The paper presents the results of studies of the structural, thermal, and transport properties of solid composite electrolytes (1 – x)(C4H9)3CH3NBF4–xCND (where CND are nanodispersed diamonds, 0 ≤ x < 1, x is the mole fraction). It was shown by the Pawley method that the crystal structure of the low-temperature (C4H9)3CH3NBF4 phase is described by the space symmetry group P42/ncm. The addition of an inert nanodiamond additive led to an increase in the electric conductivity of the composite electrolyte by four orders of magnitude to 1.3 × 10–3 S/cm at 145°C and at x = 0.98. The theoretical dependences adequately describe the experimental data in the concentration range 0 ≤ x ≤ 0.99 at temperatures of 84 and 127°C.

The ionic mobility and conductivity of composites and compounds of the eutectic and close composition obtained by different methods in the PbF2–SnF2 system are studied based on the 19F NMR and impedance data. The stages of transformation of the 19F NMR spectra of these samples, their connection with the types of ionic movements, and the possible factors determining their ionic conductivity are considered. It is shown that the composition of the majority of composites includes the fluorite phase characterized by the high values of ionic mobility and conductivity. In the region close to the eutectic, a single-phase sample with the fluorite structure is obtained for the first time. The conductivity of this phase (5 × 10–3 S/cm at 390 K) makes it possible to consider it as the basis for synthesizing functional materials.

The results of previously published studies of the ion mobility, phase transitions, and electrophysical properties of tetrafluoroantimonates(iii) with heteroatomic cation sublattices composed of alkali metal and ammonium cations are analyzed, corrected, supplemented, and summarized. The influence of outer-sphere monovalent cations of different nature on the character of ion mobility, phase transitions, and conductivity in crystalline tetrafluoroantimonates(iii) is considered. It was found that phase transitions of most compounds in question are followed by the formation of superionic β-phases with a high conductivity of the order of 10−4–10−2 S cm−1 in the temperature range of 400–500 K.

Composite solid electrolytes based on n-methyl-n-butyl-piperidinium tetrafluoroborate [(CH3)(C4H9)C5H10N]BF4–A (where A is γ-Al2O3, SiO2) were synthesized and their thermal and electrically conductive properties have been studied. It was found that the conductivity of the [C10H22N]BF4–Al2O3 composites passes through a maximum at x~0.9 and reaches a value of 4.6·10-4 S/cm at 130оC for the 0.1[C10H22N]BF4–0.9Al2O3 composite. The absence of a thermal effect at the melting temperature of the ionic salt, which indicates a high ionic conductivity, indicates that at x ≥ 0.9, n-methyl-n-butyl-piperidinium tetrafluoroborate is in the amorphous state and ion transfer occurs along the ionic salt/oxide phase boundary. In the case of [C10H22N]BF4 – SiO2 composites, the effect of a heterogeneous dopant on ion transport is less significant and the conductivity is due to the ionic salt of the additive present in the pores.

Composite materials Sm2(WO4)3-WO3 were prepared by the solid state method and their transport properties have been examined by the electrochemical impedance technique and conductivity measurements versus oxygen partial pressure. It was shown that heterogeneous doping of the oxygen ion conductor Sm2(WO4)3 with a semiconductor WO3 even at low concentration of WO3 (volume fraction f < 0.13) led to an increase in ionic conductivity of the composites by more than an order of magnitude. This effect is caused by formation of the non-autonomous interface phase Sm2W6O21 covering grain boundaries of Sm2(WO4)3. At high concentrations of WO3 (f > 0.13) the composite materials comprise biphasic mixture with mixed ionic-electronic conductivity. Dependences of the conductivity on temperature, WO3 concentration and oxygen partial pressure were described in terms of the brick-wall model (at f < 0.13) and the generalized mixing equation (at f > 0.13) and conductivity parameters of the O2− ion conducting interface phase were determined.

Organic salts tetrabutylammonium borofluorate and tetraethylammonium borofluorate are simulated by molecular dynamics as pure forms and as part of a composite with α-Al 2 O 3 limited by the (110) plane. The obtained characteristic freezing points and structural change points agree with experimental data. In the composite, the amorphous organic salt transforms into a partially ordered state with a layered structure formed by contact interactions between the oxide and the salt.

Методом молекулярной динамики моделировались органические соли - тетрабутиламмония и тетраэтиламмония борофлюораты, в чистом виде и в составе композита с α-Al2O3, ограниченного плоскостью (110). Полученные характерные температуры – замерзания, изменения структуры, согласуются с экспериментальными данными. В композите аморфная органическая соль переходит в частично упорядоченное состояние со слоистой структурой, формируемой контактным взаимодействием оксида и соли.

— Nanostructured Li 4 Ti 5 O 12 -based composites in the form of microspheres consisting of randomly packed prism-like particles have been prepared via hydrothermal treatment of TiO 2 xerogel in aqueous LiOH solutions, followed by calcination of the reaction products at t ≥ 550°C. The phase composition of the hydrothermally prepared spherical particles has been shown to correspond to α-Li 2 TiO 3 . According to elemental analysis data, the titanium and oxygen were nonuniformly distributed over the microspheres. Sequential calcination of the microspheres at t ≤ 750°C led first to the α-Li 2 TiO 3 → β-Li 2 TiO 3 phase transformation and then to the formation of nanostructured Li 4 Ti 5 O 12 spinel or spinel-based composites (Li 4 Ti 5 O 12 /TiO 2 and Li 4 Ti 5 O 12 /β-Li 2 TiO 3 ). The Li 4 Ti 5 O 12 microspheres calcined at 750°C consisted of not only the major crystalline phase but also X-ray amorphous TiO 2 (anatase) and β-Li 2 TiO 3 as impurity phases, which could not be detected by X-ray diffraction.

The structure and transport properties of the pure salt [N4]BF4 and this salt located in the contact with the (110) surface of a-Al2O3 were studied using a MD computer simulation in order to reveal the effect of the salt/oxide interface on the structure and properties of the salt. The radial distribution functions of the ions and their mean square displacements were analyzed as a function of the temperature during the cooling of the salt. It was found that in all the cases anions are more mobile than cations. The molten phase of [N4]BF4 tends to crystallize at temperature 420 K which is close to the experimental melting point. The salt located in the [N4]BF4/(110)Al2O3 interface exhibits high values of anion self-diffusion coefficients which are higher by 1.2–2 orders of magnitude than in pure salt. This effect is likely to be caused by the formation of a layered atomic structure located within a characteristic thickness of 5 nm. Despite the structuring, the structure of the salt is amorphous, no crystallization-related effect is observed. The results of MD simulations agree with the experimental effect of the conductivity enhancement observed previously in [N4]BF4-Al2O3 nanocomposites.

The properties of high-temperature phases of Et4NHSO4 and the temperature ranges of their stability were investigated. The sequence of the reversible phase transitions at 147°C and 160°C with the enthalpies of − 3.28 J/g and − 8.99 J/g, respectively, was observed. It was shown that at 160° C the I41/acd phase with the unit cell parameters a = 14.0430(8) Å, c = 25.686(3) Å with higher degree of sulfate tetrahedra disordering was formed. This phase exists up to the melting of Et4NHSO4, 245°C. The proton conductivity of Et4NHSO4 was determined firstly and the temperature dependence varies widely from 10−8 S/cm at 90°C up to ~ 10−2 S/cm at the melting. The conductivity of the Et4NHSO4 is rather low and does not exceed 5*10−6 S/cm at temperatures below 210°C. The structural closed dimers of hydrogen-bonded sulfate anions at low temperatures hinder the effective proton transfer. Spectral characteristics of room-temperature phase also have been discussed.

— CaSn(OH) 6 thermolysis products have been characterized by thermal analysis, X-ray diffraction, IR spectroscopy, low-temperature nitrogen adsorption measurements, and electron microscopy. Ionic conductivity measurements for CaSnO 3 –SnO 2 –CsNO 2 composites suggest that calcium stannate is potentially attractive for use as a heterogeneous additive to composite solid electrolytes.

A high-porosity carbonaceous material was prepared by solid-template-based template synthesis. The carbon source was phenol-formaldehyde resin of resol type; the template agent, nanocrystalline ZnO that was synthesized by thermolysis of a precursor—zinc citrate, introduced to starting materials. The carbonaceous material was synthesized by pyrolysis of the resin in the presence of the template, with subsequent removal of the template agent. The material’s specific surface area equals 1050 ± 10 m2/g. Its electrochemical characteristics are studied in a symmetrical two-electrode cell by using cyclic voltammetry at different voltage scanning rates. Its specific capacitance in acid electrolyte (1 М H2SO4) reached 61 F/g, which is approximately twice as large as that in alkali electrolyte (6 М КОН). Unusual dependence of the specific capacitance on the voltage scanning rate in the acid electrolyte was observed; the material was shown to have relatively low specific capacitance per unit surface of the electrode.

The tin(IV) strontium double hydroxide SrSn(OH)6, mixed with amorphous hydrous tin dioxide, has been synthesized by adding aqueous ammonia to strontium and tin(IV) chloride solutions to pH 10. The thermolysis of the material thus prepared and the phase composition of its decomposition products have been studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The results demonstrate that the main dehydration steps reach completion at a temperature near 350°C and that the thermolysis product is an X-ray amorphous material. At a temperature above 650°C, this material transforms into a nanocomposite consisting of a crystalline strontium stannate phase and tin dioxide. Using impedance measurements, we have determined the ionic conductivity of composite solid electrolytes prepared by adding the synthesized nanocomposites to ionic compounds.

Thermal, structural and electrical properties of composite solid electrolytes (1-x)(C4H9)(4)NBF4-xAl(2)O(3) with nanocrystalline gamma-alumina were investigated by DSC, X-ray diffraction, IR spectroscopy, impedance and electrochemical measurements. It was found that the melting enthalpy of (C4H9)(4)NBF4 in the composites strongly decreases and its value approaches to zero in the composites with x >= 0.9, where x is the molar fraction of alumina, indicating the transformation of (C4H9)(4)NBF4 to an interface-stabilized amorphous state. This effect was quantitatively interpreted in terms of the brick-wall model assuming that a layer of amorphous phase of the ionic salt is formed at salt/oxide interfaces. At the alumina concentration of x = 0.9, corresponding to a volume fraction of alumina f = 0.53, almost all the ionic salt gets into the interface layer the thickness of the amorphous layer is nearly 3 nm. These results agree with the results of X-ray diffraction studies and IR spectroscopy. Introduction of nanocrystalline gamma-alumina into the (C4H9)(4)NBF4 matrix leads to a relative increase in conductivity by more than 2 orders of magnitude, conductivity goes through a maximum of 0.21 mS/cm at 130 degrees C for the composite with x = 0.9. This composite is characterized by a non-Arrhenius temperature dependence, typical for glassy electrolytes. It was shown that the electrochemical voltage for the composite 0.1(C4H9)(4)NBF4-0.9Al(2)O(3) is nearly 4 V.

The paper presents studies of the transport and electrochemical characteristics of solid composite electrolytes (1 – x)(C2H5)3CH3NBF4–xCND (where CND is the UDA-С nanosized diamonds with Ss = 300 ± 20 m2/g, 0 < x < 1). The addition of a nanodiamonds inert additive is shown to lead to an increase in the electrical conductivity of the composite electrolyte by 2 orders of magnitude up to 1.7 × 10–3 S/cm at 200°C for x = 0.98. The theoretical dependences describe well the experimental data over the 0 < x < 0.98 concentration range at temperatures of 25–200°C. The stability of composite materials in a C/0.6(C2H5)3CH3NBF4–0.4CND/C cell was studied by cyclic voltammetry. The fundamental possibility of using the composite solid electrolytes with nanodiamonds additives in electrochemical devices is substantiated by the example of a C/0.6(C2H5)3CH3NBF4–0.4CND/C solid-state supercapacitor. Thus, it was demonstrated that nanodiamonds can be considered as an effective non-oxide additive in composite solid organic electrolytes used in electrochemical devices.

The results of studies of ion mobility and electrophysical properties of solid solutions containing bismuth trifluoride are analyzed and summarized. The influence of fluorides as constituents of solid solutions on the character of ion mobility and ionic conductivity is considered. Solid solutions with a conductivity of about 10−3−10−2 S cm−1 in the temperature range 400–550 K can be treated as promising basis for the synthesis of functional materials.

A nanostructured Li4Ti5O12/β-Li2TiO3 composite material has been prepared by hydrothermal treatment of one-dimensional layered Na2Ti3O7 structures in an aqueous LiOH solution, followed by calcination of the reaction products at t ≥ 550°С. It has been shown that, under hydrothermal conditions, Na+ → Li+ ion exchange processes and chemical interaction of components lead to the formation of the metastable cubic phase α-Li2TiO3. Calcination of the hydrothermal synthesis products leads to the α-Li2TiO3 → β-Li2TiO3 phase transformation and Li4Ti5O12 formation. Primary β-Li2TiO3 and Li4Ti5O12 nanocrystals in the powder calcined at 750°C are orientation-disordered and differ in predominant growth direction. The synergistic effect of the nanocrystals joined in the form of fragments of one-dimensional structures and forming chaotic, loosely packed aggregates leads to the formation of a nanostructured Li4Ti5O12/β-Li2TiO3 composite with enhanced grain-boundary conductivity compared to pure Li4Ti5O12 spinel.

Composite solid electrolytes (1 – х )LiTi 2 (PO 4 ) 3 – x LiClO 4 are synthesized and their conducting properties are studied. Heterogeneous doping of LiTi 2 (PO 4 ) 3 with lithium perchlorate LiClO 4 leads to a considerable increase of ionic conductivity and a decrease of activation energy as compared to the pure compound, which was not subjected to the pre-sintering. The conductivity of the composites reaches 6.8 × 10 –6 S/cm at 100°C and 3.4 × 10 –4 S/cm at 200°C with an activation energy of 0.62 eV.