State-of-charge indication in Li-ion batteries by simulated impedance spectroscopy

We here explore the possibilities of correlating experimental cell impedance with finite element methodology modelling for state-of-charge (SoC) indication in LiFePO 4 -based half-cells. The impedance response has been modelled sequentially during battery cycling using Newman theory, and is compared with experimental data. It is found that the charge-transfer resistance is dependent of SoC during battery charging, which can be modelled in good agreement with experimental results. Moreover, it is seen that cell design parameters—e.g. calendering-dependent electrode porosity—influence the EIS response and can thus be estimated using the presented methodology. Graphical Abstract