以NH4H2PO4和FeSO4.7H2O为原料,H2O2为氧化剂,通过液相法合成FePO4.xH2O前驱体,将FePO4.xH2O,Li2CO3和葡萄糖球磨混合以低温固相法合成正极材料LiFePO4,研究溶液浓度对前驱体FePO4.xH2O和LiFePO4的影响;采用X线衍射(XRD)和扫描电镜(SEM)对样品的晶体结构和形貌进行表征,采用比表面积分析和原子发射光谱分析等手段比较不同的溶液浓度对产物性能的影响。研究结果表明:当溶液浓度为0.1,0.3,0.5,1.0和1.5 mol/L时制备的FePO4.2H2O均为纯相,在溶液浓度为1.0 mol/L时合成的FePO4.xH2O含2个结晶水,即x=2;溶液浓度为1.0 mol/L时合成的FePO4.xH2O制备的LiFePO4具有良好的电化学性能;充放电容量为0.1C(其中,C为充、放电倍率)首次放电容量达154.4 mA.h/g,循环30次后容量保持率为99.7%。
FePO4.2H2O was prepared by liquid phase method in air using NH4H2PO4,FeSO4.7H2O and oxidant of H2O2 as starting materials.LiFePO4 was synthesized at low temperature with the homogeneous mixture of Li2CO3,glucose and FePO4.2H2O.The structures of FePO4.2H2O and LiFePO4 were characterized by XRD and SEM.The effect of solution concentration on FePO4.2H2O precursor and LiFePO4 was represented by specific surface area and element contents using ICP-AES.The results show that no impurities exist in FePO4.2H2O synthesized with solution concentration from 0.1 mol/L to 1.5 mol/L.LiFePO4/C made from FePO4.2H2O precursor with the solution concentration of 1 mol/L shows excellent electrochemical performance.It has an initial discharge capacity of 154.4 mA.h/g at 0.1C,and capacity retention remains 99.7 % after 30 cycles.