The influence of non-equilibrium defects on the anodic dissolution of a metal into a solid electrolyte

The galvanostatic dissolution of a parent metal Me in an electrochemical cell of the type Me/MeX/Me (MeX = cation-conducting solid electrolyte) causes periodic oscillations of the anodic overvoltage in a certain range of current density, pressure and temperature. The amplitude of these oscillations is a function of the applied mechanical pressure and their frequency depends on the electric current density. In the present study the electrode kinetics of transference cells of the type (+) Cu/AgBr/Ag (−) and (+) Cu/CuBr/Ag (−) have been investigated by galvanostatic measurements and linear sweep voltammetry, in order to obtain a better understanding of the nonlinear kinetics. During anodic dissolution the anode surface develops a porous structure which is correlated to the dislocation density of the anode. Linear sweep voltammetry measurements suggest that the rate-limiting step of anodic copper dissolution is the formation or the diffusion of metal adatoms on the metal electrode surface. A qualitative model for the influence of the processes on the oscillatory kinetics is proposed.