Sensor-less estimation of battery temperature through impedance-based diagnostics and application of DRT

Abstract

Temperature has a substantial influence on the overall safety and performance of Lithium-ion batteries. Given the constraints of onboard thermal sensors and their inability to accurately measure internal cell temperature, a reliable temperature estimation has become a crucial aspect of battery state monitoring. This study exploits the temperature-sensitivity of electrochemical impedance spectroscopy (EIS) measurements to propose a sensor-less method to accurately estimate the internal temperature of commercial lithium-ion batteries. The presented study explores the reliability and limitations of the EIS-based method via a comparative analysis on two different cell types, i.e., high impedance (cylindrical 5 Ah) and low impedance (pouch 40 Ah) cells, over a range of multiple SOCs and temperatures. Furthermore, a novel approach of distribution of relaxation times (DRT) to extract the temperature-sensitive features from EIS data is also investigated. The results show that method is capable of estimating the internal temperature of high-energy cylindrical cells with an accuracy of ±0.41 °C, and high power pouch cells with an accuracy of ±2.22 °C over the entire range of tested SOCs. Overall, the Arrhenius model (for both cell types) represents a good fit for all the extracted features with R2 > 0.9. Charge transfer resistance (RCT) was found to be the most significant predictor for cylindrical cells and ohmic resistance (Rohm) for pouch cells. Furthermore, DRT peak heights can serve as a thermally sensitive feature for cell temperature estimation with good accuracy (typically <3 °C, though dependent on cell impedance response profile), and potential for broader applicability than features derived from equivalent circuit modelling. The study illustrates the opportunities and challenges associated with implementing impedance-based temperature estimation methodologies.

Graphical abstract: Sensor-less estimation of battery temperature through impedance-based diagnostics and application of DRT

Article information

Article type
Paper
Submitted
13 May 2025
Accepted
24 Jun 2025
First published
01 Jul 2025
This article is Open Access
Creative Commons BY license

EES Batteries, 2025, Advance Article

Sensor-less estimation of battery temperature through impedance-based diagnostics and application of DRT

D. Sarwar, O. Curnick and T. Amietszajew, EES Batteries, 2025, Advance Article , DOI: 10.1039/D5EB00092K

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