钛掺杂对不同形貌LiCoO2电化学性能的影响

采用SEM、XRD、恒电流充放电、电化学交流阻抗谱等方法研究了钛掺杂对不同形貌LiCoO2电化学性能的影响. 结果表明, 钛掺杂在不改变材料晶体结构的情况下, 能显著地改善LiCoO2的电化学性能, 且在较高倍率放电制度下(1 C), 掺杂对不同形貌LiCoO2的放电电压平台的影响效果不同. 掺杂后的二次粒子团聚体以1 C放电, 20次循环后3.8 V平台(电压大于3.8 V时的放电容量占总放电容量的百分比) 的保持率为60％, 优于掺杂后的大粒径一次粒子分散体的平台保持率(40％). 电化学交流阻抗谱研究表明, 钛掺杂对于抑制LiCoO2二次粒子在高倍率放电制度下循环过程中电化学阻抗的增加更为有效.

Effect of Ti-Doping on Different Morphologic LiCoO2

The effect of Ti-doping on different morphologic LiCoO2 was characterized by scanning electron microscope(SEM) along with energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), electrochemical impedance spectroscopy(EIS), and galvanostatic charge-discharge tests. The result indicated that Ti-doping did not affect the structure of different morphologic LiCoO2 but considerably improved its electrochemical performance, especially the behavior of large current discharge(1 C). In the case of being discharged at a 1 C discharge rate, 3.8 V voltage plateau(the ratio of capacity above 3.8 V to total capacity) of secondary particles doped with TiO2 could retain 60% after 20 cycles, which was better than primary particles doped with TiO2 (40%). EIS result showed that Ti-doping could evidently suppress the increase of the electrochemical reaction resistant at large current discharge rate for secondary particles.