53rd Meeting of the International Society of Electrochemistry

Russian Journal of Electrochemistry -     

Structure and Electrochemical Behavior of Lithium-Manganese Spinels Doped with Chromium and Nickel

A series of compounds with the general formula LiMn_{2 - x - y} Cr _x Ni _y O₄, where x + y = 0.05, 0.5, or 1.0, is synthesized. It is shown that all these compounds are pure-phase spinels with parameter aequal to 0.8193-0.8236 nm. Doping a stoichiometric lithium-manganese spinel simultaneously with chromium and nickel makes the spinel structure stable. The initial specific capacity of a spinel depends on its doping degree. Doping LiMn₂O₄ with chromium and nickel simultaneously at an Mn : Cr : Ni ratio of 195 : 3 : 2 raises the spinel's specific capacity and reduces the cycling degradation. The change in the discharge capacity of LiMn_1.95Cr_0.03Ni_0.02O₄ electrodes cycled at 20, 0, and -14°C is determined.     

Products of lithium interaction with nanostructured oxides SnO2-TiO2 and mechanism of charge-discharge of electrodes in a lithium-ion battery

Products of lithium interaction with thin-film nanostructured SnO₂-TiO₂ (ST) oxides are studied with the aid of x-ray diffraction analysis and Moessbauer spectroscopy on the ¹¹⁹Sn nuclei. Electrochemical properties of a series of the ST electrodes with different concentrations of TiO₂ varied from 0 to 20 mol % are also examined. It is concluded that the specific feature of the charge-discharge mechanism of the ST electrodes is a significant participation of oxygen in reversible reactions during insertion and extraction of lithium as compared with an alloying mechanism of operation of tin-containing anodes. The leading role in this is played by titanium oxide. Remaining stable towards reduction by lithium, it facilitates the holding of the neighboring layers of SnO₂ in a nanodisperse state and in an oxidized state. The effect of a decrease in the capacity degradation in modified TiO₂ electrodes, which is discovered in this work, is attributed to the hampering of the growth of nanocrystallites of β-Sn by interlayers of tin and titanium oxides mentioned above.     

Products of Anodic Oxidation of Carbamide: Effect of Anionic Composition of Solution

The current efficiency for carbamide oxidation on smooth platinum electrode to molecular nitrogen and nitrate in sulfate, fluoride, chloride, and bromide solutions are determined. The supporting-electrolyte anion has a complex effect on the ratio between rates of these processes. Independence of the current efficiency from the solution pH in electrolysis of sulfate solutions of carbamide is confirmed.     

Lithium Intercalation into Graphite during Direct Contact and Anodic Polarization

Values of the diffusion coefficient for lithium in thermoexpanded graphite (TEG) are measured during cathodic intercalation from an aprotic electrolyte and during the TEG plate in contact with metallic lithium without electrolyte. In the course of cathodic intercalation, the diffusion coefficient is measured by method of galvanostatic switching-on curves. During TEG contact with lithium, the variation of x-ray diffraction pattern of TEG with time is recorded. It is established that during TEG contact with lithium the lattice spacing decreases and the characteristic size of TEG particles increases with time until the lithiation is complete and intercalate LiC₆ forms. Values of the diffusion coefficient determined by either method coincide and amount to 10^–10 cm² s^–1.     

Kinetics of the electrochemical oxidation of 1,1-bis-hydroperoxy-4-methylcyclohexane on platinum

The electrochemical synthesis of 3,12-dimethyl-7,8,15,16-tetraoxadispiro[5.2.5.2]hexadecane (1,2,4,5-tetraoxane) from 1,1-bis-hydroperoxy-4-methylcyclohexane on platinum electrode in a cell with separated and unseparated cathode and anode space in an aprotic solvent is conducted. The kinetics of electrochemical oxidation of 1,1-bis(hydroperoxy)-4-methylcyclohexane is studied. The current yield of the reaction is determined.     

High-voltage materials for positive electrodes of lithium ion batteries (review)

The main publications of recent years devoted to functional materials for positive electrodes of rechargeable lithium-ion batteries destined to work at the potential more positive than that of conventional lithiated oxides of cobalt and manganese are considered. The problem of electrolytes stable at these potentials is discussed briefly.     

The Use of Phosphorus in Sodium-Ion Batteries (A Review)

Russian Journal of Electrochemistry - In the recent years, attention is focused on phosphorus as the active material for negative electrodes of sodium-ion rechargeable batteries because it...     

Electrochemical oxidation of 1,1-dihydroxy-4-methylcyclohexane on platinum anode. Synthesis of 3,12-dimethyl-7,8,15,16-tetraoxadispiro[5.2.5.2]hexadecane

The possibility is shown of electrochemical synthesis of 3,12-dimethyl-7,8,15,16-tetraoxadispiro[5.2.5.2]hexadecane that belong to the class of 1,2,4,5-tetraoxanes by oxidation of 1,1-dihydroperoxy-4-methylcyclohexane using a Pt anode.