固相烧结法制备锂离子电池正极材料Li2FeP2O7及其电化学性能研究

介绍了一种先冷冻干燥后固相烧结制备正极材料Li₂FeP₂O₇的方法. 利用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)对材料的组成和形态进行表征, 并通过循环伏安曲线(CV)和电化学阻抗谱(EIS)研究了Li₂FeP₂O₇材料的电化学性能. 研究发现, 合成Li₂FeP₂O₇的最佳温度为590 ℃, 此温度下反应较完全且产物杂质较少, 1.6C倍率下的放电比容量达到55 mA·h·g^?1, 明显高于其它温度下合成样品的放电比容量. 该温度下合成的Li₂FeP₂O₇还具有低阻抗和较大的交换电流密度, 说明这种合成方式有利于提高锂离子在Li₂FeP₂O₇中的扩散.

Synthesis of Li2FeP2O7Cathode Material at Different Temperatures and Its Electrochemical Performance for Lithium Ion Batteries

The cathode material Li₂FeP₂O₇ was synthesized via freeze-drying and followed by solid state sintering method. X-ray diffraction（XRD）， scanning electron microscopy（SEM）， transmission electron microscopy（TEM） and Fourier transform infrared spectroscopy（FTIR） were used to characterize the structure， composition and morphology of the material. In addition， the electrochemical performance of the Li₂FeP₂O₇ material was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. It was found that the greatest particle quality could be acquired when the synthesis temperature of Li₂FeP₂O₇ was 590 ℃. The discharge specific capacity reached 55.0 mA·h·g^?1 at 1.6C， which was much higher than that of the samples synthesized at other temperatures. The Li₂FeP₂O₇ synthesized at 590 ℃ had a low impedance and a large exchange current density， which facilitated the diffusion of lithium ions and improved the electrochemical performance.