摘要
通过考察煤系针状焦在700~2800℃热处理过程中石墨微晶结构的变化规律及其电化学性能,并结合TG-DTG、XRD、SEM、XPS表征方法以及充放电、循环伏安曲线特征,分析了针状焦的石墨化机理及其储锂机制.研究结果表明,随热处理温度的升高,针状焦的类石墨微晶在不断长大的同时,还存在微晶在径/轴向的排列、石墨层间位错线的消失、晶界间C-C六圆环的形成、晶界的消失以及石墨层"褶皱"的平面化等复杂过程,且每个过程的驱动力不同.针状焦经过2800℃石墨化后,可获得较低的Li+充放电电位和稳定的充放电平台,且反复充放电40次后的有效嵌锂容量为305mAh/g.
Effects of heat-treatment temperature on the microstructure and electrochemical properties of coal based nee-dle coke were investigated by TG-DTG,XRD,SEM,XPS analysis and the charge/discharge,cyclic voltammetry curves.The graphitization mechanism of needle coke is suggested as well as the Li+ extraction-insertion behaviors.With the heat-treatment temperature increasing,the graphite-like crystal grows continuously attended with a complicated process,including the arrangement of crystal along radial/axial direction,dislocation dispersion among graphite layers,hexagonal carbon formation,crystal edge dispersion and folded graphite layer turning to plane.Meanwhile,the driving-forces are far different for different process.When needle coke is graphitized at 2800℃,it exhibits a lower charge/discharge potential and stable charge/discharge platform,and the insertion capacitance of Li+ can maintain at 305mAh/g even after charge/discharged for 40 cycles.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2011年第6期619-624,共6页
Journal of Inorganic Materials
基金
国家863重点项目(2008AA062302)
国家自然科学基金(20806024
50672025
5073003
51002051)
中央高校基本科研业务费专项基金(WA1014016)~~
关键词
针状焦
负极材料
锂离子电池
石墨化
needle coke
anode material
lithium ion battery
graphitization