Study of the electrochemical impedance and the linearity of the current–voltage relationship in inhomogeneous ion-exchange membranes

Study of the electrical properties of bi-layer ion-exchange membrane systems

“…The main electrical properties of inhomogeneous ion-exchange membranes when the fixed-charge distribution is a given function of the position, are now well known [2][3][4][5][6][7][8][9][10][11][12][13][14]. Most of these theoretical studies have been made by considering the fixed-charge distributions to be continuous functions of the position inside the membrane.…”

Electrochemical impedance of ion-exchange membranes in asymmetric arrangements

“…An ion-exchange membrane system with X = 5, d = 1000, d = 1000, D 1S = D 2S = 100, D 1M = D 2M = 10, z = 1, e = 1, c L = 0.5 and different values of c R such as c R < c L , has been considered. The values chosen for the parameters of the system are very similar to those used in previous papers, in which we have studied the electrochemical impedance of ion-exchange membrane systems with symmetric arrangements [3][4][5]. Using typical values of the diffusion coefficient and the ionic concentration such as D a = 10 À11 m 2 /s and c a = 20 mM [1], respectively, one obtains that the Debye length of the system, k, is approximately 3 nm.…”

“…Recent theoretical studies on the electrochemical impedance of ion-exchange membrane systems [1][2][3][4][5] have shown the analogies and differences between the impedance of these systems and that of the widely studied electrode systems [6]. In an excellent paper [1], Sistat and co-workers have obtained the analytical expression for the electrochemical impedance of an ideal ion-exchange membrane system in the low frequency range.…”

“…These authors have proposed an equivalent electric circuit to model the impedance of ion-exchange membrane systems with simultaneous direct electric current. On the other hand, the network simulation method [3][4][5] has been used to study the electrochemical impedance of different kinds of non-ideal ion-exchange membrane systems, in which the ionic transport processes are described by the Nernst-Planck and Poisson equations and, therefore, the use of an advanced numerical method is necessary. The influence of the degree of inhomogeneity of the membrane fixed-charge distribution [3,4] and the direct component of the electric current [5] on the electrochemical impedance and the linearity of the current-voltage relationship of an ion-exchange membrane system, has been analyzed and discussed.…”

How well does simple RC circuit analysis describe diffuse double layer capacitance at smooth micro- and nanoelectrodes?

“…The low potential range is typical for impedance studies where small overpotentials are preferred, but is not typical in chronoamperometry or cyclic voltammetry procedures where ranges of many units RT/F are explored in order to access different thermodynamic regimes of an electrolysis reaction. The linear range of the Nernst-Planck-Poisson equation set has recently been discussed for the related problem of an ion exchange membrane by Moya [21].…”