Towards sustainable electrochemistry: green synthesis and sintering aid modulations in the development of BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) IT-SOFC electrolytes.

In this study, BaZr0.87Y0.1M0.03O3-δ perovskite electrolytes with sintering aids (M = Mn, Co, and Fe) were synthesized by a sustainable approach using spinach powder as a chelating agent and then compared with chemically synthesized BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes for intermediate temperature SOFCs. This is the first example of such a sustainable synthesis of perovskite materials with sintering aids. Structural analysis revealed the presence of a cubic perovskite structure in BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) samples synthesized by both green and conventional chemical methods. No significant secondary phases were observed in the samples synthesized by a sustainable approach. The observed phenomena of plane shift were because of the disparities between ionic radii of the dopants, impurities, and host materials. The surface morphology analysis revealed a denser microstructure for the electrolytes synthesized via green routes due to metallic impurities in the organic chelating agent. The absence of significant impurities was also observed by compositional analysis, while functional groups were identified through Fourier-transform infrared spectroscopy. Conductivity measurements showed that BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by oxalic acid have higher conductivities compared to BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by the green approach. The button cells employing BaZr0.87Y0.1Co0.03O3-δ electrolytes synthesized by the chemical and green routes achieved peak power densities 344 and 271 mW·cm-2 respectively, suggesting that the novel green route can be applied to synthesize SOFC perovskite materials with minimal environmental impact and without significantly compromising cell performance.

High-Entropy Materials in SOFC Technology: Theoretical Foundations for Their Creation, Features of Synthesis, and Recent Achievements.

In this review, recent achievements in the application of high-entropy alloys (HEAs) and high-entropy oxides (HEOs) in the technology of solid oxide fuel cells (SOFC) are discussed for the first time. The mechanisms of the stabilization of a high-entropy state in such materials, as well as the effect of structural and charge factors on the stability of the resulting homogeneous solid solution are performed. An introduction to the synthesis methods for HEAs and HEOs is given. The review highlights such advantages of high-entropy materials as high strength and the sluggish diffusion of components, which are promising for the use at the elevated temperatures, which are characteristic of SOFCs. Application of the medium- and high-entropy materials in the hydrocarbon-fueled SOFCs as protective layers for interconnectors and as anode components, caused by their high stability, are covered. High-entropy solid electrolytes are discussed in comparison with traditional electrolyte materials in terms of conductivity. High-entropy oxides are considered as prospective cathodes for SOFCs due to their superior electrochemical activity and long-term stability compared with the conventional perovskites. The present review also determines the prioritizing directions in the future development of high-entropy materials as electrolytes and electrodes for SOFCs operating in the intermediate and low temperature ranges.