Transfer Function Establishment for Li-ion Battery Using Improved P2D Modeling Methodology

This paper presents a novel mathematical modeling method for the lithium-ion (Li-ion) battery considering the electrochemical properties (e.g., microscopic changes of the particles) and equivalent circuit model (ECM) transfer function format. The proposed model is based on the pseudo two-dimension (P2D) model, and the terminal voltage is divided into several parts, namely the open circuit voltage, the overpotential of the electrodes, electrolyte potential, internal resistance drop and so on. The model order reduction process is based on Pade approximation to simplify the partial differential equations (PDEs). The objective is to obtain an improved P2D model, namely a unified transfer function expression for the battery voltage, which has comparability with that of an ECM. This is good for implementation of the adaptive equivalent electrical parameter identification and updates, leading to possible improvement of SOC evaluation accuracy. Finally the comparison between the numerical and COMSOL results proves the correctness and validity of the proposed methodology.