Analysis of State-of-Charge Indicators for Li-Ion Batteries using Electrochemical Impedance Spectroscopy

Authors

Dipl.-Ing. Martin Arndt, M. Eng. Pascal Scholz, Dr.-Ing. Miroslav Mihajlov,
ITK Engineering GmbH, Brunswick

Summary

Today’s battery management systems are still facing problems in fulfilling their fundamental task to assure reliable and accurate estimation of unmeasurable battery states.
This paper presents experimental analysis of indicators which can be used to determine the battery State-of-Charge (SOC) by means of the Electrochemical Impedance Spectroscopy method. Deploying model-based approach, parameters of equivalent circuit models as candidates for SOC indicators are thoroughly investigated and a critical analysis of the method is presented. Alternatively, SOC indicators are examined based on complex impedance values without using battery models. The advantage of the latter approach is simpler computation and reduced measurement time.

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