分步碳包覆合成高密度LiFePO4/C复合材料

摘要

采用分步碳包覆法合成LiFePO4/C复合材料.首先,将原料Fe2O3、NH4H2PO4和葡萄糖经过固相反应合成Fe2P2O7/C复合材料,再将Fe2P2O7/C与前驱体Li2CO3、葡萄糖混合,通过二次碳包覆工艺合成LiFePO4/C复合材料,并考察合成温度对LiFePO4/C复合材料电化学性能的影响.采用X射线衍射、扫描电镜、差热-热重分析、电化学阻抗谱(EIS)和充放电测试对材料的性能进行表征.结果表明:以制取的Fe2P2O7/C为前驱体合成的LiFePO4/C复合材料具有较好的物理和电化学性能,材料的振实密度达1.26g/m3,0.1C放电容量为158.3 mA.h/g,1C初次放电比容量达到140 mA.h/g.%LiFePCVC composite was synthesized by stepwise carbon-coating. First, the precursor Te2P2O7/C was obtained by solid state reaction with Fe2O3, NH4H2PO4 and glucose, then, LiFePCVC was synthesized by mixing the precursor, Li2CO3 and glucose through stepwise carbon-coating process. The effect of synthesis temperature on the electrochemical performances of LiFePCVC composites was studied. The product were characterized by XRD, SEM, DSC-TGA, EIS and charge-discharge test. The results show that the LiFePCVC composites synthesized with Fe2P2O7 as the precursor have excellent physics and electrochemical performance, the tap density of product reaches 1.26 g/cm3, and it has discharge capacities of 158.3 mAh/g at 0.1C and 140 mAh/g at C.