Artem Ulihin

The study examined the polymerization of methacrylic acid derivatives with bulky substituents (isodecyl-, benzyl-), as well as the synthesis of their copolymer through radiation initiation followed by thermal treatment. It has been discovered that the polymerization rate in equimolar monomer mixtures substantially surpasses the rate in pure monomers. We hypothesize that the substantial degree of association with the liquid monomer hinders structural rearrangements preceding polymerization. We tested this hypothesis by employing various analytical methods.

In this work composite solid electrolytes based on the binary system of N-diethylpiperidinium tetrafluoroborate [N22pip]BF4 and lithium tetrafluoroborate (1− x){0.7[N22pip]BF4-LiBF4}–xAl2O3 were synthesized, their ionic conductivity was studied, and the galvanostatic tests were carried out in a symmetric cell with the electrodes made of metallic lithium. The values of the ionic conductivity of the obtained composites pass through a maximum at x∼0.3, reaching 6.2·10−4 S/cm at 140°C.

Search of the new composite materials with mixed oxide-ionic–electronic conductivity and studies of their characteristics are important problems in the development of oxygen separation membranes as parts of catalytic reactors for biofuel transformation into syngas. Such composites are generally based on complex oxides with perovskite, fluorite, pyrochlore structure, etc. In this work, composites based on Bi cerates, Y-doped ceria and Pr nickelate-cobaltite are synthesized and studied. The composites are synthesized via ultrasonic dispersion in isopropanol. The obtained materials are characterized by X-ray diffraction, scanning and high resolution transmission electron microscopy. Electrical conductivity of the composites is studied by impedance spectroscopy. Oxygen transport properties are investigated by isotope exchange of oxygen with C18O2 in a flow reactor. The samples are comprised of fluorite, perovskite and, sometimes, pyrochlore phases and various admixtures with different compositions, apparently, due to cation redistribution and solid state reactions between phases. The total conductivity of samples is ~10−1 S/cm at 600 °C, which is high enough for using in the oxygen separation membranes. According to the isotope exchange data, the samples possess high oxygen mobility and surface reactivity. There is a distinct nonuniformity in the oxygen mobility, which is related to the effect of fast diffusion of oxygen associated with Bi and Ce cations, as well as the features of phase composition and real/defect structure. This makes the composites studied promising for using in the oxygen separation membranes.

The search for solvents to prepare polymer electrolytes based on polyurethane elastomer by swelling method was carried out. The greatest swelling was observed in N-methyl-2-pyrrolidone, and the maximum degree of swelling was reached in 24 hours at 25°C. The swelling effect decreased with increasing the salt concentration. The ionic conductivity of the polymer electrolytes reached the maximum of 6–8·10-4 S/cm at 5 wt% of lithium salt. Using the method of galvanostatic cycling it was shown that the electrolyte was reversible by lithium ions and electrochemically stable in the voltage range up to 4.8 V.

The effect of lithium perchlorate (LiClO4) on the transport and thermal properties of the ternary system consisting of N-methyl-N-propylpiperidinium perchlorate, highly dispersed γ-aluminum oxide (having the specific surface area of 200 m2/g), and lithium perchlorate was investigated. It was shown that the obtained composites exhibited thermal stability up to at least 190°C. Using the impedance spectroscopy method, it was shown that the highest conductivity of solid electrolytes was ~10–5 S/cm at 40°C, x = 0.5, and 3·10–4 S/cm at x = 0.55 (T = 110°С).

In this work, the supporting electrolytes for solid oxide fuel cells based on samarium doped cerium oxide Ce0.8Sm0.2O1.95 were fabricated using 3D inkjet printing and layer-by-layer laser treatment followed by thermal sintering. The samples were characterized by scanning electron microscopy, X-ray diffraction analysis and impedance spectroscopy. The Vickers hardness test and three-point bending flexural test were carried out. The developed approach allows for precise control of the layer thickness and microstructure, significantly facilitating the scaling of solid oxide fuel cells production, and reducing the loss of expensive ceramic materials.

The transport, electrochemical, structural, and thermal properties of electrolytes in the ternary system [N13pip]ClO4-LiClO4-γ-Al2O3 (N13pip is N-methyl-N-ethyl-piperidinium cation) were investigated at the molar ratio [N13pip]ClO4:LiClO4 = 0.82:0.18. The addition of alumina leads to a change in the thermodynamic properties of the [N13pip]ClO4-LiClO4 system that can be explained by a partial transfer of lithium perchlorate from the organic phase to the surface of γ-Al2O3. The highest ionic conductivity of 6.2∙10–4 S/cm at 110 °C was observed for the composition containing the volume fraction (f) of γ-Al2O3 equal to 0.5. The increase in conductivity compared to the binary system 0.82[N13pip]ClO4-0.18LiClO4 is achieved due to the amorphization of the organic salt near the salt/LiClO4/oxide interfaces. Galvanostatic cycling with Li electrodes shows that composites with f = 0.5 are stable at 110 °C for at least 68 charge/discharge cycles, and the electrolyte is shown to be electrochemically stable up to 5 V. This system can be used as a solid-state electrolyte in lithium-ion current sources.

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 solid electrolytes based on n-methyl-n-butylpiperidinium tetrafluoroborate [(CH₃)(C₄H₉)C₅H₁₀N]BF₄–A (where A is γ-Al₂O₃, SiO₂) were synthesized, and their thermal and electrically conductive properties were studied. The conductivity of the (1 – x)[C₁₀H₂₂N]BF₄–xAl₂O₃ composites passes through a maximum at x ~ 0.9, reaching 4.6 × 10^–4 S/cm at 130°C for 0.1[C₁₀H₂₂N]BF₄–0.9Al₂O₃. The absence of a thermal effect at the melting temperature of the ionic salt, showing high ionic conductivity, indicates that at x ≥ 0.9 n-methyl-n-butylpiperidinium tetrafluoroborate is in the amorphous state, and ion transport occurs along the ionic salt/oxide interface. In the case of the [C₁₀H₂₂N]BF₄–SiO₂ composites, the effect of a heterogeneous dopant on the ion transport is less significant, and the conductivity is due to the ionic salt of the additive present in the pores.