EDTA辅助水热法制备性能优异的棒状LiFePO_4/C材料(英文)

EDTA-Assisted Hydrothermal Synthesis for Rod-Like LiFePO_4 with Enhanced Electrochemical Properties

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3.5nm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）.

Rod-like LiFePO4 was synthesized by hydrothermal method using ethylene diamine tetraacetic acid （EDTA） as eomplexing 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 vohammetry （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 LiFePOJC 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-l） at 0.1C. The CV and EIS results indicate the samples prepared with EDTA have a lower polarization and lower interracial resistance.