(昆明理工大學(xué) 材料科學(xué)與工程學(xué)院，昆明 650093)
摘 要: 采用交流阻抗譜研究錫電極的首次嵌鋰和第二次嵌鋰過程，對比錫納米陣列電極、錫薄膜電極和錫箔3種不同材料微觀結(jié)構(gòu)對電極交流阻抗譜特征的影響。用等效電路模型分析交流阻抗譜，得到嵌鋰過程電化學(xué)特征參數(shù)與電位關(guān)系。結(jié)果表明：錫納米陣列電極與錫薄膜、錫箔電極具有不同交流阻抗譜特征，錫納米陣列電極在中頻區(qū)出現(xiàn)雙電層阻抗；首次嵌鋰時在1.6~0.8 V之間形成固體電解質(zhì)膜(SEI)；電極材料微觀結(jié)構(gòu)顯著影響錫電極的SEI膜電阻、Warburg阻抗和鋰離子擴(kuò)散速率；錫納米陣列電極上的SEI膜電阻和Warburg阻抗最小，鋰離子擴(kuò)散能力最強(qiáng)；錫納米陣列電極上鋰的擴(kuò)散系數(shù)為4.4×10−15~1.4×10−11 cm2/s；鋰擴(kuò)散系數(shù)隨電位變化顯著。
關(guān)鍵字: 錫；錫電極；納米結(jié)構(gòu)；鋰離子；擴(kuò)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)
