LOS MONAGUILLOS [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Dehydration of Alginic Acid Cryogel by TiCl4 vapor : Direct Access to Mesoporous TiO2@C Nanocomposites and Their Performance in Lithium-Ion Batteries

A new strategy for the synthesis of mesoporous TiO2@C nanocomposites through the direct mineralization of seaweed-derived alginic acid cryogel by TiCl4 through a solid/vapor reaction pathway is presented. In this synthesis, alginic acid cryogel can have multiple roles; i) mesoporous template, ii) carbon source, and iii) oxygen source for the TiO2 precursor, TiCl4. The resulting TiO2@alginic acid composite was transformed either into pure mesoporous TiO2 by calcination or into mesoporous TiO2@C nanocomposites by pyrolysis. By comparing with a nonporous TiO2@C composite, the importance of the mesopores on the performance of electrodes for lithium-ion batteries based on mesoporous TiO2@C composite was clearly evidenced. In addition, the carbon matrix in the mesoporous TiO2@C nanocomposite also showed electrochemical activity versus lithium ions, providing twice the capacity of pure mesoporous TiO2 or alginic acid-derived mesoporous carbon (A600). Given the simplicity and environmental friendliness of the process, the mesoporous TiO2@C nanocomposite could satisfy the main prerequisites of green and sustainable chemistry while showing improved electrochemical performance as a negative electrode for lithium-ion batteries

Pitch-based carbon/nano-silicon composite, an efficient anode for Li-ion batteries

International audienc

Atomic layer fluorination of 5 V class positive electrode material LiCoPO4 for enhanced electrochemical performance

EJK would like to thank the Alistore ERI for the award of a studentship. The authors thank EPSRC Capital for Great Technologies Grant EP/L017008/1. The authors want to thank the French Research Network on the Electrochemical Energy Storage (RS2E) for YCB’s PhD grant. MD and NL are indebted to the IR-RMN-THC FR3050 CNRS for the spectrometer time access and the financial support of the NMR experiments.The surface fluorination of lithium cobalt phosphate (LiCoPO4, LCP) using a one‐step, room temperature processable, easily up‐scalable and dry surface modification method with XeF2 as fluorine source was developed. After fluorination, fluorine‐rich nanoparticles were observed mainly on the particle surface, which facilitates the improvement of surface stability and electrochemical performance such as cycling stability and rate capability, as the fluorinated LCP can be protected against side reactions with electrolyte or by‐products of electrolyte decomposition at high voltage (5 V). More importantly, the direct surface fluorination proved more efficient than adding a fluorinated electrolyte additive (i. e., FEC). These results suggest that surface fluorination using XeF2 is of great promise for practical applications of high voltage positive materials for lithium‐ion batteries.PostprintPeer reviewe

Alginic acid-derived mesoporous carbonaceous materials (Starbon®) as negative electrodes for lithium ion batteries : Importance of porosity and electronic conductivity

Alginic acid-derived mesoporous carbonaceous materials (Starbon® A800 series) were investigated as negative electrodes for lithium ion batteries. To this extent, a set of mesoporous carbons with different pore volume and electronic conductivity was tested. The best electrochemical performance was obtained for A800 with High Pore Volume (A800HPV), which displays both the highest pore volume (0.9 cm3 g−1) and the highest electronic conductivity (84 S m−1) of the tested materials. When compared to a commercial mesoporous carbon, A800HPV was found to exhibit both better long-term stability, and a markedly improved rate capability. The presence of a hierarchical interconnected pore network in A800HPV, accounting for a high electrolyte accessibility, could lay at the origin of the good electrochemical performance. Overall, the electronic conductivity and the mesopore size appear to be the most important parameters, much more than the specific surface area. Finally, A800HPV electrodes display similar electrochemical performance when formulated with or without added conductive additive, which could make for a simpler and more eco-friendly electrode processing

Sustainable polysaccharide-derived mesoporous carbons (Starbon®) as additives in lithium-ion batteries negative electrodes

For the first time, polysaccharide-derived mesoporous carbonaceous materials (Starbon®) are used as carbon additives in Li-ion battery negative electrodes. A set of samples with pore volumes ranging from ≈0 to 0.91 cm3 g-1 was prepared to evidence the role of porosity in such sustainable carbon additives. Both pore volume and pore diameter have been found crucial parameters for improving the electrodes performance e.g. reversible capacity. Mesoporous carbons with large pore volumes and pore diameters provide efficient pathways for both lithium ions and electrons as proven by the improved electrochemical performances of Li4Ti5O12 (LTO) and TiO2 based electrodes compared to conventional carbon additives. The mesopores provide easy access for the electrolyte to the active material surface, and the fibrous morphology favors the connection of active materials particles. These results suggest that polysaccharide-derived mesoporous carbonaceous materials are promising, sustainable carbon additives for Li-ion batteries

Relations Structures-Propriétés dans des matériaux hybrides multifonctionnels : Investigations structurales et théoriques

Organic/inorganic hybrid materials present the ability to mix, within one compound, the initial properties of the organic (solubility, flexibility) and inorganic (electronic, optical, magnetic properties) constituents or even show new properties that are greater than the sum of the initial properties. The work described here has been devoted to the study of structure/properties relationships within hybrid halogenometallates incorporating functionalized alkylammonium organic dications. The first part reports the study of solid state conformational changes of organic molecules included within hybrid compounds. We showed that these changes are emphasized by structural transitions. These phenomena are studied by non linear optical measurements on powder samples and on thin films samples. The second part deals with the structural and theoretical investigations of disulfide-disulfide and disulfide-iodide interactions in solid state. This work demonstrated that these interactions are weak, and mostly of orbital overlap origin. Nevertheless, they could be responsible for the crystallization of some structures showing phase transitions activated by temperature. In the last part, we underlined the influence of the functionalization of ethylammonium organic cations on the geometry of hybrid perovskites and derivatives inorganic networks. To limit steric hindrances and interactions at the organic/ inorganic interface allows the reduction of the band-gap of those compounds.Les matériaux hybrides organique/inorganique présentent la possibilité de pouvoir réunir, au sein d'un même composé, les propriétés initiales des constituants organiques (solubilité, flexibilité) et inorganiques (propriétés électroniques, optiques, magnétiques) voire de posséder des propriétés nouvelles supérieures à la simple somme des propriétés initiales. Au cours des présents travaux, nous avons porté notre attention sur les relations structures-propriétés au sein d'halogénométallates hybrides incorporant des cations organiques du type alkylammonium fonctionnalisés. Au cours de la première partie, une étude des changements conformationnels à l'état solide de molécules organiques incorporées dans des composés hybrides a été réalisée. Nous avons pu montrer que ces changements s'accompagnent de transitions structurales, phénomènes mis en évidence par les variations des propriétés optiques non linéaires à l'état massif et sous forme de films minces. La deuxième partie concerne l'étude structurale et théorique d'interactions disulfure-disulfure et disulfure-iodure à l'état solide. Ce travail montre que ces interactions intermoléculaires sont faibles, et principalement d'origine orbitalaire. Elles pourraient néanmoins être responsables de l'obtention de certaines structures présentant des transitions de phases activées par la température. Enfin, nous avons souligné l'influence de la fonctionnalisation de cations organiques du type éthylammonium sur la géométrie de réseaux inorganiques pérovskites hybrides et dérivés. Limiter la gêne stérique du cation et les interactions à l'interface organique/inorganique permet de réduire le band-gap de ces composés

Relations structures-propriétés dans des matériaux hybrides multifonctionnels (investigations structurales et théoriques)

Les matériaux hybrides organique/inorganique présentent la possibilité de pouvoir réunir, au sein d'un même composé, les propriétés initiales des constituants organiques (solubilité, flexibilité) et inorganiques (propriétés électroniques, optiques, magnétiques) voire de posséder des propriétés nouvelles supérieures à la simple somme des propriétés initiales. Au cours des présents travaux, nous avons porté notre attention sur les relations structures-propriétés au sein d'halogénométallates hybrides incorporant des cations organiques du type alkylammonium fonctionnalisés. Au cours de la première partie, une étude des changements conformationnels à l'état solide de molécules organiques incorporées dans des composés hybrides a été réalisée. Nous avons pu montrer que ces changements s'accompagnent de transitions structurales, phénomènes mis en évidence par les variations des propriétés optiques non linéaires à l'état massif et sous forme de films minces. La deuxième partie concerne l'étude structurale et théorique d'interactions disulfure-disulfure et disulfure-iodure à l'état solide. Ce travail montre que ces interactions intermoléculaires sont faibles, et principalement d'origine orbitalaire. Elles pourraient néanmoins être responsables de l'obtention de certaines structures présentant des transitions de phases activées par la température. Enfin, nous avons souligné l'influence de la fonctionnalisation de cations organiques du type éthylammonium sur la géométrie de réseaux inorganiques pérovskites hybrides et dérivés. Limiter la gêne stérique du cation et les interactions à l'interface organique/inorganique permet de réduire le band-gap de ces composés.Organic/inorganic hybrid materials present the ability to mix, within one compound, the initial properties of the organic (solubility, flexibility) and inorganic (electronic, optical, magnetic properties) constituents or even show new properties that are greater than the sum of the initial properties. The work described here has been devoted to the study of structure/properties relationships within hybrid halogenometallates incorporating functionalized alkylammonium organic dications. The first part reports the study of solid state conformational changes of organic molecules included within hybrid compounds. We showed that these changes are emphasized by structural transitions. These phenomena are studied by non linear optical measurements on powder samples and on thin films samples. The second part deals with the structural and theoretical investigations of disulfide-disulfide and disulfide-iodide interactions in solid state. This work demonstrated that these interactions are weak, and mostly of orbital overlap origin. Nevertheless, they could be responsible for the crystallization of some structures showing phase transitions activated by temperature. In the last part, we underlined the influence of the functionalization of ethylammonium organic cations on the geometry of hybrid perovskites and derivatives inorganic networks. To limit steric hindrances and interactions at the organic/ inorganic interface allows the reduction of the band-gap of those compounds.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Fermentation thanolique de m lasse par des cellules de levure immobilis es dans une mousse de polyur thane

SIGLEBSE B226668J / UCL - Université Catholique de LouvainBEBelgiu