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Kinetic behavior of LiFePO4/C cathode material for lithium-ion batteries

2007; Elsevier BV; Volume: 53; Issue: 15 Linguagem: Inglês

10.1016/j.electacta.2007.10.069

1873-3859

Fei Gao, Zhiyuan Tang,

Advanced Battery Materials and Technologies

The composite cathode materials of LiFePO4/C were synthesized by spray-drying and post-annealing method. The crystalline structure and morphology of products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The charge–discharge kinetics of LiFePO4/C electrode was investigated using electrochemical impedance spectroscopy (EIS). The results show that the increment of the resistance has a close relation to the appearance of the FePO4 phase during charge–discharge course, and that the ohmic resistance, charge transfer resistance and lithium-ion diffusion coefficients of the LiFePO4/C electrode do not change much by extended cycling tests, implying a relatively superior cyclability of the battery. The effect of cell temperature on the electrochemical reaction behaviors of LiFePO4/C electrode was also investigated using the EIS. It is confirmed that the effect of the cell temperature on the impedance results mainly from the enhancement of the lithium-ion diffusion at elevated temperatures.