A Precise, Reduced-Parameter Model of Thin Film Electrolyte Impedance

Abstract

The extreme shape factors inherent in characterizing thin film electrolytes can present a challenge to quantitative interpretation of impedance spectra. Here, the impedance of a thin film ceramic electrolyte with surface microelectrodes is modeled via direct numerical solution of current conservation. Faradaic and non-faradaic currents at the electrode-electrolyte interface are modeled phenomenologically using a formulation based on the Butler-Volmer equation. The model is able to reproduce complex, experimentally obtained impedance spectra for Pt/YSZ and Pt/GDC cells using only four adjustable, physically intuitive parameters: electrolyte conductivity, permittivity, exchange current density, and double layer capacitance. Equivalent circuit models typically used to fit these spectra instead require six or more adjustable parameters with ambiguous physical meaning. Notably, the model described here is able to capture a heretofore unexplained intermediate frequency arc seen in the experimental results. A parametric study enables the mechanism of the intermediate frequency feature to be identified as a spreading resistance in the electrolyte that vanishes at high frequencies due to low-impedance dielectric transport of current across the electrode-electrolyte interface. The fitting results are validated by comparison of the parameter values with literature reports.

High performance metal-supported solid oxide fuel cells with infiltrated electrodes

“…We previously demonstrated successful tape casting and co-sintering of YSZ (8 mol% yttria) electrolyte and electrode backbones with 434 stainless steel [12]. The desire to increase MS-SOFC performance, however, suggests the electrolyte conductivity must be increased [38,39]. Cubic 10 mol% Sc2O3 stabilized zirconia (10ScSZ, σtot,10ScSZ= 7.0 S m -1 at 700 °C) has similar properties and higher conductivity when compared to YSZ (σtot,YSZ= 2.5 S cm -1 at 700 °C) [40], and is therefore an obvious candidate.…”

Analysis of current crowding in thin film contacts from exact field solution

“…Current crowding and contact resistance are becoming increasingly important in the miniaturization of electronics [1][2][3][4][5]. How to accurately characterize these effects is an important issue [6][7][8][9][10].…”

Interrogation of Electrochemical Properties of Polymer Electrolyte Thin Films with Interdigitated Electrodes

“…), ceramic solid electrolyte films, polymers, and redox cycling of electroactive species in liquid media. [1][2][3][4][5] The sensitivity of the IDE is controlled through multiple geometric design parameters: the number of interdigitating electrode "teeth" (N), the length (l) and width (w) of the electrodes, the separation distance between electrodes (d), and the height of the film under investigation (h). Other design considerations include substrate support (e.g., Si/SiO 2 , polyimide, etc.…”