M. Lazzari

Anatase as a cathode material in lithium—organic electrolyte rechargeable batteries

A preliminary investigation of anatase, TiO2, as a positive electrode material in secondary lithium—organic electrolyte batteries is reported. n nUp to 0.6 lithium equivalents can react with 1 mole of TiO2. However, optimum cycling behaviour is obtained for regimes involving compositions between 0.15 and 0.45 Li/TiO2 mole ratio. n nUnder these conditions, prolonged cycling at 0.25 – 0.5 mA cm−2 gives satisfactory results.

The electrochromic characteristics of titanium oxide thin film electrodes

Abstract Titanium dioxide in its anatase form may react with lithium by a reversible intercalation process. This process is accompanied by a marked colour change, so that TiO 2 is of interest for the development of electrochromic displays. The electrochromic properties of thin film electrodes, obtained by a deposition on a tin oxide coated glass substrate of a TiO 2 dispersion in polyvinylalcohol, are examined in this work. The results show that the rate of the electrochromic process is controlled by the diffusion of the Li + ions throughout the TiO 2 lattice. Consequently, it is convenient to drive the electrochromic process with potentiostatic pulses and, effectively, under these conditions many cycles with initial good colour contrast and efficiencies which approach 100%, have been obtained with the TiO 2 thin film electrodes.

Electrochemical Behavior of Solid Cathode Materials in Organic Electrolyte Lithium Batteries: Copper Sulfides

The characteristics of copper sulfide cathodes have been evaluated in typical organic electrolyte lithium batteries. The behaviour of ..cap alpha..-Cu/sub 2/S (chalcocite), Cu /SUB 1.76/ S (digenite) and CuS (covellite) is discussed in terms of mechanism of reaction, discharge properties and energy content. In view of possible use in primary, voltage-compatible lithium batteries, Cu/sub 2/S shows the most interesting performance, either in terms of constancy of the operational voltage and in terms of discharge rates.

Behaviour of transition-metal disulphides as intercalation electrodes in solid-state cells

Abstract The behaviour of transition-metal disulphide electrodes in silver solid-state cells has been investigated by kinetic, diffusion and thermodynamic studies. The results indicate that the silver electrointercalation process is reversible in all the compounds examined, i.e. NbS 2 , TiS 2 and TaS 2 . Niobium disulphide appears, however, as the most promising electrode material in terms of prolonged cycling performances.

Silver mono-, di- and tetratungstates

Abstract The preparation of two forms of silver monotungstate, two forms of silver ditungstate and of silver tetratungstate is described, together with their characterisation by X-ray powder diffraction and IR spectra. Comparisons are made with structural data.

Electrochemical behaviour of tungsten oxides in lithium-organic electrolyte cells

Abstract The electrochemical behaviour of various tungsten oxides in lithium-organic electrolyte cells has been studied by voltage-composition curves, micropolarization and cycling tests. The change in structure of the oxides which follows the lithium incorporation has been investigated by X-rays showing marked differences between WO 3 , the typical crystallographic shear oxide W 20 O 58 , and the tunnel structure oxide W 18 O 49 .

Polarization of the lithium electrode in sulfuryl chloride solutions

Abstract The growth of the passivating film on a lithium electrode in contact with sulfuryl chloride solutions has been examined by micropolarization and complex impedance measurements. The results tend to confirm the hypothesis of a two-layer film, where probably the first layer is thin and compact and the second layer is porous and defective.

The kinetics of the electrochemical doping processes of polyacetylene

Abstract A study of the mechanism of the electrochemical doping processes of polyacetylene and of its influence on the performance of the polymer electrode in lithium cells, is here described on the basis of cyclic voltammetry and ac impedance results.

Interfacial properties in silver/silver glassy electrolyte/insertion electrode cells

Abstract The interphases between a silver glassy electrolyte, Ag 6 I 4 WO 4 , and an insertion electrode, such as TaS 2 , have been characterized by S.E.M. as a function of the preparation conditions of the cell, and the distribution of silver in the cathode has been studied by X-ray microprobe. The influence of the interphase morphology and the size and orientation of TaS 2 crystals has been shown and briefly discussed also with reference to the electrochemical methods of determination of chemical diffusivity.

Silver selenate and silver tellurate as positive materials for lithium primary power sources

Abstract The performances of button-type lithium cells based on Ag 2 SeO 4 and Ag 2 TeO 4 as cathodes have been determined in various organic electrolytes. These silver salts present relevant energetic properties and may be considered as interesting cathodic materials for application in primary lithium power sources. Information on the discharge processes has also been obtained by determining the electrode utilization at low rates and by X-ray analyses of the discharge products. Finally, Ag 2 SO 4 has been examined also as a cathode material in lithium cells. However, its performance was rather poor, probably because of a slight solubility in the electrolyte media considered.