The pulsed method of measuring impedance is described. The cell is galvanostatically stimulated by a bipolar current signal of square shape. The cell response is registered by sampling U+i, U−i with ...selected period Δt. The impedance spectra are calculated by direct Fourier transform. The internal resistance of the lithium sulphur cell is characteristically minimum in the calculated impedance diagrams in the frequency range of 0.035–5 Hz. It is shown that the lithium sulphur cells have maximum internal resistance at the transient between high and low voltage plateaus of charge and discharge curves. The internal resistance increases significantly during the initial stages of cycling because of the formation of passivation layers at the electrodes. It was found that the internal resistance of the lithium sulphur cell in the same charge state is governed by the way in which it is achieved. This is explained by differences in molar volumes of products generated in the sulphur electrode by electrochemical reaction during charging and discharging.
•The pulsed method as a way to determine the internal resistance of batteries.•The internal resistance of Li–S cells depends on the depth of charge and discharge.•The polarization direction of lithium sulphur cell governs the internal resistance.
We have studied the interaction of polycrystalline samples of lithium nitride with metallic lithium. We have found that upon contact, metallic lithium spontaneously dissolves into polycrystalline ...lithium nitride samples. Spontaneous penetration of metallic lithium into polycrystalline samples of lithium nitride leads to the appearance of electronic conductivity and the formation of mixed ion-electronic conductors.
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•Interaction of metallic lithium and polycrystalline lithium nitride is studied.•Metallic lithium spontaneously penetrates in a pellet of Li3N.•Penetration of lithium in Li3N leads to short circuit of the cell Li │ Li3N │ Li.•Penetration of Li in Li3N leads to the formation of mixed ion-electronic conductors.
The effect of lithium polysulfides on the amount and ratio of electrochemically active metallic lithium, electrochemically inactive metallic lithium, and chemically formed lithium compounds in the ...cathodic deposits formed on a stainless-steel electrode during galvanostatic cycling in 1 М LiClO
4
solution in sulfolane at 15, 30, 45, and 60°C is studied using the method we have developed earlier. It is shown that the increase in temperature leads to increase in the Coulomb efficiency of cycling and the amount of electrochemically active metallic lithium; a decrease in the amount of electrochemically inactive metallic lithium, regardless of the presence of lithium polysulfides in the electrolyte. When lithium polysulfides have been introduced into the electrolyte, an increase in the Coulomb efficiency of the metallic lithium cycling and a change in the ratio of various forms of lithium in the cathodic deposits toward an increase in electrochemically active lithium by about 1.5 times are observed. The lithium polysulfides are assumed to contribute to the dissolution of electrochemically inactive metallic lithium, forming an interfacial “sulfide” film at the electrode, which possessed high ionic conductivity and good protective properties, the more so, at elevated temperatures.
The quasi-isentropic compressibility of a strongly nonideal helium plasma in the pressure range 250–600 GPa is experimentally studied in devices with cylindrical geometry. The temperature at the ...front of a cylindrical shock wave in helium (
T
≈ 10 000 K) and the flight speed of the inner cascade (
W
≈ 3.5 km/s), in the cavity of which the maximum compressed plasma density is achieved, are measured. Data on the compression of a nonideal helium plasma to a density ρ ≈ 3 g/cm
3
at an approximately constant final temperature of 21000 K are obtained. The trajectories of the metallic shells compressing the plasma are detected using high-power pulsed X-ray sources with a boundary electron energy of up to 60 MeV. The helium plasma density is determined using the radii of the shells measured at the time of their “stop.” The compressed plasma pressure is obtained using gasdynamic calculations. Comparative theoretical calculations of the quasi-isentropic compression parameters have been carried out using the following two theoretical models: the traditional chemical plasma model (SAHA code) and an ab initio quantum molecular dynamics (QMD) approach. No anomaly of the experimental data in the pressure range of the plasma phase transition theoretically assumed in helium is detected.
•The full use of the energy potential of uranium raw materials.•R&D program to involve MA in mixed nitride.•Production of mixed nitride fuel with MA – homogeneous option.•Production of mixed nitride ...fuel with MA – intra-pin heterogeneity.•Development of fuel for intra-FA heterogeneity of MA transmutation.
The main results and plans for the future in the framework of R&D on the involvement of americium, neptunium (MA) in mixed nitride fuel of fast reactors are presented. Depending on the method and amount of MA introduced into the mixed nitride, R&D is carried out in three directions: homogeneous introduction of minor actinides; intra-fuel pin heterogeneity and intra-fuel assembly (FA) heterogeneity of minor actinides. At the first stage, the technology of homogeneous transmutation is being tested using dismountable FA (OU) in the BOR-60 reactor. Each OU includes 7 fuel pins. An intermediate unloading of fuel pins is planned with the corresponding additional loading of new ones and irradiation prolongation. The irradiation parameters of subsequent experimental fuel pins with MA will be specified after determining the characteristics of fuel pellets of mixed nitride with MA. In order to study the effect of MA additives on the cladding corrosion from the first batches of pellets, at the end of 2018, three experimental fuel pins with Np and Am with pellet density of ~10 g/cm3 in OU-16 were manufactured and loaded in BOR-60. Upon reaching the maximum fuel burn-up of 1.36 at% and a dose of 10.7 displacements per atom (dpa) OU-16 was unloaded for intermediate examination of fuel pins with MA. To minimize the loss of Am at the stage of fuel pellets sintering, the method of high-voltage electric impulse consolidation for pellets with Am is considered.
We present our experimental results on the compressibility of strongly coupled (nonideal) degenerate deuterium and helium plasmas quasi-isentropically compressed to pressures
P
~ 20 TPa in devices ...with a spherical geometry. The trajectories of the plasma-compressing metallic shells were recorded with the help of powerful pulsed X-ray sources (betatrons) with a boundary electron energy of 60 MeV. A high-current accelerator with a penetrability of objects with an equivalent thickness of 250-mm of lead has been used for the first time as an X-ray source in our experiments. Plasma densities up to ρ ≈ 14 g cm
–3
were determined from the measured radius of the shell at the instant of its “stopping.” We derived the compressed-plasma pressure based on our gasdynamic computations including the real characteristics of the experimental devices.
We present data on the quasi-isentropic compressibility of a strongly coupled (nonideal) plasma of a deuterium–helium mixture in the range of pressures 150–250 GPa in devices with a cylindrical ...geometry and a new result obtained in an experiment with “pure” deuterium at a pressure ~200 GPa. The trajectory of the plasma-compressing metallic shells was recorded using powerful pulsed X-ray sources with a boundary electron energy up to 60 MeV. The densities of the plasma of deuterium and its mixture with helium were determined from the measured radii of the shells at the instant of their “stopping.” We derived the pressure of the compressed plasma based on gasdynamic computations including the real characteristics of the experimental devices. The data obtained confirm the conclusion previously reached at VNIIEF about a phase transition in the plasma of compressed deuterium in the range of pressures 150–160 GPa and suggest that this phase transition is retained in the mixture of deuterium with helium.
First results on
-dependence measurements in inclusive
meson production in
interactions (
, Al, Cu, Sn, and W) are presented at
GeV/
c
. The ratios of the differential cross sections of four of these ...nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable
and transverse momentum
GeV/
c
.
mesons were detected in the decay mode
at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex.
A nonideal helium plasma has been compressed to a density of ρ ≈ 14 g/cm
3
at a pressure of
TPa (200 Mbar) in a spherical two-cascade device. The design of the device has been presented and the ...thermodynamic parameters of the helium plasma reached in it have been estimated. Data on the dynamics of the external and internal cascades in the device used to choose the calculation method have been obtained in a preliminary experiment with a hemispherical prototype. The experiment has been performed on the X-ray complex at the Russian Federal Nuclear Center All-Russian Research Institute of Experimental Physics, which includes BIM 234.3000 betatrons with a boundary energy of 60 MeV used in the multipulse bremsstrahlung generation regime with a multichannel optoelectronic system of recording X-ray images. A high-current linear accelerator LIU-R-T and an image detector assembly consisting of photochromic ADC screens have been used in addition to betatrons to detect the compressed shell cavity.
The efficiency of separate trapping of cesium oxide and molecular iodine formed during oxidative thermolysis of cesium iodide in the process of chemisorption on ceramic highly porous block-cellular ...contact elements is investigated. The dynamic sorption capacity of contact elements with an applied aluminosilicate sorption-active layer and with an active layer of silver nitrate for cesium and iodine, respectively, is determined. The developed contact elements are recommended for use in systems of local gas purification of high-temperature processing stages of recycling of spent nuclear fuel.
