Ba-doped Pr2NiO4+δ electrodes for proton-conducting electrochemical cells. Part 2: Transport and electrochemical properties

Abstract

Materials based on barium-containing Pr2NiO4+δ are considered as promising air electrodes for protonic ceramic electrochemical cells owing to a wide range of attractive properties. In the present work, we thoroughly analyze the transport properties of Pr2NiO4+δ upon its chemical modification by Ba-doping. In detail, electrical conductivity and thermo-EMF measurements of Pr2–xBaxNiO4+δ (where x = 0, 0.1, 0.2, and 0.3) allow the effects of charge carrier concentration and mobility on overall transport to be determined depending on the chemical composition and defect structure. Lower polarization resistances of the Ba-containing electrodes when used in symmetrical cells with a BaCe0.5Zr0.3Y0.1Yb0.1O3–δ proton-conducting electrolyte confirm the functional benefits of barium as a dopant. However, the obtained experimental results can be explained not only by the better transport properties of barium-containing Pr2NiO4+δ (shown in the second part of our research), but also by the improved chemical and thermal compatibilities resulting in a good interface quality in an electrolyte/electrode couple (shown in the first part).