New materials prepared in absence of Co and Sr for solid oxide fuel cells and electrolizers

GABRIEL MAGALHAES E SILVA; GRACIELA CARMEN ABUIN; ANA LAURA LARRALDE

Capital Federal

Congreso; VIII Symposium on Hydrogen, Fuel Cells and Advanced Batteries; 2022

Comisión Nacional de Energía Atómica

In the past decades, many researchers studied aboutnew forms of energy to replace the use of fossil fuels whichare responsible of serious environmental issues due to theiremissions of greenhouse gases. In this context, hydrogenhas been considered the “fuel of the future” given its highenergetic value and zero-emission combustion.One of the most promising options in terms of theefficiency of conversion devices based on hydrogen isassociated with the Solid Oxide Fuel Cells (SOFCs) and theirreversible mode: the Solid Oxide Electrolysis Cells (SOECs).These cells can work simultaneously in the so-calledReversible Solid Oxide Cells (ReSOCs): depending on the cellpolarization, devices might work as SOFC to oxidize fuels (asH2) generating electricity; or as a SOEC reducing reactivespecies (such as H2O) consuming electric energy andproducing H2. The main characteristic of these cells is thattheir main components, electrodes and the electrolyte, aresolid oxides.The crystalline structure of perovskite oxides, of generalformula ABO3, is incredible flexible and can accommodateoxygen vacancies generated due to the cation substitutionin the A and/or B sites. The hopping of these oxygenvacancies give rise to the ionic conduction within thematerial. Oxygen deficient ABO3- perovskites belong to theso-called group of mixed ionic-electronic conductors(MIECs) which are materials presenting both ionic andelectronic conduction and have shown high electrocatalyticactivity. Perovskite oxides have played vital roles in the fieldof energy conversion and storage.Conventional SOFCs operate at high temperatures (900-1000º C) which forces the usage of very expensiveinterconnection materials and generate difficulties due todiffusion and chemical reactions in the interfases, differencein the dilatation coefficients, etc. This is why new attentionhas been payed to Intermediate Temperature SOFCs (ITSOFCs)that can operate in the temperature range of 500-700º C. The most studied MIECs are the cobalt oxides butthey have a drawback regarding high thermal expansioncoefficient, low stability and high toxicity and cost of the Co[1]. The strontium has also been widely used in prototypes.Nevertheless, the latest publications indicate that thiselement tends to diffuse towards the surface of thematerials, promoting their degradation.The mentioned findings allow new research regardingthe design of efficient and atoxic materials for their use inSolid Oxide Cells.In this work, we synthetize and characterize a series ofFe-based perovskites with Ba or Ca in the A-site. We willreport the latest results of our findings including X-raydiffraction (XRD) and Rietveld analysis, X-ray fluorescence(XRF), Scanning Electron Microscopy (SEM) andElectrochemical Impedance Spectroscopy (EIS).