空气和氧气氧化沉淀法制备FePO4·2H2O及LiFePO4

Preparation of FePO4·2H2O via air and oxygen oxidizing precipitation and downstream product LiFePO4

以FeSO4·7 H2O和H3PO4为原料,用价格低廉的空气或氧气作为氧化剂,通过氧化沉淀法一步制得结晶态的FePO4·2 H2O。以此为前驱体制得的LiFePO4正极材料具有较好的性能。采用空气氧化时,0.2 C首次充放电比容量分别为153.5和140.8 mAh/g,首次库仑效率为91.7%;采用氧气氧化时,0.2 C首次充放电比容量分别为168.7和153.7 mAh/g,首次库仑效率为91.1%;循环性能和倍率性能还有待改善。用X射线衍射仪和扫描电镜等对两种方法制备的FePO4·2 H2O和LiFePO4的结构和形貌进行表征。用空气或氧气代替双氧水作为氧化剂显著降低了FePO4·2 H2O前驱体的制备成本,具有应用前景,值得深入研究。

The crystalline FePO4·2 H2O powders were synthesized by air or oxygen oxidizing precipitation method with FeSO4·7 H2O and H3PO4 as the raw materials.The LiFePO4 cathode materials prepared by using the FePO4·2 H2O powders as the precursor show good electrochemical performance.At 0.2 C,the cathode materials prepared by air oxidizing precipitation method show the initial charge and discharge specific capacity of 153.5 and 140.8 mAh/g,respectively.The initial coulomb efficiency is 91.7%.At 0.2 C,the cathode materials prepared by oxygen oxidizing precipitation method show the initial charge and discharge specific capacity of 168.7 and 153.7 mAh/g,respectively.The initial coulomb efficiency is 91.1%.The rate capability and cycling performance need to be further improved.The structure and morphology of FePO4·2 H2O and LiFePO4 prepared by the two methods were characterized by XRD and SEM.The new methods using cheap air or oxygen instead of H2O2 as the oxidants can obviously decrease the preparation cost of FePO4·2 H2O precursor,have application foreground and are worthy of in-depth study.