摘要
采用SEM ,XRD ,恒流充放电等方法研究了一种新型开环自聚酚醛树脂在不同温度下炭化产物的形态、结构及电化学储锂行为。结果表明 :酚醛树脂热解炭的微观形态为片层结构 ,具有较大的d0 0 2 值 ,较小的Lc 值和较大的La 值 ;它的电化学性质呈现出含氢炭材料的行为 ,表现出高的储锂容量和较大的不可逆容量损失 ,随着炭化温度的提高 ,所得炭的储锂容量由 6 0 0℃时的 6 16mAh/ g减小为 80 0℃时的 2 0 8mAh/g ,相应的不可逆容量损失也由 6 0 0℃的 2 19mAh/ g减小为 80 0℃的 31mAh/ g ;探讨了该聚合物炭的储锂机制 ,认为除了锂对微晶石墨片层的插层作用之外 ,还可能存在锂离子与炭材料中氢原子的结合 ,导致放电电压的滞后。但随着热处理温度的提高 ,氢含量减少 ,上述电压滞后现象也随之减弱 ,直至消失。
Carbon materials were prepared from a special phenolic resin provided by Sichuan University at temperatures from 600、℃ to 1、000、℃ by pyrolysis in an inert N 2 gas. The morphologies and microstructures of the polymer-derived carbons were characterized by means of SEM and XRD, and the corresponding electrochemical performances were investigated using charge/discharge measurements. It is found that the morphology of the phenolic resin based carbons show an apparent carbon layer structure, whose graphitic micro-crystal sizes of the resulted turbostratic carbons are as follows: the value of d 002 is about 0.39、nm, the value of L c is 1.5～2.1、nm and the value of L a is in the range of 3.7～4.7、nm, showing the polymer-derived hard carbon characteristics. The obtained materials show a capacity for lithium insertion as high as 620、mAh/g when treated at 600、℃. But the majority of this capacity shows a large hysteresis, that is the lithium is inserted near 0、V(vs. Li+/Li) and removed near 1、V. The high capacity of the phenolic resin heat-treated at a low temperature was contributed to the graphite intercalation compound mechanism and the reaction of lithium with hydrogen and oxygen which remained in the low-temperature heat-treated carbon materials. Remarkable characteristics of the resulted carbons was the higher irreversible capacity loss even heat-treated at 1、000、℃, which associated with the irreversible reaction of lithium with O and N elements remained in the resulted carbon materials.
出处
《北京化工大学学报（自然科学版）》
CAS
CSCD
2004年第1期34-38,共5页
Journal of Beijing University of Chemical Technology(Natural Science Edition)
基金
北京市科技新星计划项目 (95 4 8114 0 0 )
关键词
锂离子二次电池
炭负极材料
酚醛树脂
lithium-ion battery
carbon anode materials
phenolic resin
