Литиевые электрохимические системы

In modem technological processes increase used molten multicomponent solt mixtures. Determination of the composition and melting temperature are important in application of the compositions, identification of patterns processes occurring during melting and solidification of alloys, as well as the phases in equilibrium at a given thermodynamic conditions, possibly in the study of phase diagrams.

The corrosion and electrochemical behavior of magnesium and the MA 21 magnesium-lithium alloys in solutions of moderately acidic phosphates with various additives was studied. The inhibiting effect of nitrate and fluoride ions on the anode dissolution of these objects was revealed. Features of the electrochemical dissolution of magnesium and the magnesium-lithium alloys in nitrate phosphate solutions with fluoride ions caused by their activation-passivation competition have been noted.

Possibilities for increasing efficiency of impedance spectral measurements are investigated. It is shown that for determination of linear electrochemical impedance a linearly changing input signal is preferable, and for the quantitative estimation of non-linearity of electrochemical impedance as an input signal it is expedient to use the cosine electric beats. The constructive diagrams of generators of such signals are offered.

In article experience of application of chemical sources of a current of electrochemical system lithium – tionilchloride and batteries on their basis, in onboard systems of electrosupply of modern and perspective space-rocket technics of Russia is presented.

Samples having the chemical formula Li_0.5 Fe_{2.5 – x} Mg_xO₄ (0 ? x ? 1) were prepared by the standard ceramic method. The parts of the dielectric constant ?', ?'' and A.C. conductivity ?(?) are measured at different frequencies from 10 ^{– 2} to 10⁵ Hz in the room temperature and different cooling velocity, and then the dielectric loss tangent tg ? was calculated. The sample with x = 0.1 what was cooled quickly showed the greatest values of ?₀ as compared with the other samples.

Electrochemical behavior of Li in the systems with PE based on polymers of chlorinated polyvinylchloride and polyvinylidene fluoride were investigated by the method of cyclic voltammetry and galvanostatic cycling. Potentiodynamic investigations have shown that on lithium electrode even in the systems with polymer electrolyte the high current densities up to 5 mA/cm² are realized. Influence of polymer electrolyte composition on the properties of the interface Li/electrolyte and rechargeable work of lithium electrode has been shown.

It was studied an influence of prior carbon treatment (temperature and gas conditions, mass content of waterproofing agent) on activity of platinum catalyst, synthesized on disperse carbon carrier. It was shown that characteristics of anodic processes depend on quantity of solid polymer electrolyte in catalytic composition. Optimal content of ion exchange polymer under varied degree of carbon carrier waterproofing (used for synthesis of platinum catalyst) is not equal.

There were investigated the self-discharge dynamics in two homogeneous groups («A» and «B») of the coin lithium cells ВR2325 on the basis of superstoichiometric fluorocarbon CF1.20, selected from the uniform experimental batch of 10000 pieces. The reason of two different groups («A» and «B») appearance through 3–6 months of storage is connected with the origin of hydrogen fluoride in cathodes of group «A» cells, which will be derivated at auto catalytic hydrolysis of C-F-bonds by a moisture tracers (0.1–0.5%).

Comparative characteristic of natural and synthesized iron disulfide has been carried out. Physical, chemical and macrostructure characteristics of pyrite powders have been shown. By the methods of cyclic Vtammetry the electrochemical properties of FeS₂ – based cathodes have been investigated in non-aqueous liquid (1М LiClO₄; PC+DME) and polymer (CPVC; 1М LiClO₄; PC) electrolytes.

Major trends in cathode active material development for lithium-ion batteries have been reviewed. Statistics on all publications in «Journal of Power Sources» (from 03.2006 till 04.2007) is summarized in order to point out that the main effort in secondary batteries development is concentrated on lithium-ion batteries, especially on positive electrode study. Based on these publications the main routes for LiCoO₂ modification as well as for novel materials research have been reviewed.