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Makhonina E.V.,RAS Kurnakov Institute of General and Inorganic Chemistry | Medvedeva A.E.,RAS Kurnakov Institute of General and Inorganic Chemistry | Dubasova V.S.,Scientific Research Institute of Electrical Carbon Products | Volkov V.V.,RAS Kurnakov Institute of General and Inorganic Chemistry | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2016

The layered LiNi0.40Mn0.40Co0.20O2 compound was synthesized and modified with a mixed alumina-carbon coating by a simple soft chemical route. The simultaneous presence of alumina and carbon on the surface of coated samples was proved by ICP-AES, chemical analysis, XP spectroscopy, SEM microanalysis and local electron diffraction. For the first time, we show that the alumina epitaxial layer is formed on basal (001) facets of cathode grains, whereas side-view facets, like (010), remain free from crystalline α-Al2O3, thus leaving them easy for Li-ion diffusion into cathode structure. An amorphous carbon film was used here for better conductivity of the coating layer and prevention of the electrical contact loss between cathode grains. Electrochemical tests revealed that the mixed alumina-carbon coating applied on LiNi0.40Mn0.40Co0.20O2 stabilizes the surface structure and improves the cycling performance (3-4.5 V) and rate capability of cathodes on their basis compared with the pristine and alumina-coated LiNi0.40Mn0.40Co0.20O2 samples. © 2016 Hydrogen Energy Publications, LLC.


Makhonina E.V.,RAS Kurnakov Institute of General and Inorganic Chemistry | Medvedeva A.E.,RAS Kurnakov Institute of General and Inorganic Chemistry | Dubasova V.S.,Scientific Research Institute of Electrical Carbon Products | Volkov V.V.,Brookhaven National Laboratory | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2016

The layered LiNi0.40Mn0.40Co0.20O2 compound was synthesized and modified with a mixed alumina–carbon coating by a simple soft chemical route. The simultaneous presence of alumina and carbon on the surface of coated samples was proved by ICP-AES, chemical analysis, XP spectroscopy, SEM microanalysis and local electron diffraction. For the first time, we show that the alumina epitaxial layer is formed on basal {001} facets of cathode grains, whereas side-view facets, like {010}, remain free from crystalline α-Al2O3, thus leaving them easy for Li-ion diffusion into cathode structure. An amorphous carbon film was used here for better conductivity of the coating layer and prevention of the electrical contact loss between cathode grains. Electrochemical tests revealed that the mixed alumina-carbon coating applied on LiNi0.40Mn0.40Co0.20O2 stabilizes the surface structure and improves the cycling performance (3–4.5 V) and rate capability of cathodes on their basis compared with the pristine and alumina-coated LiNi0.40Mn0.40Co0.20O2 samples. © 2016 Hydrogen Energy Publications LLC


Pleshakov V.,Scientific Research Institute of Electrical Carbon Products
Journal of Applied Crystallography | Year: 2014

A universal algorithm for the generation of three-dimensional models of icosahedral fullerene-like carbon nanostructures has been developed. Coordinates of atoms on their surface are calculated and three-dimensional models of fulleroids - nested icosahedra - are built. A flat model consisting of five graphite layers of varying diameters is computed in an attempt to explain the nature of the diffraction maximum (d ≃ 6.81 Å, 2θ ≃ 13°) in shungite carbon by the existence of edge effects, carbon atoms or small fragments of layers in the interlayer space, or dislocation rings. © 2014.


Pleshakov V.F.,Scientific Research Institute of Electrical Carbon Products
Solid Fuel Chemistry | Year: 2015

The problem of constructing the 3D models of tetrahedral and octahedral fullerene-like carbon nanostructures was solved with the aid of an algorithm developed for the mapping of atoms in a flat carbon layer onto the surface of a polyhedron. © 2015, Allerton Press, Inc.


Bograchev D.A.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry | Vol'Fkovich Y.M.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry | Dubasova V.S.,Scientific Research Institute of Electrical Carbon Products | Nikolenko A.F.,Scientific Research Institute of Electrical Carbon Products | And 2 more authors.
Russian Journal of Electrochemistry | Year: 2013

A model of the lithium ion battery is developed which takes into account intercalation and extraction of lithium ions in the active mass of negative and positive electrodes, the dependences of equilibrium electrode potentials on the concentration of intercalated lithium, the ion transfer in pores of electrodes and the separator, the kinetics of electrode reactions, and the electric double layer charging. As the active material for the negative electrode, UAMS graphite material is used. Lithium-nickel-cobalt oxide serves as the positive electrode. The porous structure of electrodes is studied by the method of standard contact porosimetry. Sufficiently high porosity values found for both electrodes (50% for anode and 27% for cathode) made it possible to consider the interface as regards the internal pore surface found from porosimetry data rather than as regards their external surface as in the previous studies. A comparison of calculated and experimental discharge curves demonstrates their closeness, which points to the correctness of the model. By the fitting procedure, the coefficients of solid-state diffusion of lithium ions and the rate constants for reactions on both electrodes are found. © 2013 Pleiades Publishing, Ltd.

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