Accueil >
Production scientifique
(181) Production(s) de l'année 2017


Solvation and Dynamics of Lithium Ions in CarbonateBased Electrolytes during Cycling Followed by Operando Infrared Spectroscopy: The Example of NiSb 2 , a Typical Negative ConversionType Electrode Material for Lithium Batteries
Auteur(s): Marino Cyril, Boulaoued Athmane, Fullenwarth Julien, Maurin D., Louvain Nicolas, Bantignies J.L., Stievano Lorenzo, Monconduit Laure
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 121 p.26598  26606 (2017)
Ref HAL: hal01661243_v1
DOI: 10.1021/acs.jpcc.7b06685
Exporter : BibTex  endNote
Résumé: Conversiontype electrode materials show extremely interesting performance in terms of capacity, which is however usually associated with bad Coulombic efficiency. The latter is mainly the consequence of the relentless evolution of solid electrolyte interphase (SEI) formed and/or dissolved during conversion/backconversion reactions on the continuously reshaping active material surface. The thorough comprehension of the dynamic processes occurring during cycling in a working electrochemical cell, such as solvation/desolvation of ionic species and formation/dissolution of the SEI at the electrode/electrolyte interface, is thus of utmost relevance in the study of electrochemical mechanism and performance of conversiontype electrode materials. Operando Fourier transform infrared (FTIR) spectroscopy, one of the methods of choice for the study of such phenomena, was applied to study the dynamic interfacial properties of NiSb2, a representative intermetallic conversiontype electrode material for Li batteries, during cycling in the presence of a commercial electrolyte based on LiPF6 dissolved in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). Using a specifically developed in situ ATRIR electrochemical cell, it was possible to correlate the electrochemical processes to the ratio between solvent molecules associated with Li+ ions and free solvent molecules and thus to follow the dynamic evolution of the concentration of lithium in the electrolyte during cycling.



Density controls the kinetic stability of ultrastable glasses
Auteur(s): Fullerton C., Berthier L.
(Article) Publié:
Europhysics Letters (Epl), vol. 119 p.36003 (2017)
Ref HAL: hal01658154_v1
Ref Arxiv: 1706.10081
DOI: 10.1209/02955075/119/36003
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We use a swap Monte Carlo algorithm to numerically prepare bulk glasses with kinetic stability comparable to that of glass films produced experimentally by physical vapor deposition. By melting these systems into the liquid state, we show that some of our glasses retain their amorphous structures longer than 10^5 times the equilibrium structural relaxation time. This exceptional kinetic stability cannot be achieved experimentally for bulk materials. We perform simulations at both constant volume and constant pressure to demonstrate that the density mismatch between the ultrastable glass and the equilibrium liquid accounts for a major part of the observed kinetic stability.
Commentaires: 7 Pages, 6 Figures. Figures 4b) and 5b) updated, revisions to text to improve discussion, missing page numbers added to references, typos corrected. Réf Journal: EPL 119, 36003 (2017)



Methods to locate saddle points in complex landscapes
Auteur(s): Bonfanti S., Kob W.
(Article) Publié:
The Journal Of Chemical Physics, vol. 147 p.204104 (2017)



Linear and Weakly Nonlinear Models of Wind Generated Surface Waves in Finite Depth
Auteur(s): Latifi A., Manna M., Montalvo P., Ruivo M.
(Article) Publié:
Journal Of Applied Fluid Mechanics, vol. 10 p.18291843 (2017)
Ref HAL: hal01653592_v1
DOI: 10.18869/acadpub.jafm.73.243.27597
Exporter : BibTex  endNote
Résumé: This work regards the extension of the Miles’ and Jeffreys’ theories of growth of windwaves in water of finite depth. It is divided in two major sections. The first one corresponds to the surface water waves in a linear regimes and the second one to the surface water waver considered in a weak nonlinear, dispersive and antidissipative regime. In the linear regime, we extend the Miles’ theory of wind wave amplification to finite depth. The dispersion relation provides a wave growth rate depending to depth. A dimensionless water depth parameter depending to depth and a characteristic wind speed, induces a family of curves representing the wave growth as a function of the wave phase velocity and the wind speed. We obtain a good agreementbetween our theoretical results and the data from the Australian Shallow Water Experiment as well as the data from the Lake George experiment. In a weakly nonlinear regime the evolution of wind waves in finitedepth is reduced to an antidissipative Kortewegde VriesBurgers equation and its solitary wave solution is exhibited. Antidissipation phenomenon accelerates the solitary wave and increases its amplitude whichleads to its blowup and breaking. Blowup is a nonlinear, dispersive and antidissipative phenomenon which occurs in finite time. A consequence of antidissipation is that any solitary waves’ adjacent planes of constants phases acquire different velocities and accelerations and ends to breaking which occurs in finite space and in a finite time prior to the blowup. It worth remarking that the theoretical amplitude growth breaking time are both testable in the usual experimental facilities. At the end, in the context of windforced waves in finite depth, the nonlinear Schr ̈odinger equation is derived and for weak wind inputs, the Akhmediev, Peregrine and KuznetsovMa breather solutions are obtained



A model for failure in thermoplastic elastomers based on Eyring kinetics and network connectivity
Auteur(s): Aime S., Eisenmenger N. d., Engels T. a. p.
(Article) Publié:
Journal Of Rheology / Transactions Of The Society Of Rheology; Society Of Rheology  Transactions, vol. 61 p.13291342 (2017)
Ref HAL: hal01653311_v1
DOI: 10.1122/1.5000808
Exporter : BibTex  endNote
Résumé: A simple model is introduced to describe the failure mechanisms in soft thermoplastic elastomers. In particular, we address the strong embrittlement with increasing temperature observed in strain rate imposed tensile experiments. This behavior is in sharp contrast to classic thermoplastics and seems to be general for these types of systems, irrespective of their exact chemical nature. We show that a kinetic model describing the supramolecular association of hard blocks in terms of an Eyring rate equation captures the correct stress and temperature dependence of failure strain. We model the material as a transient network, whose failure is associated with the loss of connectivity. The network percolation threshold, a key parameter of the model, is studied with numerical simulations, in order to investigate the interplay between structure, connectivity, and mechanical properties.



Determination of the local density of polydisperse nanoparticle assemblies
Auteur(s): Genix A.C., Oberdisse J.
(Article) Publié:
Soft Matter, vol. 13 p.81448155 (2017)
Ref HAL: hal01653297_v1
DOI: 10.1039/c7sm01640a
Exporter : BibTex  endNote
Résumé: Quantitative characterization of the average structure of dense nanoparticle assemblies and aggregates is a common problem in nanoscience. Smallangle scattering is a suitable technique, but it is usually limited to not too big assemblies due to the limited experimental range, low concentrations to avoid interactions, and monodispersity to keep calculations tractable. In the present paper, a straightforward analysis of the generally available scattered intensity – even for large assemblies, at high concentrations – is detailed, providing information on the local volume fraction of polydisperse particles with hard sphere interactions. It is based on the identical local structure of infinite homogeneous nanoparticle assemblies and their subsets forming finitesized clusters. The approach is extended to polydispersity, using MonteCarlo simulations of hard and moderately sticky hard spheres. As a result, a simple relationship between the observed structure factor minimum – termed the correlation hole – and the average local volume fraction on the scale of neighboring particles is proposed and validated through independent aggregate simulations. The relationship shall be useful as an efficient tool for the structural analysis of arbitrary aggregated colloidal systems.



Photoluminescence from an individual doublewalled carbon nanotube
Auteur(s): Levshov D., Parret R., Tran H.N., Michel T., cao thi thanh, Nguyen Van Chuc, Arenal Raul, Popov Valentin n., Rochal Sergei b., Sauvajol J.L., Zahab A. A., Paillet M.
(Article) Publié:
Physical Review B, vol. 96 p.195410 (2017)
Ref HAL: hal01653173_v1
DOI: 10.1103/PhysRevB.96.195410
Exporter : BibTex  endNote
Résumé: We report direct and unambiguous evidence of the existence of inner semiconducting tube (ISCT) photoluminescence (PL) from measurements performed on four individual freestanding indexidentified doublewalled carbon nanotubes (DWNTs). Based on thorough Rayleigh scattering, Raman scattering, and PL experiments, we are able to demonstrate that the ISCT PL is observed with a quantum yield estimated to be a few 10−6 independent of the semiconducting or metallic nature of the outer tube. This result is mainly attributed to ultrafast exciton transfer from the inner to outer tube. Furthermore, by carrying out PL excitation experiments on the (14,1)@(15,12) DWNT, we show that the ISCT PL can be detected through the optical excitation of the outer tube, indicating that the exciton transfer can also occur in the opposite way.
