scholarly journals The effects of time-variance on impedance measurements: examples of a corroding electrode and a battery cell

2020 ◽  
Vol 10 (2) ◽  
pp. 127-140 ◽  
Author(s):  
Nicolas Murer ◽  
Jean-Paul Diard ◽  
Bogdan Petrescu
Keyword(s):  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Steel Sample ◽  
Impedance Method ◽  
Battery Cell ◽  
Low Frequencies ◽  
Impedance Measurements ◽  
Time Variance ◽  
Eis Measurements ◽  
Resistance Decrease

When performing electrochemical impedance spectroscopy (EIS) measurements on a system, we must make sure it fulfills certain conditions. One of them is that it should be stationary that is to say, steady-state and time-invariant. Commonly studied systems are time-variant, for example a corroding electrode or a battery under operation. A corroding electrode sees its polarization resistance decrease with time. A passivating electrode sees its polarization resistance increase with time. These phenomena cause a deformation of the Nyquist impedance at low frequencies. This result was first simulated and validated by experimental measurements on a corroding steel sample undergoing uniform cor­rosion. The effect of performing impedance measurements on a discharging battery was also shown. Several methods are available to check and correct time-variance. The non-stationary distortion (NSD) indicator is used to separate valid and invalid data samples and the so called “4D impedance” method can easily produce instantaneous impedance data.

MONITORED DEFORMATION BY POTENTIAL-INDUCED DEFECTS IN CH3(CH2)n−1SH SELF-ASSEMBLED MONOLAYERS ON GOLD: EIS STUDY OF CHAIN LENGTH EFFECT ON SUBDIFFUSION AND SAMs’ HETEROGENEITY

2019 ◽  
Vol 26 (10) ◽  
pp. 1950067 ◽  
Author(s):  
AHMED MOUGARI ◽  
MOKHTAR ZABAT ◽  
SMAIL BOUDJADAR
Keyword(s):  
Charge Transfer ◽  
Electrochemical Impedance ◽  
Defect Density ◽  
Charge Transfer Resistance ◽  
Electrical Circuit ◽  
Transfer Resistance ◽  
Low Frequencies ◽  
Interface Evolution ◽  
Impedance Measurements ◽  
Self Assembled

From the defects-free self-assembled organic layers (SAMs) of CH3([Formula: see text]SH molecules with short chain lengths ([Formula: see text]) electrodeposited on the (111) surface of monocrystalline gold previously prepared, monitored defects (pinholes) were potential-induced from cyclic partial reduction of SAMs at an appropriate potential. Electrochemical impedance measurements were in-situ conducted and [Fe(CN)6][Formula: see text] ions were used as probes for mass and charge transfer. Interface evolution was modeled with an equivalent electrical circuit containing two distinct constant-phase elements (CPEs). One is a generalized semi-infinite Warburg element in series with a charge transfer resistance attributed to subdiffusion phenomenon through leaky sublayers at low frequencies; the other CPE is used for characterizing the interface heterogeneity at medium and high frequencies. At low frequencies, electrochemical impedance measurements show subdiffusion phenomenon, which depends on the remaining sublayer and its thickness. When the defect density increases, diffusion tends to be ordinary, obeying the Fick’s law.

scholarly journals An Electrochemical Impedance Study of AISI 321 Stainless Steel in 0.5 M H2SO4

2011 ◽  
Vol 2011 ◽  
pp. 1-10
Author(s):  
A. Fattah-Alhosseini ◽  
M. Mosavi ◽  
A. Allahdadi
Keyword(s):  
Stainless Steel ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Electrical Circuit ◽  
Defect Model ◽  
Impedance Data ◽  
Resistance Decrease ◽  
Aisi 321 ◽  
Equivalent Electrical Circuit Model ◽  
Interfacial Impedance

The electrochemical behavior of passive films formed on AISI 321 has been examined using electrochemical impedance spectroscopy. AISI 321 is characterized by high interfacial impedance, thereby illustrating its high corrosion resistance. Results showed that the interfacial impedance and the polarization resistance initially increase with applied potential, within the low potential. However, at a sufficiently high potential ( V), the interfacial impedance and the polarization resistance decrease with increasing potential. The impedance data were adequately represented by an equivalent electrical circuit model based on point defect model, which described the behavior of the passive film on stainless steel more satisfactorily than the proposed models.

scholarly journals Inhibitory Effect of Ethanolic Extract of Propolis on Corrosion of Ferritic Stainless Steel in Chloride Media

2019 ◽  
Vol 33 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Luiza Marilac Pereira Dolabella ◽  
Thalys Eduardo dos Santos ◽  
Tulio Matencio ◽  
Wander Luiz Vasconcelos ◽  
Vanessa Lins
Keyword(s):  
Stainless Steel ◽  
Polarization Resistance ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Ethanolic Extract ◽  
Inhibitory Effect ◽  
Aqueous Sodium Chloride Solution ◽  
Maximum Inhibition ◽  
Eis Measurements ◽  
Ethanolic Extract Of Propolis

This work evaluates the inhibitory effect of ethanolic extract of propolis (EEP) on the corrosion of AISI 409 stainless steel (SS) in chloride media. Additions of 100, 200, and 500 μL of EEP in an aqueous sodium chloride solution were performed. The inhibitory effect on the SS was evaluated using electrochemical impedance spectroscopy (EIS) measurements up to 720 hours in immersion. EEP additions of 200 μL and 500 μL increased the polarization resistance of the SS. After 720 hours of immersion, the highest impedance was identified for the SS in solution with 500 μL of EEP. The maximum inhibition efficiency observed for addition of 500 μL of EEP in solution was 98.1 %, after 360 h of immersion.

Efficiency Comparison of some Natural Products on Corrosion Inhibition of Al-Mg-Si Alloy

2011 ◽  
Vol 328-330 ◽  
pp. 1206-1209 ◽  
Author(s):  
R. Rosliza ◽  
W.B. Wan Nik ◽  
Sudin Izman
Keyword(s):  
Natural Products ◽  
Corrosion Inhibition ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Tapioca Starch ◽  
Linear Polarization Resistance ◽  
Efficiency Comparison ◽  
Eis Measurements ◽  
Natural Honey

The comparison of the efficiency of some natural products (natural honey, vanillin and tapioca starch) on corrosion inhibition of Al-Mg-Si alloy is investigated in seawater solution at room temperature, using potentiodynamic polarization (PP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. The evolution of the corrosion potential (Ecorr) and corrosion current density (icorr) obtained from Tafel extrapolation of polarization curves, and the polarization resistance (Rp) values determined from LPR and EIS measurements indicate that the corrosion rates of Al-Mg-Si alloy decrease with the increasing the natural products concentration. In all cases, the increasing order of inhibition efficiency is: Natural honey < Vanillin < Tapioca starch.

scholarly journals Further Understanding of Uncertainties in the Impedance Spectrum of the Polymer Electrolyte Fuel Cell due to Inductive Effects and Oxygen Diffusion Time Constant

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Samuel Cruz-Manzo ◽  
Keyword(s):  
Charge Transfer ◽  
Time Constant ◽  
Oxygen Diffusion ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Diffusion Time ◽  
Polymer Electrolyte Fuel Cell ◽  
Low Frequencies ◽  
High Frequencies ◽  
Eis Measurements

In this study, uncertainties during the assessment of the electrochemical impedance spectrum of the polymer electrolyte fuel cell (PEFC) attributed to inductive artefacts at high frequencies and inductive loops at low frequencies as well as oxygen diffusion time constant are discussed. A validated impedance model represented as an equivalent electrical circuit of a PEFC allowed the simulation of the effect of inductive artefacts, inductive loops and oxygen diffusion time constant on electrochemical impedance spectroscopy (EIS) measurements represented in the Nyquist plot. This study considers EIS measurements reported in previous studies and provides an insight into the EIS measurements with positive imaginary components at high frequencies attributed to the intrinsic inductance of the measurement cables during EIS tests and at low frequencies attributed to electrochemical mechanisms (e.g. side reactions with intermediate species) during PEFC operation. In addition, an overview of overlapping mechanisms (charge transfer and oxygen transport resistances during the oxygen reduction reaction) on the PEFC impedance spectrum attributed to oxygen diffusion across the cathode catalyst layer is presented. EIS measurements with positive imaginary components and with overlapping effects could yield to ambiguities when studying or relating electrochemical mechanisms (ion conduction, capacitance, charge transfer and mass transport resistances) of the PEFC through a defined single frequency or a single measured value represented in the Nyquist complex-impedance plot.

scholarly journals Oxygen Diffusion and Surface Exchange Coefficients of Porous La0.6Sr0.4Co0.2Fe0.8O3-δ Decorated with Co3O4 Nanoparticles

2022 ◽  
Author(s):  
Julian Ascolani-Yael ◽  
Alejandra Montenegro-Hernandez ◽  
Laura C. Baqué ◽  
Lucía M. Toscani ◽  
Alberto Caneiro ◽  
...  
Keyword(s):  
Polarization Resistance ◽  
Surface Reaction ◽  
Electrochemical Impedance ◽  
Active Role ◽  
Co3o4 Nanoparticles ◽  
Surface Exchange ◽  
Eis Measurements ◽  
Electrochemical Model ◽  
Ion Incorporation ◽  
Tomography Data

Abstract This work presents a comparative study of the diffusion (Dchem) and surface exchange coefficients (kchem) of porous La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Co3O4 nanoparticles decorated LSCF electrodes. The study was carried out using the 3DT-EIS method, which combines Electrochemical Impedance Spectroscopy experiments with FIB-SEM tomography data through an adapted Transmission Line - Adler Lane Steele electrochemical model. A reduction of the polarization resistance of about 60% was measured for the Co3O4 decorated LSCF respect to the reference LSCF cathode, in air at 700 °C. The Co3O4 decoration was found to modify the ORR surface reaction limiting mechanism from O2 dissociation to O-ion incorporation, whereas the diffusion coefficient was not modified by the decoration, which represents a surface diffusion process for both electrodes. After the EIS measurements, the Co3O4 particles were almost no longer visible by Field-Emission SEM on the surface of the decorated sample, but signs that these particles play an active role in Sr Segregation were observed by STEM-EDS, in particular by concentrating the segregated SrO in the surroundings of the decorated particles.

scholarly journals Corrosion Resistance of a Plasma-Oxidized Ti6Al4V Alloy for Dental Applications

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1136
Author(s):  
N. Velazquez-Torres ◽  
J. Porcayo-Calderon ◽  
H. Martinez-Valencia ◽  
R. Lopes-Cecenes ◽  
I. Rosales-Cadena ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Ti6al4v Alloy ◽  
Free Corrosion Potential ◽  
Density Values ◽  
Eis Measurements ◽  
Dental Applications

A Ti6Al4V alloy was plasma-oxidized at 600 °C during 1, 2, 3, 5 and 8 h and corroded in an artificial saliva solution. Electrochemical evaluation was performed by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements during 100 h. Corroded specimens were characterized by using Raman spectroscopy and scanning electronic microscopy (SEM). All tests indicated that the highest corrosion resistance was obtained for specimen oxidized during 3 h since the noblest free corrosion potential, lowest passive and corrosion current density values, as well as the highest polarization resistance values were obtained under these circumstances. EIS measurements indicated that the highest impedance and phase angle values obtained for this specimen exhibited a high capacitive behavior typical of a very compact passive film.

Influence of VC and FEC Additives on Interphase Properties of Carbon in Li-Ion Cells Investigated by Combined EIS & EQCM-D

2020 ◽  
Author(s):  
Paul Kitz ◽  
Matthew Lacey ◽  
Petr Novák ◽  
Erik Berg
Keyword(s):  
Electrochemical Impedance ◽  
Solid Electrolyte Interphase ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Gas Analysis ◽  
Side Reactions ◽  
Ion Diffusion ◽  
Battery Cell ◽  
Anode Passivation ◽  
Order Of Magnitude ◽  
Li Ion

<div>The electrolyte additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are well known for increasing the lifetime of a Li-ion battery cell by supporting the formation of an effective solid electrolyte interphase (SEI) at the anode. In this study combined simultaneous electrochemical impedance spectroscopy (EIS) and <i>operando</i> electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) are employed together with <i>in situ</i> gas analysis (OEMS) to study the influence of VC and FEC on the passivation process and the interphase properties at carbon-based anodes. In small quantities both additives reduce the initial interphase mass loading by 30 to 50 %, but only VC also effectively prevents continuous side reactions and improves anode passivation significantly. VC and FEC are both reduced at potentials above 1 V vs. Li<sup>+</sup>/Li in the first cycle and change the SEI composition which causes an increase of the SEI shear storage modulus by over one order of magnitude in both cases. As a consequence, the ion diffusion coefficient and conductivity in the interphase is also significantly affected. While small quantities of VC in the initial electrolyte increase the SEI conductivity, FEC decomposition products hinder charge transport through the SEI and thus increase overall anode impedance significantly. </div>

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