LiNi0.5Mn1.5O4及其复合物的制备、表征及电化学性能

The Preparation、Characterization and Electrochemical Performance of LiNi0.5Mn1.5O4 and lts Composite

摘要:

为了改善LiNi0.5Mn1.5O4的电化学性能，采用喷雾干燥法和静电纺丝法合成了LiNi0.5Mn1.5O4前驱体。借助X射线衍射 (XRD)、扫描电子显微镜 (SEM)、透射电子显微镜 (TEM) 对LiNi0.5Mn1.5O4进行表征，采用恒流充放电、循环伏安及交流阻抗对其电化学性能进行测试。结果表明：静电纺丝法制备的LiNi0.5Mn1.5O4材料呈多孔的管状结构，颗粒粒径约为80 nm，其循环性能有待进一步提高。而喷雾干燥法制备的前驱体在900℃烧结合成的LiNi0.5Mn1.5O4具有明显的尖晶石结构，颗粒分布均匀，颗粒平均粒径在1~2 m之间。静电纺丝法和喷雾干燥法合成的纯相LiNi0.5Mn1.5O4在0.1C倍率下首次充放电效率分别为48.1%、50.3%。对喷雾干燥法制备的LiNi0.5Mn1.5O4前驱体经碳包覆后的材料首次充放电效率提高到53.4%，在1C倍率下循环200次后，容量保持率仍然高达93.3%，这归结于碳包覆层降低了电池的电化学转移阻抗、抑制了材料与电解液之间的反应。

Abstract:

In order to improve the electrochemical performances, the precursor of LiNi0.5Mn1.5O4 is synthesized by spray drying and electrospinning. The cathode materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performances of the battery are measured by galvanostatic charge-discharge, cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS). The results show that the as-prepared LiNi0.5Mn1.5O4 by spray drying presents the porous-tubular structure, the particle size is about 80 nm, and the cycling performance need to be improved. While the precursor is calcined at 900 ℃ to obtain the spinel LiNi0.5Mn1.5O4 with uniform particle distribution, of which the particle size is between 1 and 2 m by spray drying. The coulombic efficiency of pure LiNi0.5Mn1.5O4 at 0.1C prepared by spray drying and electrospinning are 48.1% and 50.3%, respectively. While the coulombic efficiency of carbon-coated LiNi0.5Mn1.5O4 prepared by spray drying is 53.4% and the capacity retention is still up to 93.3% even after 200 cycles at 1 C-rate, attributed to that the carbon coating layer decreased electrochemical transfer impedance (Rct) and inhibited the side reaction between material and electrolyte.