Parametric analysis using impedance spectroscopy: relationship between material properties and battery performance

The possibility of prediction of battery material performance based on para meterization of impedance spectra measured at different states of charge in boundaries of non-linear equivalent circuit model (numerical image) is dem onstrated. An impedance parameterization procedure developed in this labora tory was used to obtain all kinetically relevant parameters of LiCoO2 based composite Li-ion battery cathode materials. The accuracy of performance pr ediction was tested by comparing voltage profiles calculated on basis of nu merical image, at discharge rates ranging from 1/10C to 3C with experimenta l data. Model parameters were used to compare the relative influence from d ifferent kinetic steps on discharge behavior of composite electrode. Predic ted thickness dependence of electrode impedance was compared with experimen tal impedance spectra measured on samples with active material thickness fr om 20 to 60 mu m. The change of relative contributions of kinetic parameter s with thickness has been investigated.