(昆明理工大学 材料科学与工程学院，昆明 650093)
摘 要: 采用交流阻抗谱研究锡电极的首次嵌锂和第二次嵌锂过程，对比锡纳米阵列电极、锡薄膜电极和锡箔3种不同材料微观结构对电极交流阻抗谱特征的影响。用等效电路模型分析交流阻抗谱，得到嵌锂过程电化学特征参数与电位关系。结果表明：锡纳米阵列电极与锡薄膜、锡箔电极具有不同交流阻抗谱特征，锡纳米阵列电极在中频区出现双电层阻抗；首次嵌锂时在1.6~0.8 V之间形成固体电解质膜(SEI)；电极材料微观结构显著影响锡电极的SEI膜电阻、Warburg阻抗和锂离子扩散速率；锡纳米阵列电极上的SEI膜电阻和Warburg阻抗最小，锂离子扩散能力最强；锡纳米阵列电极上锂的扩散系数为4.4×10−15~1.4×10−11 cm2/s；锂扩散系数随电位变化显著。
关键字: 锡；锡电极；纳米结构；锂离子；扩散；交流阻抗
（College of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:Electrochemical impedance spectroscopy (EIS) was applied to studying the first and the second lithium intercalation process on tin electrodes. The characters of EIS spectra from tin electrodes with different morphologies were studied. Equivalent circuits were selected for modeling the experimental data. The dependence of electrochemical parameters on the electrode potential was obtained. The results show that the EIS spectra of tin nano-array electrode are of different characters from electrodes of tin film and tin foil. A medium-frequency ace is found on the spectra of tin nano-array electrode. The formation of solid-electrolyte layer (SEI) on the surface of tin electrode is observed in the first lithium intercalation process in the potential range of 1.6~0.8 V. The surface resistances, Warburg resistance and lithium ion diffusion coefficient are controlled by the morphology of the electrode. The lowest surface resistances and Warburg resistance and the highest diffusion coefficient are observed on the electrodes of tin nano-arrays. The diffusion coefficient of tin nano-arrays varies from 4.4×10−15 to 1.4×10−11 cm2/s, changing obviously with the electrode potential.
Key words: tin; tin electrodes; nano-structure; lithium-ion; diffusion; electrochemical impedance spectroscopy (EIS)
