关键词: 反应沉淀-焙烧法, 球形LiFePO4, 微结构, 锂离子电池

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