Distribution of relaxation times as a method of separation and identification of complex processes measured by impedance spectroscopy

2017 ◽  
Author(s):  
Justyna Bartoszek ◽  
Yi-Xin Liu ◽  
Jakub Karczewski ◽  
Sea-Fue Wang ◽  
Aleksander Mrozinski ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Relaxation Times ◽  
Complex Processes

Review on Physical Impedance Models in Modern Battery Research

2021 ◽  
Author(s):  
Rohit Gaddam ◽  
Leon Katzenmeier ◽  
Xaver Lamprecht ◽  
Aliaksandr Bandarenka
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Complex Processes ◽  
Versatile Tool ◽  
Impedance Models

Electrochemical impedance spectroscopy (EIS) is a versatile tool to understand complex processes in batteries. This technique can investigate the effects of the battery components like the electrode and electrolyte, electrochemical...

Characterization, Optical and Impedance Study of ZnSe Nanostructure

2013 ◽  
Vol 699 ◽  
pp. 490-495
Author(s):  
Ramna Tripathi ◽  
Akhilesh Kumar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Impedance Spectroscopy ◽  
Zinc Selenide ◽  
Relaxation Times ◽  
Complex Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Stability

Zinc selenide nanoparticle has been synthesized using soft chemical routes. The particles were capped using 2-mercaptoethanol to achieve the stability and avoid the coalescence. The as-obtained particles were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–VIS absorption and photoluminescence (PL) spectra. The impedance studies were carried out as a function of frequency (100 Hz–1 MHz) and temperature (298–373 K) by impedance spectroscopy. An analysis of the complex impedance (z' and z") with frequency is performed assuming a distribution of relaxation times.

scholarly journals Interrogation of the Selectivity and Electrokinetics of CO2 Reduction by AgSn Films in the Presence of Protic Organic [DBU–H]+ Cations as judged by Impedance Spectroscopy and Distribution of Relaxation Times Analysis

2021 ◽  
Author(s):  
Thabiso Kunene ◽  
Abderrahman Atifi ◽  
Joel Rosenthal
Keyword(s):  
Impedance Spectroscopy ◽  
Composite Film ◽  
Electrochemical Impedance ◽  
Relaxation Times ◽  
Composite Films ◽  
Co2 Reduction ◽  
Electrolyte Solutions ◽  
High Energy ◽  
Porous Films ◽  
Fast Kinetics

The use of renewable electricity to synthesize high energy and high value chemicals via reduction of CO2 is an attractive strategy for renewable energy storage. Improving our understanding of how heterogeneous CO2 reduction electrocatalysts function is important to designing efficient systems for conversion of CO2 into commodity chemicals such as CO and HCO2H. Both Ag- and Sn-based materials have been previously considered as CO2 reduction catalysts and offer distinct CO2RR selectivities. In this work, we have considered electrodeposited composite film electrodes prepared from electroplating baths with varying ratios of Ag+ and Sn2+ triflates to understand how the performance of such composite materials varies as a function of composition. XPS analysis confirms that for each composite film electrodes, Ag existed in the metallic (Ag0) state, while the Sn was mainly oxidized (Sn2+/4+). The AgSn composite film electrodes studied herein are therefore best considered as AgSnOx cathodes with varying ratios of Ag0:Sn2+/4+. These systems were assessed as CO2RR electrocatalysts and were found to promote the 2e–/2H+ reductions to deliver CO and HCOOH with fast kinetics and high efficiencies from electrolyte solutions containing the protic organic cation [DBU–H]+. While Sn-rich composite films showed poor selectivities for CO versus HCO2H, a significant increase in CO versus HCO2H selectivity (up to 99%) is achieved for composite film electrodes in which the Ag content ranged from 25 - 75%. By tuning the ratio of Ag0 to SnOx we prepared composite film cathode materials that support quantitative current efficiencies for generation of CO with geometric current densities approaching 30 mA/cm2 at applied overpotentials that are less than 750 mV were realized. Additionally, electrochemical impedance spectroscopy (EIS) coupled with analysis of the distribution of relaxation times (DRT) was used to better understand factors important to the composites’ activity under CO2RR conditions. Probing the dynamics with DRT analysis revealed that multiple processes relating to both adsorption and diffusion-controlled events are important to the activity of the electrocatalysts considered in this work. The collection of electroanalytical investigations suggest that synergistic interactions between Ag and SnOx give rise to porous films that support enhanced CO2RR kinetics and that mixing of Ag with SnOx enhances the efficacy of adsorption and stabilization of reduced CO2 intermediates and [DBU–H]+ cations to facilitate CO evolution at the cathode/electrolyte interface.

scholarly journals Generalized Distribution of Relaxation Times Analysis for the Characterization of Impedance Spectra

Batteries ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 53 ◽  
Author(s):  
Michael A. Danzer
Keyword(s):  
Impedance Spectroscopy ◽  
Relaxation Times ◽  
Complex Impedance ◽  
Lithium Ion ◽  
Vanadium Redox Flow Battery ◽  
Impedance Spectra ◽  
Model Free ◽  
Single Polarization ◽  
Generalized Distribution

Impedance spectroscopy is a universal nondestructive tool for the analysis of the polarization behavior of electrochemical systems in frequency domain. As an extension and enhancement of the standard impedance spectroscopy, the distribution of relaxation times (DRT) analysis was established, where the spectra are transferred from frequency into time domain. The DRT helps to analyze complex impedance spectra by identifying the number of polarization processes involved without prior assumptions and by separating and quantifying their single polarization contributions. The DRT analysis, as introduced in literature, claims to be a model-free approach for the characterization of resistive-capacitive systems. However, a data preprocessing step based on impedance models is often required to exclude non-resistive-capacitive components off the measured impedance spectra. The generalized distribution of relaxation times (GDRT) analysis presented in this work is dedicated to complex superposed impedance spectra that include ohmic, inductive, capacitive, resistive-capacitive, and resistive-inductive effects. The simplified work flow without preprocessing steps leads to a reliable and reproducible DRT analysis that fulfills the assumption of being model-free. The GDRT is applicable for the analysis of electrochemical, electrical, and even for non-electrical systems. Results are shown for a lithium-ion battery, a vanadium redox flow battery, and for a double-layer capacitor.

scholarly journals Electrical Properties of Zn-Phthalocyanine and Poly (3-hexylthiophene) Doped Nematic Liquid Crystal

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Y. Karakuş ◽  
M. Okutan ◽  
A. Kösemen ◽  
S. E. San ◽  
Z. Alpaslan ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Liquid Crystal ◽  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Absorption Coefficient ◽  
Nematic Liquid Crystal ◽  
Critical Frequency ◽  
Relaxation Times ◽  
Zinc Phthalocyanine ◽  
Absorption Coefficients

An E7 coded nematic liquid crystal was doped with zinc phthalocyanine and poly (3-hexylthiophene). A variety of properties including relaxation time, absorption coefficient, and critical frequency of this doped system were investigated using impedance spectroscopy. The doped systems displayed increased absorption coefficients in the range 0.22–0.55 and relaxation times from5.05×10−7 s to3.59×10−6 s with a decrease in the critical frequency from 3.54 MHz to 2.048 MHz.

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