Layered oxides

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Will Sodium Layered Oxides Ever Be Competitive for Sodium Ion Battery Applications?

Will Sodium Layered Oxides Ever Be Competitive for Sodium Ion Battery Applications?

The Na-ion battery technology is rapidly developing as a possible alternative to Li-ion for massive electrochemical energy storage applications because of sustainability and cost reasons. Two types of technologies based either on sodium layered oxides Na x MO 2 (x ≤ 1, M = transition metal ion(s)) or on polyanionic compounds such as Na 3 V 2 (PO 4 ) 2 F 3 as positive electrode and carbon as negative electrode are presently being pursued. Herein, we benchmark the performance of full Na-ion cells based on several sodium layered oxide materials against Na 3 V 2 (PO 4 ) 2 F 3 /hard carbon cells. Although several studies report more attractive capacities for sodium layered oxides vs. Na metal ( ∼200 mAh g −1 ) than for polyanionic phases ( ∼120 mAh g −1 ), we find that such advantages are not maintained when assembling practical full Na-ion cells; the opposite of what is found for Li-ion technology. The reasons for such a loss of supremacy of the layered oxides against polyanionic compounds are discussed in terms of materials structural stability and composition so as to identify fundamental challenges that impede their practical applications. Finally, a few perspectives are given to design better sodium layered oxide electrode materials that could outweigh the performance of today’s stellar Na 3 V 2 (PO 4 ) 2 F 3 . © The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org . [DOI: 10.1149/2.0201816jes ]
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Li-Rich Layered Oxides: Still a Challenge, but a Very Promising Positive Electrode Material for Li-Ion Batteries

Li-Rich Layered Oxides: Still a Challenge, but a Very Promising Positive Electrode Material for Li-Ion Batteries

4 I. Introduction Lithium-ion batteries entered the market in the 1990´s, they have made possible the development of the electronic market with the emergence of a large panel of applications such as portable electronics and power tools, increasingly more and more demanding in energy and power, but also in weight and volume restrictions. Lithium-ion batteries are still at the center of researches to challenge recent concerns: transportation with different degrees of electrification, large scale stationary storage of renewable energies produced by wind and solar farms, and improvement of the grid reliability and stability in helping to compensate for imperfections due to energy mix. All these new applications and demands are pushing further the development of the Li-ion technology and its market. Indeed, even if considered as mature, improvements are still possible: in this chapter devoted to layered oxides, currently at the positive electrodes in most of the commercial Lithium-ion batteries, we will discuss the possible tracks to follow to increase further their energy, stability, etc. Early Lithium-ion
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The Role of Divalent (Zn 2+ /Mg 2+ /Cu 2+ ) Substituents in Achieving Full Capacity of Sodium Layered Oxides for Na-Ion Battery Applications

The Role of Divalent (Zn 2+ /Mg 2+ /Cu 2+ ) Substituents in Achieving Full Capacity of Sodium Layered Oxides for Na-Ion Battery Applications

Abstract: O3 type layered sodium transition metal oxides, e.g. NaNi 0.5 Mn 0.5-z Ti z O 2 , having one sodium per transition metal ion could be attractive positive electrode materials for achieving high energy density sodium-ion batteries provided we can reversibly utilize their full Na content. However, the layered structure on cycling undergoes series of phase transitions in which the fully de- sodiated O1 phase shows huge reduction in cell volume together with cation migration both of which are detrimental for long term cycling performance. Hence, the practical capacity of layered oxides is restricted to solely ~0.5-0.6 Na (oxidation up to ~4 V vs Na + /Na 0 ), avoiding the
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Decoupling the effect of vacancies and electropositive cations on the anionic redox processes in Na based P2-type layered oxides

Decoupling the effect of vacancies and electropositive cations on the anionic redox processes in Na based P2-type layered oxides

5. Conclusion We compared two members of the same solid solution in which we can discriminate the effects, on the anionic redox, of different activation sources (vacancies, Mg 2þ ) with the one associated to the cation vacancies occurring at lower voltage and being irreversible. We demonstrated the importance of the cation vacancies and Mg 2þ distribution in ruling the reversibility of the anionic redox process with the process being irre versible when the vacancies are pinned to local structural distortion in a disorder way during the charging process and reversible when the Mg 2 þ distribution is ordered. Additionally, we provided evidence, via operando XRD, for enhancement of the compositional stability range of the P2 type structure till high state of charge which is consistent with the lowering of charge carried out by the oxygen due to the anionic redox process. Practically wise, this is beneficial as it enables to recover the capacity usually lost by the need to add electrochemically inactive element (such as Al, and many others) to stabilize P2 structure. Although anionic redox activity in layered oxides has been intensively studied, this work brings another dimension in decoupling the importance of cation vacancies vs highly electropositive cations (Mg 2þ ) in governing the activation and
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Decoupling the effect of vacancies and electropositive cations on the anionic redox processes in Na based P2-type layered oxides

Decoupling the effect of vacancies and electropositive cations on the anionic redox processes in Na based P2-type layered oxides

5. Conclusion We compared two members of the same solid solution in which we can discriminate the effects, on the anionic redox, of different activation sources (vacancies, Mg 2þ ) with the one associated to the cation vacancies occurring at lower voltage and being irreversible. We demonstrated the importance of the cation vacancies and Mg 2þ distribution in ruling the reversibility of the anionic redox process with the process being irre versible when the vacancies are pinned to local structural distortion in a disorder way during the charging process and reversible when the Mg 2 þ distribution is ordered. Additionally, we provided evidence, via operando XRD, for enhancement of the compositional stability range of the P2 type structure till high state of charge which is consistent with the lowering of charge carried out by the oxygen due to the anionic redox process. Practically wise, this is beneficial as it enables to recover the capacity usually lost by the need to add electrochemically inactive element (such as Al, and many others) to stabilize P2 structure. Although anionic redox activity in layered oxides has been intensively studied, this work brings another dimension in decoupling the importance of cation vacancies vs highly electropositive cations (Mg 2þ ) in governing the activation and
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Sodium electrochemical deintercalation and intercalation in O3-NaRhO2 and P2-NaxRhO2 layered oxides

Sodium electrochemical deintercalation and intercalation in O3-NaRhO2 and P2-NaxRhO2 layered oxides

from the potassium phase P2-K 0.62 RhO 2 . This type of synthesis was conducted here for the first time on layered oxides with 4d transition metals. The phase diagram of both structures was explored by sodium electrochemical deintercalation/inter- calation in a battery. The existence of single phases was shown with presumably different physical properties. As an exam- ple, the O’3-Na 1/2 RhO 2 compound electrochemically obtained for the first time exhibits a metallic behavior whereas the O3-

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Unlocking anionic redox activity in O3-type sodium 3d layered oxides via Li substitution

Unlocking anionic redox activity in O3-type sodium 3d layered oxides via Li substitution

cationic migration, voltage hysteresis and voltage fade in layered 3d transition metal oxides. It 12[r]

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Prediction of isoelectric point of manganese and cobalt lamellar oxides : application to controlled synthesis of mixed oxides

Prediction of isoelectric point of manganese and cobalt lamellar oxides : application to controlled synthesis of mixed oxides

To restack the building blocks, the easiest strategy is to use electrostatic attractions of oppositely charged slabs dispersed in a suspension. This surface charge is the origin of the driving force for a controlled assembly of multiple lamellae, but is dependent on experimental conditions. Determination and prediction of isoelectric point (IEP) is therefore of great importance to reach controlled assembly of oligolamellae and obtain mixed layered oxides. We present here for the first time the application of the Multisite Complexation model (MUSIC) to theoretically predict the IEP of the lamellar units, depending on the mean oxidation state of the transition metals present in the slabs. We show that this model, developed for the determination of monometallic oxide IEP, is also robust even when the restacked materials become more complex, i.e. when nature and oxidation states of the metal ions vary.
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Graphene-supported 2D cobalt oxides for catalytic applications

Graphene-supported 2D cobalt oxides for catalytic applications

Loïc Michel, a Sécou Sall, a Thierry Dintzer, a Cerise Robert, a Antoine Demange a and Valérie Caps a * 2D materials are attracting increasing attention in many strategic applications. In particular, ultra-thin non-layered oxides have been shown to outperform their 3D counter-parts in several health and energy applications, such as the removal of toxic carbon monoxide by low temperature oxidation and the development of high performance supercapacitors. The general reason for that is the increased surface-to-volume ratio, which allows to maximize exposure of active species and enhance exchange between the (limited) bulk and the surface. The challenge is to synthesize such 2D configurations of 3D oxides, which generally requires quite harsh multi-step, multi-reagent chemical processes. Here we show that natural graphite can be used as a templating matrix to grow non-stoichimetric 2D transition metal oxides. We focus on highly porous, highly reduced cobalt oxides grown from cobalt nitrate and sodium borohydride under sonication. Extensive characterization, including nitrogen physisorption, thermogravimetric analysis (TGA), scanning and transmission electron microscopies (SEM/TEM), X-ray diffraction (XRD), temperature programmed oxidation and reduction (TPO/TPR), Fourier Transformed Infrared (FTIR) and Raman spectroscopies, highlights the specific features of the 2D morphologies (nanosheets and nanofilms) obtained. For comparison, 3D morphologies of Co 3 O 4 spinel nanocrystallites are grown from stacked 2D cobalt phthalocyanine-graphene precursors upon controlled thermal oxidation. Finally, low temperature CO oxidation catalysis evidences the superior performance of the graphene-supported CoO-like cobalt oxide 2D nanosheets.
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Co–Ce Oxides Supported on SBA-15 for VOCs Oxidation

Co–Ce Oxides Supported on SBA-15 for VOCs Oxidation

Keywords: SBA-15; Co–Ce oxides; catalytic combustion; methane; propane; n-hexane oxidation; mesoporous structure 1. Introduction The major air pollutants are volatile organic compounds (VOCs). They contribute to a number of environmental problems such as formation of ground-level ozone, formation of photochemical smog, and toxic air emissions. The European Commission presented the so-called Green Deal in December 2019, also known as the Green Pact, which is a set of policies aimed at making Europe climate neutral by 2050. The plan is to reduce greenhouse gas production at least by 50% compared to 1990 levels, as well as zero pollution by 2050, whether soil, air, or water pollution. There are many different techniques for VOCs removal, such as adsorption, absorption, biofiltration, combustion (incineration), and catalytic oxidation. The choice of the technique to be used depends on the VOCs nature and concentration and waste gas flow rate. Catalytic incineration is a competitive abatement technique for VOCs’ neutralization, especially when the organics cannot be recycled, sold, or are present in low concentration. Compared with thermal incineration, catalytic oxidation occurs at lower temperatures and, thus, it requires lower energy cost and gives no NOx emission. Metal oxides or supported noble metals are used in catalytic oxidation. Metal oxides are alternative to noble metals as catalysts for total oxidation [ 1 ].
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Cation-disordered oxides for rechargeable lithium battery cathodes

Cation-disordered oxides for rechargeable lithium battery cathodes

To analyze the change in the crystal structure during cycling, we performed ex situ XRD on the carbon-coated Li 1.211 Mo 0.467 Cr 0.3 O 2 electrode before cycling, after one cycle, after two cycles, and after ten cycles between 1.5−4.3V at 32.7 mA/g (Fig. 2-17). From the XRD patterns, dramatic changes in the pattern are seen after the first cycle. Before cycling, the XRD pattern shows a pattern of a layered-rocksalt structure (space group: R-3m) in which the Li layers and the TM layers form alternating layers within an oxygen FCC framework (Fig. 2-1a). However, after the first cycle, the (003) peak which is an indicative of the layered structure is almost completely gone, 73 and the XRD pattern resembles a pattern of a disordered-rocksalt structure (space group: Fm-3m). Based on the XRD refinements (Fig. 2-18), we estimate 34 to 52 % of the TM ions to be in Li layers after ten cycles. This indicates substantial cation-mixing between the Li and TM layers, known to be detrimental to the performance of layered materials. The structural evolution of Li 1.211 Mo 0.467 Cr 0.3 O 2 to a disordered structure can also be confirmed
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Direct electroreduction of oxides in molten fluoride salts

Direct electroreduction of oxides in molten fluoride salts

A complete conversion of Fe 3 O 4 pellet into metallic iron, pre- sented in Fig. 5 (b), has been obtained when a higher electrical charge imposed: I = −0.1 A, t = 10,000 s and m = 275 mg. No oxide phase was detected and the sample was only composed of Fe and frozen salts. The resulting product was very porous and had a coral- like structure due to the oxygen removal. This typical pattern is commonly obtained after the direct reduction of oxides, as UO 2 in molten chlorides [24] .

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Nanostructured zinc and tin oxides for gas sensors

Nanostructured zinc and tin oxides for gas sensors

ACKNOWLEDGMENTS: PRES, Région Midi-Pyrénées (NELI program -Nez Electronique Intégré-), BPI France and Sigfox SA for « Object’s World » project funding, and V. Collière (TEMSCAN Toulouse ) for SEM and TEM images. Nanostructured zinc and tin oxides for gas sensors J. Jonca, 1 A. Ryzhikov, 1 M. L. Kahn, 1 K. Fajerwerg, 1,2 P. Menini, 2, 3 A. Chapelle, 2, 3 C. H. Shim, 3,4 A. Gaudon, 4 P. Fau 1,2

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Tritium trapping by metal oxides in radioactive wastes

Tritium trapping by metal oxides in radioactive wastes

be prepared to compare catalyzer influence: a reference and three other mixes with an add of 1% of a catalyst. Oxidizing powders are prepared using the same protocol as V.Chaudron [2]. Both of oxides MnO2, Ag2O and catalyzer are firstly weighted, crushed in a milling machine and screened. Then, for 20 g of powder, 8 mL of water is added to soak the mix of oxides. Last step consists of heating the powder up to 100°C during 2h to remove any trace of water.

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Comparative study of layered material models

Comparative study of layered material models

Categories and Subject Descriptors (according to ACM CCS) : I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Color, shading, shadowing, and texture 1. Motivation Most materials are made of layers, which makes the model- ing of surface scattering challenging. Only a few analytical layered material models exist in the literature, with the aim of reaching the highest physical accuracy while remaining in geometric optics. Thus, the impact of approximations made by such models remains unclear.

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The Bjerkreim-Sokndal layered intrusion, Southwest Norway

The Bjerkreim-Sokndal layered intrusion, Southwest Norway

The two basal zones of MCU III (MCU IIIa and the olivine-bearing MCU IIIb) can be traced for about 19 km from the southwestern flank of the Bjerkreim lobe where they abut onto anorthosites of the Haland-Helleren massif, round the hinge zone of the syncline, to the northern flank. Here these two zones thin gradually towards the south-east and wedge out completely approaching the Teksevatnet area where phiC of MCU ΠIc overlies apparently identical phiC of MCU IIc. The country-rock gneisses form a protrusion in the Teksevatnet area, to the east of which only MCUs III and IV appear to be developed. These relationships are illustrated in Figure 3 which is based on seven profiles studied in detail by Nielsen and Wilson (1991). The base of MCUIV is in contact with modally layered cumulates of MCU IIIe in all the profiles except D (in Figure 3) where it overlies MCU Hid. The olivine-bearing zone (MCU IVb) has a fairly constant thickness (75-100 m) along its entire strike length of-24 km, whereas the underlying MCU IVa is absent on the northern flank, reaches a maximum thickness of-90 m in profile D in the central, axial region where MCU IIIe is absent, and thins towards the southern flank where it has a thickness of about 10 m. MCU IVc varies in thickness from about 40-100 m, but this variation does not appear to be related to the location of the profiles.
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Transition metal oxides for combustion and depollution processes

Transition metal oxides for combustion and depollution processes

products. 6.7. Oxidation of automotive soots Automotive converters were implanted in Europe after 1990. The first regulation for soot particle emissions (EURO 1) specified that Diesel cars could not emit more than 140 mg particles/km. Drastic improvements of the Diesel engines such as direct injection at very high pressure allow the car makers to meet the European standards up to 2008. EURO 4 imposing less than 5 mg/km after 2009, followed by EURO 5 and 6 restricting the emissions at 4.5 mg/km, could not be respected by the most sophisticated, modern engines which emitted 20- 30 mg particles in the best conditions. It was then necessary to implement Diesel particulates filters (DPF) on Diesel cars. These filters should be regenerated to avoid anomalous pressure drops in the exhaust pipe and defective engine operation. This involves burning the soots regularly, in the presence of a catalyst to lower the ignition temperature. The catalyst may be added to the fuel (fuel-borne catalyst, some ppm of a Ce or a Fe compound) or wash-coated on the filter walls. Catalysts added to the filter are generally composed of noble metals (mainly Pt). However, a great number of studies have been made to replace these NPs by oxide catalysts, much less expensive. Most studies are carried out by mixing carbon powder representative of soots with the catalysts. The catalytic activity is evaluated by a temperature-programmed oxidation in air. Single oxides were first evaluated. The study of Neeft et al. gives a good overview of the performance of 14 oxides and 4 alkali metal carbonates [203]. The main results of this study (Table 6.3) are: (i) Co 3 O 4 is a very performing oxide, combining
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Ballistic resistance of multi-layered steel shields

Ballistic resistance of multi-layered steel shields

At high velocity impact by the light conical-nose projectile, which is the least detrimental projectile, the double-layered shield with the upper layer of high ducti[r]

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Layered surface fluid simulation for surgical training

Layered surface fluid simulation for surgical training

Bleeding Rendering: During the final rendering, blood information is fetched from the simulation results using a custom texture filtering approach similar to the one used in inter-frame [r]

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Guide to optical spectroscopy of layered semiconductors

Guide to optical spectroscopy of layered semiconductors

Emission dynamics.- The detected luminescence sig- nal from a layered semiconductor is the result of an intri- cate interplay between radiative and non-radiative energy relaxation. Time-resolved PL can be performed using a pulsed laser excitation and measuring the recombina- tion (emission) time. In clean TMD samples the strong exciton oscillator strength leads to an intrinsic radiative lifetime of the order of 1 ps at low temperature [138]. Lo- calised emitters recombine considerably slower and also dark excitons have a lifetime up to 3 orders of magnitude longer. In the time domain, low temperature measure- ments on high quality samples allow spectrally isolating each transition (either with bandpass filters or with a spectrometer) and then studying the emission dynamics of each optical transition separately [78, 121, 139].
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