基于同步辐射的X射线吸收谱探讨LiFe_xMn_(1-x)O_2的精细结构（英文）  

Insight into fine structures of LiFe_xMn_(1-x)O_2 bysynchrotron radiation-based X-rayabsorption spectroscopy

作　　者：吴桂贤[1] 赵海峰[2] 黄伟峰[3] 陶石[1] 张凌铭 余蓁[1] 储旺盛[1] 韦世强[1] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,安徽合肥230026 [2]中国科学院高能物理研究所,北京100049 [3]北京大学工程学院,高能电池材料理论技术重点实验室,北京100871

出　　处：《中国科学技术大学学报》2017年第5期369-376,391,共9页JUSTC

基　　金：Supported by the National Natural Science Foundation of China(11179001,11275227)

摘　　要：利用共沉淀法合成出了一系列化合物LiFe_xMn_(1-x)O_2(0≤x≤1),电化学测试表明LiFe_(0.25)Mn_(0.75)O_2可逆容量最高,当倍率为0.1C(1C=140mA/g)时,可逆容量可达180mAh/g.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线吸收谱(XAS)对所制备的材料的组成、形貌和精细结构进行了表征.XRD和XAS的结果显示LiFe_xMn_(1-x)O_2(0<x<1)含有三重晶体相即尖晶石相(LiMn_2O_4)、富锂相(Li_2MnO_3)和层状相(LiFeO_2).另外,XAS结果证明材料中的Mn相和Fe相是随机堆叠的.该研究表明Fe的替代影响了晶体相的组成和Mn相的局域结构,进而调节了该正极材料的电化学性能,得到当x=0.25时最优的电化学性能.LiFexMn1-xO2（0≤x≤1） compounds were synthesized by the co-precipitation method. Electrochemical tests show that the LiFe0.25Mn0.75O2 composite has a maximum reversible capacity of 180 mAh/g at 0.1 C（1 C=140 mA/g）. These as-prepared samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray absorption spectroscopy （XAS）. XRD and XAS results show that the LiFex Mn1-xO2 （0〈x〈1） samples actually have multiple crystal phases, especially the spinel phase （LiMn2O4）, Li-rich phase （Li2MnOa） and layered phase （LiFeO2）. Moreover, XAS reveals that the Mn-phase and the Fe-phase are randomly stacked in the samples. The work shows the doping of Fe influences the crystal phase and local structure of the Mn-phase upon the samples and then adjusts the electrochemical performances of the cathode materials, giving an optimal proportion （x =0.25） of the spinel and Li-rich and layered phase.

关 键 词：X射线吸收谱 锂离子电池 多重相 局域结构 

分 类 号：O611.4[理学—无机化学]