尖晶石LiMn_2O_4材料的高温固相合成及性能表征

Characterization of Spinel LiMn_2O_4 Material Synthesized by High-Temperature Solid-State Process

本文采用热重分析仪（TGA）、X-射线衍射仪（XRD）、扫描电子显微镜（SEM）、电池测试系统等方法研究了尖晶石LiMn2O4材料的高温固相合成过程的相转变、形貌变化、晶格常数及电化学性能等变化规律。结果表明：合成温度较低时（≤823 K）,样品由尖晶石型LiMn2O4相、微量MnO2相（673 K）或Mn2O3相（823 K）组成;当合成温度高于973 K时,样品由热稳定性能较好的纯尖晶石型LiMn2O4相组成,呈规则的球形或近球形,粒径范围为0.5-5μm。随着合成温度的升高,LiMn2O4样品的点阵常数、晶胞体积、颗粒尺寸等有不同程度的增加,放电容量呈先增后减的规律。

The phase transformation,the morphology,the crystal parameter and the electrochemical performance of the spinel LiMn2O4 material during the high temperature solid state process were investigated by means of the thermal gravimetric analysis（TGA）,X-ray diffraction（XRD）,scanning electron microscope（SEM） and battery testing system.The results show that the sample consists of the spinel LiMn2O4,MnO2,or Mn2O3 phases when the synthetic temperature is lower than 823 K, the specimen is stable and composed of the single-phase spinel LiMn2O4 phase. The particles of the specimen are spheroid or sphere, and the size of the particles were 0.5-5 μm when the temperature was higher than 973 K. The lattice parameters, cell volume and particle size of the LiMn2O4 sample increase, and the initial discharge-capacity of the specimen increase and then decrease with increasing synthetic temperature.