锂离子电池石墨负极嵌脱锂机理研究

Research on mechanism of insertion/deinsertion lithium for graphite negative electrode of lithium ion batteries

利用循环伏安、交流阻抗等方法考察了石墨电极的嵌脱锂机理.研究结果表明:石墨电极阳极过程的速度控制步骤是锂离子在石墨体相中的扩散步骤,其嵌脱锂过程分别在0.20/0.22 V,0.11/0.14 V,0.08/0.10 V(vs.Li/Li+)处存在3个明显的充放电平台,每个平台为1个两相共存区,可能分别对应3个锂石墨层间化合物的相变过程:LiG2(八阶)LiC36(四阶);LiC36(四阶)LiC12(二阶);LiC12(二阶)LiC6(一阶).

The mechanism of insertion/deinsertion of lithium ion in graphite electode means of cyclic vohammetry technique and electrochemical impedance spectroscopy. was investigated by The results showed that the rate-limiting step of the electrode process was the diffusion of lithium in the graphite. There were three distinct charge-discharge platforms respectively at 0.20/0.22 V, 0. 11/0. 14 V, 0.08/0. 10 V （ vs·Li/Li＋） in the process of insertion and deinsertion of lithium ion. Each platform is a two-phase coex- istence region, may be corresponding to the phase transition process of three lithium-graphite intercalation compounds：LiC72（8 steps）→LiC36（4 steps）,LiC36（4 steps）→LiC12（2 steps）,LiC12（2 steps）→LiC6（1 steps）.