中空八面体锂离子电池正极材料LiFePO_4的制备及电化学性能

Preparation of LiFePO_4 Lithium-ion Battery Material With Hollow Octahedron Structure and Its Electrochemical Performance

以醋酸锂、磷酸、七水合硫酸亚铁为原料,聚乙二醇为分散剂,通过一步水热法制备得到中空八面体LiFePO_4锂离子电池正极材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学性能测试仪对样品晶型、形电化学性能进行了表征测试。研究结果表明,在2.5~4.2 V电压范围内,以0.1 C(17 mA/g)倍率进行充放电,样品首次放电比容量为129.6 mA·h/g;0.2、0.5、1、2和5 C的充放电倍率时,首次放电比容量分别达到123.6、119.7、114.1、99.5g和90.6 mA·h/g。10 C的充放电倍率时首次放电比容量为84.3 mA·h/g,说明中空八面体LiFePO_4在高倍率下表现出优异的电化学性能。

LiFePO4 lithium-ion battery material with hollow octahedron structure was synthesized by one-pot hydrothermal method using CH3COOLi, H3PO4 and FeSO4·7H2O as raw materials, polythylene glycol as dispersant. Crystal structure, morphology and electrochemical performance of the material were characterized by XRD, SEM and electrochemical measurements. The synthesized LiFePO4 sample exhibits an initial discharge capacity of 129.6 mAh/g in the voltage range window of 2.5-4.2 V at 0.1 C（17 mA/g）. At 0.2, 0.5, 1, 2 and 5 C, the initial discharge capacity is 123.6, 119.7, 114.1, 99.5 and 90.6 mA·h/g, respectively. While an initial discharge capacity 84.3 rnA.h/g still can be achieved at 10 C, indicating that the LiFePO4 sample has an excellent electrochemical performance at high rates.