球形Li_2FeSiO_4/C正极材料的制备与性能研究

Preparation of spherical Li_2FeSiO_4/C cathode material and its performance

以正硅酸乙酯、草酸亚铁、碳酸锂为原料采用两步沉淀工艺制备了球形Li2FeSiO4/C正极材料。利用粉末X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、交流阻抗分析（EIS）和恒流充放电测试方法对样品的结构、形貌和电化学性能进行了分析。结果表明：850℃下进行10 h处理的样品材料颗粒呈球形形貌,颗粒尺寸在400-600nm之间,分布较为均匀;并且在该条件下制备的样品具有较高的电导率（1.244×10^-13 cm2/S）,在0.1C放电下的首次充电比容量为162.2 m Ah/g,放电比容量为153.1 m Ah/g,具有较高的库仑效率（94.4%）,经过50周循环后容量保持率仍为87.9%,说明该方法制备的球形Li2FeSiO4/C材料具有良好的电化学性能。

The cathode material of Li2FeSiO4/C for lithium-ion battery was prepared via two steps precipitation method, which were synthesized with TEOS, FeC2O4·2H2O and Li2CO3 as reaction reagents. The structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction （XRD）, scanning electron micrograph （SEM）, transmission electron microscope （TEM）, EIS tests and the constant current charge-discharge tests. The results indicate that the sample heated for 10 h at 850 ℃ presents the spherical morphology. The size of Li2FeSiO4 particles was approximately 400-600nm and distributed consistently. The samples had high electrical conductivity under this condition（1.244 × 10^-13 cm^2/s）. The first charge and discharge capacity of 162.2, 153.1 mAh/g can be obtained at 0.1C rate, The coulomb efficiency is 94.4%. The capacity is maintained at 87.9% after 50 cycles which illustrates the method of preparation of spherical Li2FeSiO4/C material had a good electrochemical performance.