A new method for the solid-phase synthesis of the superionic conductor CsAg 4 Br 2.5 I 2.5 is proposed, which facilitates the preparation of a single-phase product. The thermal behavior of CsAg 4 Br 2.5 I 2.5 in the temperature range from –160 to +190°С was studied by differential scanning calorimetry, and the absence of polymorphous transitions was confirmed; the only first-order phase transition is observed near 177°C and corresponds to the incongruent melting of the solid electrolyte. It is shown that the dense ceramics can be obtained from CsAg 4 Br 2.5 I 2.5 powder by pressing at room temperature; the optimal value of pressure is determined. Studies of the electrical transport characteristics of CsAg 4 Br 2.5 I 2.5 included measurements of the ionic conductivity by the four-probe method in the range of –60…+120°C and an assessment of the electronic component of the conductivity by the Hebb–Wagner method. The contribution of electron transfer is shown to be negligibly small (~10 –9 S cm –1 ), and the ionic conductivity is close to that of the well-known superionic conductor RbAg 4 I 5 and is characterized by a low activation energy (10.3 kJ mol –1 ). The oxidation potential determined by the stepwise polarization method is 0.78 V, which is noticeably higher than that of RbAg 4 I 5 . The absence of first-order phase transitions at temperatures below the melting point, combined with high ionic conductivity, makes the CsAg 4 Br 2.5 I 2.5 compound more attractive for low-temperature applications, and the increased electrochemical stability makes it more attractive for use in chemical power sources as compared to RbAg 4 I 5 .

A new method for the solid-phase synthesis of the superionic conductor CsAg4Br2.5I2.5 is proposed, which facilitates the preparation of a single-phase product. The thermal behavior of CsAg4Br2.5I2.5 in the temperature range from –160 to +190°С was studied by differential scanning calorimetry, and the absence of polymorphous transitions was confirmed; the only first-order phase transition is observed near 177°C and corresponds to the incongruent melting of the solid electrolyte. It is shown that the dense ceramics can be obtained from CsAg4Br2.5I2.5 powder by pressing at room temperature; the optimal value of pressure is determined. Studies of the electrical transport characteristics of CsAg4Br2.5I2.5 included measurements of the ionic conductivity by the four-probe method in the range of –60…+120°C and an assessment of the electronic component of the conductivity by the Hebb–Wagner method. The contribution of electron transfer is shown to be negligibly small (~10–9 S cm–1), and the ionic conductivity is close to that of the well-known superionic conductor RbAg4I5 and is characterized by a low activation energy (10.3 kJ mol–1). The oxidation potential determined by the stepwise polarization method is 0.78 V, which is noticeably higher than that of RbAg4I5. The absence of first-order phase transitions at temperatures below the melting point, combined with high ionic conductivity, makes the CsAg4Br2.5I2.5 compound more attractive for low-temperature applications, and the increased electrochemical stability makes it more attractive for use in chemical power sources as compared to RbAg4I5.

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.

Two types of treatment of the initial mechanical mixture [silicon nanopowder and graphene oxide (GO)] for obtaining Si/RGO nanocomposites were used: reduction in hydrazine vapor and heat treatment at 550°C in an argon atmosphere. It was shown that the type of reduction has an influence on the morphological and electrochemical characteristics of the composites due to the formation of defects and the presence of nitrogen in the graphene network. Less defective and nitrogen doped Si/RGO composites have a better electrochemical behavior as an active material of negative electrode for lithium-ion batteries. The discharge capacity of electrodes based on Si/RGO nanocomposites amounted to 437 mA h g–1 without polymer binder and 1192 mA h g–1 with CMC as a binder.

The first theoretical study of alkali-metal ion transport in a polymeric inorganic electrolyte based on a dimethyl sulfoxide-plasticized Nafion membrane is reported. The structure and intermolecular interactions in XNafion · nDMSO (X = Li, Na, K, Rb, and Cs; n = 8 and 12) ionomers are simulated by the DFT method with hybrid density functionals B3LYP, wB97XD, and PBE taking into account periodic boundary conditions and the projector augmented wave (PAW) method in the VASP and GAUSSIAN program packages. According to the calculations, the barriers rise from 0.2 to 0.4 eV in the series Li–K but lower to 0.3–0.2 eV as the radius increases further in the series Rb, Cs. These results are quantitatively consistent with experimental conductivity activation energy data: 0.26 (Li+), 0.37–0.38 (Na+, K+), 0.27 (Rb+), and 0.20 (Cs+) eV. The conclusion is drawn about the structure and conductivity of the electrolyte depending on the nature of the cations.

Experimental results on the development of two original approaches to obtaining new nanocomposite proton exchange membranes for low-temperature fuel cells are generalized. The first approach consists in in situ modification of the transport channels of commercial proton exchange membranes of the Nafion brand with interpenetrating polymer networks of the introduced polyelectrolyte based on cross-linked polystyrene sulfonate. The second approach is to create a proton exchange nanoscale phase based on polystyrene sulfonate in commercial hydrophobic polymer films. Polystyrene sulfonate is formed during thermal polymerization of styrene sorbed in the films without using ionizing radiation, followed by sulfonation. The influence of the conditions for obtaining membranes on the composition, morphology, transport properties, and results of testing the membranes in low-temperature fuel cells is considered.

Nanoparticles with a core-shell structure of Si@SiO2 with an average size of about 50 nm were obtained by plasma chemical synthesis through the decomposition of monosilane. Electrochemical impedance spectroscopy (EIS) was used to study the behavior of anodes based on the composite Si@SiO2 during the cyclic charge/discharge. Based on the results of Si@SiO2 anodes studies by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) in conjunction with thermodynamic modeling (TM), assumptions were made about chemical and electrochemical processes occurring during prolonged cycling in the electrolyte 1 M LiPF6 in ethylene carbonate/diethyl carbonate (1:1 v/v). (C) 2016 Elsevier Ltd. All rights reserved.

Electrocatalysts based on platinized titania modified with ruthenia (0–9 mol %) were studied. The synthesized materials were investigated as working electrodes in potentiometric sensors sensitive to hydrogen and carbon monoxide. All electrocatalysts showed reproducible behavior at pure gas concentrations from 400 to 4000 ppm. In CO-H2 mixtures with comparable concentrations of both gases, the sensors were selective toward hydrogen at ≥0.05 mol % Ru, but not selective to hydrogen or CO at less than 0.05 mol % Ru in the substrate.

Proton conductivity of special class of aromatic sulfonic acids is described, in particular, calixarene sulfonic acids that consist of flat anionic layers interlinked by labile two-dimensional hydrogen-bond network. High proton conductivity of their hydrates was observed earlier. The dependence of their transport characteristics (the proton conductivity, the activation energy of conductivity) was shown to have threshold character. The studied systems' behavior is described on basis of percolation model that assumes changing of the proton transport mechanism at low water content in the structure.

В данной работе были исследованы электрокатализаторы на основе платинированного диоксида титана, модифицированного диоксидом рутения 0–9 мол. %. Полученные материалы были исследованы в качестве рабочих электродов в потенциометрических сенсорах, чувствительных к водороду и угарному газу. Все электрокатализаторы показали воспроизводимые результаты в диапазоне концентраций чистых газов от 400 до 4000 ppm. Исследования в смесях H2 при сопоставимых концентрациях обоих газов показали, что при концентрации Ru в носителе 0.05 мол. % сенсоры селективны к водороду, при концентрации Ru менее 0.05 мол. % они не селективны ни к СО, ни к водороду.

Описана протонная проводимость особого класса ароматических сульфоновых кислот – каликс-аренсульфокислот, которые имеют структуру в виде плоских анионных слоев, соединенных между собой лабильной двумерной сеткой водородных связей. У этих соединений ранее была обнаружена высокая протонная проводимость в кристаллогидратах. Показано, что зависимость транспортных характеристик (протонной проводимости, энергии активации проводимости) носит пороговый характер. Предложено описание поведения исследованных систем на основе перколяционной модели, предполагающей смену механизма переноса протонов при малом содержании воды в структуре.

The catalysts on carbon nanofibers with various platinum contents were synthesized. The morphology, resistance to oxidation, and electrochemical behavior of the catalysts in the reactions that occur in fuel cells were studied. The dependence of the specific output of cathodes of hydrogen-air fuel cells on the sizes of the platinum clusters was established.

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