# Theory of Impedance Spectroscopy for Lithium Batteries

**Authors:** Fabian Single, Birger Horstmann, Arnulf Latz  
**arXiv:** [1908.00962](https://arxiv.org/abs/1908.00962)  
**Date:** 2019-08-02  
**Summary page:** https://www.summarizepaper.com/en/paper/1908.00962v1/

## Key points

- Authors Fabian Single, Birger Horstmann, and Arnulf Latz present a physics-based model for impedance spectroscopy in lithium batteries
- Model focuses on electrochemical cells with planar electrodes and includes the solid-electrolyte interphase (SEI) as a porous surface film
- Two key improvements: consistent description of lithium transport through electrolyte and SEI, analytical solution to show impedance signals' dependence on transport parameters
- Model offers an analytic expression for cell impedance covering both bulk and surface processes
- Importance of electrolyte convection in concentrated electrolytes highlighted through concentration polarization signals analysis
- Complex impedance expression simplified and compared to common equivalent circuit models within specific parameter ranges to demonstrate effectiveness
- Experimental comparisons with lithium metal electrodes reveal large transference numbers for lithium ions, suggesting similarities between lithium-ion transport through SEI and solid electrolytes
- Study published in The Journal of Physical Chemistry C provides valuable insights into impedance spectroscopy for lithium batteries and advances understanding of battery technology

## Summary

In their article "Theory of Impedance Spectroscopy for Lithium Batteries," authors Fabian Single, Birger Horstmann, and Arnulf Latz present a comprehensive physics-based model for impedance spectroscopy in lithium batteries. The model focuses on electrochemical cells with planar electrodes and incorporates the solid-electrolyte interphase (SEI) as a porous surface film. The authors introduce two key improvements to standard impedance models: a consistent description of lithium transport through both the electrolyte and SEI, and an analytical solution to reveal the full dependence of impedance signals on transport parameters. This developed model provides an analytic expression for cell impedance that encompasses both bulk and surface processes. By analyzing concentration polarization signals, the authors highlight the importance of electrolyte convection in concentrated electrolytes. They also simplify their complex impedance expression and compare it to common equivalent circuit models, demonstrating its effectiveness within specific parameter ranges. Furthermore, experimental comparisons with lithium metal electrodes reveal large transference numbers for lithium ions, indicating similarities between lithium-ion transport through the SEI and solid electrolytes. This analysis sheds light on the intricate nature of lithium battery behavior and emphasizes the significance of understanding transport mechanisms in optimizing battery performance. Published in The Journal of Physical Chemistry C, this study provides valuable insights into impedance spectroscopy for lithium batteries and contributes to advancing our knowledge of battery technology.