Fabrication of Bimetallic (NiFe) Anode-Supported SOFCs with Direct Ceramic Inkjet Printing

Anode-supported solid oxide fuel cells (SOFCs) based on nickel-iron supports were fabricated, and their performance evaluated at the intermediate temperatures. The ratio of NiO to Fe₂O₃ in the metal support was 7 to 3 on a molar basis. Fe₂O₃ and NiO powders and appropriate sintering aids were mixed in the desired proportions and discs were die-pressed. The goal of using sintering aids was to adjust the thermal expansion of the support and the electrolyte to a close match within the sintering temperature region. The functional coatings were sequentially applied on the metal support by the use of Direct Ceramic Inkjet Printing (DCIJP) of suspension inks. The use of DCIJP enables the formation of very thin electrolyte coatings (~10µm), which is challenging for the more conventional ceramic methods. It also allowed infiltration of the support composites into the porous scaffolding of the support, thus extending the active anode area. The reduction of utilised and wasted amounts of active materials can lead to significant cost reductions in the fabrication of the final cell. Two distinct cell structures were produced - first one consisted of four distinct layers- metal support (NiFe), anode functional layer (Ni/GDC), electrolyte (10Sc1CeSZ) and cathode (LSCF+ GDC) and the second one where the anode deposition was omitted and the anode was formed by infiltration of ink directly into the NiFe support during the printing of the electrolyte. Cells were tested with hydrogen as fuel and air as oxidant at temperatures up to 750^oC. XRD and SEM examination indicated that the good performance of the button cells can be ascribed to the optimized composition and microstructure of the anode. The present work shows that high performance FeNi based cells can be successfully fabricated by the sole use of ceramic technology - DCIJP.