Academic literature on the topic 'Metavanadate electrolyte'

V₂O₅ oxide was obtained in thin layers on an anode of 18Н12Х9Т stainless steel from an aqueous solution of ammonium metavanadate followed by treatment at 300 and 500&deg;C. It was investigated in the redox reaction with lithium to be compared with analogues obtained from oxovanadium sulfate solution to be used in a lithium thin layer battery. The physical-chemical and structural properties, the morphology of the surface of the deposits were determined using X-ray phase analysis, IR absorption spectroscopy, thermoanalytical study, and atomic force microscopy. Large-block deposits with a smooth surface structure precipitated from a solution of NH₄VO₃ differ significantly from the deposits with a branched surface structure obtained from a solution of oxovanadium sulfate. The hydrated electrolysis product VO₂ nV₂O_5&nbsp;(<em>n </em>= 1&ndash;3) with the presence of NH₄⁺ after high-temperature treatment is transformed into&nbsp;orthorhombic V₂O₅. The discharge characteristics of V₂O₅in the redox reaction with lithium in a liquid-phase electrolyte 1 mole/l LiClO₄, propylene carbonate, dimethoxyethane differ from those in a polymer electrolyte with a polyvinyl chloride matrix including propylene carbonate, LiN(CF₃SO₂)₂. The discharge capacity of V₂O₅ obtained from the metavanadate solution at the treatment <em>T</em> = 300 С (7 h) decreases in a liquid-phase electrolyte from 250 mAh/g to 110 mAh/g in the 40th cycle, while in a polymer electrolyte - from&nbsp;210 mAh/g to 100 mAh/g at an earlier cycling stage. The reversibility of the electrode process is lost at the stage of phase transition (&delta;-&gamma;) in V₂O₅ near a voltage of 2.3 V. Annealing the deposits at 500&deg;С increases the discharge capacity of V₂O₅ obtained from a solution of oxovanadium sulfate. The large-block structure of the deposits obtained from the metavanadate electrolyte does not allow increasing their heating to 500&deg;С due to the loss of adhesion of the deposits to the metal base. The branched structure of the deposits obtained from the solution of oxovanadium sulfate promotes their better adhesion to the base than a large-block structure of the deposits obtained from the metavanadate solution. For the usage of V₂O₅ obtained from the metavanadate solution in the lithium battery system, it is necessary to find ways to modify the morphology of the deposit surface. V₂O₅deposition in the presence of Co²⁺ can contribute to the fragmentation of the block structure.

Hybrid composite oxide material is obtained by transient electrolysis method on the surface of carbon fiber substrate having the ability to reverse electrochemical intercalation of lithium. It is established that electrochemical characteristics of the hybrid composite oxide material depend on the concentration of sodium metavanadate in the solution of cathodic degreasing electrolyte during the preparation of carbon substrate surface.

Heterogeneous vanadium-oxide compounds (bronzes, vanadates) attract the attention of developers of lithium batteries due to an increased structural stability of those oxides in the redox reaction with lithium as compared with the resistance of V₂O₅ oxide, a traditional intercalation electrode material for Li-batteries. Structural stabilization improves the discharge characteristics of Li-batteries based on potassium-containing and sodium-containing vanadium oxide compounds. In this work, the combined effect of potassium and sodium ions on the electrochemical transformation of vanadium oxide compounds in electrodes for usage in a Li-battery was investigated. According to the data of the X-ray phase analysis, dispersed deposits were obtained at the anode, depending on the composition of the electrolyte. From the solutions of potassium metavanadate in the presence of sodium ions, the deposits contain Na₅V₁₂O₃₂ and KV₅O₁₃ vanadates; from the solutions of vanadyl sulfate in the presence of potassium and sodium ions, vanadates Na₁₀V₂₄O₆₄ and KV₅O₁₃ are formed. The evaluation of the electrochemical parameters of the synthesized material indicates the possibility of its use&nbsp;&nbsp;in Li-batteries. The cycling efficiency of vanadates obtained from vanadyl sulfate solutions in thin-layer ballastless electrodes of a lithium battery exceeds that of V₂O₅ oxide. The positive combined potassium-sodium effect can be useful for the implementation of thin-layer lithium batteries based on electrochemically synthesized K, Na (V-oxide compounds) obtained from a solution of vanadyl sulfate.

Functional compositions based on multicomponent systems of oxygen-containing salts of s1-elements are widely used in various fields of industry, science and technology: electrometallurgy of light, refractory and heavy metals, as well as metallothermy, pyrometallurgy, promising fluxes for welding and soldering metals, chemical power sources. In the work the triangulation of the Na+, K+ || VO3–, SO42– ternary reciprocal system of sulfates and metavanadates of sodium and potassium on simplices was carried out. The phase states of the Na+, K+ || VO3–, SO42– ternary reciprocal system was investigated by differential thermal analysis (DTA). T–x diagram of the stable secant K2SO4–NaVO3 was constructed, which is the diagonal of the system composition square and which has a eutectic with a melting point of the quasi-double eutectic of 575 °C and a specific melting enthalpy value of 206 kJ/kg. In the NaVO3–Na2SO4–K2SO stable triangle, a minimum of solid solutions with a temperature of 559 °C and an enthalpy of 190 kJ/kg was determined. In the NaVO3–KVO3–K2SO4 stable triangle, the three-component eutectic with a minimum melting point in the system of 474 °C has a minimum specific melting enthalpy of 183 kJ/kg. Compositions of the triple peritectic Р 482 °С and the three-component minimum of solid solutions M 559 °С were determined. The maximum crystallization fields of the system composition square correspond to potassium sulfate and continuous solid solutions of sodium and potassium sulfates. Low-melting mixtures of quasi-double eutectic, ternary eutectic, and ternary minimum can be used as molten electrolytes for medium-temperature chemical current sources and as heat storage materials. For citation: Istomova M.A., Garkushin I.K. Investigation of the Na+, K+ || VO3–, SO42– ternary reciprocal system and measurement of the nonvariant compositions melting enthalpy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 38-44. DOI: 10.6060/ivkkt.20246706.6983.

Aluminum-air batteries are a front-runner technology in applications requiring a primary energy source. Aluminum-air flow batteries have many advantages, such as high energy density, low price, and recyclability. One of the main challenges with aluminum-air batteries is achieving high power while parasitic corrosion and self-discharge are minimized. In this study, the optimization of an aluminum-air flow cell by multiple-parameters analysis and integration of a four-cell stack are shown. We also studied the incorporation of ammonium metavanadate (NH4VO3) as anticorrosive in 4 mol L-1 KOH electrolyte by discharge and polarization plots. It was concluded that NH4VO3 is an efficient anticorrosive at low currents, but it limits the battery reaction at high-current and high-power applications. Nevertheless, high currents inhibit the corrosion reaction using 4 mol L-1 KOH electrolyte, allowing high power and capacity without anticorrosive additives. The flow in the stack also plays a significant role, and parallel flow is suggested over cascade flow since the latter results in the progressive accumulation of hydrogen as the electrolyte flows through the stack.

In this paper, a black ceramic coating is produced on the surface of 7075 aluminum alloy by plasma electrolytic oxidation (PEO) in a silicate electrolyte containing ammonium metavanadate (NH4VO3). The PEO processed sample is further subjected to hydrothermal treatment (HT) and fluorination treatment (FT) to obtain a superhydrophobic PEO/HT/FT coating. The 21‐day air durability test and the tape stripping test showed that the superhydrophobic surface showed excellent air durability and mechanical durability. The anti‐reflection test study found that the average anti‐reflection of the PEO/HT/FT coating is as high as 96.6% in the wavelength range between 400nm and 1000nm. Furthermore, electrochemical test results show that the corrosion current density of the PEO/HT/FT coating decreases to 2.49 × 10‐6 A/cm2, three orders of magnitude lower than the aluminum substrate, and the anti‐corrosion efficiency is as high as 99.87%. The preparation of PEO/HT/FT coating provides more methods for the wide application of Al alloy in aerospace field.This article is protected by copyright. All rights reserved.

Lithium metavanadate (LiVO3) is a typical ionic conductor with a monoclinic pyroxene-type structure at ambient conditions. Here, we investigated the structural and electrical transport properties of LiVO3 under high pressures by combining in situ Raman scattering, x-ray diffraction, impedance spectroscopy measurements, and first-principles calculations. All experimental and theoretical results demonstrated that LiVO3 undergoes a structural transition from monoclinic to triclinic phase at around 5 GPa, during which partial VO4 tetrahedrons are transformed into a VO6 octahedron. The ion migration of LiVO3 was significantly suppressed above 5 GPa and an ionic–electronic transition was discovered at 10.7 GPa. The structural evolution involving coordination environment change results in an electron density rearrangement around Li and O atoms, which are responsible for the transformation of electrical transport mechanism in LiVO3 under high pressures. These results expand our understanding of the electrical and structural properties of LiVO3 under high pressures and provide insights into the pressure effects on ion migration in solid electrolytes.