphite Containing Rhombohedral Phase as Negative for Li-ion Batteries

作　　者：时志强[1] 王成扬[1] 樊丽萍[1] 周小野 

机构地区：[1]天津大学化工学院绿色合成与转化教育部重点实验室,天津300072 [2]天津市铁中煤化工有限公司,天津300110

出　　处：《天津大学学报（自然科学与工程技术版）》2005年第2期154-158,共5页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(50172034).

摘　　要：利用天然石墨的XRD结晶参数计算了 5种天然石墨样品的菱形石墨含量,采用恒电流充放电和循环伏安方法研究了天然石墨HT10在 1mol/LLiPF6 /EC+EMC(1∶1,体积比)和 1mol/LLiPF6 /EC+EMC+PC(3∶3∶4,体积比)电解液中的电化学性能.结果表明,HT10在 2种电解液中均保持了较高的放电容量和较好的循环性能,且放电容量均在 330mAh/g以上,首次库仑效率均大于 8700.采用循环伏安和SEM分析了充放电过程中形成SEI膜的情况,良好的SEI膜保证了锂离子的通过而阻止溶剂的共嵌入;同时在 1mol/LLiPF6 /EC+EMC+PC(3∶3∶4,体积比)中石墨片层经多次充放电后剥离形成了疏松的多孔性物质.The contents of rhombohedral phase of five natural graphites were calculated by applying XRD crystalline parameters. The electrochemical performances of natural graphite HT10 using 1 mol/L LiPF_6 ethylene carbonate(EC)/ethyl methyl carbonate(EMC) 1∶1(volume ratio) and 1 mol/L LiPF_6 EC/EMC/propylene carbonate(PC) 3∶3∶4 (volume ratio) electrolyte mixture were analyzed by galvanostatic charge/discharge and cyclic voltammetry methods. The results show natural graphite HT10 has excellent cycling performances for both EC/EMC and EC/EMC/PC electrolytes, in both cases that the discharge capacities are over 330 mAh/g, and the first columbic efficiency is more than 87~0_0. The formation process of solid electrolyte interface (SEI) film in the charge/discharge process is analyzed by cyclic voltammetry and scanning electron microscopy (SEM). It is proved that excellent SEI ensures lithium ions transit and inhibits the solvent cointercalation. Furthermore, loose and porous exfoliation matter denuded from the layer of graphite in 1 mol/L LiPF_6 EC/EMC/PC 3∶3∶4 (volume ratio) electrolyte is observed after several cycles.

关 键 词：天然石墨 菱形相 电解液 共嵌入 剥落 

分 类 号：TM912.9[电气工程—电力电子与电力传动]