Microstructural development of Ni-1Ce10ScSZ cermet electrode for Solid Oxide Electrolysis Cell (SOEC) application

The microstructure of the cathodes plays a crucial role in the performance of the cell and electrocatalytic reduction of steam into hydrogen in SOEC applications. In the present work, a novel ionic-conducting ceramic 1Ce10ScSZ is used for the Ni-1Ce10ScSZ cermet cathode electrode development, as it has better ionic conductivity than the conventional 8YSZ. For this, symmetrical cells were fabricated using screen printing technique. The dominant factors such as sintering temperature, composition and thickness on the microstructure and polarisation resistance of the cermet are suitably optimized. 1300 °C was found to be the most convenient sintering temperature and the 60% NiO–40% 1Ce10ScSZ (by volume) as the most suitable composition. Further, the coating thickness of 35 μm corresponding to 5 layers of coating was found to be resulting in minimum polarisation resistance (determined from electrochemical impedance studies) of 0.95 Ω cm2 in moistened Ar–2% H2 and 0.79 Ω cm2 moistened H2 at 800 °C. The aging rate as determined from the increase in polarisation resistance was 0.01 Ω cm2/h in moistened Ar–2% H2 and 0.04 Ω cm2/h in moistened H2. The effects of parameters like current collecting layers and interface layers were also investigated. Thus, a novel Ni-1Ce10ScSZ cermet electrode having slow aging, low electrode–electrolyte polarization resistance and robust microstructure is developed.