Change in the content of lithium sulfide is quantitatively studied through the methods of precipitation and back iodometric titration in lithium-sulfur cells during charge-discharge cycling for 100 ...cycles. It is shown that in the initial cycles (25 cycles) of charge-discharge cycling, electrochemically inactive lithium sulfide accumulates. The predominantly inactive lithium sulfide accumulates in the sulfur electrode. It is likely that lithium sulfide is deposited in the pores of the carbon material, blocks the pores and loses the ability to participate in the electrochemical reactions.
On the surface of the lithium electrode, a surface layer containing lithium sulfide is formed during the cycling of the lithium-sulfur cells and is in equilibrium with the electrolyte system. It is found that lithium sulfide does not accumulate on the lithium electrode for at least 100 charge-discharge cycles.
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•Lithium sulfide content in Li-S cells is studied.•Lithium sulfide does not accumulate on lithium electrodes over 100 cycles.•Lithium sulfide is blocked in the pores of carbon particles of positive electrode.
The results of comparative studies of the effect of current density on the average discharge voltage and specific discharge capacity of carbon electrodes based on heat-treated petroleum coke and ...graphite are presented. The carbon obtained by heat treatment of petroleum coke is shown to have better kinetic characteristics than graphite. The increase in the current density from 0.2 mA/cm
2
(36 mA/g) to 2 mA/cm
2
(364 mA/g) leads to a decrease in the discharge capacity of heat-treated petroleum coke by 26%; graphite, by 93%. When the current density is restored to 0.2 mA/cm
2
, the discharge capacity of carbon electrodes is also restored to its initial value. The increase in the current density is also shown to lead to increase in the average discharge voltage of lithium–carbon cells. Thus, with the increase in current density from 0.2 to 2 mA/cm
2
, the average discharge voltage of the lithium–carbon cells with the electrode active component of the heat-treated petroleum coke increased from 0.39 to 0.62 V; that of graphite, from 0.14 to 0.35 V.
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The results of the palynological study of the Kurshskaya Formation stratotype (Primorsky quarry, Kaliningrad Oblast) are presented. The lower part of the Kurshskaya Formation (Member of “chocolate” ...clays) contains an assemblage of latest Eocene dinoflagellate cysts
Areosphaeridium diktyoplokum
,
Glaphyrocysta semitecta
, and
Cordosphaeridium funiculatum
. The formation is characterized by four spore-pollen assemblages: (1) latest Eocene
Pinuspollenites–Inaperturopollenites–Sciadopityspollenites
assemblage in the “chocolate” clays and in the lower part of brown sands; (2) early Oligocene
Sequoiapollenites–Betulaepollenites betuloides
assemblage in the lower part of the brown sands member; (3) early Oligocene
Boehlensipollis hohli–Carpinipites carpinoides
in the middle part of brown sands member; (4) late Oligocene–early Miocene
Alnipollenites
–
Corylopollis
assemblage in the upper part of the brown sands of the Kurshskaya Formation. In total, the Kurshskaya Formation is terminal Eocene–early Miocene in age. The lower part of the Zamland Formation, which overlies the Kurshskaya Formation, contains the presumably middle Miocene
Pinuspollenites
–
Tricolporopollenites pseudocingulum
–
T. euphorii
assemblage. Based on the obtained palynological data, the depositional settings at the end of the Eocene–Oligocene–early Miocene in the South Baltic region are reconstructed. The regression of the marine basin began as early as the end of the Priabonian, the climate was still quite warm and humid, close to subtropical. Mesophytic mixed coniferous-broad-leaved forests grew along the shores of the strait, lowlands were occupied by marsh vegetation. Cooling at the Eocene/Oligocene boundary resulted in the appearance of hemlock in plant communities and increase in the proportion of catkins (alder, birch, hornbeam). Presumably, in the late Oligocene–early Miocene, the proportion of small-leaved trees, especially alder and hazel, sharply increased in mesophytic forests, while the number of pine trees decreased. Wetter and warmer climatic conditions are assumed for the early Miocene: this time is characterized by an increase in the number of walnut, cypress, and Cyrillaceae. In the middle Miocene, the climate was still quite warm, but drier, and such moisture-loving species as
Podocarpus
, spruce,
Glyptostrobus
, and swamp cypress disappeared from plant communities.
The possibility of analyzing the electrochemical impedance spectra of lithium–lithium cells using the Distribution of Relaxation Times (DRT) function is studied. A comparative analysis of the ...electrochemical impedance spectra of lithium–lithium cells obtained during long-term storage at a constant temperature and at different temperatures was performed using the method of either equivalent electrical circuits or the DRT function. The analysis of the impedance of lithium–lithium cells by the DRT function is shown to allow estimating the number of layers in the surface film on the lithium electrodes and evaluating their physical parameters—the resistance and capacitance. It has been established that with a long exposure of lithium–lithium cells at the temperature of 30°C, the number of layers in the surface film and its resistance decreased. With the increase in the temperature, the physical properties of the layers of the surface film are differentiated and its total resistance decreased. The analysis of the electrochemical impedance spectra of lithium–lithium cells by the DRT functions is more informative than the method of equivalent electrical circuits.
Substituted phthalonitriles containing a 2-cyclohexylphenol fragment and nitro- or 1-benzotriazolyl groups, and also phthalonitrile containing two 2-cyclohexylphenoxy groups, were synthesized using ...4-bromo-5-nitro- and 4,5-dichlorophthalonitriles. Tetramerization of these precursors with zinc acetate hexahydrate resulted in the corresponding octasubstituted zinc phthalocyanines. Their spectral properties were studied.
An approach for the determination of the melting point of electrolyte solutions using the molecular dynamics method is considered. In order to calculate the melting point of the electrolyte ...solutions, it is proposed to successively calculate the density of the system using the molecular dynamics approach in the temperature range, which includes the expected melting point. The melting point was identified as the temperature at which the temperature dependence of density of the studied solutions registered an inflection point. The proposed approach is verified using sulfolane and solutions of lithium salts in sulfolane as examples, and a good agreement between the melting point determined using differential scanning calorimetry and the calculated temperature is observed. The discrepancy between the calculated and the experimental values of the densities of the studied systems did not exceed 3%.
For the first time, in the conditions of the Magadan region, have been carried out studies on the use of a feed additive (FA) based on mountain pine in combination with lichens in the rations of ...young cattle (C) of Holstein breed and cross-bred young of Holstein and Aberdeen Angus breeds of the dairy and growing period. The use of FA positively affects the growth rate, daily average growth, blood counts, young growth resistance and digestibility of feed. The live-weight of the experimental gobies of Holstein breed at the age of 16 months, which additionally received the FA ration, exceeded the rate of the control group up to 2.15 kg (0.58%), the crossbreeds of the Aberdeen-Angus breed exceeded the rate of a control group up to 9.55 kg (2.3%) (P≤0.05). The relative growth rate (according to S. Brody) of gobies at the age of 16 months, which got FA was higher than of gobies of the control groups. The growth rate of experimental gobies of Holstein breed is 0.12% higher, and of crossbred gobies is 2.57% higher respectively. A study of the hematological composition of the blood of experimental half-blood gobies of the Aberdeen-Angus breed showed that relative to the control group, the concentration of eosinophils increases by 0.4%, monocytes 0.8%, lymphocytes by 7.2%, the concentration of band neutrophil decreases by 1%, segmented neutrophils by 7.4%. The young of the experimental groups had better digestibility of dietary nutrients and feed costs per 1 kg of growth in comparison with the control groups.
The paper is focused on the effect of homogenous and inhomogeneous magnetic fields on crystallization, and some physical and chemical properties of silver azide (morphology, electric resistance, ...defect structure, reactivity) as well. The authors put forward an efficient procedure for growing crystals with specified sizes, reactivity and minimized impurities.
In this paper, we consider canonical
-planar mappings of spaces with affine connection on two symmetric spaces. The basic equations of such mappings are obtained in the form of a closed system of ...Cauchy-type equations in covariant derivatives. The number of essential parameters on which its solution depends has been established.
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