Nonlinear electrochemical impedance spectroscopy for lithium-ion battery model parameterization

TL;DR

This paper develops a nonlinear electrochemical impedance spectroscopy approach to estimate lithium-ion battery model parameters, incorporating nonlinear diffusion and asymmetric kinetics, validated with experimental data.

Contribution

It introduces analytical formulas for nonlinear impedance up to the second harmonic, enabling detailed physical interpretation and improved parameter estimation for battery models.

Findings

Accurate impedance data fitting achieved

Nonlinear diffusion model may not be suitable for studied cells

Excellent voltage response prediction with fitted parameters

Abstract

In this work we analyse the local nonlinear electrochemical impedance spectroscopy (NLEIS) response of a lithium-ion battery and estimate model parameters from measured NLEIS data. The analysis assumes a single-particle model including nonlinear diffusion of lithium within the electrode particles and asymmetric charge transfer kinetics at their surface. Based on this model and assuming a moderately-small excitation amplitude, we systematically derive analytical formulae for the impedances up to the second harmonic response, allowing the meaningful interpretation of each contribution in terms of physical processes and nonlinearities in the model. The implications of this for parameterization are explored, including structural identifiability analysis and parameter estimation using maximum likelihood, with both synthetic and experimentally measured impedance data. Accurate fits to impedance data are possible, however inconsistencies in the fitted diffusion timescales suggest that a nonlinear diffusion model may not be appropriate for the cells considered. Model validation is also demonstrated by predicting time-domain voltage response using the parameterized model and this is shown to have excellent agreement with measured voltage time-series data (11.1 mV RMSE).