Dielectric Properties of Materials Showing Constant-Phase-Element (CPE) Impedance Response

Orazem, Mark E.; Frateur, Isabelle; Tribollet, Bernard; Vivier, Vincent; Marcelin, Sabrina; Pébère, Nadine; Bunge, Annette L.; White, Erick A.; Riemer, Douglas P.; Musiani, Marco

doi:10.1149/2.033306jes

Cited by 440 publications

(187 citation statements)

References 25 publications

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“…A strong implicit assumption underlying the use of the power-law model, previously developed [3,4] and applied to films of various chemical natures [5,6], in the analysis of the impedance of anti-corrosion coatings was that the non-ideally capacitive behaviour was the result of the uptake of the electrolytic solution, not of a pre-existing variation of resistivity along the film thickness.…”

Section: Introductionmentioning

confidence: 99%

Impedance analysis of the distributed resistivity of coatings in dry and wet conditions

Nguyen

Musiani

Orazem

et al. 2015

Electrochimica Acta

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A commercial coating (epoxy-polyaminoamide waterborne paint) deposited on a 2024 aluminium alloy was characterized by impedance measurements, first in dry conditions and then as a function of the immersion time in NaCl solutions (wet conditions). The behaviour of the dry coating was close to that of an ideal capacitor and could be accurately modelled with the power-law model corresponding to a constant phase element (CPE) behaviour. Upon immersion in NaCl solutions, the behaviour of the wet coating became progressively less ideal, i.e. farther from a capacitive behaviour. This result provided support to the hypothesis that an inhomogeneous uptake of the electrolyte solution was the cause of the often observed non-ideal responses of wet coatings. The experimental EIS data recorded for immersion times up to 504 hours were compared with models assuming either a power-law or an exponential variation of the coating resistivity along its thickness, respectively implying a phase angle independent of frequency or slightly dependent on it.

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Section: Introductionmentioning

confidence: 99%

Impedance analysis of the distributed resistivity of coatings in dry and wet conditions

Nguyen

Musiani

Orazem

et al. 2015

Electrochimica Acta

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“…) and ε is the dielectric constant of the passive film which can be assumed as 15.6 for stainless steels 35,36 . Using these values the thickness of the passive film was determined as 14.5 nm which is higher than other reported values for the passive film in stainless steels in low-chloride containing solutions (0.5 nm to 6 nm) [37][38][39][40] .…”

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confidence: 99%

Electrochemical Study of the AISI 409 Ferritic Stainless Steel: Passive Film Stability and Pitting Nucleation and Growth

et al. 2017

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The aim of the present work was to study the passive film stability and pitting corrosion behavior of the AISI 409 stainless steel. The electrochemical tests were carried out in 0.1 M NaCl solution at room temperature. The general electrochemical behavior was assessed using electrochemical impedance spectroscopy (EIS) measurements whereas the semiconducting properties of the passive film were evaluated by the Mott-Schottky approach. Pitting corrosion was investigated using potentiodynamic and potentiostatic polarization tests. Surface morphology was examined using confocal laser scanning microscopy and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the composition of precipitates that could act as preferential sites for the onset of pitting corrosion. The results showed that the passive film presents n-type semiconductive behavior. Grain boundaries played an important role as pitting initiation sites for the AISI 409 stainless steel.

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“…35,37, rather than the approximation for dilute solutions. The capacitive impedance Z t is defined as Z t = 1 (iω) γ C with frequency ω, constant-phase exponent γ (accounting for non-ideal response such as variations in dielectric constant 38,39 ), and theoretical maximum capacitance C. Among the various datasets tested the fitted γ values varied between 0.92 and 0.99, with unity for an ideal capacitor. The electronic impedance Z e is defined as Z e = t σ s,ef f A with effective electronic conductivity σ s,ef f measured to be 0.72 S/m based on the dry resistance of the electrode.…”

Section: Resultsmentioning

confidence: 99%

Capacitive Performance and Tortuosity of Activated Carbon Electrodes with Macroscopic Pores

Reale

Smith

2018

J. Electrochem. Soc.

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The rate of ionic conduction through the electrolyte of porous electrodes is determined in part by the tortuosity, a factor describing the effective length an ion must travel through the microstructure's pores. To facilitate ionic conduction and adsorption into the electric double-layers of capacitive electrodes, we show that macroscopic pores can be added to reduce the effective tortuosity by providing more direct paths to capacitive interfaces. We show experimental and simulated results of fabricating and testing electrodes that are machined to include macro-pores aligned normal to current collectors. Through the reduction of tortuosity, these "bi-tortuous" electrodes surpass unpatterned electrodes in effective ionic conductivity and capacitance. The degree of improvement is dependent on the electrodes' thickness and charging rate. Potable water demand together with agricultural and industrial needs are likely to drive the desalination of seawater, wastewater, and brackish water resources, and capacitive deionization (CDI) is one potential technology for these purposes.1 In CDI anions and cations are removed from feedwater solution by way of capacitive adsorption into electric double-layers (EDLs). The rate of salt removal in CDI ultimately influences the cost of water production, and, hence, achieving high salt removal rates is critical to making economical CDI devices. Salt removal rate typically increases with the current density used 2 because one electron is transferred for every monovalent ion adsorbed when co-ion adsorption is negligible. Thick electrodes in CDI have the potential to increase areal capacitance and enable the treatment of concentrated salt water, but such electrodes typically suffer from cracking during fabrication, increased ionic resistance, and energy consumption that typically restricts thickness to less than 350 μm.3 While alternative strategies can be used to eliminate these effects (including flow-electrode architectures 4 and intercalation-based electrodes 5-7 ) strategies to simultaneously increase salt removal rate with conventional EDL-based electrodes are desirable.In porous electrodes, including both EDL-and intercalation-based, microstructure is known to influence internal resistance, capacitance, and energy efficiency. In particular, the tortuosity τ of a porous electrode material is the ratio of the microscopic path length that an ion takes within pores normalized by the Cartesian distance between the endpoints of the path. [8][9][10] In general, porous electrodes exhibit tortuosity exceeding unity as a result of the random arrangement of impenetrable solid matrix comprising the electrode. Aside from its geometric interpretation, tortuosity impacts electrode charging dynamics by way of the effective ionic conductivity κ ef f = κ 0 ε/τ and the effective ionic diffusivity D ef f = D 0 ε/τ, where κ 0 and D 0 are the bulk values of ionic conductivity and diffusivity, and ε is porosity. 8,[11][12][13][14] The reduction of the effective transport property relative to its corres...

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Dielectric Properties of Materials Showing Constant-Phase-Element (CPE) Impedance Response

Cited by 440 publications

References 25 publications

Impedance analysis of the distributed resistivity of coatings in dry and wet conditions

Impedance analysis of the distributed resistivity of coatings in dry and wet conditions

Electrochemical Study of the AISI 409 Ferritic Stainless Steel: Passive Film Stability and Pitting Nucleation and Growth

Capacitive Performance and Tortuosity of Activated Carbon Electrodes with Macroscopic Pores

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