E-mail: [email protected], [email protected][中文文摘]运用电化学阻抗谱研究了商品化尖晶石LiMn2O4电极在1mol/L LiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯)电解液中―10～30℃范围内的阻抗谱特征、固体电解质相界面(SEI)膜阻抗、电子电阻和电荷传递电阻等随温度的变化.研究结果表明,尖晶石LiMn2O4电极的阻抗谱特征与温度有关,随温度的升高,与活性材料电子电导率相关的半圆和与SEI膜相关的半圆会发生重叠而成为一个半圆.通过选取适当的等效电路拟合了实验所得的电化学阻抗谱数据,测得尖晶石LiMn2O4电极在1mol/LLiPF6-EC:DEC电解液中,锂离子迁移通过SEI膜的离子跳跃能垒平均值为15.49kJ/mol;电子电导率的热激活化能平均值为24.21kJ/mol;嵌入反应活化能平均值为53.07kJ/mol。[英文文摘]Variations of impedance spectra,electronic resistance,and the resistances of the solid electrolyte interphase(SEI) film,as well as the charge transfer reaction of commercially spinel LiMn2O4 electrode were investigated by electrochemical impedance spectroscopy(EIS) in 1 mol/L LiPF6-EC(ethylene carbonate):DEC(diethyl carbonate) electrolyte solutions with the temperature in the range of-10～30 ℃.It is found that,the common EIS features of spinel LiMn2O4 electrode are related to the temperature,the semicircles observed in the Nyquist diagram which related to the electronic conductivity of the material and the semicircles related to the SEI film become to overlap each other to form one semicircle at higher temperatures.
The experimental EIS data was simulated by a suitable equivalent circuit that includes elements related to the electronic and ionic transport in addition to the charge transfer process. In 1 mol/L
LiPF6-EC:DEC electrolyte solutions, the energy barriers for the ion jump relating to migration of lithium
ions through the SEI film of the spinel LiMn2O4 electrode were determined to be 15.49 kJ/mol, the thermal
active energy of the electronic conductivities to be 24.21 kJ/mol, and the intercalation-deintercalation reaction
active energies to be 53.07 kJ/mol, respectively.国家重点基础研究和发展规划(No2009CB220102);中国矿业大学青年科技基金(NoON080282),中国矿业大学人才引进经费(NoZX280),中国矿业大学科技攀登计划(NoON090237)资助项
