Development and Evaluation of a Physicochemical Equivalent Circuit Model for Lithium-Ion Batteries

Physicochemical models of lithium-ion cells, like the Doyle Fuller Newman (DFN) model, are omnipresent in battery research and development as they provide crucial insight into the cell, while equivalent circuit models dominate the area of application-oriented models, where speed is paramount. In this work, we develop and analyze a model that combines the two approaches using equivalent circuits and the DFN theory. By using a generalized approach to equivalent circuits, we model the necessary electric and diffusional processes analogously. The developed model accounts for all physical processes and internal states contained in the standard DFN model. We investigate the impact of model discretization and compare the developed model to a reference DFN implementation. Agreement between the models for both the predicted cell voltage and internal states shows that the developed equivalent circuit model provides a physically meaningful description of a lithium-ion battery, thereby successfully combining the two main modeling approaches for lithium-ion batteries.