尖晶石LiCo_xMn_(2-x)O_4的电化学阻抗谱分析  

Electrochemical impedance spectroscopy analysis of spinel LiCo_xMn_(2-x)O_4

作　　者：崔永丽[1] 谭晓晓[1] 庄全超[1] 

机构地区：[1]中国矿业大学材料科学与工程学院,江苏徐州221116

出　　处：《电池》2010年第5期245-248,共4页Battery Bimonthly

摘　　要：用溶胶-凝胶法合成尖晶石LiCoxMn2-xO4（x=0.1、0.2、0.3和0.4）。随着Co掺杂量x的提高,样品的首次比容量降低,循环性能提高。LiCo0.1Mn1.9O4的电化学阻抗谱（EIS）高频区域拉长压扁的半圆由两个半圆重叠而成,分别归属于Li＋通过SEI膜的迁移和LiMn2O4的电子电导率。在首次充放电过程中,3.95~3.70 V时SEI膜的阻抗增大,可能是Li＋嵌入时颗粒膨胀导致晶体畸变所致;随着电极电位升高,电子传输电阻Re总体减小,电荷传递电阻Rct先减小,后增大。Spinel LiCo, Mn2-xO4 （ x = 0.1,0.2,0.3 and 0.4） was synthesized by sol-gel method. With the increasing of Co doping amount x, the initial specific capacity of the sample decreased, the cycle performance increased. The elongated and squashed semicircle in high frequency area of electrochemical impedance spectroscopy（EIS） plots of LiCo0.1 Mn1.9O4 was overlapped by two semicircles which belonged to the Li＋ migration through SEI film and the electron conductivity of LiMn2O4, respectively. The resistance of SEI Film increased at 3.95 - 3.70 V in initial charge-discharge process, it might caused by the crystal distortion led by the volume expansion of particles during Li＋ insertion. With the increasing of electrode potential, the electron transfer resistance Re was decreased overall, the charge transfer resistance Rct was first decreased and then increased.

关 键 词：锂离子电池 掺杂 SEI膜 电化学阻抗谱(EIS) 

分 类 号：TM912.9[电气工程—电力电子与电力传动]