Parametrization of a Doyle-Fuller-Newman (DFN) Model for a Commercial 37Ah Li-Ion Battery and Validation with Incremental Capacity Analysis

Abstract

Physico-chemical modeling is considered as a very interesting way of simulating the behavior of a Li-ion battery cell by linking its internal state to its performance and aging. However, an accurate parametrization of such models is necessary for a truly representative outcome. In the case of commercial batteries, the parametrization procedure is hardly ever entirely undergone, leaving room for parameters tweaking and inaccurate simulation results. In the framework of this work, over 70% of the parameters were measured for a Samsung SDI 37Ah Li-ion prismatic battery (NMC111/Graphite) for PHEV (Plug-in Hybrid Electric Vehicle) applications. A Doyle-Fuller-Newman (DFN) Pseudo 2D model is chosen based on the work of Dufour et al.1. The major electrochemical characterization technics and measurement results for every component in the cell will be presented. The cells were opened in the ante-mortem procedure2, materials were identified, geometrical parameters were measured and samples were taken for coin-cell experiments. A small portion of the electrolyte was recovered and studied to conclude that it was made of EC-DMC-EMC at 1:1:2 portions. A similar solution was synthetized in order to conduct ionic conductivity measurements at temperatures ranging from -30 to 60°C. Samples from the separator were taken for both effective ionic conductivity and porosity measurements. The tortuosity of the electrodes was calculated via an EIS (Electrochemical Impedance Spectroscopy) with a blocking-electrodes configuration, and finally the diffusion factor in the active particles was estimated via GITT (Galvanostatic Intermittent Titration Technique) experiments. A very slow current regime was used to lithiate and de-lithiate the active materials in a half-cell experiment for electrode balancing purposes. The model was compiled using COMSOL Multiphysics 5.5, and results were compared to validation experiments conducted on the full-setup prismatic cell. The charge curve was validated under different current and power regimes at 25°C, and the Incremental Capacity (IC) curve showed a reasonable accuracy. With this in hand, the following step would be to couple this performance model to an aging model and to compare the evolution of the IC peaks with the experimental aging.