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1.
Chem Commun (Camb) ; 59(8): 1066-1069, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36606800

RESUMO

A Li6PS5Cl-rich composite is prepared using a PEG-borate ester solid-state polymer electrolyte (BSPE). BSPE is a highly accessible compound with high ionic conductivity and excellent electrochemical stability against Li metal. Thereby, the stability of the Li6PS5Cl-rich composite with BSPE improved significantly.


Assuntos
Boratos , Eletrólitos , Íons , Lítio , Metais , Ésteres , Polímeros
2.
Carbohydr Polym ; 269: 118332, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34294342

RESUMO

Chitin is mainly extracted from crustaceans, but this resource is seasonally dependent and can represent a major drawback to satisfy the traceability criterion for high valuable applications. Insect resources are valuable alternatives due to their lower mineral content. However, the deacetylation of chitin into chitosan is still an expensive process. Therefore, we herein compare the impact of both DES/IL-pretreatments on the efficiency of the chemical deacetylation of chitin carried out over two insect sources (Bombyx eri, BE and Hermetia illucens, HI) and shrimp shells (S). The results showed that chitosans obtained from IL-pretreated chitins from BE larva, present lower acetylation degrees (13-17%) than DES-pretreated samples (18-27%). A selective N-acylation reaction with oleic acid has also been performed on the purest and most deacetylated chitosans leading to high substitution degrees (up to 27%). The overall approach validates the proper chitin source and processing methodology to achieve high quality and highly functionalizable chitosan.

3.
Chem Mater ; 33(14): 5652-5667, 2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34483480

RESUMO

Solid electrolytes are crucial for next-generation solid-state batteries, and Na3PS4 is one of the most promising Na+ conductors for such applications, despite outstanding questions regarding its structural polymorphs. In this contribution, we present a detailed investigation of the evolution in structure and dynamics of Na3PS4 over a wide temperature range 30 < T < 600 °C through combined experimental-computational analysis. Although Bragg diffraction experiments indicate a second-order phase transition from the tetragonal ground state (α, P4̅21 c) to the cubic polymorph (ß, I4̅3m) above ∼250 °C, pair distribution function analysis in real space and Raman spectroscopy indicate remnants of a tetragonal character in the range 250 < T < 500 °C, which we attribute to dynamic local tetragonal distortions. The first-order phase transition to the mesophasic high-temperature polymorph (γ, Fddd) is associated with a sharp volume increase and the onset of liquid-like dynamics for sodium-cations (translational) and thiophosphate-polyanions (rotational) evident by inelastic neutron and Raman spectroscopies, as well as pair-distribution function and molecular dynamics analyses. These results shed light on the rich polymorphism of Na3PS4 and are relevant for a range host of high-performance materials deriving from the Na3PS4 structural archetype.

4.
Inorg Chem ; 59(9): 6528-6540, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32286842

RESUMO

Solid electrolytes have regained tremendous interest recently in light of the exposed vulnerability of current rechargeable battery technologies. While designing solid electrolytes, most efforts concentrated on creating structural disorder (vacancies, interstitials, etc.) in a cationic Li/Na sublattice to increase ionic conductivity. In phosphates, the ionic conductivity can also be increased by rotational disorder in the anionic sublattice, via a paddle-wheel mechanism. Herein, we report on Na4Zn(PO4)2 which is designed from Na3PO4, replacing Na+ with Zn2+ and introducing a vacancy for charge balance. We show that Na4Zn(PO4)2 undergoes a series of structural transitions under temperature, which are associated with an increase in ionic conductivity by several orders of magnitude. Our detailed crystallographic study, combining electron, neutron, and X-ray powder diffraction, reveals that the room-temperature form, α-Na4Zn(PO4)2, contains orientationally ordered PO4 groups, which undergo partial and full rotational disorder in the high-temperature ß- and γ-polymorphs, respectively. We furthermore showed that the highly conducting γ-polymorph could be stabilized at room temperature by ball-milling, whereas the ß-polymorph can be stabilized by partial substitution of Zn2+ with Ga3+ and Al3+. These findings emphasize the role of rotational disorder as an extra parameter to design new solid electrolytes.

5.
Carbohydr Polym ; 228: 115382, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31635752

RESUMO

Chitins of different purity grades (45%, 89.7% and 93.3%) were efficiently extracted from Bombyx eri larva and fully physico-chemically characterized. Compared to commercially available and extracted α-chitin from shrimp shell, the collected data showed that insect chitins had similar characteristics in terms of crystallographic structures (α-chitin), thermal stability and degree of acetylation (>87%). The major differences lay in the crystallinity indexes (66% vs 75% for shrimp chitin) and in the morphological structures. Furthermore, low ash contents were determined for the insect chitins (1.90% vs 21.73% for shrimp chitin), making this chitin extraction and purification easier, which is highly valuable for an industrial application. Indeed, after only one step (deproteinization), the obtained chitin from Bombyx eri showed higher purity grade than the one extracted from shrimp shells under the same conditions. Insect chitins were then subjected to room temperature ionic liquid (RTIL) pretreatment prior to enzymatic degradation and presented a higher enzymatic digestibility compared to commercial one whatever their purity grade and would be thus a more relevant source for the selective production of N-acetyl-D-glucosamine (899.2 mg/g of chitin-2 stepsvs 760 mg/g of chitin com). Moreover, for the first time, the fermentescibility of chitin hydrolysates was demonstrated with Scheffersomyces stipitis used as ethanologenic microorganism.


Assuntos
Bombyx/metabolismo , Quitina , Crustáceos/metabolismo , Animais , Quitina/química , Quitina/isolamento & purificação , Larva/metabolismo
6.
Sci Rep ; 9(1): 18031, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31792314

RESUMO

Among the 3D-printing technologies, fused deposition modeling (FDM) represents a promising route to enable direct incorporation of the battery within the final 3D object. Here, the preparation and characterization of lithium iron phosphate/polylactic acid (LFP/PLA) and SiO2/PLA 3D-printable filaments, specifically conceived respectively as positive electrode and separator in a lithium-ion battery is reported. By means of plasticizer addition, the active material loading within the positive electrode is raised as high as possible (up to 52 wt.%) while still providing enough flexibility to the filament to be printed. A thorough analysis is performed to determine the thermal, electrical and electrochemical effect of carbon black as conductive additive in the positive electrode and the electrolyte uptake impact of ceramic additives in the separator. Considering both optimized filaments composition and using our previously reported graphite/PLA filament for the negative electrode, assembled and "printed in one-shot" complete LFP/Graphite battery cells are 3D-printed and characterized. Taking advantage of the new design capabilities conferred by 3D-printing, separator patterns and infill density are discussed with a view to enhance the liquid electrolyte impregnation and avoid short-circuits.

7.
Inorg Chem ; 55(24): 12775-12782, 2016 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-27989176

RESUMO

In the search for new cathode materials for sodium ion batteries, the exploration of polyanionic compounds has led to attractive candidates in terms of high redox potential and cycling stability. Herein we report the synthesis of the two new sodium transition-metal pentaborates Na3MB5O10 (M = Fe, Co), where Na3FeB5O10 represents the first sodium iron borate reported at present. By means of synchrotron X-ray diffraction, we reveal a layered structure consisting of pentaborate B5O10 groups connected through M2+ in tetrahedral coordination, providing possible three-dimensional Na-ion migration pathways. Inspired by these structural features, we examined the electrochemical performances versus sodium and showed that Na3FeB5O10 is active at an average potential of 2.5 V vs Na+/Na0, correlated to the Fe3+/Fe2+ redox couple as deduced from ex situ Mössbauer measurements. This contrasts with the case for Na3CoB5O10, which is electrochemically inactive. Moreover, we show that their electrochemical performances are kinetically limited, as deduced by complementary ac/dc conductivity measurements, hence confirming once again the complexity in designing high-performance borate-based electrodes.

8.
Phys Chem Chem Phys ; 18(22): 14960-9, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-27189653

RESUMO

In the search for new cathode materials for Li-ion batteries, borate (BO3(3-)) based compounds have gained much interest during the last two decades due to the low molecular weight of the borate polyanions which leads to active materials with increased theoretical capacities. In this context we herein report the electrochemical activity versus lithium and the ionic conductivity of a diborate or pyroborate B2O5(4-) based compound, Li6CuB4O10. By combining various electrochemical techniques with in situ X-ray diffraction, we show that this material can reversibly insert/deinsert limited amounts of lithium (∼0.3 Li(+)) in a potential window ranging from 2.5 to 4.5 V vs. Li(+)/Li(0). We demonstrate, via electron paramagnetic resonance (EPR), that such an electrochemical activity centered near 4.25 V vs. Li(+)/Li(0) is associated with the Cu(3+)/Cu(2+) redox couple, confirmed by density functional theory (DFT) calculations. Another specificity of this compound lies in its different electrochemical behavior when cycled down to 1 V vs. Li(+)/Li(0) which leads to the extrusion of elemental copper via a conversion type reaction as deduced by transmission electron microscopy (TEM). Lastly, we probe the ionic conductivity by means of AC and DC impedance measurements as a function of temperature and show that Li6CuB4O10 undergoes a reversible structural transition around 350 °C, leading to a surprisingly high ionic conductivity of ∼1.4 mS cm(-1) at 500 °C.

9.
J Am Chem Soc ; 136(36): 12658-66, 2014 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-25121348

RESUMO

High-performing Fe-based electrodes for Li-based batteries are eagerly pursued because of the abundance and environmental benignity of iron, with especially great interest in polyanionic compounds because of their flexibility in tuning the Fe(3+)/Fe(2+) redox potential. We report herein the synthesis and structure of a new Fe-based oxysulfate phase, Fe2O(SO4)2, made at low temperature from abundant elements, which electrochemically reacts with nearly 1.6 Li atoms at an average voltage of 3.0 V versus Li(+)/Li, leading to a sustained reversible capacity of ≈125 mAh/g. The Li insertion-deinsertion process, the first ever reported in any oxysulfate, entails complex phase transformations associated with the position of iron within the FeO6 octahedra. This finding opens a new path worth exploring in the quest for new positive electrode materials.

10.
Carbohydr Res ; 381: 12-8, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24056009

RESUMO

The use of Brønsted acid ionic liquid (BAIL) as a catalyst for the activation of unreactive and unprotected glycosyl donors has been demonstrated for the first time in aqueous solution.


Assuntos
Ácidos/química , Hexoses/síntese química , Líquidos Iônicos/química , Pentoses/síntese química , Catálise , Glicosilação , Hexoses/química , Estrutura Molecular , Pentoses/química , Soluções , Água/química
11.
Molecules ; 18(9): 11512-25, 2013 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-24048284

RESUMO

D-Xylose-based ionic liquids have been prepared from D-xylose following a five steps reaction sequence, the key step being a click cycloaddition. These ionic liquids (ILs) have been characterized through classical analytical methods (IR, NMR, mass spectroscopy, elemental analysis) and their stability constants, Tg and Tdec, were also determined. Considering their properties and their hydrophilicity, these compounds could be alternative solvents for chemical applications under mild conditions.


Assuntos
Líquidos Iônicos/síntese química , Xilose/química , Catálise , Química Click , Cobre/química , Reação de Cicloadição , Estabilidade de Medicamentos , Metilação , Termogravimetria
12.
J Am Chem Soc ; 131(25): 8984-8, 2009 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-19476355

RESUMO

The use of lithiated redox organic molecules containing electrochemically active C=O functionalities, such as lithiated oxocarbon salts, is proposed. These represent alternative electrode materials to those used in current Li-ion battery technology that can be synthesized from renewable starting materials. The key material is the tetralithium salt of tetrahydroxybenzoquinone (Li(4)C(6)O(6)), which can be both reduced to Li(2)C(6)O(6) and oxidized to Li(6)C(6)O(6). In addition to being directly synthesized from tetrahydroxybenzoquinone by neutralization at room temperature, we demonstrate that this salt can readily be formed by the thermal disproportionation of Li(2)C(6)O(6) (dilithium rhodizonate phase) under an inert atmosphere. The Li(4)C(6)O(6) compound shows good electrochemical performance vs Li with a sustained reversibility of approximately 200 mAh g(-1) at an average potential of 1.8 V, allowing a Li-ion battery that cycles between Li(2)C(6)O(6) and Li(6)C(6)O(6) to be constructed.

13.
J Colloid Interface Sci ; 290(1): 208-19, 2005 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-15936767

RESUMO

Boehmite xerogels are prepared by hydrolysis of Al(OC4H9)3 followed by peptization with HNO3 (H+/Al = 0, 0.07, 0.2). XRD and TEM show that these gels are made of nanosized crystals (5-9 nm in width and 3 nm thick). According to the amount of acid, no significant differences are found in size and shape, but only in the spatial arrangement of the crystallites. Nitrogen adsorption-desorption isotherms of nonpeptized gels are of type IV, whereas isotherms of peptized gels are of type I. These isotherms are analyzed by the t-plot method. The majority of pore volume results from intercrystalline mesopores, but the peptized gels also contain intercrystalline micropores. The particle packing is very dense for the gel peptized with H+/Al = 0.2 (porosity = 0.26), but it is less dense in non-peptized gel (porosity = 0.44). Heating these gels under vacuum creates, from 250 degrees C onwards, an intracrystalline microporosity resulting from the conversion of boehmite into transition alumina. But heating also causes intercrystalline micropores collapsing. The specific surface area increases up to a limit temperature (300 degrees C for nonpeptized gels and 400 degrees C for peptized) beyond which sintering of the particles begins and the surface decreases. The PSD are calculated assuming a cylindrical pore geometry and using the corrected Kelvin equation proposed by Kruk et al. Peptized xerogels give a monomodal distribution with a maximum near 2 nm and no pores are larger than 6 nm. Nonpeptized gels have a bimodal distribution with a narrow peak near to 2 nm and a broad unsymmetrical peak with a maximum at 4 nm. Heating in air above 400 degrees C has a strong effect on the porosity. As the temperature increases, there is a broadening of the distribution and a marked decrease of small pores (below 3 nm). However, even after treatment at 800 degrees C, micropores are still present.


Assuntos
Hidróxido de Alumínio/química , Óxido de Alumínio/química , Nanoestruturas/química , Cristalização , Géis , Hidrólise , Microscopia Eletrônica de Transmissão , Ácido Nítrico/química , Tamanho da Partícula , Porosidade , Sensibilidade e Especificidade , Propriedades de Superfície , Temperatura , Difração de Raios X
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