Browsing by Author "Zabara, Mohammed Ahmed"

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Open Access
Application of the kramers–kronig relations to multi-sine electrochemical impedance measurements
(Institute of Physics Publishing, 2020) You, C.; Zabara, Mohammed Ahmed; Orazem, M. E.; Ulgut, Burak
Impedance spectra obtained by fast Fourier transformation of the response to a multi-sine potential perturbation are shown to be consistent with the Kramers–Kronig relations, even for systems that are nonlinear and nonstationary. These results, observed for measurements on a Li/SOCl2 battery, were confirmed by numerical simulations. Consistency with the Kramers–Kronig relations was confirmed by use of the measurement model developed by Agrawal et al. and by a linear measurement model approach developed by Boukamp and implemented by Gamry. The present work demonstrates that application of the Kramers–Kronig relations to the results of multi-sine measurements cannot be used to determine whether the experimental system satisfies the conditions of linearity, causality and stability.
Open Access
Characterization of different electrolyte composition Lithium Thionyl Chloride reserve battery by Electrochemical Impedance Spectroscopy
(Electrochemical Society, Inc., 2021-05-19) Zabara, Mohammed Ahmed; Göçmez, Hasan; Karabatak, Akın; Ülgüt, Burak
Electrochemical Impedance Spectroscopy (EIS) characterization for electrochemical processes in Lithium Thionyl Chloride reserve primary battery is shown. Two different electrolyte compositions are used to distinguish the changes in the EIS response. Galvanostatic EIS at discharge technique is used to obtain Kramers-Kronig compatible data for the reserve primary battery. The EIS data is analyzed by means of Equivalent Circuit models. The analysis shows the presence of five time-constants belonging to the electrochemical processes at Lithium anode, Solid Electrolyte Interface and the porous Carbon cathode. The change in the electrolyte composition causes the variation in the Solid Electrolyte Interface configuration and the kinetics of the Li anode processes. No variation in the cathode electrochemical processes observed by changing the electrolyte. The obtained results show the power of the non-destructive and in situ EIS technique to reveal the parameters for the electrochemical processes inside energy storage systems.
Open Access
Electrochemical Impedance Spectroscopy based voltage modeling of lithium Thionyl Chloride (Li∖SOCl2) primary battery at arbitrary discharge
(Elsevier, 2020-02) Zabara, Mohammed Ahmed; Ulgut, Burak
Primary batteries possess high energy densities that is beneficial to numerous important applications where recharging is impossible or impractical. The ability to accurately predict the voltage behavior of the battery under certain discharge regime is crucial in battery selection. In this work, Electrochemical Impedance Spectroscopy based approach is applied to predict the voltage of Lithium Thionyl Chloride (Li/SOCl2) primary battery under two discharge conditions. The predicted voltage responses show high accuracy with minor deviations related to the passivation phenomena at the anode. Relevant corrections were made to improve the accuracy of the simulated voltages. The modeling method shows accurate voltage predictions at all states of charge. Moreover, the method was used to predict the voltage of Lithium Manganese Dioxide (Li/MnO2) primary battery. The results show decent match with the experimental values demonstrating the applicability of the method to other chemistries of primary batteries.
Open Access
Linear and nonlinear electrochemical impedance spectroscopy studies of Li/SOCl2 batteries
(Electrochemical Society Inc., 2019) Zabara, Mohammed Ahmed; Uzundal, Can Berk; Ülgüt, Burak
Performing accurate, linear and stable Electrochemical Impedance Spectroscopy of Li/SOCl2 based batteries (and more generally, all primary batteries) is challenging due to the lack of a (well-defined) charging reaction. The difficulty stems from irreversible operation chemistry (compromising stable operation) and the inconsistent anode passivation of the cell. The very scarce literature examples lack proper measurement protocol and accurate EIS data for Li/SOCl2 that can be modeled. In this study, we demonstrate how these challenges can be overcome by performing Galvanostatic-EIS in discharge mode and investigate the details of how experimental parameters influence not only the measurement, but also the cell itself. We present linear and stable data that is compatible with the Kramers-Kronig relations in frequency ranges as wide as 10 kHz to 1 mHz for fully charged to fully discharged cells. Moreover, we utilize Harmonic Analysis to study the nonlinearities in the measurement and further show that the passivation of the anode is a major cause for the nonlinearities.
Open Access
Methods—unexpected effects in galvanostatic EIS of randles' cells: Initial transients and harmonics generated
(Electrochemical Society, Inc., 2022-03-17) Katırcı, Gökberk; Zabara, Mohammed Ahmed; Ülgüt, Burak
Non-linear EIS analysis is gaining wider attention and interest due to the deeper understanding that is provided especially when combined with linear EIS. The nonlinear part of the data can get corrupted due to a number of effects. One of these is the initial transient, which is the response right after excitation signal is applied before a steady-state is reached. In this study, we demonstrate this phenomenon through analyzing simplified Randles' cells via Kirchoff's laws. To get rid of the effects of the initial transient, instrument manufacturers typically discard some fraction of the response, the effectiveness of which, as demonstrated here has to be checked.
Open Access
Non-linear harmonics in EIS of batteries with lithium anodes: Proper controls and analysis
(Elsevier, 2022-10-10) Zabara, Mohammed Ahmed; Katırcı, Gökberk; Ülgüt, Burak
Non-linear Harmonic Analysis is used to investigate the distortions accompanying the Electrochemical Impedance Spectroscopy (EIS) measurements. The distortions emerge from non-linearity and non-stationarity due to the underlying redox reactions as well as the capacitance. Identifying each response and its source is crucial to correlate the obtained harmonics to their corresponding electrochemical processes. In this study, we identify the distortions of Galvanostatic-EIS measurements of Lithium Primary Batteries by means of comparing mathematical simulations and experimental measurements. The simulations were performed on RC-based equivalent circuit models, which showed the presence of certain distortions. The experimental measurements displayed distortions in the form of both non-linearity and non-stationarity in the case of batteries. The level of the harmonics in the measurements is either similar or higher than the harmonics simulated in the RC equivalent circuits at different frequencies. The obtained harmonics compared to simulations highlights the importance of control measurements before the analysis of non-linear harmonics of EIS measurements galvanostatically excited.
Open Access
Operando investigations of the interfacial electrochemical kinetics of metallic lithium anodes via temperature-dependent electrochemical impedance spectroscopy
(American Chemical Society, 2022-06-28) Zabara, Mohammed Ahmed; Katırcı, Gökberk; Ülgüt, Burak
One of the major hurdles in the utilization of metallic lithium anodes is understanding the Li+transfer kinetics through the solid electrolyte interface (SEI) in addition to Li oxidation. Electrochemical impedance spectroscopy (EIS) combined with temperature variation provides deeper comprehension and reveals kinetic parameters of individual processes separately. In this study, we report temperature-dependent EIS analysis of metallic Li anodes to shed light on the kinetics of anodic/interfacial processes at different states of charge and wide temperature ranges (-25 to 75 °C), utilizing lithium thionyl chloride (Li/SOCl2) and lithium manganese dioxide (Li/MnO2) primary batteries as model systems. We found in both batteries that the impedance of the SEI processes is highly temperature-dependent with non-Arrhenius behavior at temperatures greater than 35 °C. Conversely, the kinetics of the anodic process showed small temperature dependence that is explained by the Arrhenius equation throughout the temperature range studied. The results provide a deeper understanding of the underlying processes separately in metallic Li anodes under operando and real-time conditions. © 2022 American Chemical Society. All rights reserved.
Open Access
Performance modeling of unmanaged hybrid battery/supercapacitor energy storage systems
(Elsevier, 2021-09-13) Zabara, Mohammed Ahmed; Uzundal, Can Berk; Ülgüt, Burak
Unmanaged hybrid battery/supercapacitor energy storage systems possess higher performance with lower cost and complexity compared to not only individual cells, but also electronically managed hybrid systems. Achieving full performance requires the understanding of the power distribution and predicting their best combinations. In this work, a semi-empirical modeling methodology is presented that can predict the current distribution and the voltage response of battery/supercapacitor hybrid systems under arbitrary charge/discharge profiles. Results are presented for the assessment of hybrid systems under real life scenarios. The key strength of the presented method is that it is free of any parametrization, fits or subjective inputs. The modeling methodology is validated with experimental measurements for two different Li-ion battery chemistries, namely Lithium Iron Phosphate and Lithium Vanadium Pentoxide, connected in parallel to wide range of supercapacitors. Finally, we outline several design rules for hybrid storage systems for different use cases.