摘要
除了材料自身改性研究外,应用研究也是高容量硅碳复合材料的研究重点。以X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了硅碳复合材料和导电剂的形貌特征,以电化学方法研究了3种不同形貌的复合导电剂(片状与小颗粒、类球形与小颗粒、纤维状与小颗粒)对硅碳电极的电化学性能的影响。结果表明,形貌和颗粒大小与活性材料本身差异较大的导电添加剂有利于改善电极导电性,提升电极循环性能。气相生长炭纤维和炭黑颗粒在电极的表面和截面分散均匀,组成三维导电网络。气相生长炭纤维和炭黑颗粒的协同作用有利于改善硅/石墨电极的循环性能。硅碳电极20周(电流密度0.15 m A·cm^(-2))的容量保持率增加了8%,较大电流密度下(0.75m A·cm^(-2))其容量保持率由78%提高到90%。类球形石墨-炭黑颗粒复合导电剂使得Si/C电极的首次库仑效率提高到82%以上。
Application research of high capacity silicon carbon composite materials was also important for themselves, in addition to modification research. X-ray diffraction（ XRD ）, scanning electron microscope （ SEM ） and transmission electron microscope （ TEM ） were used to study the morphology features of silicon carbon composite materials and conductive agents. Electrochemical method was used to research the effect of three different composite conductive agents with different morphologies （ flake-like ＆ pellet, spherical ＆ pellet, fiber ＆ pellet） on electrochemical performance of Si/C electrode. The results showed, conductive agents and active materials had great difference in morphology and particle size. The conductive agents helped to improve electrode conductivity and cycle performance. Vapor grown carbon fiber（VGCF） and carbon black（S-p） pellet were uniformly dispersed in the surface and cross-section of the electrode, constructing three dimensional conductive network. VGCF and S-p showed a synergistic effect, improving the cycle performance of silicon/graphite electrode. After the 20th cycle, the capacity retention ratio of the Si/C electrode increased by 8% （current density 0.15 mA.cm-2 ）, and it increased from 78% to 90% when under larger current density （0.75 mA .cm-2 ）. For spherical graphite （TB17） and carbon black（ S-p）, the composite conductive agent made the first coulomb efficiency of Si/C electrode up to 82%.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2016年第10期1029-1037,共9页
Chinese Journal of Rare Metals
基金
北京市科技计划项目(Z151100000115015)资助
关键词
导电剂形貌
锂离子电池
硅碳复合材料
电化学性能
conductive agents morphology
lithium-ion battery
Si/C composites
electrochemical performance
