Self-Supported Solid Oxide Fuel Cells by Multimaterial 3D Printing

Abstract

Nowadays, renewable energy increases its contribution to the present energy scenario. In this regard, the implementation of energy storage and sources as the electrolysers and fuel cells gives the opportunity to transform the surplus of renewable energy to the form of hydrogen, by water electrolysis and the use of this hydrogen as a fuel for energy generation by the reverse mode of the same devices, in the so-called power to gas and gas to power routes. Among the different technologies of fuel cells and electrolysers, the high temperature technology based on ceramic solid oxides presents the best efficiencies. However, the fabrication of this devices implies several manufacturing procedures and multiple intermediate steps of fabrications, such as tape-casting, screen-printing, annealing, manual stacking, joining, sealing, etc. As a result, the SOC production process becomes more expensive and time-consuming. Recently, it has been demonstrated that the application of additive manufacturing (AM) technologies for functional ceramics fabrication, specially to SOC production, leads to significant improvement of the process. AM represents freedom of design, that allows to enhance the performance of the SOC-based device, an increase of manufacturing speed and productiveness, while the waste material is reduced. As a final result, one-step printed monolithic SOFC stack could be produced combining different AM technologies in a single printing process.For this purpose, hybrid 3D printing technology which combines stereolithography (SLA) and robocasting (direct ink writing, DIW) has been developed. Thus, the technique uses 8YSZ for the electrolyte fabrication by SLA and deposition of electrodes and interconnectors by DIW. The elaborated hybrid multimaterial 3D printing technology renders possible complete SOC stack fabrication as a single-step process. Complete fully printed SOFC cells, their co-sintering process and their characterization are here presented while the advantages and limitations of the fabrication process are discussed.