单分散花状分级结构LiFePO4的合成及其电化学性能

来源期刊:中南大学学报(自然科学版)2015年第8期

论文作者:唐新村 龚美丽 黄富勤 晋媛 郑贞苗

文章页码:2819 - 2824

关键词:LiFePO4;花状结构;锂离子电池;溶剂热

Key words:LiFePO4; flower-like structure; lithium ion battery; solvothermal

摘    要:以乙二醇为溶剂,尿素为添加剂,采用溶剂热法制备锂离子电池正极材料磷酸铁锂(LiFePO4)。采用XRD,BET,SEM和TEM等对产物的结构和形貌进行表征,运用恒流充放电测试对LiFePO4/C复合材料的电化学性能进行研究。研究结果表明:花状分级结构的LiFePO4由单晶纳米片组成,且具有开放多孔的特性,其单分散性良好,粒径约为8 μm,振实密度达1.2 g/cm3。LiFePO4/C样品的首次放电比容量达152.4 mA·h/g;在0.2C,1C和2C倍率下比容量分别为134.3,118.5和103.7 mA·h/g;当放电倍率为2C时,经过5个循环后,容量保持在 100.1 mA·h/g,容量保持率为96.7%。

Abstract: The LiFePO4 for Li-ion battery cathode was prepared via solvothermal method using ethylene glycol (EG) as solvent and urea as additive. The crystalline structure and particle morphology of the cathode materials were characterized by high energy synchrotron X-ray diffraction (XRD), brunauer-emmett-teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively, and electrochemical properties of the LiFePO4/C composite were tested by constant current source charging and discharging methods. The results indicate that the monodisperse flower-like LiFePO4 with the diameter of 8 μm and the tap density of 1.2 g/cm3 is composed of single crystal nanoplates, and these nanoplates interweave together forming an open porous structure. The initial discharge capacity is 152.4 mA·h/g, and the LiFePO4/C composite delivers a capacity of 134.3, 118.5 and 103.7 mA·h/g at the rate of 0.2C, 1C and 2C, respectively. The discharge capacity is 100.1 mA·h·g-1 with the capacity retention ratio of 96.7% after 5 charge-discharge cyclings.

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