skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A physical interpretation of impedance at conducting polymer/electrolyte junctions

Abstract

We monitor the process of dedoping in a planar junction between an electrolyte and a conducting polymer using electrochemical impedance spectroscopy performed during moving front measurements. The impedance spectra are consistent with an equivalent circuit of a time varying resistor in parallel with a capacitor. We show that the resistor corresponds to ion transport in the dedoped region of the film, and can be quantitatively described using ion density and drift mobility obtained from the moving front measurements. The capacitor, on the other hand, does not depend on time and is associated with charge separation at the moving front. This work offers a physical description of the impedance of conducting polymer/electrolyte interfaces based on materials parameters.

Authors:
; ; ;  [1];  [2]
  1. Department of Bioelectronics, Ecole Nationale Supérieure des Mines, CMP-EMSE, MOC 880 route de Mimet, 13541 Gardanne (France)
  2. Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)
Publication Date:
OSTI Identifier:
22251621
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 4; Journal Issue: 1; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CAPACITORS; ELECTROLYTES; FILMS; IMPEDANCE; INTERFACES; ION DENSITY; POLYMERS; RESISTORS; SPECTRA; SPECTROSCOPY

Citation Formats

Stavrinidou, Eleni, Sessolo, Michele, Sanaur, Sébastien, Malliaras, George G., E-mail: malliaras@emse.fr, and Winther-Jensen, Bjorn. A physical interpretation of impedance at conducting polymer/electrolyte junctions. United States: N. p., 2014. Web. doi:10.1063/1.4863297.
Stavrinidou, Eleni, Sessolo, Michele, Sanaur, Sébastien, Malliaras, George G., E-mail: malliaras@emse.fr, & Winther-Jensen, Bjorn. A physical interpretation of impedance at conducting polymer/electrolyte junctions. United States. doi:10.1063/1.4863297.
Stavrinidou, Eleni, Sessolo, Michele, Sanaur, Sébastien, Malliaras, George G., E-mail: malliaras@emse.fr, and Winther-Jensen, Bjorn. 2014. "A physical interpretation of impedance at conducting polymer/electrolyte junctions". United States. doi:10.1063/1.4863297.
@article{osti_22251621,
title = {A physical interpretation of impedance at conducting polymer/electrolyte junctions},
author = {Stavrinidou, Eleni and Sessolo, Michele and Sanaur, Sébastien and Malliaras, George G., E-mail: malliaras@emse.fr and Winther-Jensen, Bjorn},
abstractNote = {We monitor the process of dedoping in a planar junction between an electrolyte and a conducting polymer using electrochemical impedance spectroscopy performed during moving front measurements. The impedance spectra are consistent with an equivalent circuit of a time varying resistor in parallel with a capacitor. We show that the resistor corresponds to ion transport in the dedoped region of the film, and can be quantitatively described using ion density and drift mobility obtained from the moving front measurements. The capacitor, on the other hand, does not depend on time and is associated with charge separation at the moving front. This work offers a physical description of the impedance of conducting polymer/electrolyte interfaces based on materials parameters.},
doi = {10.1063/1.4863297},
journal = {AIP Advances},
number = 1,
volume = 4,
place = {United States},
year = 2014,
month = 1
}
  • This study describes the biodegradable acid doped films composed of chitosan and Perchloric acid with different ratios (2.5 wt %, 5 wt %, 7.5 wt %, 10 wt %) was prepared by the solution casting technique. The temperature dependence of the proton conductivity of complex electrolytes obeys the Arrhenius relationship. Proton conductivity of the prepared polymer electrolyte of the bio polymer with acid doped was measured to be approximately 5.90 × 10{sup −4} Scm{sup −1}. The dielectric data were analyzed using Complex impedance Z*, Dielectric loss ε’, Tangent loss for prepared polymer electrolyte membrane with the highest conductivity samples atmore » various temperature.« less
  • The ac impedance spectra of polymer electrolyte fuel cell (PEFC) cathodes measured under various experimental conditions are analyzed. The measurements were carried out in the presence of large dc currents. The impedance spectrum of the air cathode is shown to contain two features: a higher frequency loop or arc determined by interfacial charge-transfer resistance and catalyst layer properties and a lower frequency loop determined by gas-phase transport limitations in the backing. The lower frequency loop is absent from the spectrum of cathodes operating on pure oxygen. Properties of measured impedance spectra are analyzed by a PEFC model to probe themore » effect of ac perturbation. Comparison of model predictions to observed data is made by simultaneous least squares fitting of a set of spectra measured for several cathode potentials. The spectra reveal various charge and mass-transfer effects in the cathode catalyst layer and in the hydrophobic cathode backing. Three different types of losses caused by insufficient cell hydration, having to do with interfacial kinetics, catalyst layer proton conductivity, and membrane conductivity, are clearly resolved in these impedance spectra. The data reveal that the effective tortuous path length for gas diffusion in the cathode backing is about 2.6 times the backing thickness.« less
  • Electrochemical impedance spectroscopy (EIS) has become a very important tool in the analysis of corrosion and essentially all electrochemical phenomena. In the evaluation of impedance data, the electrochemical interphase often is described by an equivalent circuit relevant for the conditions of the experiment, using circuit elements that represent the various physical processes present. However, this approach is limited in that the use of passive elements, such as capacitor or a physical distribution of capacitors (e.g., in a transmission line), to describe other phenomena such as adsorption and mass transport (via the Warburg impedance [Z{sub W}]), mathematically may mimic the voltage-currentmore » characteristics of the process to be modeled but does not provide an understanding of the phenomena taking place. The physical origin of the capacitive behavior of (Z{sub W}) and adsorption pseudocapacitance is discussed. A simple derivation of Z{sub W}, based only on the Nernst diffusion layer thickness ({delta} = ({pi}Dt){sup 1/2}), is presented. An alternate equivalent circuit is proposed in which Z{sub W} is represented by a series combination of a resistor (the Warburg pseudoresistance [R{sub W}]) and a capacitor (the Warburg pseudocapacitance [C{sub W}]). The values of these new circuit elements are independent of potential. On the other hand, they are proportional to {omega}{sup {minus}1/2}, leading to the so-called constant phase element that is observed experimentally. In contrast, the usual elements employed in equivalent circuit models to describe the voltage-current characteristics of the interphase (e.g., the faradaic resistance, double-layer capacitance, and adsorption pseudocapacitance) are independent of frequency but may change with potential over many orders of magnitude. It is shown that the frequency dependence of C{sub W} and R{sub W} follows from the well-known dependence of {delta} on the square root of time.« less