溶胶凝胶法制备LiFePO_4F及其电化学性能研究  

Electrochemical Properties of LiFePO_4F Synthesized by a Novel Sol-gel Process

作　　者：李臻[1] 周菁[1] 

机构地区：[1]郑州轻工业学院材料与化学工程学院,河南郑州450000

出　　处：《广东化工》2016年第8期26-27,13,共3页Guangdong Chemical Industry

摘　　要：采用溶胶-凝胶法制备了锂磷铝石型晶体LiFePO_4F。采用X射线衍射法(XRD)和扫描电镜法(SEM)表征了所合成材料的结构和形貌;采用恒流充放电法以及交流阻抗法表征了所合成材料的电化学性能。结构表征结果表明,所合成的LiFePO_4F材料具有P1空间对称群,与天然锂磷铝石(LiAlPO_4(OH,F))为同一种结构,颗粒大小为400~600 nm;电化学测试结果表明,所合成的材料具有148 mAh·g^(-1)的初始比容量,同时循环性能优良。文章通过交流阻抗技术估算了锂离子在该种材料中的扩散系数,结果表明,该材料的锂离子扩散系数比未改性的橄榄石型LiFePO_4大3个数量级。A novel sol-gel process was used to synthesize LiFePO4F. X-ray diffraction （XRD） and scanning electron microscope （SEM） were implemented to characterize the structure and morphology of the sample. For studying the electrochemical performance, galvanostatic mode and electrochemical impedance spectroscopy （EIS） were adopted. The obtained crystalline powder is isostructural with amblygonite, adopting a triclinic PI spacegroup. The particle size of the obtained material is 400-600 rim. The initial galvanostatic discharge-charge capacity is 148 mAh·g^-1, and the cyclic performance is excellent. Furthermore, the diffusion coefficient of the LiFePO4F. firstly studied by EIS in the paper, is higher than that of ray, LiFePO4 by three orders of magnitude.

关 键 词：正极材料 锂离子电池 锂磷铝石 

分 类 号：TG139.7[一般工业技术—材料科学与工程]