Correlation of Ac-impedance and in situ X-ray spectra of LiCoO2

In-situ X-ray and AC-impedance spectra have been obtained simultaneously during the deintercalation of lithium from LiCoO2 using a specially designed electrochemical cell. The AC-dispersions have been correlated with the cell parameters obtained from the X-ray spectra. The correlation confirms previous hypothesis on the interpretation of the AC-dispersions in terms of an equivalent circuit comprising an element that relates the change of the intrinsic electronic conductivity, occurring at the early stages of deintercalation, to the semiconductor to metal transition caused by the change of the cell parameters

Structural change of carbon supported Pt nanocatalyst subjected to a step-like potential cycling in PEM-FC

Abstract In this paper we present detailed X-ray absorption fine structure (XAFS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations of the changes in the local geometric and electronic structure of Pt nanoparticles used as a cathode catalyst in proton exchange membrane fuel cell (PEMFC), working under controlled potential cycling conditions. The body of the results obtained suggests that in the first stage of \{PEMFC\} operation, small particle dissolution was a dominant process. Subsequent 100 h of work led to the progressive agglomeration of nanoparticles followed by a pronounced growth of the mean nanoparticle size. At the same time, high-quality \{XAFS\} spectra analysis demonstrated that negligible changes in structural local ordering and a slight increase in Pt 5d-electron density occurred during the whole \{FC\} operation period under consideration

Nanostructured tin-carbon/ LiNi0.5Mn1.5O4 lithium-ion battery operating at low temperature

An advanced lithium ion battery using nanostructured tinecarbon lithium alloying anode and a high voltage LiNi0.5Mn1.5O4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the battery is assured by the use of an electrolyte media based on a LiPF6 salt dissolved in EC-DEC-DMC, i.e. a mixture particularly suitable for the low temperature application. Cycling tests, both in half cells and in full lithium ion battery using the SneC anode and the LiNi0.5Mn1.5O4 cathode, performed in a temperature range extending from room temperature to "30 C, indicate that the electrode/electrolyte configuration here adopted may be suitable for effective application in the lithium ion battery field. The full cell, cycled at -5 °C, shows stable capacity of about 105 mAh g-1 over more than 200 chargee-discharge cycles that is considered a relevant performance considering the low temperature region

Exploring the Low Voltage Behavior of V2O5Aerogel as Intercalation Host for Sodium Ion Battery

Boosted by costs benefits, the development of room temperature Na-ion batteries is strongly desired for stationary applications. In this study we explore the possible use of V2O5 aerogel as anode material for sodium ion batteries. The aerogel is able to reversibly insert more than 3 Eq. of sodium in the voltage range 0.1 V–4 V vs. Na/Na+ demonstrating to possess additional capacity when cycled to lower voltage. The anode delivers about 200 mAh g−1 in the voltage range 0.01 V–1.5 V vs. Na/Na+. The preliminary characterization of a full Na-ion cell made coupling the V2O5 aerogel anode with carbon-coated Na3V2(PO4)3 cathode is also reported. The cell, showing an average voltage of 2.5 V, performed 200 cycles with good efficiency and a maximum specific capacity of 113 mAh per gram of anode material

DIVULGAÇÃO DE ATIVOS INTANGÍVEIS: UM ESTUDO EM ORGANIZAÇÕES DO SETOR FINANCEIRO E OUTROS DA BM&FBOVESPA / Disclosure of intangible assets: a study in organizations of the Financial sector and Others from BM&FBOVESPA

A crescente evolução dos mercados e das tecnologias de informação tem moldado um cenário de mudanças drásticas nos regulamentos contábeis. Um fato que marcou a contabilidade no Brasil nos últimos anos foi o processo de convergência às normas internacionais de contabilidade, instituído pela Lei n. 11.638/2007, que trouxe consigo novos padrões a serem seguidos. A divulgação de ativos intangíveis foi um deles, tornando-se obrigatória para as companhias de capital aberto. Este estudo teve como objetivo avaliar o nível de divulgação de informações relativas a ativos intangíveis em empresas do setor Financeiro e Outros listadas na BM&FBovespa, entre os anos 2010 e 2012. A pesquisa caracteriza-se como descritiva, documental e quantitativa, compreendendo uma amostra de 34 empresas financeiras. O método aplicado foi a estatística descritiva e a regressão linear múltipla a partir dos dados coletados do check list elaborado com base nos requisitos de divulgação do CPC 04. Os resultados denotam que o nível de divulgação dos intangíveis por parte das empresas investigadas é baixo. Além disso, o tamanho da empresa é a única variável testada que explica de modo significativo a evidenciação dos ativos intangíveis. Palavras-chave: Ativos intangíveis. Índice de divulgação. Instituições financeiras

Electrocatalytic properties of platinum nanocenters electrogenerated at ultra-trace levels within zeolitic phosphododecatungstate cesium salt matrices

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