Current Distribution in Short-Circuited Electrochemical Systems with an Elongated Element

Abstract

The presented work is devoted to the study of current distribution in an electrochemical system with a non-homogeneous elongated element. The aim of research is to study the properties of dendritic point contacts obtained by the method of cyclic electrochemical switching using a macromodel. Using Ohm's and Faraday's laws, the basic equation of electrochemical kinetics, and the Sharvin formula, theoretical equations have been obtained to estimate the current distribution in a non-homogeneous elongated element and the lifetime of the contacts. It has been shown that the main characteristic of an elongated element is the elongation factor. It is the ratio l2/d and allows us to estimate the distribution of current between the electron and ion conductivity channels in the cell. It has been established that a metal conductor immersed in an electrolyte solution and connected to the power supply terminals has a linear distribution of electrochemical potential. In such a conductor, there is an inversion point where the potential sign changes. This causes the appearance of cyclic electrochemical switching effect. It is described by the following scheme: formation and growth of a dendritic contact – dendrite connection of the electrodes – dissolution of the tip of the dendrite touching the anode – destruction of the contact – formation and growth of the next contact. In a system with a non-homogeneous elongated element that models point contact with massive current-feeding conductors, there is a parameter A, which is the ratio of the fraction of the ionic current to the total current in the circuit. As the conductor resistance increases, the behavior of the system with an elongated element approaches the behavior of a classical electro-chemical cell with two spatially separated electrodes. Using the results of theoretical explanations and experimental research on current distribution made it possible to calculate the lifetime of dendritic contacts. Comparison of the calculated and experimental dependence showed their satisfactory convergence. The obtained result is important in the application of dendritic contacts as sensitive elements of gas sensors.