锂离子电池正极材料LiMnO_2的电化学阻抗谱研究

Electrochemical Impedance Spectrum of LiMnO_2 as Cathode Materials for Lithium-ion Batteries

通过球形扩散模型给出了一种测定锂离子在电极材料中固相表观扩散系数的计算方法(修正Warburg阻抗法),研究了LiMnO2电极的交流阻抗和锂离子的扩散行为。研究表明,材料合成温度影响电极反应表面电荷传递和材料中的锂离子扩散特性。用熔盐浸渍法在500℃保温12h合成的LiMnO2正极材料的锂离子表观扩散系数为1.49×10-10cm2/s。

A novel electrochemical method （modified Warburg impedance method） has been developed to determine the apparent diffusion coefficient of lithium ion within insertion-host materials on the basis of the spherical diffusion model. The electrochemical impedance spectrum （EIS） and diffusion coefficient of lithium ion for LiMnO2 were also studied. The results showed that the transfer of surface electrons increases and lithium ion diffusion decreases with raising reaction temperature. The lithium ion apparent diffusion coefficient of using LiMnO2 samples with pure phase prepared by melting impregnation method at 500℃ for 12h as cathode material is 1.497 ×10^-0 cm2/S.