锂离子电池Li1.08Fe（PO4）1.08/C正极材料制备与电化学性能

以液相沉淀法制备的Li3PO4和NH4H2PO4均匀混合物为原料,合成了Fe2+空位的橄榄型锂离子电池Li1.08Fe-(PO4)1.08/C正极材料。X射线衍射光谱法(XRD)和扫描电子显微镜法(SEM)分析结果表明,采用Fe2+空位与碳包覆方法获得了较小晶胞体积和细小球形颗粒的Li1.08Fe(PO4)1.08/C粉末。0.2 C倍率电化学性能测试结果表明,纯Li1.08Fe-(PO4)1.08的首次放电比容量达142.4 mAh/g,而包覆9.23%C的Li1.08Fe(PO4)1.08的首次放电比容量达153.3 mAh/g、0.5 C倍率循环100次后的放电比容量为144.5 mAh/g。

Preparation and electrochemical performance of Li1.08Fe(PO4)1.08/Ccathode for lithium-ion batteries

The pure ordered olivine compound of Li1.08Fe(PO4)1.08/C with an orthorhombic structure(space group Pnma) and Fe2+ vacancy was successfully synthesized with Li3PO4-NH4H2PO4 as raw material.The Li3PO4-NH4H2PO4 mixture was prepared by phosphate precipitation method with LiOH and NH4H2PO4 as starting material.The results of XRD and SEM show that the crystal structure and particle morphology of Li1.08Fe(PO4)1.08 powder are greatly influenced by creating the Fe2+ vacancy in the crystal cell and by coating carbon at the surface of particle.The electrochemical testing indicates that the bare Li1.08Fe(PO4)1.08 cathode has the initial discharge specific capacity of 142.4 mAh/g at 0.2 C.The 9.23% C-Li1.08Fe(PO4)1.08 cathode possesses the excellent performance with an initial discharge specific capacity of 153.3 mAh/g at 0.2 C ratio and with a discharge specific capacity of 144.5 mAh/g in the 100th cycle.