前驱体固相法制备硅酸铁锂正极材料

Synthesis of Lithium Iron Siliate Electrode Materials via Precursor Solid-State Reaction

以碳酸锂或乙酸锂、草酸亚铁和正硅酸乙酯为原料,蔗糖为碳源,乙酸为催化剂,通过溶胶·凝胶法制备前驱体,再采用固相反应法在600℃、氮气气氛中一步烧结制备了碳包覆硅酸铁锂(Li2FeSiO4/C)正极材料。将其组装成电池进行电化学性能测试。用X射线衍射和扫描电镜表征Li2FeSiO4/C的结构、形貌和晶粒尺寸。结果表明:以乙酸锂为锂源制备的Li2FeSiO4/C结晶良好,基本无杂相,晶粒尺寸为50～200 nm,分布较均匀;在C/16、C/10、1C和2C(1C=166 mA/g)放电速率下,放电比容量分别达153、138、131 mA·h/g和93 mA.h/g,经过30个充放电循环后,容量几乎没有衰减。

The carbon-coated Li2FeSiO4 cathode materials were prepared via a solid-state reaction by one-step calcination of precursors,which were synthesized in a sol-gels process with Li2CO3 or CH3COOLi·2H2O,FeC2O4·2H2O and Si（C2H5O）4 as reaction reagents,sucrose as a carbon source and HAc as a catalyst,under N2 atmosphere at 600 ℃.The electrochemical performance was examined by assembling a battery with the Li2FeSiO4/C samples.The X-ray diffraction and scanning electron microscopy were used to characterize the structure,morphology and grain size of the as-prepared sample.The results indicate that the Li2FeSiO4/C samples prepared by CH3COOLi·2H2O as a lithium source exhibits a good crystallinity with little impurities.The sizes of Li2FeSiO4/C particles were approximately 50-200 nm.The discharge capacities of 153,138,131 and 93 mA·h/g could be obtained at C/16,C/10,1C and 2C rate,respectively.No apparent capacity loss was observed after 30 cycles.