Silver/Silver Chloride Electrode: Reaction Paths on Discharge

Abstract

Elementary processes for the reduction of thin films of silver chloride on silver have been investigated using rotating disk techniques. Experiments were carried out in i, 2, and 4N solutions of KCI. The effective diffusion coefficients of the prevalent species of silver ion in 2 and 4N KCl are about 1.42 and 0.31 X 10 -5 em2/sec, respectively. Reduction of thin AgCl films on Ag can be carried out at high rates, 100-200 mA/cm 2 at 300 mV overpotential, two orders of magnitude higher than that for the reduction of dissolved AgCI from bulk solution at 2000 rpm. A linear i ----l] relationship and its independence of the state of charge suggest that liquid phase transport occurs, possibly followed by a rate controlling process of surface diffusion.The silver/silver chloride electrode is an example of the class of battery electrodes which consists of a dispersed, sparingly soluble reactant within a continuous, conductive matrix. Electrodes of this class have a structure which is repeatedly encountered in practical batteries. Recent theoretical studies (1, 2) have indicated that a great variety of current density distributions may exist in such systems, e.g., exhibiting maxima and/or minima in the discharge profile, depending on local conditions governing mass and charge transfer. Identification and evaluation of local conditions during electrode charge or discharge are consequently necessary not only for more accurate assessment of electrode behavior in terms of the developing theory, founded on firm experimental bases and corresponding closely to reality, but also to help ascertain conditions of the recently predicted current distributions. The present work on the reaction paths of reduction at silver/silver chloride electrodes was accordingly undertaken to provide information that may be of use in interpreting behavior of electrodes in this important class. Summary of Reaction PathsSparingly soluble reactants.--In general, the proc-

Electrochemical investigations regarding the bioavailability of silver after potentiodynamic corrosion load of precious metal alloys Part 1: Binary model alloys

“…Experimental results based on these alloys are in accordance with the theoretical predictions of a kinetic model which was first introduced by Katan [4,5].…”

“…For the interpretation of the experimental data, a kinetic model introduced by Katan [4,5] who intensively studied the different transport phenomena during the electrochemical oxidation and reduction of silver spheres in KCl-electrolytes, was used. This concept has proved to be very fruitful since it allows the consideration of all aspects of electrochemical induced AgCl deposition and dissolution.…”

“…This results in an AgCl-dissolution directly at the interface between the [4,5] regarding the dissolution of AgCl-surface layers induced by cathodic reduction Abb. 12.…”

“…12. Schematische Darstellung der durch kathodische Reduktion induzierten Silberchlorid-Deckschichtenauflo Èsung nach Katan [4,5] electrode surface and the AgCl-layer. The rate of the necessary partial reactions are strongly determined by diffusion processes in the electrolyte and near the surface of the studied alloys.…”

Silver/Silver Chloride Electrode: Charging of a Porous Structure

“…Katan, et al [6,7 tudied surface morphology after charge and discharge in an attempt to obtain data necessery for modeling the sparingly sol ble reactantconductive matrix system. In an extension of this approach, Benn.L.on and et at [8] selected a different geometry to simulate the electrode behavior and employed X-ray element scanning analyses combined with scanning electron microscopy to arrive at the nature of the controlling elementary procesA.…”