Electrochemical reactions at a copper electrode in copper-conducting solid electrolytes

Abstract

Potentiostatic measurements are used to show that, depending on the overvoltage sign, either electrochemical deposition or dissolution of copper occurs at the Cu/Cu₄RbCl₃I₂ interface at overvoltages η > 8–10 mV. At η = 10–100 mV, the reaction rate is limited by the formation and expansion of dissolution centers at the copper surface during anodic polarization and crystallization centers, during cathodic polarization. At η > 120 mV, the reaction rate is limited by charge transfer; the exchange current density is 2.7 mA cm⁻² and the anodic transfer coefficient is ∼0.45. Under anodic polarization, formation of electron holes in the electrolyte occurs in parallel with the copper anodic dissolution. Therefore, nonstoichiometry of the electrolyte emerges in the near-electrode layer and divalent copper accumulates there.