Experimental Parameterization of a Pseudo Two-Dimensional (P2D) Model for Lithium Ion Batteries: A Study of a Commercial Cell

Abstract

Modelling of lithium ion batteries is important, as it provides a way to predict their performance under various operating conditions, as well as the state of health during cycling, thereby providing key guidance in the designing of these devices. Among the numerous models studied in literature, the pseudo two-dimensional (P2D) model developed by the Newman group, is one of the most widely adopted lithium-ion battery model.1 To build a precise P2D battery model with predictive value, one crucial part is parameterization. However, accurate measurement of such complex physical and chemical processes is challenging and existing literature data is incomplete at best.2 In this contribution, we adapt and demonstrate an experimental procedure to determine a complete set of parametric inputs required for a P2D model with reduced order. Designing the experiments with the model explicitly in mind, allows us to identify the crucial inputs, to able the model to capture the existing system accurately as well to use it as a predictive tool for the design of new systems. Experimental results presented herein are based on a commercially available cylindrical cell from LG Chem. (M50), of which the design and material content is unknown. The electrodes were extracted from this commercial cell to enable material characterization. The physical and chemical parameters of the electrodes and cells were investigated; the chemical and structural properties analysed with X-ray diffraction, electron microscopy and inductively coupled plasma – optical emission spectroscopy (ICO-OES) techniques. The electrochemical properties such as the electronic and ionic conductivities were analysed in small test coin and Swagelok™ cells with extracted electrodes under different charging and relaxation conditions.