Binder-Free Cnt Cathodes for Li-O2 Batteries with More Than One Life

[Abstract]: Li-O2 batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, a facile method to fabricate free-standing is established, binder-free electrodes for LOBs in which multi-wall carbon nanotubes form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate high reproducibility upon cycling in LOBs. After cell death, efficient and inexpensive methods to wash away the accumulated discharge products are demonstrated, as reconditioning method. The second life usage of these electrodes is validated, without noticeable loss of performance. These findings aim to assist in the development of greener high energy density batteries while reducing manufacturing and recycling costs.This research was supported by the French Ministry Higher Education, Research and Innovation. The authors acknowledge the European Synchrotron Radiation Facility for provision of beam time (in-house research time) using the ID16B beamline. They also acknowledge use of the Cambridge XPS System, part of Sir Henry Royce Institute – Cambridge Equipment, EPSRC grant EP/P024947/1 and Dr. Carmen Fernandez-Posada for XPS data acquisition and processing. I.T. and C.P.G. acknowledge funding from the European Research Council (ERC) BATNMR project. A.A.F. acknowledges the European Union's Horizon 2020 research and innovation program for the funding support through the European Research Council (grant agreement 772873, “ARTISTIC” project). A.A.F. acknowledges Institut Universitaire de France for the support. Work performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.Engineering and Physical Sciences Research Council; EP/P024947/1U.S. Department of Energy; DE-AC02-06CH1135

Combining X-ray Nano-CT and XANES Techniques for 3D Operando Monitoring of Lithiation Spatial Composition evolution in NMC Electrode

In this study, we present a well-defined methodology for conducting Operando X-ray absorption near-edge structure spectroscopy (XANES) in conjunction with transmission X-ray nano computed tomography (TXM-nanoCT) experiments on the LiNi$_{0.5}$Mn$_{0.3}$Co$_{0.2}$O$_2$ (NMC) cathode electrode. To minimize radiation-induced damage to the sample during charge and discharge cycles and to gain a comprehensive 3D perspective of the (de)lithiation process of the active material, we propose a novel approach that relies on employing only three energy levels, strategically positioned at pre-edge, edge, and post-edge. By adopting this technique, we successfully track the various (de)lithiation states within the three-dimensional space during partial cycling. Furthermore, we are able to extract the nanoscale lithium distribution within individual secondary particles. Our observations reveal the formation of a core-shell structure during lithiation and we also identify that not all surface areas of the particles exhibit activity during the process. Notably, lithium intercalation exhibits a distinct preference, leading to non-uniform lithiation degrees across different electrode locations. The proposed methodology is not limited to the NMC cathode electrode but can be extended to study realistic dedicated electrodes with high active material (AM) density, facilitating exploration and quantification of heterogeneities and inhomogeneous lithiation within such electrodes. This multi-scale insight into the (de)lithiation process and lithiation heterogeneities within the electrodes is expected to provide valuable knowledge for optimizing electrode design and ultimately enhancing electrode performance in the context of material science and battery materials research.Comment: 6 figures (SI, 3 figures

Stochasticity of Pores Interconnectivity in Li–O2 Batteries and its Impact on the Variations in Electrochemical Performance

While large dispersions in electrochemical performance have been reported for lithium oxygen batteries in the literature, they have not been investigated in any depth. The variability in the results is often assumed to arise from differences in cell design, electrode structure, handling and cell preparation at different times. An accurate theoretical framework turns out to be needed to get a better insight into the mechanisms underneath and to interpret experimental results. Here, we develop and use a pore network model to simulate the electrochemical performance of three-dimensionally resolved lithium−oxygen cathode mesostructures obtained from TXM nanocomputed tomography. We apply this model to the 3D reconstructed object of a Super P carbon electrode and calculate discharge curves, using identical conditions, for four different zones in the electrode and their reversed configurations. The resulting galvanostatic discharge curves show some dispersion, (both in terms of capacity and overpotential) which we attribute to the way pores are connected with each other. Based on these results, we propose that the stochastic nature of pores interconnectivity and the microscopic arrangement of pores can lead, at least partially, to the variations in electrochemical results observed experimentally

Directed Assembly of Soft Anisotropic Nanoparticles by Colloid Electrospinning.

Directed assembly of triblock copolymer worms to produce nanostructured fibers is achieved via colloid electrospinning. These copolymer worms are conveniently prepared by polymerization-induced self-assembly in concentrated aqueous dispersion. Addition of a second water-soluble component, poly(vinyl alcohol), is found to be critical for the production of well-defined fibers: trial experiments performed using the worms alone produce only spherical microparticles. Transmission electron microscopy studies confirm that the worm morphology survives electrospinning and the worms become orientated parallel to the main axis of the fibers during their generation. The average deviant angle (θdev ) between the worm orientation and fiber axis decreases from 17° to 9° as the worm/PVA mass ratio increases from 1.15:1 to 5:1, indicating a greater degree of worm alignment within fibers with higher worm contents and smaller fiber diameters. Thus triblock copolymer fibers of ≈300 ± 120 nm diameter can be readily produced that comprise aligned worms on the nanoscale

Hyperthermic effects of dissipative structures of magnetic nanoparticles in large alternating magnetic fields

Targeted hyperthermia treatment using magnetic nanoparticles is a promising cancer therapy. However, the mechanisms of heat dissipation in the large alternating magnetic field used during such treatment have not been clarified. In this study, we numerically compared the magnetic loss in rotatable nanoparticles in aqueous media with that of non-rotatable nanoparticles anchored to localised structures. In the former, the relaxation loss in superparamagnetic nanoparticles has a secondary maximum because of slow rotation of the magnetic easy axis of each nanoparticle in the large field in addition to the known primary maximum caused by rapid Néel relaxation. Irradiation of rotatable ferromagnetic nanoparticles with a high-frequency axial field generates structures oriented in a longitudinal or planar direction irrespective of the free energy. Consequently, these dissipative structures significantly affect the conditions for maximum hysteresis loss. These findings shed new light on the design of targeted magnetic hyperthermia treatments

Anisotropic nanomaterials: structure, growth, assembly, and functions

Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications

Place du score calcique coronarien semi-quantitatif chez les patients hospitalisés pour maladie veineuse thromboembolique dans l’estimation du risque de thrombose veineuse non provoquée et le pronostic à un an

Médecine GénéraleIntroduction : Le cumul des facteurs de risque cardiovasculaire (FRCV) d’athérosclérose est associé au risque de maladie veineuse thrombo-embolique (MVTE) non provoquée, à la gravité de l’embolie pulmonaire (EP) ainsi qu’à la récidive de MVTE. Le score calcique coronarien semi-quantitatif (OCAC) obtenu via tomodensitométrie est un marqueur de risque cardiovasculaire infra-clinique superposable au score d’Agatston. L’objectif de notre étude est de savoir si l’OCAC, reflet de l’atteinte athéromateuse artérielle secondaire aux FRCV, est aussi associé à la MVTE non provoquée et pourrait ainsi constituer un marqueur de récidive de MVTE ou de pronostic à court et long terme. Matériels et méthodes : Nous avons calculé l’OCAC de manière rétrospective sur les scanners et angioscanners thoraciques des patients issus du registre REMOTEV (registre observationnel prospectif continu des patients consécutifs hospitalisés dans le service de médecine vasculaire du CHRU de Strasbourg pour un épisode aigu d’embolie pulmonaire) entre novembre 2013 et décembre 2016 et ayant au moins un an de suivi. L’OCAC a été évalué comparativement aux FRCV d’athérosclérose dans le risque de MVTE non provoquée, à la gravité de l’EP et au risque de récidive. Nous avons aussi modulé l’OCAC par le sPESI pour l’évaluation du pronostic à court et long terme du patient. Résultats : Le cumul des FRCV est associé au risque de MVTE non provoquée et à la gravité de l’EP. A contrario, si l’OCAC est corrélé positivement au cumul des FRCV, il n’est pas associé au risque de MVTE non provoquée ou à sa récidive. Par contre, l’OCAC compris entre 4 et 12 est significativement associé au risque de faire une EP à risque intermédiaire haut ou à haut risque par rapport à un OCAC à 0 (p - 0.001 ; OR 1.84 ; [IC 95% 1.21-2.81]). L’augmentation du score calcique dans chaque classe (1-3 et ≥4) est associée à un surrisque de mortalité à 1 an (p-0.001). L’augmentation de l’OCAC total de 1 point est significativement associée au risque de mortalité au long cours (p - 0.001 ; OR 1.30 ; [IC 95 % 1.21 – 1.40]). Les patients avec une troponine positive - 0.04 µg/L ont 1.62 fois plus de risque [IC 95 % (1.05 -2.5) p- 0.001] d’avoir un score calcique compris entre 1 et 3 versus 0 et 4.18 fois plus de risque [(IC 95% 2.56-6.80) p - 0.001] d’avoir un score calcique entre 4 et 12 versus 0. Donc les patients ayant une troponine positive ont 3 fois plus de risque d’avoir un OCAC ≥ 4. Discussion/conclusion : L’OCAC est un marqueur de gravité de l’embolie pulmonaire et pourrait faire suggérer que le biomarqueur « troponine » augmenté dans les EP à risque intermédiaire pourrait être le reflet des répercussions hémodynamiques de l’EP mais aussi d’un infarctus de type II. L’OCAC est également un marqueur de mortalité à un an chez les patients porteurs d’une MVTE permettant l’identification d’une population particulièrement à risque ayant présenté un sPESI ≥ 1 et un OCAC ≥4. Son estimation n’entraine aucun examen ni coût supplémentaire. L’OCAC devrait être réalisé en pratique courante afin d’identifier les patients à plus haut risque de mortalité à un an après un épisode d’EP, justifiant alors d’une intensification de la surveillance médicale, d’un traitement cardioprotecteur, voire d’une exploration coronarienne.Introduction: The accumulation of cardiovascular risk factors (CVRF) for atherosclerosis is associated with the risk of unprovoked thromboembolic venous disease (VTE), the severity of pulmonary embolism (PE) and the recurrence of VTE. The ordinary coronary artery calcium score (OCAC) obtained via computed tomography is a sub-clinical cardiovascular risk marker that can be superimposed on the Agatston score. The objective of our study is to determine whether OCAC, a reflection of arterial atheromatous damage secondary to CVRF, is also associated with unprovoked VTE and could thus be a marker for recurrence of VTE or prognosis in the short and long term. Materials and methods: We calculated OCAC retrospectively on chest scans and angioscanners of patients from the REMOTEV registry (continuous prospective observational record of consecutive patients hospitalized in the vascular medicine department of the CHRU de Strasbourg for an acute episode of PE) between November 2013 and December 2016 and having at least one year of follow-up. OCAC was evaluated against atherosclerosis CVRF in the risk of unprovoked VTE, severity of PE and risk of recurrence. We also modulated OCAC with sPESI for the evaluation of the patient's short and long-term prognosis. Results: The accumulation of CVRF is associated with the risk of unprovoked VTE and the severity of PE. Conversely, if OCAC is positively correlated with the accumulation of CVRF, it is not associated with the risk of unprovoked VTE or its recurrence. On the other hand, OCAC between 4 and 12 is significantly associated with the risk of doing a high intermediate or high risk PE compared to an OCAC at 0 (p - 0.001 ; OR 1.84 ;[CI 95% 1.21-2.81]). The increase in the calcium score in each class (1-3 and ≥) is associated with an excess mortality risk at 1 year (p-0.001). The 1 point increase in total OCAC is significantly associated with long-term mortality risk (p - 0.001 ; OR 1.30 ;[95% CI 1.21 - 1.40]). Patients with a positive troponin - 0.04 µg/L have a 1.62-fold increased risk[95% CI (1.05 -2.5) p-0.001] of having a calcium score between 1 and 3 versus 0 and 4.18 times increased risk [ 95% CI 2.56-6.80) p-0.001] of having a calcium score between 4 and 12 versus 0. Therefore patients with a positive troponin are 3 times increased risk of having an OCAC ≥ 4. Discussion/conclusion: OCAC is a marker of pulmonary embolism severity and may suggest that the increased "troponin" biomarker in intermediate risk PEs may reflect the hemodynamic effects of PE but also of a type II infarction. OCAC is also a marker of mortality at one year in patients with an VTE disease that allows the identification of a particularly at-risk population that has a sPESI ≥ 1 and an OCAC ≥4. Its estimate does not involve any examination or additional cost. OCAC should be performed in routine practice to identify patients at higher risk of death at one year after an episode of PE, warranting increased medical surveillance, cardioprotective treatment, or even coronary exploration