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S Laruelle

Publications and source records attributed to S Laruelle.

4 recordsLinked to original sources
PubMed2006

Apparent mismatch between extended x-ray absorption fine structure and diffraction structures of crystalline metastable WO3 phases.

The local structure of monoclinic, monohydrate, hexagonal, and pyrochlore WO3 phases was investigated by the extended x-ray absorption fine structure spectroscopy as preliminary studies of model compounds of amorphous and thin film WO3 based electrochromic species. In the four cases, we found a large W-O distribution of distances ranging from 1.70 to 2.35 A. The apparent discrepancy of these results and previously published crystal structures are discussed and interpreted as the detection of vacancies and local distortion disorder.

Journal Article↗
PubMed2005

Characterization of lithium alkyl carbonates by X-ray photoelectron spectroscopy: experimental and theoretical study.

Lithium alkyl carbonates ROCO2Li result from the reductive decomposition of dialkyl carbonates, which are the organic solvents used in the electrolytes of common lithium-ion batteries. They play a crucial role in the formation of surface layers at the electrode/electrolyte interfaces. In this work, we report on the X-ray photoelectron spectroscopy (XPS) characterization of synthesized lithium methyl and ethyl carbonates. Using Hartree-Fock ab initio calculations, we interpret and simulate the valence spectra of both samples, as well as several other Li alkyl carbonates involved in Li-ion batteries. We show that Li alkyl carbonates can be identified at the electrode's surface by a combined analysis of XPS core peaks and valence spectra.

Journal Article↗
PubMed2000

Nano-sized transition-metal oxides as negative-electrode materials for lithium-ion batteries.

Rechargeable solid-state batteries have long been considered an attractive power source for a wide variety of applications, and in particular, lithium-ion batteries are emerging as the technology of choice for portable electronics. One of the main challenges in the design of these batteries is to ensure that the electrodes maintain their integrity over many discharge-recharge cycles. Although promising electrode systems have recently been proposed, their lifespans are limited by Li-alloying agglomeration or the growth of passivation layers, which prevent the fully reversible insertion of Li ions into the negative electrodes. Here we report that electrodes made of nanoparticles of transition-metal oxides (MO, where M is Co, Ni, Cu or Fe) demonstrate electrochemical capacities of 700 mA h g(-1), with 100% capacity retention for up to 100 cycles and high recharging rates. The mechanism of Li reactivity differs from the classical Li insertion/deinsertion or Li-alloying processes, and involves the formation and decomposition of Li2O, accompanying the reduction and oxidation of metal nanoparticles (in the range 1-5 nanometres) respectively. We expect that the use of transition-metal nanoparticles to enhance surface electrochemical reactivity will lead to further improvements in the performance of lithium-ion batteries.

Journal Article↗