以FeC2O4-2H2O、NH4H2PO4、Li2CO3和乙炔黑为原料,采用两步固相反应法制备了高密度LiFePO4/C正极复合材料.利用差热(DSC),热重(TGA)和X射线衍射(XRD)等分析手段具体探讨了第一步固相反应中可能存在的反应过程和中间产物.利用扫描电镜表征了复合材料LiFePO4/C中LiFePO4微粒形貌和接触状态.结果表明,乙炔黑的含量是影响LiFePO4微粒尺寸和微粒间接触界面的重要因素.在一次热处理的基础上,二次球磨和烧结有利于第二次固相反应过程中反应物质的接触和传质,较一步固相法提高了生成的LiFePO4的振实密度.当乙炔黑的含量(质量分数)为0.1%～1.5%时,两步固相法所制正极材料LiFePO4/C的振实密度可达到1.7 g/cm3,初次放电容量达到105 mA.h/g.
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