EDTA辅助水热法制备性能优异的棒状LiFePO4/C材料

以乙二胺四乙酸为配位剂采用水热法制备了棒状LiFePO₄/C材料。采用X射线衍射、扫描电镜、透射电镜、循环伏安、交流阻抗和恒电流充放电测试等对材料进行表征。结果表明:乙二胺四乙酸对材料的形貌和电性能均有很大影响。通过加入乙二胺四乙酸, 材料的形貌由不规则的颗粒变为棒状的颗粒且颗粒的厚度由140~200 nm减少至40~90 nm, 材料的表面包覆约3.5 nm的均匀碳层, 且该材料极化较小且界面阻抗较低。0.1C放电比容量为167 mAh·g^-1(接近理论容量170 mAh·g^-1)。

EDTA-assisted Hydrothermal Synthesis for Rod-Like LiFePO4 with Enhanced Electrochemical Properties

Rod-like LiFePO₄ was synthesized by hydrothermal method using ethylene diamine tetraacetic acid (EDTA) as complexing agent to control the growth of the crystal. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge test. The results show that EDTA has great influence on the morphology and electrochemical performance. The crystal morphology develops from irregular particles to rod-like particles and the thickness of the particles decreases from 140~200 nm to 40~90 nm by adding EDTA and the obtained LiFePO₄/C with EDTA exhibits a homogenous carbon coating layer with a thickness of ~3.5 nm. The discharge capacity is 167 mAh·g^-1 (close to the theoretical capacity of 170 mAh·g^-1) at 0.1C. The CV and EIS results indicate the samples prepared with EDTA have a lower polarization and lower interfacial resistance.