scholarly journals On the correct choice of equivalent circuit for fitting bulk impedance data of ionic/electronic conductors

2016 ◽  
Vol 108 (15) ◽  
pp. 152901 ◽  
Author(s):  
Miguel A. Hernández ◽  
Nahum Masó ◽  
Anthony R. West
Keyword(s):  
Equivalent Circuit ◽  
Correct Choice ◽  
Impedance Data ◽  
Electronic Conductors

scholarly journals CATHODIC HYDROGEN EVOLUTION ON COBALT MONOSILICIDE IN POTASSIUM HYDROXIDE SOLUTION

2017 ◽  
Vol 60 (10) ◽  
pp. 9
Author(s):  
Artyom Sh. Shamsutdinov ◽  
Anatoliy B. Shein
Keyword(s):  
Equivalent Circuit ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrode Surface ◽  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Cobalt Silicide ◽  
Impedance Measurements ◽  
Hydroxide Solution ◽  
Impedance Data

The kinetics of hydrogen evolution reaction on cobalt monosilicide CoSi in potassium hydroxide solution was studied using methods of polarization and impedance measurements. Electrochemical impedance of CoSi was studied in 1 M KOH at 21-22 °C in the range of potentials of hydrogen evolution. Solutions were prepared from high-purity reagents and de-ionized water (Milli-Q). The working solutions were de-aerated with hydrogen (purity 99.999 %). Cobalt silicide was prepared from silicon (99.99 % purity) and electrolytic cobalt (99.98 % purity) by Czochralski method (pulling from the melt at speed of 0.4 mm/min). Electrodes were cut using electric-spark method. The working electrode surface was 0.4 – 0.6 cm2. Before measurements, the working electrode surface was abraded with emery papers of 1000 and 2000, cleaned with ethanol and washed in the working solution. Electrochemical measurements were carried out in three-electrode electrochemical cell with cathodic and anodic compartments separated with a porous glass diaphragm. Potentials Е were changed from low to high cathodic polarisations and vice versa. Before recording an impedance spectrum at each potential value, the electrode was polarised under potentiostatic conditions until constant value of current was reached. The electrode potentials are given with respect to the SHE. Impedance measurements were carried out using FRA Solartron and potentiostat Solartron 1280 (Solartron Analytical) in the frequency range from 10 kHz to 0.01 Hz (10 points per decade). The alternating signal amplitude was 10 mV. The CorrWare2, ZPlot2 and ZView2 software (Scribner Associates, Inc.) was used for measuring and processing the impedance data. In 1 М KOH polarization curve for CoSi-electrode has Tafel plot with the slope bk = 0.113 V. Earlier it was established that b for Со2Ѕі and CoSi2 at these conditions were 0.123 and 0.105 V, respectively, while b for Co was equal to 0.144 V. Tafel slope for cobalt monosilicide is less than Co, i.e. the difference between the current densities on the silicide and cobalt increases with increasing in cathodic polarization. At a constant electrode potential E, the current density i for CoSi is higher than for Co (at E = -1.2 V the value of i for CoSi is equal to 1.58 mA/cm2, and for Co i = 0.32 mA/cm2). Nyquist diagrams consist of the combination of capacitive semicircle at high frequencies and an inductive arc at low frequencies. Impedance spectra of cobalt silicide can not be accurately described by a simple equivalent circuit consisting of parallel-connected charge transfer resistance and the double layer capacitance. In order to describe the behavior of CoSi - electrode in 1 M KOH solution in the range of investigated potentials the equivalent circuit was used which was obtained in several works as a model of two-stage process with the adsorption of intermediate substances, in particular for hydrogen evolution reaction. In order to analyze the impedance data we used the diagnostic criteria for hydrogen evolution reaction mechanisms, based on the dependence of equivalent circuit elements on the overvoltage and OH- ions concentration, which were previously proposed. Determination of the kinetic parameters (rate constants and transfer coefficients) of hydrogen evolution reaction steps on the basis of the impedance data has been considered. Hydrogen evolution reaction on CoSi electrode in alkaline solution is discussed using the proposed criteria. It has been shown that hydrogen evolution reaction on CoSi in potassium hydroxide solution proceeds through the Volmer-Heyrovsky route with Heyrovsky reaction as the rate-determining and with the Langmuir isotherm for hydrogen adsorption. Forcitation:Shamsutdinov A.Sh., Shein A.B. Cathodic hydrogen evolution on cobalt monosilicide in potassium hydroxide solution. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 9-15

scholarly journals Automatic Identification Algorithm of Equivalent Electrochemical Circuit Based on Electroscopic Impedance Data for a Lead Acid Battery

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1353
Author(s):  
Javier Olarte ◽  
Jaione Martínez de Ilarduya ◽  
Ekaitz Zulueta ◽  
Raquel Ferret ◽  
Unai Fernández-Gámiz ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Electrochemical Impedance ◽  
Differential Evolution Algorithm ◽  
Automatic Identification ◽  
Identification Algorithm ◽  
Evaluation Procedures ◽  
Impedance Data ◽  
Simplex Search ◽  
Equivalent Circuit Parameters ◽  
Electrochemical Model

Obtaining tools to analyze and predict the performance of batteries is a non-trivial challenge because it involves non-destructive evaluation procedures. At the research level, the development of sensors to allow cell-level monitoring is an innovative path, and electrochemical impedance spectrometry (EIS) has been identified as one of the most promising tools, as is the generation of advanced multivariable models that integrate environmental and internal-battery information. In this article, we describe an algorithm that automatically identifies a battery-equivalent electrochemical model based on electroscopic impedance data. This algorithm allows in operando monitoring of variations in the equivalent circuit parameters that will be used to further estimate variations in the state of health (SoH) and state of charge (SoC) of the battery based on a correlation with experimental aging data corresponding to states of failure or degradation. In the current work, the authors propose a two-step parameter identification algorithm. The first consists of a rough differential evolution algorithm-based identification. The second is based on the Nelder–Mead Simplex search method, which gives a fine parameter estimation. These algorithm results were compared with those of the commercially available Z-view, an equivalent circuit tool estimation that requires expert human input.

scholarly journals Dipolar relaxation and impedance of an yttria-stabilised zirconia ceramic electrolyte

2016 ◽  
Vol 4 (4) ◽  
pp. 1298-1305 ◽  
Author(s):  
Miguel A. Hernandez ◽  
Anthony R. West
Keyword(s):  
Equivalent Circuit ◽  
Long Range ◽  
Zirconia Ceramic ◽  
Zirconia Ceramics ◽  
Dipolar Relaxation ◽  
Equivalent Circuit Analysis ◽  
Ceramic Electrolyte ◽  
Impedance Data ◽  
Oxide Ion Conduction ◽  
Oxide Ion

Equivalent circuit analysis of ac impedance data for yttria-stabilised zirconia ceramics shows evidence for dipole relaxation at intermediate frequencies in addition to the long range, oxide ion conduction.

Equivalent Circuit for EIS Study on Rusted Marine Cast Iron Artifacts

2015 ◽  
Vol 1094 ◽  
pp. 316-319
Author(s):  
Wei Zhen Ouyang
Keyword(s):  
Cast Iron ◽  
Equivalent Circuit ◽  
Complex Plane ◽  
Immersion Time ◽  
Complex Impedance ◽  
Impedance Spectra ◽  
Low Frequencies ◽  
Impedance Data ◽  
Iron Artifacts ◽  
Straight Lines

EIS technique was employed to study corrosion of the rusted cast iron artifacts in seawater. The impedance spectra show characteristic of diffusion in the complex plane. At low frequencies, the complex impedance data trace out straight lines with less slopes with increasing immersion time. Equivalent circuit provides useful information that the rusted iron undergoes severe corrosion in seawater in the presence of porous scale. SEM results reveal the morphologies of the three main iron oxyhydroxides.

Equivalent circuit for a GaAs CCD

1993 ◽  
Vol 140 (6) ◽  
pp. 377
Author(s):  
S. Pennathur ◽  
H.H.L. Kwok
Keyword(s):  
Equivalent Circuit

Rational Choice of Information Form Converters for Automated Systems in Construction

2020 ◽  
pp. 60-65
Keyword(s):  
Rational Choice ◽  
Construction Industry ◽  
Correct Choice ◽  
Automated System ◽  
Digital Code ◽  
Automated Control ◽  
Sigma Delta ◽  
Processor Core ◽  
Building Monitoring ◽  
High Level

In automated control systems for technical processes, the conversion of a continuous signal into a digital code and vice versa from a digital code to a continuous (analog) value is widely used. For direct type converters often used the term ADC, the reverse - DAC. The characteristics of the converters often dramatically affect the parameters of the entire automated system. The importance of the correct choice of ADCs and DACs has especially increased recently in connection with the mass introduction of microcontrollers MC. Indeed, in addition to the ADC and DAC, it is necessary to place the processor core in the microcontroller's crystal, I/O interfaces and many other elements necessary for the functioning of the MC. The use of information converters in the construction industry imposes additional requirements on converters: for example, in building monitoring systems, precision ADCs with extremely high accuracy are often required (while performance may be low), in other applications it is necessary to provide the necessary parameters at a high level of industrial interference, etc. This article explores issues related to the rational choice of ADCs and DACs, taking into account current trends in the IT field and the specifics of work in the construction industry. Sigma-Delta converters are noted as the most promising models of direct type converters.

Linear Equivalent Circuit and Current Sources Model Including Separation Resistances in the Ground Connection for Multiple Power-Supply Pin LSI

2010 ◽  
Vol 130 (11) ◽  
pp. 1897-1906
Author(s):  
Yoshiyuki Saito ◽  
Masakatsu Yasuhara ◽  
Yuichi Mabuchi ◽  
Tohlu Matsushima ◽  
Takashi Hisakado ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Power Supply ◽  
Multiple Power
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