New approach for the calculation of impedance spectra out of time domain data

The distribution of relaxation times as basis for generalized time-domain models for Li-ion batteries

“…It contains the following steps: 1) Measurements: (i) C/40 discharge as quasi-stationary OCVcurve, (ii) EIS measurements with a variation of the SOC, (iii) current pulses followed by a relaxation phase with a variation of the SOC for parameterization and (iv) current profiles for validation. 2) Parameterization: In order to reduce measurement time, the low frequency part of the impedance spectra is obtained by transforming the current pulse measurements into frequency domain [48]. Then impedance spectra from EIS and pulse measurements are merged and the DRT is calculated for each SOC.…”

Application of Electrochemical Impedance Spectroscopy to Ferri/Ferrocyanide Redox Couple and Lithium Ion Battery Systems Using a Square Wave as Signal Input

“…Many researchers have used EIS to detect battery degradation [1][2][3][4]. In our previous study, an equivalent circuit for a wide range of impedance spectra was proposed to analyze lithium-ion batteries (LIBs) [5][6][7][8][9][10]. The equivalent circuit was redesigned for the analysis of an LIB with a characteristic electrode shape and electrochemical reactions of the electrode [5].…”

“…These methods using Fourier transformation are called FFT impedance or FT-EIS. It was reported that white noise [11,12], pseudo-random noise (pseudo-white noise) [12][13][14][15][16][17], pseudo-random signals [18], multi-sine waves (superimposed sine waves) [19,20], step signals [10,12,[21][22][23][24][25], and square pulses [26,27] can be applied to FFT impedance. An on-line FFT impedance measurement system using pseudo-white noise as the input signal was developed by one of our authors [14,15], and its application to in situ EIS was reported [15][16][17].…”

Measurements of Electric Performance and Impedance of a 75 Ah NMC Lithium Battery Module

“…4,7,8 Klots et al have recently presented a work on combined TDM and EIS measurements of a Li-ion cell with an internal resistance on the order of 0.5 . 9 Here we present results on combined TDM and EIS measurements, but we use the TDM method to simultaneously obtain impedance spectra on eight cells in a battery module, and the cell impedances are on the order of 1 m .…”