水热法制备准球形掺Ti4 -LiFePO4/C纳米粉体及温度对其电化学性能影响的研究

Temperature-dependent electrochemical properties of similar spheric-like nanostructured doped Ti4 -LiFePO4/C powders by hydrothermal synthesis

摘要:

以(NH4)2FeSO4、LiOH、Ti(SO4)2以及H3PO4为原料一步水热合成法制备不同温度下掺Ti4 -LiFePO4，然后进行碳包覆，XRD和SEM表明制备的样品为单一相的准球形纳米粉体；激光粒度分析表明在160℃温度下合成的粉体平均粒径最小，大约在140nm左右；恒电流充放电及电化学阻抗谱测试材料电化学性能表明在160℃温度下合成的掺Ti4 -LiFePO4/C材料充放电性能最好，0.1C倍率下首次放电容量为 160.97 mAh g-1，0.5C倍率下经过50次放电，容量保留率为95.28%，通过电化学阻抗计算出锂离子扩散系数为1.78?0-12cm2 s-1。

Abstract:

Doped Ti4 -LiFePO4/C was synthesized by a step hydrothermal method at different temperatures using (NH4)2FeSO4、LiOH、Ti(SO4)2 and H3PO4 as raw material and then modified with carbon coating. X-ray diffraction patterns and scanning microscopy images along with energy dispersive spectroscopy mappings have verified the com electron homogeneous existence of coated carbon and doped Ti4 in LiFePO4 particles with phospho-olivine structure and an average size of 140 nm at 160℃. The electrochemical performances of the material have been studied galvanostatic charge-discharge measurements and electrochemical impedance spectroscopy. The results show the material is the best electrochemical performance at 160℃. The initials discharge capacity of 160.97mAh g?1 at 0.1C, a capacity retention of 95.28% after 50 cycles at 0.5C and a increased lithium ion diffusion coefficient of 1.78?0-12 cm2 s-1.