物理化学学报 >> 2002, Vol. 18 >> Issue (08): 705-709.doi: 10.3866/PKU.WHXB20020807

研究论文 上一篇    下一篇

恒压-恒流充电容量比值法测定石墨电极中的锂离子扩散系数

唐新村;何莉萍;陈宗璋;夏熙   

  1. 湖南大学化学化工学院,长沙　410082;新疆大学应用化学研究所,乌鲁木齐　830046
  • 收稿日期:2001-12-05 修回日期:2002-03-28 发布日期:2002-08-15
  • 通讯作者: 陈宗璋 E-mail:tangxincun@sina.com.cn

Determination of the Li＋ Diffusion Coefficient in Graphite By the Method of the Ratio of Potentio-charge Capacity to Galvano-charge Capacity

Tang Xin-Cun;He Li-Ping;Chen Zong-Zhang;Xia Xi   

  1. College of Chemistry and Chemical Engineering, Hunan University, Changsha　410082;Institute of Applied Chemistry, Xinjiang University, Wulumuqi　820046
  • Received:2001-12-05 Revised:2002-03-28 Published:2002-08-15
  • Contact: Chen Zong-Zhang E-mail:tangxincun@sina.com.cn

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摘要： 通过球形扩散模型推导了恒压-恒流充电容量比(简称RPG)与石墨电极中锂离子固相扩散系数的关系,给出了一种测量锂离子在石墨负极中固相扩散系数的新方法即RPG法.理论结果表明固相扩散系数D与RPG值q,颗粒半径R和恒流充电时间tG有关.当q ≤ 0.5时,其关系式可通过最小方差线性化拟合为D=R2/(15.36qtG) (q ≤ 0.5).实验结果表明,RPG法具有非常好的重现性,不同恒流充电电流和时间下测得1.5 V(vs Li/Li＋)的锂离子固相扩散系数值均在1.060×10－10 cm2•s－1左右.采用RPG法对石墨电极在1.0～2.5 V(vs Li/Li＋)高电压区的锂离子固相扩散系数进行了测试,结果表明在1.0～2.5 V的高电压区,随着电压的升高,D值从4.292×10－10 cm2•s－1减小到1.219×10－11 cm2•s－1.

关键词: 恒压-恒流充电容量比, 固相扩散系数, 石墨, 锂离子电池

Abstract: A novel electrochemical method (RPG method) has been theoretically and experimentally developed to determine the diffusion coefficient of intercalary species within insertion-host materials on the basis of the spherical diffusion model. Theoretical results show that the diffusion coefficient D is dependent to the ratio (q) of the potentio-charge capacity to the galvano-charge capacity (abridged as RPG), the radius of insertion-host particle R, and the galvano-charge time tG. The RPG equation obtained is as D=R2/(15.36qtG)(q ≤ 0.5).Using this method, the values of the Li＋ diffusion coefficient determined at different galvano-charge currents with 1.5 V cutoff voltage are all around the value of 1.060×10－10 cm2•s－1.This result indicates that the RPG method has a good reliability for determination of the diffusion coefficient. The Li＋ diffusion coefficient in graphite has been reduced from 4.292×10－10 to 1.219×10－11 cm2•s－1 among the voltage range of 1.0～2.5 V (vs Li/Li＋),respectively.

Key words: Ratio of potentio-charge capacity to galvano-charge capacity, 　 Diffusion coefficient, Graphite, Lithium-ion batteries