Investigation of diffusivity in nanometer-thick yttria-stabilized zirconia by chronoamperometry and its formalism

This work aims to demonstrate that chronoamperometry is a valuable tool for determining diffusivities in all-solid-state nanometer-thick cells. The transient current in chronoamperometry of electrochemical cells under constant voltage is described by firstly considering purely capacitive processes, defined by RC circuit equations, and then purely diffusive processes, by Cottrell's equations. The physical meaning of the equations has been amply described in liquid cells with porous electrodes but scarcely in solid-state cells. Thus, we studied Metal/Insulator/Metal nano-cells with Ru and Au electrodes, Yttria Stabilized Zirconia (YSZ) electrolyte at temperatures between 50 and 170 & DEG;C and voltages between 0.5 V and 1.5 V, where non-Faradaic processes occur. The calculated diffusive and capacitive contributions at different temperatures obey the Arrhenius law. The activation energy was associated with vacancies, the major carrier during electrical transport. The analysis discusses other parameters, such as capacitance, effective concentration, and leakage current. The experimental diffusivity of YSZ electrolytes was compared with diffusivity values obtained by the statistical moment method.

Automated summary

This work demonstrates the use of chronoamperometry as a valuable tool for determining diffusivities in all-solid-state nanometer-thick cells. The transient current in electrochemical cells under constant voltage is described using RC circuit equations for purely capacitive processes and Cottrell's equations for purely diffusive processes. The study focuses on Metal/Insulator/Metal nano-cells with Ru and Au electrodes and YSZ electrolyte, and shows that the diffusive and capacitive contributions at different temperatures follow the Arrhenius law. The analysis also explores other parameters such as capacitance, effective concentration, and leakage current, and compares experimental diffusivity values with those obtained by the statistical moment method.