Electrolyte-centered approach to infiltration technology: surway of enhanced air electrodes for ZrO₂-based solid oxide cells

Due to significant progress in the development of thin-film deposition technology, the operating temperatures of electrochemical cells with conventional Y₂O₃-stabilized ZrO₂ electrolytes has been substantially reduced. However, the selection of suitable air electrodes for ZrO₂-based solid oxide fuel, electrolysis and reversible cells operating at intermediate temperatures (IT, 600–750°C) is still problematic. This issue is related to both insufficient oxygen reduction reaction activity at reduced temperatures characteristic to air electrode materials traditionally used in combination with Y-stabilized ZrO₂ in high-temperature devices, as well as the thermomechanical/chemical incompatibility of most state-of-the-art electrode materials with Zr-containing electrolytes. Infiltration is a viable method for fabricating nanocomposite electrodes under mild sintering conditions to avoid mismatch issues. This review adopts an electrolyte-centered approach, offering a comprehensive summary of the progress made in applying the infiltration technique to the development of air electrodes for electrochemical cells with ZrO₂-based electrolytes. A review of the performance enhancement of air electrodes with the electrolyte and porous backbones, obtained by infiltrating electron-conducting and mixed ionic-electronic conducting materials, catalytically active oxides and noble metals. The use of infiltration to improve the performance of air electrodes in commercial cells is being explored. The review reveals the excellent benefits of the infiltration technology in designing solid oxide cells that satisfy intermediate temperature criteria, as well as large-scale manufacturing. The bibliography includes 397 references.