Batteries, Vol. 7, Pages 36: Determination of the Distribution of Relaxation Times simply by Means of Pulse Evaluation for Offline and On-line Diagnosis of Lithium-Ion Batteries
Batteries doi: 10. 3390/batteries7020036
Authors: Erik Goldammer Julia Kowal
The distribution of relaxation times (DRT) analysis of impedance spectra is a proven method to determine the number associated with occurring polarization processes within lithium-ion batteries (LIBs), their particular polarization contributions and characteristic time constants. Direct dimension of a spectrum simply by means of electrochemical impedance spectroscopy (EIS), however, experiences from a high expenditure associated with time for low-frequency impedances and a lack associated with general availability in many online applications. In this particular study, a method is certainly presented to derive the DRT by evaluating the particular relaxation voltage after the current pulse. The technique was experimentally validated making use of both EIS and the proposed pulse evaluation in order to determine the DRT associated with automotive pouch-cells and an aging study was carried out. The DRT derived from time domain information provided improved resolution associated with processes with large time period constants and therefore allowed changes in low-frequency impedance and the correlated destruction mechanisms to be recognized. One of the polarization contributions identified could become determined as an sign for the potential chance of plating. The novel, general approach for batteries was tested using a sample rate of 10 Hertz and only requires rest periods. Therefore, the method applies in battery management systems and contributes to improving the reliability plus safety of LIBs.