稀土元素对LiMn2O4电极材料相结构及性能的影响

Effects of rare earth elements on phase structure and properties of the spinel LiMn_2O_4 electrode material

采用X射线衍射仪、扫描电子显微镜、电池测试系统等研究了不同稀土掺杂元素La、Ce、Nd等对Pechini法合成的LiMn2O4材料的相结构、形貌及电化学性能的影响规律。结果表明,合成的LiMn2O4、LiLa0.03Mn1.97O4、LiLa0.01Ce0.01Nd0.01Mn1.97O4样品具有纯尖晶石型LiMn2O4结构,LiLa0.015Ce0.015Mn1.97O4样品由LiMn2O4相及微量杂质相CeO2组成;样品呈规则的近球形或球形,其粒径范围为0.5-2.5μm。稀土元素取代使LiMn2O4材料的初始容量略有降低、循环稳定性能有较大增加,LiMn2O4、LiLa0.03Mn1.97O4、LiLa0.015Ce0.015Mn1.97O4、LiLa0.01Ce0.01Nd0.01Mn1.97O4样品的初始容量分别为126.0、120.0、117.3、124.0 mA.h/g,经30次循环充放电后的容量分别为88.9、102.7、101.6、109.1 mA.h/g。

The effects of the rare earth elements such as lanthanum,cerium and neodymium on phase structure,the micrograph and electrochemical performance of the spinel LiMn2O4 cathode material prepared by Pechini process were investigated by means of XRD,SEM and battery testing system.The results show that the LiMn2O4,LiLa0.03Mn1.97O4,LiLa0.01Ce0.01Nd0.01Mn1.97O4 samples are composed of single-phase spinel LiMn2O4 phase,and the LiLa0.015Ce0.015Mn1.97O4 sample is consist of the LiMn2O4 and CeO2 phases,the particles of the specimen are spheroid or sphere,and the size of the particles are 0.5~2.5 μm.The initial discharge capacity of the LiMn2O4 sample decreases,and the cyclic stability of the specimen increases with partial replacement of manganese by rare earth elements.The discharge-capacity of LiMn2O4,LiLa0.03Mn1.97O4,LiLa0.015Ce0.015Mn1.97O4,LiLa0.01Ce0.01Nd0.01Mn1.97O4 samples are 126.0,120.0,117.3 and 124.0 mA·h/g after the first charge/discharge cycle,and are 88.9,102.7,101.6 and 109.1 mA·h/g after the 30 th cycles.