A Physically-Based Electrical Model for Lithium-Ion Cells

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Brivio, C.
Musolino, V.
Merlo, M.
Ballif, C.
Prediction of battery performance is essential in assessing the technical and economic viability of battery systems. We present a novel impedance-based model of a lithium-ion cell that accounts for the dynamic response of battery cells as a nonlinear function of the state of charge (SoC). The model is composed of impedance blocks connected in series. Each block is derived from a specific electrochemical equation linked to the battery operation. The state of charge is estimated from the voltage of a nonlinear capacitance, thereby addressing the intercalation of ions into the electrode structure. The developed procedure to identify the parameters of the individual impedance blocks is applied to a commercial lithium-ion cell (lithium nickel oxide). Validation in the time domain shows high accuracy of the model (RMSE < 1% at ambient temperature for SoCs between 20% and 80% and for all current rates allowed by the manufacturer) in estimating the voltage at the device''s terminals, efficiency, power and energy density under different current rates.
Publication Reference
Ieee Transactions on Energy Conversion, vol. 34 (2), pp. 594-603, Jun 2019.