Литиевые электрохимические системы

Reversible lithium intercalation from a non-aqueous electrolyte into thin films of tin (0.1–1 mcm) and carbon (-3 mcm) was studied by means of electrode impedance spectroscopy. The measurements were made within a frequency range of 10⁵–10^-2 Hz at a varying lithium concentration in the matrix. The paper discusses several versions of electrical equivalent circuits to simulate the experimental impedance spectra, and the concentration dependence of the lithium diffusion coefficient.

Characteristics of electrodes materials beyond the border used in lithium-ion power sources production are considered. The lines of investigations on realizing new promise materials are anylyzed.

The ways to improve technical parameters of lithium-fluorocarbon cells are investigated. The possibility to create such cells operable at high temperatures is shown. The prototypes of the cells are manufactured. A high-temperature version of the cells is shown to have energy density higher by 20% than that of standard samples.

A new method of synthesis of high dispersive (S_уд > 20 m²/g) lithium monoaluminates (?- and ?-LiAlO₂) is proposed. The method is based on the interaction of Li-Al layered double hydroxides and dawsonite with lithium carbonate. Process of lithium aluminates formation was investigated by methods of X-ray diffraction, thermal and chemical analysis, IR-spectroscopy.

The principles of the construction and the algorithm of the operation of the power supply source for the implanted electromechanical artificial heart have been considered. The results of it's stend-based and real-life tests are included. Also the advantages of the construction of the power supply on the basis of lithium-ion and lithium-polymer accumulators are eliminated.

The principles of the construction the systems of the control and methods of the leveling the voltage cell in lithium storage batteries have been considered.

Chemical interactions in the cathode half-element of lithium ion batteries with LiCoO₂ as cathode and 1.15 M ILiPF₆, in mixture of al-kylcarbonates as electrolyte had been studied by using a number of calculation and experimental methods. It was found that the layer of chemical interactions products on the surface of LiCoO₂ grains comprised LiF and LiPO₃ and, also, CoF₂, which passed to the electrolyte solution with time.

The present paper sets forth the lecture presented at VIII International Conference "Fundamental problems of energy conversion in lithium electrochemical systems". The paper reviews modern tendencies in lithium-ion batteries development, including researches in new materials for negative and positive electrodes and liquid electrolytes.

At present LiCoO₂ is commercially available material for positive electrodes of lithium-ion batteries. For further improvement of its properties a number of doped samples of lithium cobaltite were synthesized. Mg and Ti were used as dopants. Crystal structure of LiCo_{1 – x – y}Mg_xTi_yO₂ was studied with XRD, whereas chemical composition was determined with atomic absorption spectroscopy, complexometric titration as well as inductively-bonded plasma. The average initial discharge capacity amounted to 145 to 150 mA·h/g.

Silicon electrodes with regular porous structure were prepared by the photoelectrochemical etching of single-crystal n-type silicon wafers, followed by the removal of the substrate. Electrodes with pores having circular and square section were studied. The porosity was increased via additional oxidation with the subsequent etching of oxide. The electrochemical characteristics of anodes were found to depend on porosity, electrodes with porosity 60-70% possessing maximal capacity for lithium reversible insertion.