A lithium-ion battery equivalent circuit model based on a hybrid parametrization approach

Abstract

This paper proposes an improved lithium-ion battery equivalent circuit model that can simulate the current-voltage characteristics of the battery under various operating conditions. Specifically, a hybrid parametrization approach is adopted by combining the electrochemical impedance spectroscopy and the hybrid pulse power characterization techniques for the identification and quantification of all loss contributions in a lithium-ion battery cell, for a wide operating frequency range. Moreover, the proposed equivalent circuit model considers the variation of the state of charge, the temperature and the charging-discharging current, and since it can be easily realized by utilizing the existing hardware for the cell equalization, it can be a useful tool for a wide range of real-time applications. The above are realized based on analytical equations of the battery performance with respect to the aforementioned operating parameters' variations. The effectiveness and feasibility of the proposed model is experimentally verified on a commercial, high energy capacity cylindrical lithium-ion battery cell of 3.25 Ah by comparing the model voltage performance with the real voltage of the cell during dynamic operating conditions and with variable surface temperature values.