Guy  Campet

Sui-Yang  Huang

Editorial

The evolution of the specific surface area and crystallite size of SnO2 powders, prepared from a sol-gelprocess, was studied as a function of the calcination temperature of the stannic hydroxyde colloid, andfor two different pH values &#40;7.5 and 12.5&#41; of the collo&#239;dal state. The samples were characterized byTGA, IR spectroscopy, BET, and XRD techniques. The crystallite size and specific surface area werestrongly affected not only by the calcination temperature, but unexpectedly, by the initial pH value ofthe collo&#239;dal state. A framework model, relating the pH dependence to the resulting properties, ispresented.

S. D. Han

S. Y. Huang

G.  Campet

M. A. Kennard

Y. M. Son

Influence of the pH Values of the Sol&#8211;Gel State on the Properties of SnO2 Powders Obtained From a Sol&#8211;Gel Route

Nanocrystalline TiO2 films were explored for the first time as electrode material for a rechargeable
lithium intercalation cell, i.e., Li/LiCF3SO3 + PC/TiO2. Two kinds of nanocrystalline films, TiO2
F387 (Degussa) and TiO2 colloid-240, were investigated. These films exhibited excellent performance
renderings them a promising choice for secondary battery applications. At a current density of 0.01
mA/cm2, two voltage plateaus at 1.78 and 1.89 V were observed for TiO2 F387 films during charge and
discharge, respectively. The TiO2 electrode charge capacity per unit weight rose with decreasing
current density. The highest capacity, obtained at a current density of 0.005 mA/cm2 and a final
discharge voltage of 1.4 V, was 265 mAh/g corresponding to a lithium insertion ratio of x = 0.8.
Nanocrystalline TiO2 colloid-240 films showed a similar performance. The cycle life of a TiO2
colloid-240 cell at a high current density was found to be excellent; a capacity loss lower than 14% has
been observed over 100 charge/discharge cycles.

Sui-Yang Huang

Ladislav Kavan

Andreas Kay

Michael Grätzel

Ivan Exnar

Nanocrystalline TiO2 Electrodes Exhibiting High Storage Capacity and Stability in Rechargeable Lithium Batteries

Sol-gel processes make it possible to develop new hybrid electrolyte materials of the type ceramic-polymer,known as Nano-Crystallite-Insertion-Material &#40;NCIM&#41;. They can be used in reversible alkalielectrochemical cells after insertion with cations such as Li&#43;. In the present study, TiO2-polyethylene oxide hybrid materials were synthesized from TiCl4 and from Ti ethoxide. Their structure is analyzed inrelation with the processing parameters. A primary evaluation of the nanoscale composite materials forreversible Li insertion was performed.

A. C. Pierre

E.  Duguet

J.  Portier

TiO2&#8211;Polymer Nano&#8211;Composites bySol&#8211;Gel

Fine grained SnO2 powders have been obtained using an unconventional method. It deals with the wellknown polymerization method starting from the metallic halide SnCl4 with polyethylene oxide &#40;PEO&#41;.With this method, SnO2 powders, which are free from water and hydroxyl group contaminations andpossess small crystallite size &#40;<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>&#x2248;</mml:mo><mml:mn>50</mml:mn><mml:mtext>&#x2009;</mml:mtext><mml:mover><mml:mtext>A</mml:mtext><mml:mo>&#x2218;</mml:mo></mml:mover></mml:mrow></mml:math>&#41;, are obtained by appropriate pyrolysis of the polymer. Consequently,these powders show good ability to insert reversibly lithium ions in the Li/Li&#43;/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Li</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>SnO2 cell.Indeed, by minimizing the size of the crystallites, the formation of defect-bonds is favored, particularlyat the crystallite surface, acting as reversible &#40;de&#41;grafting sites of Li&#43;. Finally, an easy-to-carry outmethod to determine the chemical diffusion coefficient of lithium has been proposed.

S. H. Pulcinnelli

C. V. Santilli

Reversible Electrochemical Insertion of Lithium in Fine Grained Polycrystalline Powders of SnO2

We propose an unconventional method to obtain fine-grained SnO2 and WO3 powders. It uses asprecursors, polymer complexes between polyethylene oxide &#40;POE&#41; and SnCl4 or WCl6 respectively. Bypyrolysis of these complexes in the 350-550&#8451; temperature range, metal-oxide powders possessing smallcrystallite sizes are obtained. They are free from water and hydroxyl group contaminations, which is anadded advantage where the application of these materials to Li-batteries is concerned. We have,indeed, demonstrated that these powders show good ability to insert reversibly lithium ions in theLi/ Li&#43;/SnO2 &#40;WO3&#41; cells.

M. C.R. Shastry

J. C. Lass&#232;gues

H. S. Dweik

A New Method for the Preparation of Fine-Grained SnO2 and WO3 Powders: Influence of the Crystallite Size on the Electrochemical Insertion of Li&#43; in SnO2 and WO3 Electrodes

A new family of insertion-compound electrodes, so called NCIMs &#40;Nano-Crystallite-Insertion-Materials&#41; has been proposed: the major requirement is that the electrode materials have to be polycrystalline with a crystallite and particle size as small as possible &#40;the accepted definition being that manycrystallites make a particle&#41;. Indeed, by minimizing the size of the crystallites, the formation of defectsis favored, particularly at the crystallite surface, acting as reversible &#40;de&#41;grafting sites of Li&#43;. Also, thecation-anion bonding is weakened not only in the grain boundary region but also within the crystalliteclose to its surface: then the electrochemical insertion of Li&#43; takes place through easy bondingrearrangements.

N.  Treuil

C.  Delmas

A.  Pierre

Mechanisms of the Reversible Electrochemical Insertion of Lithium Occurring with NCIMs&#40;Nano&#8211;CrystalliteInsertion&#8211;Materials&#41;

George Ting-Kuo Fey

New High Voltage Cathode Materialsfor Rechargeable Lithium Batteries

Advances in Electrode Materials Research

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Active and Passive Electronic Components provides a forum for the science and technology of all types of electronic components, and publishes experimental and theoretical papers on topics such as transistors, hybrid circuits and sensors.

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Active and Passive Electronic Components

Advances in Electrode Materials Research for Rechargeable Lithium Batteries

Advances in Electrode Materials Research for Rechargeable Lithium Batteries

Articles

Editorial

Influence of the pH Values of the Sol–Gel State on the Properties of SnO₂ Powders Obtained From a Sol–Gel Route

Nanocrystalline TiO₂ Electrodes Exhibiting High Storage Capacity and Stability in Rechargeable Lithium Batteries

TiO₂–Polymer Nano–Composites by Sol–Gel

Reversible Electrochemical Insertion of Lithium in Fine Grained Polycrystalline Powders of SnO₂

A New Method for the Preparation of Fine-Grained SnO₂ and WO₃ Powders: Influence of the Crystallite Size on the Electrochemical Insertion of Li⁺ in SnO₂ and WO₃ Electrodes

Mechanisms of the Reversible Electrochemical Insertion of Lithium Occurring with NCIM_s (Nano–Crystallite Insertion–Materials)

New High Voltage Cathode Materials for Rechargeable Lithium Batteries

Advances in Electrode Materials Research