N. N. Batalov

Synthesis and Electrical Properties of Lithium Metazirconate

Lithium metazirconate Li2ZrO3 with a monoclinic lattice is synthesized; the lattice parameters are: a = 0.5432 nm, b = 0.5427 nm, c = 0.903 nm, γ = 112.72°, and Z = 4. The conductivity of both the stoichiometric compound and samples rich or deficient in Li2O near this composition is determined. The conductivity of the synthesized compound reaches 0.029 S cm–1 at 600°C. The activation energy for the high-temperature segment is 13.8 kJ mol–1. An abnormal behavior (abrupt jump) of the temperature dependence of the conductivity at 430°C is discovered and attributed to a phase transition. The change in the structure in this temperature domain (400 to 500°C) is corroborated by the high-temperature X-ray analysis.

Transport Properties of Ca1 – xMnO3 – δ + xCeO2(0 < x ≤ 0.15) Mixtures

Data are presented on the temperature-dependent electrical conductivity and thermoelectric power of Ca1 – xMnO3 – δ + xCeO2 (0 < x ≤ 0.15) mixtures obtained as intermediate products in the synthesis of Ca1 – xCexMnO3 – δ solid solutions. The electrical properties of the mixtures are shown to be dominated by those of the perovskite-like phase Ca1 – xMnO3 – δ and to depend on Ca concentration. All of the samples with 0 ≤ x ≤ 0.15 exhibit n-type conductivity. The charge transport in CaMnO3 – δ below 930 K is attributable to small-polaron hopping. At higher temperatures, conduction through delocalized states seems to prevail. In the Ca1 – xMnO3 – δ + xCeO2 mixtures with 0.05 ≤ x ≤ 0.15, small-polaron hopping is observed between 160 and 920 K. Below 160 K, the temperature variation of conductivity in the samples with x = 0.1 and 0.15 follows Motts law.

Lithium ion conductivity of LiLaO2-Li2ZrO3 solid solutions

The limits of the LiLaO2-and Li2ZrO3-based solid solutions in the LiLaO2-Li2ZrO3 system have been determined: 0–10 mol % Li2ZrO3 and 0–5 mol % LiLaO2, respectively. We have studied the transport properties (electronic conductivity, temperature and composition dependences of conductivity and activation energy) of lithium lanthanate and the solid solutions in the LiLaO2-Li2ZrO3 system. Conduction in LiLaO2 is likely due to lithium ion transport through a polyhedral network.

Study of ion transport in Li2ZrO3 solid electrolytes with different lithium isotope ratios

Lithium ionic conductivity and spin-lattice relaxation rates were measured in Li2ZrO3 solid electrolytes with different 6Li and 7Li ratios. It is found that single-isotope electrolytes undergo a transition to the superionic state in the temperature range of 430–450 K, accompanied by an abrupt increase in conductivity. As a result of introduction of the other type of the isotope, the conductivity jump disappears in this temperature range. The transition to the superionic state is attributed to the redistribution of lithium ions over energetically nonequivalent lattice sites.

Optimization of the preparation conditions of Li 7 La 3 Zr 2 O 12 ceramic electrolyte for lithium power cells

Results of a study of how the density and electrical conductivity of a Li7La3Zr2O12 ceramic depends on the sintering temperature were used to determine the optimal conditions for formation of the system under study as a solid electrolyte with a conductivity of 3.7 × 10−2 S cm−1 at 185°C for electrochemical devices.

Influence of Soaking in the Molten (Li0.62K0.38)2CO3Eutectic on the Structure and Conductivity of LiMnxFe1 – xO2and Li1 – yMnyFeO2 + δ

The phase composition, structure, and 920-K electrical conductivity of LiMnxFe1 – xO2(0 < x≤ 1) and Li1 – yMnyFeO2 + δ(0 < y≤ 1) materials prepared by solid-state reactions in air at 1270 K were studied before and after soaking in molten (Li0.62K0.38)2CO3 . The highest conductivity of ≃32 S/m was found in the spinel solid solution Li0.2Mn0.8FeO2 + δ(δ = 2/3). Soaking in the carbonate melt converted all Li1 – yMnyFeO2 + δsamples into rocksalt solid solutions and reduced their conductivity.

Electrical Conductivity of Li6BeO4–Li5AlO4 Solid Solutions

Lithium orthoberyllate, Li6BeO4 , was shown to have a pseudocubic structure with a= 8.834 Å, b= 8.977 Å, and c= 9.125 Å. The Li6BeO4–Li5AlO4 system contains Li5AlO4- and Li6BeO4-based solid solutions in the ranges 0–30 and 70–100 mol % Li6BeO4 , respectively. The highest electrical conductivity in the Li6BeO4–Li5AlO4 system is attained at 70 mol % Li5AlO4 (2.2 × 10–3 S/cm at 550°C). The electronic contribution is no greater than 0.1%.

Effect of substituting6Li for7Li on ionic conductivity of α-Li3BO3

The ionic conductivity of γ-Li3BO3 is measured in wide intervals of temperatures and7Li to6Li ratios. It is found that the conductivity and activation energy vary nonmonotonically with variations in concentrations of the two isotopes; the concentration dependence of electroconductivity has a minimum, and that of the activation energy has a maximum at a7Li :6Li ratio of about 50 : 50 at. %; and the activation energy for conduction by6Li exceeds that by7Li

Electrochemical activity of solid solutions La1 -xSrxCoO3 in the oxygen electroreduction reaction in carbonate melts

Solid solutions Lad1-xSrxCoO3 are synthesized. An X-ray diffraction study reveals the formation of a rhombohedrically distorted perovskite-like phase. The kinetics and mechanism of the electroreduction of oxygen at the synthesized compounds in Li2CO3-K2CO3 (62: 38 mol %) and Na2CO3-Cs2CO3 (39:61 mol %) melts are studied by static coulometry and chronoamperometry. The exchange current grows with the strontium content in samples. The obtained apparent reaction orders of 0 and 0.14 by O2 and CO2 contradict all mechanisms offered earlier for the oxygen electroreduction at a gold electrode. A new mechanism is offered, in which the limiting step is the transfer of oxygen ions from the solid phase into the melt with corresponding changes in the electron subsystem of the electrode material.

Preparation of composite materials based on vinylidene fluoride-hexafluoropropylene copolymer and lithium halides (LiCl and LiF)

The possibility of preparing a film with uniform distribution of filler particles by casting from a joint solution of vinylidene fluoride-hexafluoropropylene copolymer and lithium halides in dimethylformamide was examined.