用于可充锂电池的高倍率磷酸铁(II)锂正极材料

本文以聚氧化乙烯为碳源，用柠檬酸辅助湿化学法合成了高倍率的碳包覆的LiFePO₄。使用热重、粉末X射线衍射、扫描电子显微镜、透射电子显微镜、循环伏安、电化学阻抗和恒流充放电表征材料的结构和电化学性质。结果表明，该材料组成为5 wt%疏松多孔的碳包覆相纯度很高的小的LiFePO₄颗粒。该材料适用于高倍率充放电，在5 C、10 C和20C的放电倍率下可以分别得到120、90和60 mAh·g^-1的稳定容量。

High‐rate Lithium Iron(II) Phosphate as Cathode Material for Rechargeable Lithium Batteries

High‐rate carbon coated LiFePO₄ was synthesized by citric acid assistant aqueous chemical route employing polyethyleneoxide as the carbon source. The structural and electrochemical properties were intensively investigated by thermogravimetry, powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge‐discharge tests. The results of structural tests showed that the material consisted of small LiFePO₄ particles of good phase purity and the particles of the material were coated and connected with approximate 5 wt% incompact porous carbon. The material performed very well in electrochemical measurements, and was suitable for high‐rate charge and discharge. The material exhibited stable discharge capacities of 120, 90 and 60 mAh·g^?1 at 5 C, 10 C and 20 C rates respectively (1 C=150 mA·g^?1, charge at 1 C).