A Method for Monitoring State-of-Charge of Lithium-Ion Cells Using Multi-Sine Signal Excitation

In this paper, a method for monitoring SoC of a lithium-ion battery cell through continuous impedance measurement during cell operation is introduced. A multi-sine signal is applied to the cell operating current, and the cell SoH and SoC can be simultaneously monitored via impedance at each frequency. Unlike existing studies in which cell impedance measurement is performed ex situ through EIS equipment, cell state estimation is performed in situ. The measured impedance takes into account cell temperature and cell SoH, enabling accurate SoC estimation. The measurement system configured for the experiment and considerations for the selection of measurement parameters are described, and the accuracy of cell SoC estimation is presented.

Automated summary

This paper introduces a new method for monitoring the State of Charge (SoC) of a lithium-ion battery cell through continuous impedance measurement during cell operation. Unlike traditional ex situ impedance measurements, this method performs in situ cell state estimation considering cell temperature and State of Health (SoH), leading to accurate SoC estimation. The experimental setup and selection of measurement parameters are described, along with the accuracy of cell SoC estimation.