氟、锌离子共掺杂的LiFePO4／C阴极材料的制备及其在锂离子电池中的电化学性能研究

摘要

以醋酸锂、硝酸亚铁和磷酸二氢铵为主要原料，柠檬酸为溶剂和碳源，采用溶胶⁃凝胶法在氩气保护下合成橄榄石型LiFePO4阴极材料．为了改善电池的电化学性能，在LiFePO4阴极材料的制备过程中添加了氟和锌离子．采用扫描电镜、X线衍射光谱和恒电流充⁃放电测试系统分别表征了材料的微观结构、形貌和电化学性能．结果表明，氟和锌离子的添加能影响LiFePO4作为锂离子电池阴极材料的微结构及电化学性能．在室温下，LiFe1－yZny（PO4）1－x／3Fx／C （x＝y＝0．01）作为阴极材料制备的电池在0．1 C的倍率下放电，首次放电容量为166．0 mAh·g－1，表明氟和锌离子共掺杂的材料在高倍率电流下具有更好的电化学性能．%The olivine⁃type cathode materials of LiFePO4 were synthesized through sol⁃gel method using CH3COOLi·H2O,Fe(NO3)·9H2O and NH4H2PO4as raw materials and citric acid as solvent and carbon source under argon atmosphere. Fluorine and znic have been added to improve the electrochemical performances of cell. The microstructure, morphology and electrochemical performances were systematically investigated by scanning electron microscopy ( SEM ) , X⁃ray diffraction ( XRD ) , and galvanostatic charge⁃discharge testing. The results showed that the addition of Fluorine and znic affected the microstructures and electrochemical properties on the resulting LiFePO4 cathode in lithium ion batteries. LiFe1-yZny(PO4)1-x/3Fx/C ( x=y=0. 01) cathode materials presented a high discharge capacity of 166. 0 mAh·g-1 at the rate of 0. 1 C at room temperature. The samples after doping showed better electrochemical performance in relative high rates.