C-LiFePO4/聚三苯胺复合锂离子电池正极材料的制备与性能

通过低温溶剂热法和高温热处理技术合成了橄榄石结构的LiFePO₄/carbon (C-LiFePO₄)纳米材料. 在此基础上，通过溶液共混法制备了一种新型的聚三苯胺(PTPAn)修饰包覆的C-LiFePO₄复合锂离子电池正极材料(C-LiFePO₄/PTPAn). 利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、电化学阻抗谱(EIS)以及恒电流充放电等测试方法，考察PTPAn 包覆量对C-LiFePO₄/PTPAn 复合正极材料性能的影响. 结果表明：通过溶液共混法PTPAn能够致密地包覆在C-LiFePO₄表面，形成一个有效的电子/离子传输通道从而有效提高CLiFePO₄基复合材料的电化学活性. 所有样品中C-LiFePO₄/10% (w) PTPAn作为正极材料呈现出最佳的电化学性能，在0.1C倍率恒流充放电下材料首次放电比容量为154.5 mAh·g^-1，在10C高倍率恒流充放电下材料的放电比容量达到114.2 mAh·g^-1. 当C-LiFePO₄/PTPAn 复合材料表面包覆的PTPAn 含量进一步增加，复合材料的电化学性能出现下降的趋势. 电化学阻抗测试表明PTPAn包覆层明显减小了C-LiFePO₄电极的电荷转移电阻.

Preparation and Performances of C-LiFePO4/Polytriphenylamine Composite as Cathode Material for Lithium-Ion Batteries

An olivine LiFePO₄/carbon (C-LiFePO₄) nanocrystallinematerial was prepared using a low-temperature solvothermalmethod, followed by a high-temperature post-annealing process. Then polytriphenylamine (PTPAn)-modified C-LiFePO₄ (C-LiFePO₄/PTPAn) was prepared, as a composite for novel cathodes for lithium-ion batteries, by solution blending of the C-LiFePO₄ nanocrystallinematerial and the electroactive conducting polymer PTPAn. The effects of PTPAn coating of the C-LiFePO₄/PTPAn samples were investigated using X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electronmicroscopy (TEM), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge testing. The results indicated that the solution blending method produced a compact PTPAn coating on the C-LiFePO₄, providing an effective electronic/ionic conducting pathway and enhancing the electrochemical activities of C-LiFePO₄-based composites. The C-LiFePO₄/10%(w) PTPAn electrode displayed an improved initial discharge capacity of 154.5mAh·g^-1 at 0.1C, a superior high-rate performance discharge capacity of 114.2 mAh·g^-1 at 10C, and excellent cycling stability.With further increases in the PTPAn content of the coating on the C-LiFePO₄/PTPAn composite, the electrochemical properties of the composite decreased. Electrochemical impedance measurements also demonstrated that the PTPAn coating significantly decreased the charge-transfer resistance of the C-LiFePO₄ electrode.