Electronic module for the thermal monitoring of a Li-ion battery cell through the electrochemical impedance estimation

Electrochemical impedance is a not directly measurable parameter of the Li-ion cells that can be exploited to retrieve useful information about the state of the cell itself, such as the State of Charge or the internal temperature. This complex parameter depends on the frequency, which means that it's real and imaginary parts change in function of the frequency at which the cell is activated. Nowadays impedance is mainly measured using laboratory equipment as part of dedicated benchmarks, requiring expensive facilities and relatively long procedures. In this paper we propose a new solution to get the impedance value of a Li-ion cell by using both an efficient approach minimizing the test duration, and an innovative electronic solution suitable for automotive embedded needs. The electrochemical impedance is then analysed to deduce the cell's internal temperature with experimental results.