Cu微粒包覆Cu/LiFePO4正极材料的制备及性能研究

用高温固相反应法制备Cu微粒包覆的锂离子电池正极材料Cu/LiFePO4。采用X射线衍射、场发射扫描电镜对材料的物相结构和颗粒形貌进行分析和观察,采用恒流充放电、慢扫描循环伏安法和电化学阻抗谱法测试材料的电化学性能。结果表明,Cu微粒包覆使复合材料颗粒分散更均匀,结晶更明显;Cu/LiFePO4（n（Cu）∶n（Li）=1∶15）正极材料首次放电比容量最高为142.8 mA.h/g,与纯LiFePO4正极材料的对应值151.7 mA.h/g相比有所下降;虽然Cu微粒的加入在一定程度上能够提高材料的电子导电率,但在第一周充电时Cu即发生不可逆氧化,导致该复合材料具有较低的放电比容量和较大的首次不可逆容量损失。

Preparation and electrochemical performance of Cu/LiFePO_4 cathodes with Cu-coated

High temperature solid state reaction method was employed to prepare the Cu-coated cathode materials Cu/LiFePO4 for lithium-ion battery.X-ray diffraction（XRD） and field emission scanning electron microscopy（FE-SEM） are used to analyze the physical properties.The electrochemical properties of Cu/LiFePO4 used as cathodes for lithium-ion battery were investigated by constant current charging and discharging,slow scan cyclic voltammetry and electrochemical impedance spectroscopy.The results show that coating with Cu made the particles of Cu/LiFePO4 disperse more evenly.The initial discharge capacity of Cu/LiFePO4（n（Cu）∶n（Li）=1∶15）,which is the best sample,is 142.8 mA·h/g.It is lower than the initial discharge capacity of LiFePO4（151.7 mA·h/g）.However,the improvement in the electronic conductivity made by coating with Cu particles could not deny the fact that non reversible oxidation of Cu particles took place in the first cycle of the charge and discharge,which should be responsible for the first irreversible capacity loss of the material.