On Equivalent Circuit Modeling for Lithium-ion Batteries Operating over Broad Current Ranges

Abstract

Advanced battery management is as important for lithium-ion battery systems as the brain is forthe human body. Its performance rests on the use of fast and accurate battery models. However, themainstream equivalent circuit models and electrochemical models have yet to meet this need well,due to their struggle with either predictive accuracy or computational complexity. This problemhas acquired urgency as some emerging battery applications running across broad current ranges,e.g., electric vertical take-off and landing aircraft, can hardly find usable models from the literature.Motivated to address this problem, we develop an innovative model in this study. Called BattX,the model is an equivalent circuit model that draws comparisons to a single particle model withelectrolyte and thermal dynamics, thus combining their respective merits to be computationallyefficient, accurate, and physically interpretable. The model design pivots on leveraging multiple circuits to approximate major electrochemical and physical processes in charging/discharging.Given the model, we develop a multipronged approach to design experiments and identify its parameters in groups from experimental data. Simulation and experimental validation proves that theBattX model is capable of conducting accurate voltage prediction for charging/discharging acrosslow to high C-rates.