Micro-Tubular SOFCs with Nickelate Cathode Support

Micro-tubular solid oxide fuel cells (SOFCs) can be mechanically supported by the anode, electrolyte and cathode or by a metal which acts simultaneously as the current collector. Cathode-supported cells (CSC) are advantageous for cathode current collection and anode redox stability, two well-known challenges for SOFCs. In this work, a tubular CSC based on neodymium nickelate (Nd1.95NiO4+δ) with a gadolinium-doped ceria (10GDC) interlayer, scandia-doped zirconia (10ScSZ) electrolyte layer and NiO-YSZ anode was chosen. Nickelates have shown superior electrochemical properties over commonly used LSM-cathodes at intermediate temperatures (IT-SOFC) of 600-700°C and are therefore even more promising. Nickelate tubes were fabricated by different routes such as cold-isostatic pressing, extrusion and slip-casting. Microstructural parameters of the prepared tubes vary according to the fabrication process and the utilized pore former. Tubes prepared by cold-isostatic pressing and slip-casting show a homogeneous pore size across the tube wall whereas tubes prepared by extrusion have an optimized microstructure with surface pores of only 1-2 micrometers in diameter and large voids of up to 100 micrometers in the tube wall. This is shown in Fig. 1a,b.