Strategies to obtain efficient symmetrical electrodes for solid oxide cells.

Abstract

There is an increase interest on finding alternative energy technologies that can cope with the current energy demand while mitigating the climate change. Among those technologies, Solid Oxide Cells (SOCs) are promising electrochemical devices that can efficiently convert fuels (e.g. hydrogen, methane) into electricity under fuel mode, as well as producing fuels from water and CO2 under electrolysis mode. In order to improve the durability of these devices, a new concept of symmetrical SOCs have been developed, where the same electrode material is used as both air and fuel electrode. However, the main challenge of symmetrical electrodes is that they need to operate efficiently under both oxidizing and reducing atmospheres.

There are several strategies to synthesize high-performing symmetrical electrodes. In this work, we study three of them: i) preparation of novel materials based on Ti-doped Sr0.95FeO3-δ (SFT) and layered Pr0.5Ba0.5FeO3 (PBF) perovskites; ii) exsolution of Ni nanoparticles in Ni-doped PBF; and iii) tailoring of the electrode/electrolyte interface with a nanocomposite active layer. With that purpose, the electrode powders are prepared by the freeze-drying precursor method and screen-printed onto La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) electrolyte, while the nanocomposite active layer is deposited in one-step by the spray-pyrolysis technique onto the electrolyte. A thorough characterization of the materials is performed regarding their crystal structure, microstructure and electrochemical properties.