Volume 24, Nº 2 (2024)
Articles
Probabilistic models of the capacity of the electrode material in a wide range of current loads
Resumo
An approach for constructing mathematical models of the current dependence of the capacity of electrode materials is proposed. The approach involves analyzing the probabilities of favorable and unfavorable events occurring on the elements of electrical equivalent circuits that can be used to model the electrode. Several probabilistic models that correspond to different combinations of a capacitor, a Warburg element and a constant phase element in an electrical circuit are proposed. As an example, the validation of specific models to describe the experimental current dependences of the capacity of Li3V2(PO4)3 or Li4Ti5O12 based composite electrodes with carbon nanomaterial is shown. The approach allows approximating such dependencies for a wide range of current loads – from 0.1 to 50 C.
Electrochemical Energetics. 2024;24(2):59-75
59-75
Ni-Mo and Ni-Mo-Co composite catalytic alloys for alkaline water electrolysis
Resumo
Currently, a large number of studies on alkaline water electrolysis are being carried out with the aim of reducing the specific energy costs for the hydrogen evolution reaction and the oxygen evolution reaction. This work is devoted to the methods of synthesis of highly dispersed composite coating on the surface of nickel foam and the methods of the formation of bi- and ternary catalytic alloys based on molybdenum using electrochemical deposition. During the study of the samples morphological and element-by-element analyses were carried out and the activity indicators of the synthesized highly effective catalytic coatings were obtained.
Electrochemical Energetics. 2024;24(2):76-87
76-87
Lithium borates as a surface protective layer for lithium-manganese spinel
Resumo
The protective properties of the coating applied to the surface of lithium-manganese spinel (LiMn2O4), using the eutectic composition of Li2O : B2O3 = 47 : 53 (wt.) with the melting point of 650°C, were studied. The content of the eutectic lithium borate varied from 1% to 10%. The electrochemical behavior of the obtained materials in the cathode half-cells of lithium-ion battery was studied at room temperature. It was shown that an abnormally large decrease in the specific capacity of lithium-manganese spinel took place simultaneously with the stabilizing effect. The side chemical reactions that occur between LiMn2O4 and the eutectic lithium borate during annealing while applying a protective layer were analyzed. The chemical stability of lithium-manganese spinel (LiMn2O4) and the manganese-containing solid solution with the layered structure, LiNi1/3Mn1/3Co1/3O2, with respect to enriched lithium borates, was compared.
Electrochemical Energetics. 2024;24(2):88-102
88-102
Phase complex modeling and experimental identification of the compositions of low-melting electrolyte mixtures in the stable triangle LiF-NaF-KCl of the quaternary reciprocal system Li+ ,Na+ ,K+ ||F− ,Cl−
Resumo
Alkali metal halides are used as heat-storing materials, electrolytes for chemical power sources and solvents for inorganic substances. Using three-dimensional vector graphics software, a 3D model of the phase equilibrium states of the quasi-ternary system LiF-NaF-KCl, which is a stable triangle of the four-component reciprocal system Li+ ,Na+ ,K+ ||F-,Cl, was constructed. Based on the 3D model, the polythermal and isothermal sections and the polytherm of crystallization of the phases were constructed for the first time. The stable nature of the LiF-NaF-KCl triangle is confirmed by thermodynamic calculations for several temperatures of interaction of mixtures of the substances being a part of the unstable LiCl-NaF-KF triangle. The crystallization polytherm allows us to select mixture compositions in the temperature range from 590 to 650 and from 590 to 700°C for practical use as molten electrolytes for mid-temperature chemical current sources.
Electrochemical Energetics. 2024;24(2):103-112
103-112