温度对LiCoO2中锂离子嵌脱过程的影响

摘要 运用EIS研究了LiCoO2正极在1M LiPF6-EC:DEC:DMC和1M LiPF6-PC:DMC+5%VC电解液中0~30℃范围内阻抗谱特征、SEI膜阻抗、电子电阻和电荷传递电阻等随温度的变化。结果表明，LiCoO2正极的EIS谱特征与温度有关，随温度的升高其低频区域在1M LiPF6-EC:DEC:DMC和1M LiPF6-PC:DMC+5%VC电解液中分别于10和20℃出现反映锂离子固态扩散的斜线。LiCoO2正极在 1M LiPF6-EC:DEC:DMC和1M LiPF6-PC:DMC+5%VC电解液中，锂离子迁移通过SEI膜的离子跳跃能垒平均值分别为37.74和26.55KJ/mol；电子电导率的热激活化能平均值分别为39.08和53.81KJ/mol；嵌入反应活化能平均值分别为68.97和73.73KJ/mol。

Effects of of Temperature on the Process of Lithium Intercalation-deintercalation in LiCoO2

Abstract Variations of impedance spectra, electronic resistance, and the resistances of the SEI film and the charge transfer reaction of LiCoO2 electrode in the 1M LiPF6-EC:DEC:DMC and 1M LiPF6-PC:DMC+5%VC electrolyte solutions with the temperature in the range 0~30℃, had been investigated by electrochemical impedance spectroscopy (EIS). It is found that, the common EIS features of LiCoO2 electrode in the 1M LiPF6-EC:DEC:DMC and 1M LiPF6-PC:DMC+5%VC electrolyte solutions are related to the temperature, a straight line reflecting solid state Li ion diffusion in the bulk of active mass appears at 10 and 20℃ respectively. The energy barrier for the ion jump related to migration of lithium ions through the SEI film of LiCoO2 electrode in the 1M LiPF6-EC:DEC:DMC and 1M LiPF6-PC:DMC+5%VC electrolyte solutions is 37.74 and 26.55 KJ/mol, the thermal active energy of the electronic conductivity is 39.08 and 53.81 KJ/mol, and the intercalation-deintercalation reaction energy is 68.97and 73.73 KJ/mol, respectively.