双相碳改性硅酸铁锂正极材料研究

Research on Two-Phase Carbon Modified Li_2FeSiO_4 as Cathode Material

以活化的天然石墨为碳源,采用固相辅助回流法成功合成了双相碳改性的Li2FeSiO4复合材料。采用XRD、SEM、HRTEM和Raman光谱分析了Li2FeSiO4/(C+G)复合材料的物相、形貌及其微观结构;并研究了活化石墨用量对Li2FeSiO4/(C+G)复合材料的电化学性能的影响。结果表明:活化石墨以石墨微晶和无定形碳的形态共存于Li2FeSiO4/(C+G)材料中,活化石墨用量为5%时所得样品的首次放电容量较高(170.3 mAh·g-1),循环50次后其容量保持率为88.7%,表现出了良好的电化学性能。

Two-phase carbon modified Li2FeSiO4 composites （Li2FeSiO4/（C＋G）） were synthesized via solid-state reaction assisted with refluxing. Activated natural graphite was chosen as carbon source. The phase and the microstructure of Li2FeSiO4/（C＋G） were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscopy （TEM） and Raman spectrometry （Raman）. The effect of activated graphite content on the electrochemical performance of Li2FeSiO4/（C＋G） was also investigated. The results show that activated graphite exists in Li2FeSiO4/（C＋G） samples in the form of amorphous carbon as well as graphite crystallite. Li2FeSiO4/（C＋G） composite prepared with 5wt% activated graphite achieved the excellent electrochemical performance with a higher initial discharge capacity of 170.3 mAh·g-1 and with a capacity retention ratio of 88.7% after 50 cycles.