Parameterization of a Physico-Chemical Model of a Lithium-Ion Battery: I. Determination of Parameters

Abstract

The parameterization of a physico-chemical model constitutes a critical part in model development. Conclusions about the internal state of a battery can only be drawn if a correct set of material parameters is provided for the material combination under consideration. In this work, parameters to fully parameterize a physico-chemical model for a 7.5 Ah cell produced by Kokam are determined and are compared with existing literature values. The paper presents parameter values and procedures to determine the parameters. Cells were opened under argon atmosphere and the geometrical data were measured. Hg-porosimetry was conducted to determine porosity, particle radius as well as tortuosity of the electrodes and the separator. Conductivity and diffusion constants of the electrolyte as well as the electronic conductivity of the active material were measured detecting the voltage response to a dc current. Finally, electrochemical measurements were conducted on laboratory-made coin cells in order to determine open circuit voltage curves, diffusion coefficients and charge transfer kinetics of the electrodes as well as their balancing. In part II of this paper, a physico-chemical model is introduced and a validation of the measured parameter set is given by comparing model results with experiments.