锂离子电池正极材料LiFePO_4/C的合成研究

Synthesis of LiFePO_4/C Cathode Material for Lithium-ion Battery

以三价铁化合物作为铁源,采用碳热还原法一步合成得到锂离子电池正极材料LiFePO4。利用X射线衍射仪、扫描电镜、碳硫分析法和电化学性能测试方法对磷酸铁锂材料的物相结构、表面形貌、含碳量(质量分数)以及电性能进行分析研究。讨论了烧结温度、烧结时间和掺碳量对材料电性能的影响。结果表明,LiFePO4的电性能与烧结温度、时间以及掺碳量有密切的关系,在优化试验条件下制备的正极材料LiFePO4,以电流密度为17mA·g-1充放电,首次放电容量达到141.8mAh·g-1,80次循环后放电容量为137.7mAh·g-1,容量保持率为97.1%。

The cathode material LiFePO4 was synthesized by carbothermal method, using ferric compound as the raw material. The crystalline structure, morphology, carbon contents and electrochemical performances were investigated by X-ray diffraction, scanning electromicroscope, carbon/sulfur analyzer and electrochemical tests. The effects of synthesis time, temperature and carbon contents on electrochemical performances of LiFePO4 material were discussed. The results show that electrochemical performances are significantly dependent on synthetic conditions, such as synthesis time, temperature and carbon contents. Under optimum conditions the initial discharge specific capacity of the material is up to 141.8 mAh·g^-1 at the current density 17 mA·g^-1, and the discharge capacity remains at 137.7 mA·g^-1 after 80 cycles with a capacity maintenance of 97.1%.