Determination of the Impedance of Lithium-ion Batteries Using Methods of Digital Signal Processing

This paper presents the design, implementation and verification of methods to determine the electrochemical impedance spectrum of a Lithium-Ion battery by using methods of digital signal processing. The principle is to excite the battery by applying a current step and measuring the voltage response. Both signals, the stimulation and response signal, are the basis of the signal processing algorithm. The method is verified theoretically with a very good accuracy by a computer simulation and was successfully applied to real cells under laboratory conditions. The reference impedance spectra for the evaluation are produced by the electrochemical impedance spectroscopy (EIS) technique.