Ceria-based materials for high-temperature electrochemistry applications

This paper describes the experimental studies of multi-component solid state electrolytes based on CeO2 and their application in intermediate temperature electrochemical devices. Two important aspects are emphasized: the effect of different dopants’ ionic radius and concentration on the electrical properties of CeO2-based solid solutions in air and the influence of combined dopants on the electrolytic properties of solid electrolytes from the standpoint of the critical oxygen partial pressure pO2 at which point the values of the electronic and ionic components of conductivity are equal. Examples of usage of the developed multi-component Ce0.8(Sm0.75Sr0.2Ba0.05)0.2O2-δ electrolyte synthesized by solid state, laser evaporation and combustion methods and composites on the base of Ce0.8(Sm0.8Sr0.2)0.2O2−d electrolyte as a component of electrochemical devices such as solid oxide fuel cell, gas sensors and as a component of the mixed ionic and electronic conducting (MIEC) membranes for hydrogen and syngas gas production are cited.The present work was financially supported by Russian Foundation for Basic Research and Government of Sverdlovsk region, grant no. 13-03-96098

Place of Electrophoretic Deposition Among Thin-Film Methods Adapted to the Solid Oxide Fuel Cell Technology: a Short Review

Thin film technologies have attracted ever-growing interest in different industrial areas. Concerning solid oxide fuel cells (SOFCs), especially devices operating in the intermediate temperature range, such technologies are applied particularly for the deposition of dense, gas-tight electrolyte films with a thickness of several μm to decrease ohmic resistance and enhance the cell performance. The main requirements for the technology selected are its low cost, simplicity of the equipment used, short deposition time and flexibility regarding the cell shape. First, we overview thin-film technologies adapted to the deposition of SOFC functional layers, discussing their strengths and weaknesses, with special attention given to electrophoretic deposition (EPD) as being the most simple and cost-effective colloidal method to fabricate different electrolyte films. Then we present the contribution of our scientific group in the development of the EPD method. The preparation of stable suspensions for the EDP is one of the key requirements for its successful implementation and reproducibility; this was considered in detail and the effect of self-stabilization in suspensions based on nanopowders (7–15 nm), obtained by the method of laser evaporation with consequent condensation, was discussed. Such suspensions, exhibiting high positive ζ-potential values (30–50 mV), were shown to be suitable for EPD without the addition of dispersants or iodine. The requirements for the electrode substrates were formulated and a model of particle aggregation near the porous substrate surface was proposed. Deposition parameters were established for different electrolyte films – commonly used yttria-stabilized zirconia, single and multiply doped CeO2 and proton-conducting doped BaCeO3 electrolytes. As was shown, the deposition on the highly conducting cathode substrates is simpler to implement than the EPD on non-conducting anode substrates and, in addition, it produces high quality films which render high OCV values and superior SOFC performance.This work was performed within the framework of a budget task of the Institute of Electrophysics, UB RAS and the SOFC development task of the Institute of High Temperature Electrochemistry, UB RAS, and partially supported by the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211)

The Influence of the Substituting Element (M = Ca, Sr, Ba) in La1.7M0.3NiO4+Оґ on the Electrochemical Performance of the Composite Electrodes

The actual work focuses on the development of electrochemically active and stable electrodes for a high temperature proton-conducting electrolyte with a perspective of application in intermediate temperature electrochemical devices. The comparative study of the electrochemical performance of the La1.7M0.3NiO4+δ – based (M = Ca, Sr,Ba) composite cathodes with proton-conducting BaCe0.89Gd0.1Cu0.01O3 or oxygen-ionconducting Ce0.8Sm0.2O1.9 ceramic components in contact with the proton-conducting electrolyte BaCe0.89Gd0.1Cu0.01O3 was performed by an impedance spectroscopy in wet air during 1500 h. The composites were used as functional layers in bi-layered electrodes with current collector layers made of 98 wt.% LаNi0.6Fe0.4O3 + 2 wt.%CuO or 99.4 wt.% La0.6Sr0.4MnO3 + 0.6 wt.% CuO

Short review on recent studies and prospects of application of rare-earth-doped La2NiO4+δ as air electrodes for solid-oxide electrochemical cells

Received: 16 October 2023. Accepted: 2 November 2023. Published online: 14 November 2023.Solid solutions based on the rare earth substituted lanthanum nickelate La2NiO4+δ are considered as promising air electrode materials for electrochemical applications. The present focus review summarizes recently published papers dealing with synthesis methods and investigations of the crystal structure, physicochemical properties, oxygen diffusion and electrochemical activity of La2–xLnxNiO4+δ (Ln = Pr, Nd, Sm, Eu, Gd) electrode materials. It highlights the application advantages and drawbacks of the Ln-substituted La2NiO4+δ for solid oxide fuel and electrolysis cells and compared to the non-substituted La2NiO4+δ.The authors are grateful to Mr. Roman Ivanov, engineer of the Department of Technical Physics, Physico-technological Institute UrFU, for help with the graphical visualization of data

Electrophoretic deposition of coatings and bulk compacts using magnesium-doped aluminum oxide nanopowders

Received: 06.04.2021. Revised: 02.05.2021. Accepted: 03.05.2021. Available online: 07.05.2021.The authors are grateful to D.Sc. prof. A.P. Safronov (Ural Federal University) for valuable advice during the preparation of the manuscript, to the head of the laboratory of impulse processes Dr. I.V. Beketov and junior researcher Mr. A.V. Bagazeev (IEP UB RAS) for the development of the method for producing nanopowders (EEW method), and to scientific researcher Dr. A.S. Farlenkov (Ural Federal University) for conducting electron microscopic studies.The electrophoretic deposition (EPD) of coatings and bulk compacts in a wide range of thicknesses (from 23 to 1800 μm) from stable suspensions of a magnesium-doped aluminum oxide nanopowder with subsequent sintering of samples into dense ceramics was studied. The initial nanopowder was obtained by the method of electric explosion of an Al-Mg alloy wire with a Mg content of 1.3 wt. %. The study of the dispersion composition, kinetics of deaggregation under the ultrasonic treatment and zeta potential in the nanopowder-based suspensions was carried out. It was shown that a nearly linear increase in the deposited mass and thickness of EPD deposits occurred at a constant voltage of 20 V and an average deposition current of approximately 40 μA when the deposition time was varied from 1 to 180 min. Drying of the coatings with a thickness of less than 35 μm led to the formation of a net of small cracks, while drying of the bulk compacts with a thickness of more than 1 mm occurred without cracking. The ceramic bulk sample with a thickness of 1.2 mm and the density of 98.7% TD was successfully obtained by sintering at 1650 °C for 4 h. It was characterized by a dense grain structure with an average grain size of 5 μm and the presence of a small number of closed pores less than 1 μm in size. Sintering of ceramics was revealed to be accompanied by the formation of a MgAl2O4 crystalline spinel phase, localized mainly at grain boundaries.The work was partially carried out using the equipment of the shared access centers of the Institute of Electrophysics (IEP UB RAS) and Institute of High Temperature Electrochemistry (IHTE UB RAS), Composition of compounds

Physicochemical Properties and Electrochemical Performance of the La1.7Ca0.3Ni1-yCuyO4+ δ Cathodes

The results of present work demonstrate that the developed La1.7Ca0.3Ni1-yCuyO4+δ-based electrode can be considered as prospective cathode for intermediate temperature solid oxide fuel cells

The influence of low-intensity pulses of electromagnetic fields, synchronized with the bioelectrical activity of the brain, on the change in ergotropic and trophotropic functions

The purpose of the study is to reveal the influence of low-intensity pulses of electromagnetic fields on changes of ergotropic and trophotropic functions and to make Conclusions about their predominance in the right and left hemispheres based on the results.Цель исследования — выявить воздействие низкоинтенсивных импульсов электромагнитных полей на изменение эрготропных и трофотропных функций, и на основе результатов сделать выводы о их преобладании в правом и левом полушарии

ELECTROPHORETIC DEPOSITION OF CeO2-BASED THIN-FILM ELECTROLYTE, MODIFIED SrTiO3, FOR ANODE-SUPPORTED SOFC

The aim of this work was to determine the possibility of creation the dense CeO2-based electrolyte membranes on anode substrates by the electrophoretic deposition. The SDC suspensions were modified by the SrTiO3 addition. The microstructure studies of deposited and sintered films were carried.Исследование выполнено за счет гранта Российского научного фонда № 22-23-00066, https://rscf.ru/project/22-23-00066/

PHYSICO-CHEMICAL PROPERTIES OF A COMPLEX OXIDE Pr1.6Ca0.4Ni1-уCuуO4 AS A CATHODE MATERIAL FOR MEDIUM-TEMPERATURE SOFC

In this paper, a correlation was carried out between the conditions of various synthesis methods, the crystal structure and the physicochemical properties of complex oxides with the Raddlesden-Popper structure Pr1.6Ca0.4Ni1-УCuУO4

Novel materials for solid oxide fuel cells cathodes and oxygen separation membranes: Fundamentals of oxygen transport and performance

In the field of modern hydrogen energy, obtaining pure hydrogen and syngas and then being able to use them for green energy production are significant problems. Developing solid oxide fuel cells (SOFC) and catalytic membranes for oxygen separation as well as materials for these devices is one of the most likely ways to solve these problems. In this work, the authors’ recent studies in this field are reviewed; the fundamentals of developing materials for SOFC cathodes and oxygen separation membranes’ permselective layers based on research of their oxygen mobility and surface reactivity are presented. Ruddlesden – Popper phases Ln2–xCaxNiO4+δ (LnCNO) and perovskite-fluorite nanocomposites PrNi0.5Co0.5O3–δ–Ce0.9Y0.1O2–δ (PNC–YDC) were studied by isotope exchange of oxygen with C18O2 and 18O2 in flow and closed reactors. For LnCNO a high oxygen mobility was shown (D* ~ 10–7 cm2/s at 700 °C), being provided by the cooperative mechanism of oxygen migration involving both regular and highly-mobile interstitial oxygen. For PNC–YDC dominated a wide fast diffusion channel via fluorite phase and interphases due to features of the redistribution of cations resulting in superior oxygen mobility (D* ~ 10–8 cm2/s at 700 °C). After optimization of composition and nanodomain structure of these materials, as cathodes of SOFC they provided a high power density, while for asymmetric supported oxygen separation membranes – a high oxygen permeability. © 2020Support of different parts of the work by the Russian Science Foundation (Project 16-13-00112) and the budget project №AAAA-A17-117041110045-9 for Boreskov Institute of Catalysis is gratefully acknowledged. The authors from the Ural Federal University are grateful to the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211). Ce 0.9 Y 0.1 O 2–δ |Ce 0.9 Gd 0.1 O 2–δ |Ni/Zr 0.84 Y 0.16 O 2–δ anodic half-cells and Ni/Al foam substrates were kindly provided by H.C. Starck, Germany and Powder Metallurgy Institute NAN Belarus, respectively. Authors would like to appreciate International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19, Wroclaw, Poland, June 9-12, 2019) Organization Committee