锂离子电池正极材料LiFePO_4的制备及电化学性能研究

Preparation and Electrochemical Properties of LiFePO_4 Cathode Material for Lithium Ion Battery

以Li3PO4和Fe(3PO4).28H2O为原料,采用固相法成功制备了锂离子电池正极材料LiFePO4,并讨论了Li3PO4用量对材料的影响。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和充放电测试等手段对最终产物的物相、形貌和电化学性能进行了表征。结果表明,按计量比制备的LiFePO4样品具有较好的电化学性能,以0.1、0.5、1和5 C(1C=150 mA/g)的倍率进行充放电,首次放电比容量分别为135.6、123.8、116.2和56.5 mAh/g。磷酸锂过量8%制备的样品具有较好的高倍率性能,5C时放电比容量为80.3 mAh/g;而磷酸锂过量30%的样品则具有很好的小倍率放电比容量,0.1C时放电比容量为151.1 mAh/g。

LiFePO4,as cathode material of lithium ion batteries,was successfully prepared by solid state reaction using Li3PO4 and Fe3（PO4）2·8H2O as precursors.The effect of Li3PO4 amount on the performances of LiFePO4 was studied.The morphology and microstructure of the products were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results show that the sample prepared by stoichiometric ratio presents good electrochemical performance.The initial discharge capacity of the sample reaches high values of 135.6,123.8,116.2 and 56.5 mAh/g at the rate of 0.1,0.5,1 and 5C（1C=150 mA/g）,respectively.The sample with an excess of 8% Li3PO4 shows better high-rate capacity,it delivers a discharge capacity of 80.3 mAh/g at 5 C.While the sample with an excess of 30% Li3PO4 exhibits better low-rate capacity,it delivers a discharge capacity of 151.1 mAh/g at 0.1 C.