электропроводность

This work is dedicated to phosphoric acid esters working as solvents for lithium-ion and supercapacitor (SC) electrolyte. The electrical conductivity of electrolytes based on phosphoric acid esters, lithium salts, commonly used in lithium-ion batteries (LIB), and salts used in SC technology was measured. The thermodynamic stability of new electrolytes in comparison with other solvents used in chemical power sources technology was also estimated. It was shown that the thermodynamic stability of phosphoric acid ester increases in a homologous series.

The phase composition, thermal coefficient of linear expansions (TCLE) and electrical conductivity of (PrXLa1-X)1.85Sr0.15Ni0.9Сu0.1O4 (X=0.0; 0.1; 0.5; 0.9 и 1) (X=0.0; 0.1; 0.5; 0.9 and 1), Pr1-YSrYNiO4 (Y= 0.0; 0.05; 0.1; 0.15; 0.16 and 0.2) and Pr1.84Sr0.16Ni1-ZCuZО4 (Z=0.0; 0.1; 0.5 and 1) are investigated at air in the temperature range 100–1000 °C.The thermal coefficient of linear expansion of (Pr1-XLaX)2-YSrYNi1-ZCuZO4 are in range of (11.6–16.3) 10-6 deg-1 and depends on the size and type of addition.

The phase composition, conductivity and corrosion resistance under the Molten Carbonate Fuel Cell (MCFC) operating conditions of synthesized using common ceramic and cocrystallization techniques samples of LaLi_0.1Со_0.1Fe_0.8O_{3 – δ} have been studied. It was found, that the phase composition of synthesized by ceramic technique sample differed from the nominal composition. This difference arose from the formation of complex oxide (La_1-yLi_y)(Li_0.1-yCo_xFe_{0.9 – x})O_{3 – δ'}, y ≤ 0.1, and La₂O₃. Synthesized by cocrystallization technique sample was found to be of single phase. Its conductivity differed from the conductivity of two phase sample. Under MCFC operating conditions the difference in properties of synthesized by both techniques samples diminished and converged towards the properties of the sample prepared by ceramic technique.

????

New potassium-conducting solid electrolytes in the mixed alumoferrite system K_0.90Ba_0.05Al_1-хFe_хO were synthesized and studied. The effect of increasing conductivity with simultaneous presence of aluminium and ferrum cations has been established. The maximum conductivity in the system reaches very high values: – 6·10^-2 S·cm^-1 at 400°C, 2·10^-1 S·cm^-1 at 700°C. Possible nature of obtained results is discussed.

Theoretical research of conductivity of polymeric insulators in the normal state and at emergency is carried out. Analytical description of temperature and electric effects on the normal conductivity of a polymer and on its electric longevity is given.

The methods for the synthesis of lithium iron phosphate LiFePO₄ with olivine structure have been developed. New materials based on lithium iron phosphate, including doped with metals, the «LiFePO₄ + carbon» composites obtained by pyrolysis of organic compounds have been synthesized. Crystallographic characterization of the synthesized materials was carried out; their electrochemical characteristics of the extraction and intercalation of lithium have been identified. A correlation between the crystallographic and electrochemical characteristics of the materials was found. It was confirmed that an effective way to improve the electrical conductivity of LiFePO₄ is to create a carbon shell of the products of pyrolysis of organic compounds on the material's particles surface. A correlation of electrical conductivity and temperature of synthesis of the material was determined. The sequence of chemical interaction between precursors for the synthesis of LiFePO₄ is defined; the mechanism of solid-phase interaction is described.

The phase composition, thermal coefficient of linear expansion and electrical conductivity of r_1.85Sr_0.15Ni_1-xCu_xO₄ (0.0; 0.1; 0.5; 0.9 и 1), Pr₂NiO₄ and Pr₂CuO₄ are investigated at air in the temperature range 100-1000°C.
The thermal coefficient of linear expansion are in range of ((11.2–16.6)·10^-6 deg_-1. The TCLE of some composition close to TCLE of solid electrolyte La_0.9Sr_0.1Ga_0.8Mg_0.2O_2.85 (LSGM) и Ce_0.9Gd_0.1O_2-Δ (CGO). Pr_1.85Sr_0.15Ni_0.1Cu_0.9O₄ has the highest conductivity at temperatures above 350°C.

The possibility of using organic esters of phosphoric acid as a solvents for the electrolyte for lithium-ion systems and supercapacitors was investigated. Supercapacitors based on activated carbon Norit Supra and on the electrolyte being studied showed fine electrochemical performance which is comparable with standard electrolytes based on propylene carbonate. Lithium-ion batteries (Li4Ti5O12-LiNiO2 system) also showed a good performance. The conductivity of electrolytes based on tributyl phosphate was measured, as well as its thermodynamic stability was estimated.