水热法制备准球形掺Ti^(4+)-LiFePO_4/C纳米粉体及温度对其电化学性能的影响

Hydrothermal Synthesis of Quasi-spherical Nanostructured Doped Ti^(4+)-LiFePO_4/C Powder and Its Temperature-dependent Electrochemical Properties

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℃下合成的粉体平均粒径最小,约为140 nm;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℃下合成的掺Ti4+-LiFePO4/C材料充放电性能最好,0.1 C倍率下首次放电容量为160.97 mA·h/g,0.5 C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1.78×10-12cm2/s。

Doped Ti4＋-LiFePO4/C was synthesized by one-step hydrothermal method at different temperatures using （NH4 ）2 FeSO4, LiOH, Ti （SO4 ）2 and H3 PO4 as raw materials. Then, the product was modified with carbon coating. X-ray diffraction patterns and scanning microscopy images along with energy dispersive spectroscopy mappings have verified the tom 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 performance of the material has been studied through galvanostatic charge-discharge measurements and electrochemical impedance spectroscopy. The material shows the best electrochemical performance at 160 ℃,with the initial discharge capacity of 160. 97 mA . h/g at 0. 1 C, a capacity retention of 95.28% after 50 cycles at 0.5 C and an increased lithium ion diffusion coefficient of 1.78 x 10-12 cmZ/s.