机械活化辅助固相法合成LiFePO_4-C材料及性能

Synthesis and Characteristics of LiFePO_4-C Materials Prepared by Mechanical Activation and Subsequent Solid State Reaction

为研究机械活化处理对原料形貌和终产物电化学性能的影响,通过机械化学活化辅助固相法,以碳酸锂(Li2CO3)、磷酸二氢铵(NH4H2PO4)和草酸亚铁(FeC2O4·2H2O)为原料,蔗糖为碳源,合成LiFePO4-C复合材料。利用X射线衍射、扫描电镜、LAND电池测试系统等对合成材料进行表征和电化学性能检测。结果表明,通过机械活化,原料达到微米级的均匀混合和充分接触,提高了反应活性,利于传质过程和高温固相反应,获得颗粒细小均匀、结晶良好的LiFePO4-C材料,放电比容量为146.93 mA·h/g(充放电倍率为0.2 C),40次循环后放电比容量为143.40 mA·h/g,容量保持率为97%。

To investigate the influence of mechanical activation treatment on morphology and electrochemical properties of in-situ carbon-coated LiFePO4 cathode materials,the mechanical activation and subsequent solid state reaction was employed,Li2CO3,NH4H2PO4 and FeC2O4·2H2O were used as starting materials,and sucrose was used as carbon source.The crystalline structure and morphology and the electrochemical tests of the prepared materials were investigated with XRD,SEM and LAND battery testing system.The results show that the precursor with the high reacting activity is prepared by ball-milling,which attain the micron grade mixing and full contact.The well-crystallized LiFePO4-C composite materials with homogeneous fine particle size are obtained,which have the discharge specific capacity of 146.9 mA·h/g at 0.2 C current,and the discharge capacity remains at 143.40 mA·h/g after 40 cycles with a capacity maintenance of 97%.