Electrochemical Impedance Spectroscopy Study of a Hydrogen Electrode Reaction at a Zn Electrode in a Molten LiCl−KCl−LiH System

Abstract

The hydrogen electrode reaction involving hydride ion, H-, at a Zn electrode is investigated in a molten LiCl-KCl-LiH system at 673 K. The charge-transfer resistances were measured by electrochemical impedance spectroscopy in the overpotential region of 0.10 < or = eta < or = 0.35 V and over the H- concentrations of 1.5 x 10(-4) < or = C(H)- < or = 1.2 x 10(-3) mol cm(-3). The logarithm plot of the charge-transfer resistance against the overpotential at C(H)- = 3.0 x 10(-4) mol cm(-3) gives the symmetry factor, beta, of 0.50 and the exchange current density, j0, of 5.8 x 10(-3)A cm(-2), respectively. Analysis of the dependence of j0 on H- concentration independently gives a beta of 0.55. The reasonable beta values indicate that the H- <==> H(ad)(M) + e- step is rate-determining.

Electrochemical Impedance Spectroscopy Study of the Mass Transfer in an Anode-Supported Microtubular Solid Oxide Fuel Cell

“…The performance of this type of the cell significantly depends on the fuel utilization and the partial pressure, indicating the effect of the fuel mass transfer. The resistances in the equivalent circuit can be written as the derivatives of the anode, Ohmic, and cathode overpotentials because EIS measures voltage drops in an infinitesimal interval of the current (Konomi & Saho, 2006;Nakajima et al, 2005). The resistances are non-Ohmic resistance and depend on current density (Nakajima et al, 2006).…”

The Surface Adsorption of Hydride Ions and Hydrogen Atoms on Zn Studied by Electrochemical Impedance Spectroscopy with a Non-Equilibrium Thermodynamic Formulation

“…This anodic reaction has been studied at sequences of overpotentials [3]. Arguments for the importance of this electrode were given in our previous works [3]. Arguments for the importance of this electrode were given in our previous works [3].…”

“…EIS analysis of polarized or unpolarized electrodes is normally examined using equivalent circuits. The resistance to, e.g., charge transfer can then be used to find information about the symmetry factor in the Tafel equation, and the exchange current density [3]. The work by Harrington and Conway [2] for electrosorbed intermediates is classical in this context.…”

“…This anodic reaction has been studied at sequences of overpotentials [3]. This anodic reaction has been studied at sequences of overpotentials [3].…”

“…Impedance spectra for the Zn surface [3] were analyzed using an equivalent circuit to the one illustrated in Figure 1. This circuit shall be predicted applying non-equilibrium thermodynamics theory for surfaces to reactions A and B.…”