INOR 301 |
| Lithium iron phosphate(LiFePO4) is a promising cathode material for lithium rechargeable batteries. However, the poor rate performance has limited its application. To date, most of the effects to improve the rate capacity of LiFePO4 have focused on the incorporation of conductive carbon into the active material powders to form carbon-coated LiFePO4 (LiFePO4/C). The goal of this research was to study the effect of polymer precursors on the performance of the LiFePO4/C composite. A co-precipitation method was applied to prepare a series of LiFePO4/C materials by calcinating amorphous LiFePO4 with different polymer compounds at 750oC. The materials were characterized by X-ray diffraction, scanning electron microscopy, particle size analysis, thermal analysis, BET specific surface area, Raman spectral analysis and electrochemical methods. The obtained LiFePO4/C composites showed a well-ordered olivine-type LiFePO4 structure with a minor Fe2P impurity. The occurrence of the Fe2P phase can be attributed to the relatively high temperature of 750oC. The LiFePO4/C composites produced by pyrolysis of SBS polymer exhibited a better capacity compared to other types of polymer compounds. The SBS showed a better performance because its decomposition temperature was close to the temperature of the LiFePO4 phase transformation resulting in a fine particle size and uniform carbon distribution on the composite surface. Five samples were prepared with 0, 5, 10, 20, 30 wt.% SBS added to the amorphous LiFePO4 particles. The increasing amount of SBS exhibited a higher capacity. |
|
Synthesis and Characterization of Materials
7:00 PM-10:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Inorganic Chemistry |