掺杂元素La、F对尖晶石LiMn2O4材料结构及性能的影响

Effects of Doping Elements Lanthanum and Fluorine on Structure and Electrochemical Performance of Spinel LiMn_2O_4 Cathode Material

采用X-射线衍射仪（XRD）、扫描电子显微镜（SEM）、电池测试系统等研究了掺杂元素La、F对高温固相合成尖晶石型LiMn2O4材料的相结构、形貌、活化性能、循环稳定性能的影响。结果表明：掺杂元素La、F可有效地提高LiMn2O4样品的充放电效率、循环稳定性能；随着掺杂元素F含量的增加，LiMn2O4。R样品的初始容量降低、循环稳定性能呈现出先增后减的变化规律；当掺杂元素La、F的含量较少时，LiLayMn2-yO4-x样品具有纯的尖晶石LiMn2O4结构，样品呈球形或近球形，粒径范围为0．5～2．5μm，LiLa0.02Mn1.98O3.95F0.05样品的初始放电容量为123．6mAh／g，经30次循环充放电后的容量为114．6mAh／g，容量保持率为92．7％，具有较好的活化性能和循环稳定性能。

The effects of the doping elements such as La and F on the phase structure, the morphology, the activate and electrochemical properties of the spinel LiMn2O4 cathode material prepared by high temperature solid state reaction were investigated by means of the X-ray diffraction （XRD）, scanning electron microscope （SEM） and battery testing system this paper. The results showed that the initial discharge capacity of the LiMn2O4-xFx sample decreased, and the cyclic stability of the specimen increased and then decreased with increasing of the content of the replacement elements Fluorine. The capacity ratio of discharge to charge and the cyclic stability of the LiMn2O4 sample were improved with the manganese and Oxygen partial replaced by La and F, respectively. The LiLayMn2-yO4-xFx sample was composed of single-phase spinel LiMn2O4 when the content of the doping elements La and F was minor, the particles of the specimen were spheroid or sphere, and the sizes of the particles were 0.5-2.5μm. The discharge-capacity of the LiLa0.02Mn1.98O3.95F0.05 sample was 123.6 mAh/g and 114.6 mAh/g after the first and the 30th charge/discharge cycles, respectively.