Abstract:

Electrochemical impedance spectroscopy (EIS) was applied to study the reaction kinetics of layer lithium cobalt nickel manganese oxide material. Effects of the battery structure, charge depth and temperature on the layer lithium cobalt nickel manganese oxide cathode electrodes were tested by EIS. The results show that the inductance appears in the 18650 winding cells while not in 2032 cells. The whole process consists of overcoming strcture force period of oxygen layers crystal lattice in the rang of 2.0--2.7V, lithium-ion membranes forming period in the range of 2.7--3.65V and interface electrical double layer forming period in the range of 3.65--4.25V.The charge transfer rate and Li-ion diffuse rate are improved with temperature increasing. The charge transfer and lithium ion diffusion activation energies are 20.48kJ/mol and 48.67kJ/mol respectively, so the lithium ion diffusion process is the control process of the whole electrochemical reaction.

Key words: lithium-ion batteries, cathode materials, lithium cobalt nickel manganese oxide, electrochemical impedance spectroscopy