锂在锂离子电池石墨电极中电化学嵌脱层的可逆性

The reversibility of graphite electrode of lithium electrochemical intercalation for the lithium-ion rechargeable batteries

对石墨化热处理温度与其充放电性能的关系以及锂在石墨负极中不能可逆嵌脱的原因进行了研究 .在不同的最高热处理温度 (tmax为 2 0 0 0 ,2 2 5 0 ,2 5 0 0 ,2 75 0 ,3 0 0 0℃ )下对石油焦和针状焦进行石墨化处理 ,采用X射线衍射、Raman光谱法研究了试样的晶体学参数 ,采用恒电流法、原位XRD法研究了锂在上述材料中进行嵌脱层时的容量和可逆性 .研究结果表明 :为了获得最佳电化学性能的负极材料 ,必须针对不同的原材料采取合适的热处理工艺 ;为了避免充放电过程中石墨微晶层离 ,石墨化程度不能太高 ,碳层平面之间必须有一定数量的sp3 键相联 .

The effects of heat treatment temperature on the charging discharging performance of graphite materials and the reason have been studied. One kind of petroleum coke and one kind of needle coke were graphitized at different maximum heat treatment temperature ( t max are 2 000, 2 250, 2 500, 2 750, 3 000 ℃). The crystallite parameters of this graphitized products were studied by X ray diffraction and Raman spectrums. The capacity and the reversibility of electrochemical intercalation deintercalation of lithium into this graphitized products were studied by galvanostatic method and in situ X ray diffraction. The results show that the appropriate heat treatment temperature must be considered in order to get the materials with the best electrochemical performance, and t max depends on precursor cokes. We find that the degree of graphitized can′t be too high and a small quantity of sp 3 bond must exist to connect the carbon plans together and to avoid the exfoliation of graphite microcrystallites during charging and discharging. [