关键词: 锂离子电池, 尖晶石LiMn₂O₄, SEI膜, 电子电阻, 电荷传递电阻

Variations of impedance spectra, electronic resistance, and the resistances of the solid electrolyte interphase (SEI) film, as well as the charge transfer reaction of commercially spinel LiMn₂O₄ electrode were investigated by electrochemical impedance spectroscopy (EIS) in 1 mol/L LiPF₆-EC (ethylene carbonate):DEC (diethyl carbonate) electrolyte solutions with the temperature in the range of －10～30 ℃. It is found that, the common EIS features of spinel LiMn₂O₄ electrode are related to the temperature, the semicircle observed in the Nyquist diagram which related to the electronic conductivity of the material and the semicircles related to the SEI film become to overlap each other to form one semicircle at higher temperatures. The experimental EIS data was simulated by a suitable equivalent circuit that includes elements related to the electronic and ionic transport in addition to the charge transfer process. In 1 mol/L LiPF₆-EC:DEC electrolyte solutions, the energy barriers for the ion jump relating to migration of lithium ions through the SEI film of the spinel LiMn₂O₄ electrode were determined to be 15.49 kJ/mol, the thermal active energy of the electronic conductivities to be 24.21 kJ/mol, and the intercalation-deintercalation reaction active energies to be 53.07 kJ/mol, respectively.

Key words: lithium-ion battery, spinel LiMn₂O₄, SEI film, electronic resistance, charge transfer reaction resistance