Battery research and software
Research Papers

Measurement Approaches for Thermal Impedance Spectroscopy of Li-ion Batteries

Battery performance, lifetime and safety are highly dependent on temperature. With the recent high demand for power capabilities, heat management has become increasingly relevant.

TWAICE / Apr 12, 2023

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Two novel measurement methods for capturing the thermal behaviour of Li-ion cells in the frequency domain

Authors: Cedric Kirst, Juan Ramos Zayas, Jan Singer

Highlights

  • Two new measurement approaches for Thermal Impedance Spectroscopy of Li-ion cells
  • Reduction of the state of the art thermal measurement time by 62%
  • Thermal models show a MAE below 0.3 K on a validation measurement in the time domain

This work introduces two novel measurement methods for capturing the thermal behaviour of Li-ion cells in the frequency domain. For the validation, we compare them to the state of the art measurement method, in which the battery is thermally stimulated by a set of discrete frequencies, each tested individually in a sequential manner.

All experiments are conducted with a cylindrical 18650 LFP-Graphite cell and lead to similar thermal impedance spectra. We validate a 0-D thermal model fitted to the respective measurement results with a thermal step response in the time domain. The results show, that all three models accurately represent the thermal behaviour of a Li-ion cell, with a mean absolute error below 0.3 K on the validation test. A spider-web diagram classifies and compares the given methods based on five values showing, that the state of art thermal measurement time can be reduced by 62% while also increasing the impedance measurement resolution by measuring multiple frequencies simultaneously.

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