Effects of temperature on the intercalation-deintercalation process of lithium ion in LiCOO2

The temperature dependent properties of the impedance spectral characters, the electronic resistance, the resistances of the SEI (solid electrolyte interphase) film as well as the charge transfer reaction of the LiCoO2 electrode in 1 mol/L LiPF6-EC (ethylene carbonate); DEC (diethyl carbonate):DMC (dimethyl carbonate) and I mol/L LiPF6-PC (propylene carbonate):DMC+5% VC (vinylene carbonate) electrolyte solutions were studied and reported. The temperature was varied from 0 to 30 degrees C. The studies of electrochemical impedance spectroscopy (EIS) revealed that, the common EIS features' of the LiCoO2 electrode in the I mol/L LiPF6-EC:DEC:DMC and I mol/L LiPF6-PC:DMC+5% VC electrolyte solutions were related to the temperature, and a straight line reflecting solid state Li ion diffusion in the bulk of active mass appeared at 10 and 20 V, respectively. In I mol/L LiPF6-EC:DEC:DMC and I mol/L LiPF6-PC:DMC+5% VC electrolyte solutions, the energy barriers for the ion jump relating to migration of lithium ions through the SEI film of the LiCoO2 electrode were determined to be 37.74 and 26.55 kJ/mol, the thermal active energy of the electronic conductivities to be 39.08 and 53.81 kJ/mol, and the intercalation-deintercalation reaction active energies to be 68.97 and 73.73 kJ/mol, respectively.