沉淀-碳热还原联合法制备橄榄石磷酸铁锂

Synthesis of lithium iron phospho-olivines by aqueous precipitation and carbothermal reduction

以FeSO4·7H2O，NH4H2PO4和H2O2为初始原料，通过液相沉淀制得前驱体FePO4，然后通过碳热还原得到LiFePO4／C。X射线衍射和扫描电镜分析表明：560，600，700和800℃合成的样品均为LiFePO4／C，LiFePO4颗粒粒径随合成温度的升高而逐渐增大，560℃合成材料的颗粒粒径分布在0．3～0．4μm之间；而800℃合成材料的颗粒粒径则达到0．6～0．7μm，反应剩余的碳黑直接分布在LiFePO4颗粒之间，有利于提高其电子导电率。560℃样品在放电倍率为0．1C时的首次放电比容量为151mA·h／g（0．1C），而当放电倍率达到1C时，放电比容量为129mA·h／g，且具有良好的循环性能。

LiFePO4 was prepared by carbothermal reduction of FePO4 which was synthesized by aqueous precipitation from FeSO4·7H2O and NH4H2PO4 and hydrogen peroxide as the oxidizing agents. Samples were characterized by XRD and SEM. It is shown that the pure and homogenous LiFePO4 was successfully synthesized at 560, 600, 700 and 800 ℃, with average particle sizes about 0.3 - 0.4 μm for the material synthesized at 560 ℃ and 0.6 - 0.7 μm at 800 ℃. The residual carbon during processing was coated on LiFePO4, resulting in the enhancement of the material＇s electronic properties. The discharge capacity of the material synthesized at 560 ℃ is 151 mA·h/g at 0.1 C rate and 129 mA·h/g at 1 C rate.