Are the ohmic and polarization resistances of solid oxide electrochemical cells independent from each other?

Solid oxide electrochemical cells (SOCs) operating at low and intermediate temperatures represent a promising technology for efficient and environmentally friendly energy conversion. The performance of these cells is predominantly governed by their total area specific resistance, which comprises two principal components: the ohmic resistance (associated with ionic transport within the electrolyte) and the polarization resistance (originating from electrode reaction kinetics). Consequently, the rational design of high-performance SOCs necessitates the independent optimization of these resistive contributions. It is generally accepted that ohmic and polarization resistances are intrinsic properties of the electrolyte and electrodes, respectively, and can thus be controlled separately through material doping or microstructural engineering of the corresponding components. However, the electrolyte and electrode materials form a common area (interface), indicating their close relation to each other. In the present study, a simple experiment was conducted to confirm the relationship between ohmic and polarization resistances. In detail, several symmetrical cells were prepared using the same electrode material and various electrolytes. It was shown that the polarization resistance of the electrode was as low as higher ionic conductivity of the electrolytes under identical experimental conditions. The obtained results are further discussed within the broader context of literature data for protonic ceramic fuel and electrolysis cells, revealing a commonality: the performance of the electrode is not an isolated property but is intrinsically linked to the characteristics of the electrolyte with which it interfaces.