Abstract: Spherical LiFePO4 particles were synthesized by combined process of precipitation and calcination from FeSO4, H3PO4, LiOH and NH3×H2O. The precursor, a mixture of spherical Fe3(PO4)2 and Li3PO4 particles, and products derived from calcination of the precursor were characterized by XRD and SEM. The formation process of LiFePO4 from the reaction of Fe3(PO4)2 and Li3PO4 was analyzed by TG-DSC. The results show that the formation process and microstructure of olivine LiFePO4 were largely influenced by the structural characteristics and mixing state of spherical Fe3(PO4)2 and Li3PO4 particles. The spherical Fe3(PO4)2 particles with a high tap density and good fluidity consist of very small sheet-like or stick-like crystallites, which are arranged radically in the sphere and form an ordered structure. After subsequent calcination of Fe3(PO4)2 and Li3PO4 at 700℃ for 3 h under atmosphere of N2 and H2, the precursor was transformed into a single olivine LiFePO4 particle material with porous structure, diameters around 1~13 mm and a tap density of 1.25 g/cm3, which would be a promising cathode material for dynamic green Li-ion batteries.

Key words: reaction precipitation-calcination process, spherical LiFePO4, microstructure, lithium-ion battery

摘要： 以FeSO4, H3PO4, LiOH和氨水为原料，采用反应沉淀-焙烧法制备了球形LiFePO4颗粒. 利用XRD和SEM对Fe3(PO4)2和Li3PO4、前驱体及其焙烧产物进行了表征；利用TG-DSC分析了Fe3(PO4)2和Li3PO4反应形成LiFePO4的过程. 结果表明，LiFePO4的形成过程及其微结构与两反应物的结构特征及其混合状态有关，制备的Fe3(PO4)2微球由片状或棒状微晶沿径向有序排列叠砌而成，内部呈辐射状构架，密度高、分散性和流动性好. 由球形Fe3(PO4)2和Li3PO4均匀混合的前驱体在700℃下于N2和H2气氛中焙烧3 h得到晶粒细小、无其他杂相、多孔的LiFePO4球形粉体，粒径为1~13 mm，粉体振实密度为1.25 g/cm3. 该粉体有望用作动力型绿色锂离子电池正极材料.

关键词: 反应沉淀-焙烧法, 球形LiFePO4, 微结构, 锂离子电池