High-temperature glassy-ceramic sealants SiO_2-Al_2O_3-BaO-MgO and SiO_2-Al_2O_3-ZrO_2-CaO-Na_2O for solid oxide electrochemical devices

Glasses of the SiO_2-Al_2O_3-BaO-MgO and SiO_2-Al_2O_3-ZrO_2-CaO-Na_2O systems were synthesized in the perspective to apply them as sealants in SOFC at operating temperatures of 700-900 °C. Thermal properties of the chosen glass compositions and their compatibility with the SOFC materials(YSZ-electrolyte and alloy-interconnector Crofer22 APU, 15Х25Т) were investigated by means of synchronic thermal analysis and high-temperature dilatometry. The elemental analysis was performed by atomic emission spectroscopy. The average values of the temperature coefficients of the linear extension are 10.0×10^(-6) °С^(-1) for glass 45%SiO_2-15%Al_2O_3-25%BaO-15%MgO and 9.5×10^(-6) °С^(-1) for glass 60%SiO_2-10%Al_2O_3-10%ZrO_2-5%CaO-15%Na_2O. The gluing microstructure in YSZ/glass/Crofer22 APU was studied by scanning electron microscopy. The crystallization process of silicate phases was revealed to occur in the SiO_2-Al_2O_3-BaO-MgO glass. The analysis of the crystallization products was performed by Raman spectroscopy and X-ray diffraction. Glassy ceramics was proved to possess better parameters in comparison with amorphous glass to be used as a sealant in electrochemical sensors and oxygen sensors. The SiO_2-Al_2O_3-ZrO_2-CaO-Na_2O low-temperature amorphous glass can be applied in SOFC.

Diffusion in the aged aluminium film on iron

Metallic coatings of many types can be applied to steel to provide outstanding, long-term corrosion protection. A thin A1 film is studied at an Fe substrate by the molecular dynamics method at temperatures ranging from 300 K to 1173 K. A1 atoms are found to penetrate the Fe matrix at a temperature of 873 K. The potential energy of the system changes step-like at a temperature of 1173 K. At such temperature mean square atomic displacement significantly changes. The behaviors of the A1 and Fe diffusion coefficients are mainly determined by the temperature dependence of the diffusion activation energy.

Hydrogen production from methane and carbon dioxide mixture using all-solid-state electrochemical cell based on a proton-conducting membrane and redox-robust composite electrodes

In recent years, interest in hydrogen as a fuel has sharply increased in the field of alternative and green energy due to its high energy capability and zero-emission behaviour. As a result, research in the development of new highly efficient methods for producing high-purity hydrogen is relevant. This paper presents, for the first time, the test results of an electrochemical cell with a proton-conducting La_(0.9)Sr_(0.1)ScO_(3-δ) electrolyte and symmetrical Sr_(1.95)Fe_(1.4)Ni_(0.1)Mo_(0.5)O_(6-δ)+ La_(0.9)Sr_(0.1)Sc_(0.9)Co_(0.1)O_(3-δ) electrodes as a hybrid setup for electricity generation in proton ceramic fuel cell mode, for hydrogen separation from H_(2)+ Ar mixture and the production of high-purity hydrogen from methane with simultaneous CO_(2) utilization.It was found that this electrochemical cell generates high flow rates of hydrogen during its separation through a proton-conducting membrane from H_(2)+ Ar mixture, about 500 cm^(3)h^(-1)cm^(-2)at a current density of 0.6 A cm^(-2)as well as about 370 cm^(3) h^(-1)cm^(-2)at a current density of 0.5 A cm^(-2) from CH_(4)+ CO_(2) mixture at 800 ℃ which shows that these cells are promising for hydrogen production.

Electroextraction of neodymium from LiCl-KCl melt using binary liquid Ga-Al cathode

The electrochemical behaviour of Nd(Ⅲ)ion was investigated on inert W,active Ga and Ga-AI cathodes.It is established that the reduction of Nd(Ⅲ)ion on the inert electrode is a consecutive two-step process while that on the active electrodes is a one-step process.The apparent standard potential of the Nd(Ⅲ)/Nd redox couple at different temperatures was determined by open-circuit chronopotentiometry and semi-differential method,and the relationship between temperature and apparent standard potential was further discussed.The thermodynamic properties of Nd in Ga and Ga-Al electrodes such as activity coefficient and activity were evaluated via intermittent coulomb titration and temperature dependence test,and the effect of temperature on activity coefficient was verified.Finally,Nd was successfully extracted in form of alloy from molten salt by galvanostatic electrolysis,in which the current efficiency of91.7%for the electroextraction indicates that the binary liquid Ga-Al electrode has favorable performance.

Technological achievements in the fabrication of tubular-designed protonic ceramic electrochemical cells

Protonic ceramic electrochemical cells provide an excellent basis for the advancement of high-temperature solid oxide devices,offering potential solutions to a range of challenges in the hydrogen energy and carbon capture fields.The facilitated ionic transport in proton-conducting electrolytes enables these cells to operate at temperatures 100◦C–500◦C lower than those of conventional solid oxide cells with known zirconia electrolytes.As a result,promising performances have been reported for various types of proton ceramic electrochemical cells.Nevertheless,these advancements have been demonstrated only at the laboratory scale,whereas their ZrO2-based counterparts have already been commercialized.This review presents an overview of the fundamental and applied aspects related to the fabrication of tubular protonic ceramic electrochemical cells and their subsequent characterization as hydrogen permeation membranes,hydrogen pumps,hydrogen sensors,fuel cells,electrolysis cells,and electrochemical reactors.A specific focus is placed on the technological aspects of the tube preparations derived from the original powder sources as well as the dimensional characteristics of the tubes,which serve as an indicator of scaling.Therefore,this review serves as a starting point for the development and scaling of protonic ceramic electrochemical cells,with the potential for large-scale production.