A set of computational and experimental methods is used in the study of chemical side interactions in the LiMn2O4-based lithium-ion cathodic half-cell over the 25–60°C temperature range. The degradation of LiMn2O4-spinel-based electrodes is shown to start upon the LiMn2O4 granules contacting the standard (basic) electrolyte solution (1 m LiPF6 in a mixture of ethylene carbonate and dimethyl carbonate (1 : 1, by wt)). It is established that under current-less conditions, the degradation of the LiMn2O4-based electrode is caused by the mutual thermodynamic instability between LiMn2O4 and the LiPF6 lithium salt. The equilibrium interaction products are determined, and the mechanism of the critical temperature influence on the degradation of lithium-ion batteries with lithium–manganese spinel is refined. A model is proposed for the primary surface layer at the LiMn2O4/electrolyte interface formation and evolution, which explains the distinctive features of the degradation processes in this system.

CsAg4Br3–хI2+х solid solutions with x=0.38; 0.50; 0.63 were prepared by solid-phase synthesis; the single-phase of the products was confirmed by X-ray diffraction and differential scanning calorimetry. Studies of the electrical transport characteristics of CsAg4Br3–хI2+х included measurements of the ionic conductivity by the four-probe method in the range of –50…+120°C and an evaluation of the electronic component of the conductivity by the Hebb-Wagner method. It was shown that the ionic conductivity of CsAg4Br3–хI2+х solid solutions in the studied range of compositions is practically independent of x and is very close to that of the well-known superionic conductor RbAg4I5. The activation energy of conduction for all studied compounds is about 10 kJ mol–1. The oxidation potential determined by the stepwise polarization technique for CsAg4Br3–хI2+х solid solutions is noticeably higher than that of RbAg4I5, and is in the range of 0.75–0.78 V (vs. Ag0/Ag+). The high electrochemical characteristics of CsAg4Br3–хI2+х (0.38≤x≤0.63) and the absence of polymorphic transitions in the studied range from –160°C to the melting point (175 – 178°С) make these materials promising for use in electrochemical devices based on solid electrolytes, especially for low temperature applications.

Solid solutions CsAg4Br3 – хI2 + х (x = 0.38; 0.50; 0.68) are prepared by solid-state synthesis; the single phase of the products is confirmed using the methods of X-ray diffraction and differential scanning calorimetry. The studies of electrotransport characteristics of CsAg4Br3 – хI2 + х involve measuring the ionic conductivity by the four-probe method in the temperature interval from –50 to +120°C and estimating its electronic component by the Hebb–Wagner method. It is shown that in the studied interval of compositions, the ionic conductivity of CsAg4Br3 – хI2 + х solid solutions is practically independent of x, approaching the conductivity of the well-known superionic conductor RbAg4I5. The activation energy of conduction is found to be about 10 kJ mol–1 for all compounds studied. The oxidation potential determined by the method of stepwise polarization for CsAg4Br3 – хI2 + х solid solutions is considerably higher as compared with RbAg4I5, being in the range of 0.75–0.78 V (vs. Ag0/Ag+). The high electrochemical characteristics of CsAg4Br3 – хI2 + х (0.38 ≤ x ≤ 0.63) and the absence of polymorphic transitions in the considered interval from –160°С to the melting point (175–178°С) make these materials promising for the use in electrochemical devices, especially in low-temperature applications.

The process of lithium diffusion in the cathode material of lithium–manganese chemical power sources after a short-term discharge is investigated by analyzing the relaxation parameters of electrochemical noise and the magnitude of the injected lithium layer Magnetoresistance. Fluctuations in the lithium diffusion flux are shown being the source of electrochemical noise in this chemical power source. The data obtained also confirm the assumption made in the literature about the formation, during the cell discharge, of a poorly conducting phase with a spinel crystal structure in the surface layer of MnO2 particles, which inhibits the diffusion process.

In this work the optimum composition of anode material for all-solid-state batteries based on silver and solid electrolyte CsAg4I2.5Br2.5 was determined. For this, electronic conductivity of the mixture of the solid electrolyte and carbon black was studied. The percolation behavior of systems was studied. Percolation thresholds were determined for each system theoretically and experimentally. It was shown that the electrochemically accessible silver surface in the anode material has non-monotonic dependence on the silver content. As a consequence, the exchange current in the cell also has a maximum.

Measurements of the magnetoresistance of the cathode material of a lithium-manganese battery were carried out at various depths of discharge. Two important results were obtained. Firstly, it is possible to record a significant value (up to 50%) of magnetoresistance in polycrystalline MnO2-LixMnO2 powder and measure its relaxation following lithium intercalation. Moreover, by extrapolating the relaxation curve, it is shown that the magnetoresistance can exceed 50% at the moment of intercalation. Secondly, the relaxation of magnetoresistance following intercalation is observed to coincide with the process of rapid relaxation of electrochemical noise in lithium-manganese power sources. This concurrence supports the hypothesis that the cause of the observed electrochemical flicker noise is the diffusion smearing of the intercalated lithium layer the migration of its ions into the crystallite bulk.

Measurements of electrochemical noise in solid-state electrochemical cells with a heteropolycompound- based electrolyte are carried out. The noise power spectral density is calculated using various detrending methods. The impedance real component is calculated by means of the Nyquist formula. The results of the calculations are compared with the data obtained by the electrochemical impedance classical method.

The electrochemical noise of a polymer membrane hydrogen-air fuel cell operating at different load currents was measured in serial experiments. Spectral power densities of the noise are shown to be divided into three regions. At frequencies greater than 3–10 Hz, the spectrum dependence has a constant slope of − 2 in the bilogarithmic coordinates. At frequencies 0.3–5 Hz, there is a horizontal plateau in which length is determined by the value of a load. At frequencies less than 0.3 Hz, the dependence of spectral power density has a slope of − 2. Medium-frequency plateau and high-frequency slope of spectral power densities of the noise were approximated by model RC circuits. The values of Faradic resistance and double-layer capacitance connected in parallel were obtained from the electrochemical impedance data. At load voltages higher 0.5 V, the height of the plateau was shown to be proportional to the 2.68 power of the load current value.

Electrochemical noise of a Li/SOCl 2 primary battery was measured during discharge at a constant value resistor. The amplitude of the noise was found to be razing during discharge process. Power spectral density calculation method was used to analyze electrochemical noise. It was found that the slope of power spectral density frequency dependences increases with the battery discharging. The electrochemical impedance of the battery was measured during galvanostatic discharge and investigated using equivalent circuit analysis method. The correlations and some interactions between impedance components and electrochemical noise characteristics during battery discharge process were found and analyzed.

This work is devoted to preparation of a hybrid material based on Nafion® 212 membrane doped with nanoparticles of silica and cesium acid salt of phosphotungstic heteropolyacid. The benefits of this material are concerned with its increased conductivity at low humidity. Conductivity and properties of the membranes were studied as a function of relative humidity under the FC operating regime at room temperature. As compared with the commercial Nafion® 212 membrane, the MEA based on this material shows a lower power density at 100% relative humidity of the supplied gases (hydrogen, air). As the relative humidity decreases, power density of the cell based on hybrid membrane increases and overruns the performance of the commercial Nafion® 212 membrane at 100% RH. Explanation of the observed phenomena is proposed.

An algorithm for analyzing electrochemical noise based on Chebyshev spectroscopy using the sample median is presented. Chebyshev spectroscopy with the sample median nicely complements Chebyshev spectroscopy with the sample mean. Chebyshev noise spectroscopy with the sample median can be used to distinguish between corrosion processes, which cannot be achieved using Chebyshev spectroscopy with the sample mean. This “median Chebyshev spectroscopy” can be effectively used to diagnose the electrochemical noise of corrosion systems and electrochemical power sources.

The algorithm of orthogonal expansions is applied to the problem of extraction of diagnostic information from random noise. It is shown that the spectral analysis of electrochemical noise can be performed by a unified algorithm regardless of the type of orthogonal expansion used. A multi-channel indicator of color of electrochemical noise can be constructed on the basis of the orthogonal expansions. It is concluded that the algorithm of orthogonal expansions is an advantageous tool for noise monitoring and noise diagnostics of practically important electrochemical devices, including the devices of electrochemical energetics and systems of protection against corrosion.

A new characteristic of the electrochemical noise spectrum, namely, the variability of an individual line in the discrete Chebyshev spectrum, is discussed. For Chebyshev transforms that have the normal (Gaussian) probability distribution, the proposed variability is 1. In a model experiment, the effect of the lowfrequency harmonic disturbance (drift) and the high-frequency harmonic disturbance (aliasing component) on the variability of an individual line in the Chebyshev noise spectrum is studied. The potentialities of the new approach are demonstrated for a noise electrochemical system involving corrosion processes. The variability of the corrosion process is shown to exceed the variability of the Gaussian noise by a factor of 1.5. The proposed characteristic of electrochemical noise spectrum, namely, the variability of individual line in the discrete Chebyshev spectrum can be a useful informative parameter for the electrochemical noise diagnosis in various electrochemical systems including chemical power sources and fuel cells in which electrochemical corrosion processes can occur.

The effect of a change in the ambient temperature and humidity on the behavior of calix(4)arene- para -sulfonic acid was studied. For the calixarene under study, at least two stable hydrates were observed: tetra- and octahydrate. The number of water molecules in the crystalline hydrate of the acid was confirmed by simultaneous thermal analysis data and the shape of the IR spectra and diffraction patterns. The change in the composition of the hydrate from n = 4 to n = 20 affected the conductivity but slightly; in the region of phase transitions between the hydrates, the activation energy of conductivity changed abruptly.

Исследовано поведение каликс(4)арен-пара-сульфокислоты при изменении температуры и влажности окружающей среды. Для исследуемого каликсарена наблюдается как минимум два стабильных гидрата: тетра- и октагидрат. Количество молекул воды в кристаллогидрате исследуемой кислоты подтверждено данными синхронного термического анализа, видом ИК-спектров и дифрактограмм. При этом изменение состава гидрата с n = 4 до n = 20 слабо влияет на проводимость, а в области фазовых переходов между гидратами наблюдается скачкообразное изменение энергии активации проводимости.