Fe2 P对LiFePO4/C复合材料性能的影响

采用固相法合成LiFePO4和LiFePO4/C复合材料,研究了蔗糖分解的碳包覆对LiFePO4材料性能的影响.XRD检测纯LiFePO4为单一的橄榄石相,而LiFePO4/C复合材料中出现高导电物质Fe2P相;SEM显示样品的粒径均在1μm以下,包覆碳样品的晶粒更小,但出现团聚现象.此方法合成的纯LiFePO4初始容量高达136.6 mAh/g.Fe2P的存在使LiFePO4材料的大电流放电能力得到提高.

Influence of Fe2 P on the Performance of LiFePO4/C Composite Material

Pure LiFePO4 and LiFePO4/C composite cathode materials were synthesized by solid-state method and effect of carbon coat-ing on the performance of LiFePO4 was studied. The XRD pattern of the pure LiFePO4 shows a siagh-phase olivine, but the ones of LiFePO4/C composite materials show a impurity phase Fe2P with high electronic conductivity. From the SEM images, it can be seen that the particle sizes of the samples are less than 1 μm. Though the carbon-coated samples have smaller particle sizes, some of them are in the form of particle agglomerates. The first cycle discharge capacity of the pure LiFePO4 reaches 136. 6 mAh/g, then the electro-conductive Fe2 P among LiFePO4/C increases the performance of them at high rate charge/discharge.