尖晶石LiMn_2O_4中锂离子嵌入脱出过程的电化学阻抗谱研究  

Electrochemical Impedance Spectroscopic Studies of Insertion and Deinsertion of Lithium Ion in Spinel LiMn_2O_4

作　　者：庄全超[1] 魏涛[1] 魏国祯[2] 董全峰[2] 孙世刚[2] 

机构地区：[1]中国矿业大学材料科学与工程学院,徐州221116 [2]固体表面物理化学国家重点实验室厦门大学化学化工学院化学系,厦门361005

出　　处：《化学学报》2009年第19期2184-2192,共9页Acta Chimica Sinica

基　　金：国家重点基础研究和发展规划"973"项目(No.2009CB220102);中国矿业大学青年科技基金(No.ON080282)资助项目

摘　　要：运用电化学阻抗谱(EIS)研究了尖晶石LiMn2O4电极的首次充放电过程.发现EIS谱高频区域拉长压扁的半圆是由两个半圆相互重叠而成的,分别归属于与锂离子通过固体电解质相界面膜(SEI膜)的迁移和与尖晶石LiMn2O4材料的电子电导率相关的特征.通过选取适当的等效电路,对实验所得的电化学阻抗谱数据进行拟合,获得尖晶石LiMn2O4电极首次充放电过程中SEI膜电阻、电子电阻和电荷传递电阻等随电极极化电位变化的规律.根据研究结果提出了嵌锂物理机制模型.The processes of insertion and deinsertion of lithium ion in a spinel LiMn2O4 electrode during the first charge-discharge cycle were investigated by electrochemical impedance spectroscopy （EIS）. The results illustrate that the depressed semicircle in the high frequency region consists of two semicircles that are overlapped each other, and were assigned respectively to lithium-ion migration through solid electrolyte interphase （SEI） film as well as the electronic properties of the material. An appropriate equivalent circuit was proposed to fit the experimental EIS data and variations of the resistance of SEI film, the electronic resistance of the material and the resistance of charge transfer along with the increase and decrease of electrode polarization potential were quantitatively analyzed. Based on the EIS results and analysis, a physical mechanism of lithium insertion and deinsertion was suggested.

关 键 词：锂离子电池 尖晶石LIMN2O4 SEI膜 电子电导率 电化学阻抗谱 

分 类 号：TM912[电气工程—电力电子与电力传动]