Литиевые электрохимические системы

Techniques of synthesis of high-effective nanostructured electrocatalysts for electrochemical systems with proton-exchange membrane (PEM) are described, their structural and electrochemical properties are investigated. Current-voltage curves of membrane-electrode assemblies (MEA) on the basis of synthesized electrocatalysts within PEM fuel cell, water electrolyser and reversible cell are obtained.

Methods of synthesis were developed; nanosize two- and three-component Ru-based cathode catalysts RuM/C and RuMSe/C (М – Ni, Co, Fe, V) supported on carbon XC-72 were synthesized and analyzed. The effect of different precursors, metal ratio, synthesis conditions, and nature of the Fe-group metal on the catalytic system activity in the oxygen reduction reaction is studied. The studies were performed using the method of the rotating disk electrode (RDE) in 0.5M H₂SO₄ and at the temperature of 60°C.

The method of a rotating disk electrode leads studying the basic laws of electrochemical behaviour of mediator as basic electroactive component of bioelectrochemical system and influence of speed of rotation of an electrode, concentration of mediator, glucose and microbial cells are certain for the general speed of process bioelectrocatalitic oxidation of glucose.

The influence of the concentration of antimony, tin, cadmium, calcium, silver, and barium on some characteristics of lead-antimony and lead-calcium alloys was studied. The cadmium-doped and barium-doped alloys show the best corrosion resistance among the lead-antimony and lead-calcium alloys, respectively.

Effect of high-collated carbon clusters (soots containing fullerenes and nanopipes) on electrode pastes structure have been studied and their positive effect on characteristics of the obtained active masses has been shown. Effect of partial hydrophobization of negative active mass (NAM) on efficiency of the closed oxygen cycle has been studied. Effect of different additives (С₇H₆O₂, C₈H₈O₂, (-CF₃-CF₂₅-)QZ) on ?_H2 have been studied.

The concept of processing of the positive electrode material taken from fulfilled alkaline accumulators, based on primary separation of an iron component from nickel at stages of hydrometallurgical repartition, is presented..

This paper represents performance of air-hydrogen free-breathing Fuel Cell (FC) in limited volume conditions. Research work was carried out with thin two-cell stacks related to use in prototype of particular power source system, which includes aluminium-water microgenerator of hydrogen. In small current densities field (<200 mA/cm²) it was established, that after FC had been confined within the small volume, characteristics of FC became better than in non-limited-volume conditions due to self humidification.

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.

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.

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.