Fe_2P对LiFePO_4/C复合材料性能的影响(英文)

Influence of Fe_2 P on the Performance of LiFePO_4/C Composite Material

采用固相法合成LiFePO_4和LiFePO_4/C复合材料,研究了蔗糖分解的碳包覆对LiFePO_4材料性能的影响。XRD检测纯LiFePO_4为单一的橄榄石相,而LiFePO_4/C复合材料中出现高导电物质Fe_2P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LiFePO_4初始容量高达136.6mAh/g.Fe_2P的存在使LiFePO_4材料的大电流放电能力得到提高。

Pure LiFePO_4 and LiFePO_4/C composite cathode materials were synthesized by solid-state method and effect of carbon coating on the performance of LiFePO_4 was studied.The XRD pattern of the pure LiFePO_4 shows a single-phase olivine,but the ones of LiFePO_4/C composite materials show a impurity phase Fe_2P with high electronic conductivity.From the SEM images,it can be seen that the particle sizes of the samples are less than 1μm.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 LiFePO_4 reaches 136.6 mAh/g,then the electro-conductive Fe_2P among LiFePO_4/C increases the performance of them at high rate charge/discharge.