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Flax (Linum usitatissimum L.) seed oil, which accumulates in the embryo, and mucilage, which is synthesized in the seed coat, are of great economic importance for food, pharmaceutical as well as chemical industries. Theories on the link between oil and mucilage production in seeds consist in the spatio-temporal competition of both compounds for photosynthates during the very early stages of seed development. In this study, we demonstrate a positive relationship between seed oil production and seed coat mucilage extrusion in the agronomic model, flax. Three recombinant inbred lines were selected for low, medium and high mucilage and seed oil contents. Metabolite and transcript profiling (1H NMR and DNA oligo-microarrays) was performed on the seeds during seed development. These analyses showed main changes in the seed coat transcriptome during the mid-phase of seed development (25 Days Post-Anthesis), once the mucilage biosynthesis and modification processes are thought to be finished. These transcriptome changes comprised genes that are putatively involved in mucilage chemical modification and oil synthesis, as well as gibberellic acid (GA) metabolism. The results of these integrative biology approach, suggest that transcriptional regulations of seed oil and fatty acid (FA) metabolism could occur in the seed coat during the mid-stage of seed development, once the seed coat carbon supplies have been used for mucilage biosynthesis and mechanochemical properties of the mucilage secretory cells.

Motivated by the request to build shape-conformable flexible, wearable and customizable batteries while maximizing the energy storage and electrochemical performances, additive manufacturing (AM) appears as a revolutionary discipline. Battery components such as electrodes, separator, electrolyte, current collectors and casing can be tailored with any shape, allowing the direct incorporation of batteries and all electronics within the final three-dimensional object. AM also paves the way toward the implementation of complex 3D electrode architectures that could enhance significantly the power battery performances. Transitioning from conventional 2D to complex 3D lithium-ion battery (LIB) architectures will increase the electrochemically active surface area, enhance the Li+ diffusion paths, thus leading to improved specific capacity and power performance [1]. Our recent modeling studies [2] involving the simulation of a classical Ragone plot illustrated that a gyroid 3D battery architecture has +158% performance at a high current density of 6C, in comparison to planar geometry. In this presentation, an overview of current trends in energy storage 3D printing will be discussed [3-11]. A summary of our recent works on lithium-ion battery 3D printing via Thermoplastic Material Extrusion / Fused Deposition Modeling will be presented [12-16]. The development of printable composite filaments (Graphite-, LiFePO4-, Li2TP-, PEO/LiTFSI-, SiO2-, Ag/Cu-based) corresponding to each part of a LIB (electrodes, electrolyte, separator, current collectors), and the importance of introducing a plasticizer (polyethylene glycol dimethyl ether average Mn 500 for polylactic acid) as an additive to enhance the printability will be addressed. Printing of the complete LIB in a single step using multi-material printing options, and the implementation of a solvent-free protocol [14] will also be discussed. Second part of this presentation will be dedicated to AM of batteries by means of Vat Photopolymerization (VPP) processes, including stereolithography, digital light processing and two-photon polymerization (offering a greater resolution down to 0.1μm), to print high resolution battery components [10]. Composite resins formulation approaches based on the introduction of solid battery particles or precursor salts will be introduced [17, 18]. Finally, an overview of our ongoing project dedicated to AM of sodium-ion batteries from resources available on the Moon and Mars will be presented. Due to its relative abundance in the Lunar regolith, the development of a composite photocurable resin loaded with TiO2 negative electrode material and conductive additives, to feed a VPP printer, will be discussed [18]. [1] Long et al., Three-dimensional battery architectures, Chemical Reviews 104(10) (2004) 4463-4492. [2] Maurel et al., Considering lithium-ion battery 3D-printing via thermoplastic material extrusion and polymer powder bed fusion, Additive Manufacturing (2020) 101651. [3] Maurel et al., Overview on Lithium-Ion Battery 3D-Printing By Means of Material Extrusion, ECS Transactions 98(13) (2020) 3-21. [4] Ragones et al., Towards smart free form-factor 3D printable batteries, Sustainable Energy & Fuels 2(7) (2018) 1542-1549. [5] Reyes et al., Three-Dimensional Printing of a Complete Lithium Ion Battery with Fused Filament Fabrication, ACS Applied Energy Materials 1(10) (2018) 5268-5279. [6] Yee et al., Hydrogel-Based Additive Manufacturing of Lithium Cobalt Oxide, Advanced Materials Technologies 6(2) (2021). [7] Saccone et al., Understanding and mitigating mechanical degradation in lithium–sulfur batteries: additive manufacturing of Li2S composites and nanomechanical particle compressions, Journal of Materials Research (2021). [8] Tagliaferri et al., Direct ink writing of energy materials, Materials Advances 2(2) (2021) 25. [9] Sun et al., 3D Printing of Interdigitated Li-Ion Microbattery Architectures, Advanced Materials 25(33) (2013) 4539-4543. [10] Maurel et al., Toward High Resolution 3D Printing of Shape-Conformable Batteries via Vat Photopolymerization: Review and Perspective, IEEE Access 9 (2021) 140654-140666. [11] Seol et al., All-Printed In-Plane Supercapacitors by Sequential Additive Manufacturing Process, Acs Applied Energy Materials 3(5) (2020) 4965-4973. [12] Maurel et al., Highly Loaded Graphite-Polylactic Acid Composite-Based Filaments for Lithium-Ion Battery Three-Dimensional Printing, Chemistry of Materials 30(21) (2018) 7484-7493. [13] Maurel et al., Three-Dimensional Printing of a LiFePO4/Graphite Battery Cell via Fused Deposition Modeling, Scientific Reports 9(1) (2019) 18031. [14] Maurel et al., Environmentally Friendly Lithium-Terephthalate/Polylactic Acid Composite Filament Formulation for Lithium-Ion Battery 3D-Printing via Fused Deposition Modeling, ECS Journal of Solid State Science and Technology 10(3) (2021) 037004. [15] Maurel et al., Poly(Ethylene Oxide)-LiTFSI Solid Polymer Electrolyte Filaments for Fused Deposition Modeling Three-Dimensional Printing, Journal of the Electrochemical Society 167(7) (2020). [16] Maurel et al., Ag-Coated Cu/Polylactic Acid Composite Filament for Lithium and Sodium-Ion Battery Current Collector Three-Dimensional Printing via Thermoplastic Material Extrusion, Frontiers in Energy Research 9(70) (2021). [17] Martinez et al., Additive Manufacturing of LiNi1/3Mn1/3Co1/3O2 battery electrode material via vat photopolymerization precursor approach, (submitted). [18] Maurel et al., Vat Photopolymerization Additive Manufacturing of Sodium-Ion Battery TiO2 Negative Electrodes from Lunar In-Situ Resources, (submitted).

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.

International audience; The external seed coat cell layer of certain species is specialized in the production and extrusion of a polysaccharide matrix called mucilage. Variations in the content of the released mucilage have been mainly associated with genetically regulated physiological modifications. Understanding the mucilage extrusion process in crop species is of importance to gain deeper insight into the complex cell wall biosynthesis and dynamics. In this study, we took advantage of the varying polysaccharide composition and the size of the flax mucilage secretory cells (MSCs) to study mucilage composition and extrusion in this species of agricultural interest. We demonstrate herein that flax MSCs are structured in four superimposed layers and that rhamnogalacturonans I (RG I) are firstly synthesized, in the upper face, preceding arabinoxylan and glucan synthesis in MSC lower layers. Our results also reveal that the flax mucilage release originates from inside MSC, between the upper and deeper layers, the latter collaborating to trigger polysaccharide expansion, radial cell wall breaking and mucilage extrusion in a peeling fashion. Here, we provide evidence that the layer organization and polysaccharide composition of the MSCs regulate the mucilage release efficiency like a peeling mechanism. Finally, we propose that flax MSCs may represent an excellent model for further investigations of mucilage biosynthesis and its release.

In this paper, the development of an environmentally-friendly lithium-terephtalate/polylactic acid (Li2TP/PLA) composite filament, for its use, once 3D-printed via Fused Deposition Modeling (FDM), as negative electrode of a lithium-ion battery is reported. Solvent-free formulation of the 3D-printable filament is achieved through the direct introduction of synthesized Li2TP particles and PLA polymer powder within an extruder. Printability is improved through the incorporation of poly(ethylene glycol) dimethyl ether average Mn∼500 (PEGDME500) as plasticizer, while electrical performances are enhanced through the introduction of carbon black (CB). Thermal, electrical, morphological, electrochemical and printability characteristics are discussed thoroughly. By taking advantage of the 3D-printing slicer software capabilities, an innovative route is proposed to improve the liquid electrolyte impregnation within the 3D-printed electrodes.

In this paper, the ability to 3D print lithium-ion batteries through Pmnbspace thermoplastic material extrusion and polymer powder bed fusion is considered. Focused on the formulation of positive electrodes composed of polypropylene, LiFePO4 as active material, and conductive additives, advantages and drawbacks of both additive manufacturing technologies, are thoroughly discussed from the electrochemical, electrical, morphological and mechanical perspectives. Based on these preliminary results, strategies to further optimize the electrochemical performances are proposed. Through a comprehensive modeling study, the enhanced electrochemical suitability at high current densities of various complex three-dimensional lithium-ion battery architectures, in comparison with classical two-dimensional planar design, is highlighted. Finally, the direct printing capability of the complete lithium-ion battery by means of multi-materials printing options processes is examined.

Ferroelectric nanodomains give rise to diffuse X-ray scattering peaks in ultrathin films. Here we study a Pb(Zr0.2Ti0.8)O3/SrTiO3 superlattice, using X-ray diffraction and transmission electron microscopy, We show that both elastic relaxation and ferroelectric nanodomain pattern can contribute to distinct satellite peaks in the X-ray scattering pattern. We show that transmission electron microscopy is required to disentangle elastic relaxation and ferroelectric domain contributions to the in plane X-ray scattering profile.

Additive manufacturing technologies open the way to the direct-integration of electronics and solid-state battery within the final 3D object. Here, a 3D printable polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) filament (2.18 × 10−3 S cm−1 at 90 °C) optimized to be used as solid polymer electrolyte in a lithium-ion battery is produced to feed a fused deposition modeling (FDM) 3D-printer. Due to its relatively poor mechanical properties compared to classical polymer filament such as polylactic acid (PLA), deep modifications of the 3D-printer were implemented in order to facilitate its printability. The solid polymer electrolyte thermal, structural, morphological, mechanical and electrical characterization is reported. Interestingly, using three different electrochemical impedance spectroscopy sample holders (lateral, sandwich and interdigitated-comb), we demonstrate that conductivity values differs for a same sample, highlighting the PEO chains orientation effect on the conductivity measurements.

Artificial (BiFeO3)0.5Λ/(LaFeO3)0.5Λ superlattices have been grown by pulsed laser deposition. The periodicity Λ was varied from 150 A to 25 A and the relative ratio between BiFeO3 (BFO) and LaFeO3 (LFO) is kept constant in each period. X-ray diffraction, transmission electron microscopy, and Raman spectroscopy investigations indicate antiferroelectric-like structures for large periodicity (Λ ≥ 76 A), while Pnma LaFeO3-like structures are observed for small periodicity Λ ≤ 50 A. Room temperature magnetic measurements were obtained by vibrating sample magnetometry and suggest antiferromagnetic ordering with weak ferromagnetism. Temperature dependent x-ray diffraction studies show an important shift of paraelectric-antiferroelectric phase transition scaling with BFO thickness. Strain and size effects explain this behavior and discussion is also made on the possible role of the oxygen octahedral rotation/tilt degree of freedom.

This work describes the influence of a high annealing temperature of about 700C on the Si(substrate)/Si3N4/TiOx/Pt/LiCoO2 multilayer system for the fabrication of all-solid-state lithium ion thin film microbatteries. Such microbatteries typically utilize lithium cobalt oxide (LiCoO2) as cathode material with a platinum (Pt) current collector. Silicon nitride (Si3N4) is used to act as a barrier against Li diffusion into the substrate. For a good adherence between Si3N4 and Pt, commonly titanium (Ti) is used as intermediate layer. However, to achieve crystalline LiCoO2 the multilayer system has to be annealed at high temperature. This post-treatment initiates Ti diffusion into the Pt-collector and an oxidation to TiOx, leading to volume expansion and adhesion failures. To solve this adhesion problem, we introduce titanium oxide (TiOx) as an adhesion layer, avoiding the diffusion during the annealing process. LiCoO2, Pt and Si3N4 layers were deposited by magnetron sputtering and the TiOx layer by thermal oxidation of Ti layers deposited by e-beam technique. Asdeposited and annealed multilayer systems using various TiOx layer thicknesses were studied by scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS). The results revealed that an annealing process at temperature of 700C leads to different interactions of Ti atoms between the layers, for various TiOx layer thicknesses (25–45 nm)., This work was financially supported by FEDER/ COMPETE and FCT funds with the Projects PTDC/ EEA-ELC/114713/2009, PEst-C/QUI/UI0686/2013 and UID/EEA/04436/2013, first author scholarship SFRH/BPD/95905/2013 and second author scholarship SFRH/BD/78217/2011. This work was carried out with the support of the Karlsruhe Nano Micro Facility (KNMF, www.kit.edu/knmf), a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu).

This work reports the fabrication and characterization of lithium cobalt oxide films (LiCoO2) on flexible Kapton® substrate. LiCoO2 is commonly used as cathode of lithium microbatteries but needs an annealing of 700 °C, which is not compatible with most flexible substrates. LiCoO2 films were deposited by reactive RF sputtering followed by an annealing process at 400 °C for 1 h in vacuum and air atmospheres both in silicon and Kapton® substrates. Raman spectroscopy, X-ray diffraction patterns and scanning electron microscopy images were used to evaluate samples crystallinity and morphology. Films fabricated in Kapton® and silicon substrates were compared., This work was financial supported by FEDER/COMPETE and FCT funds with the Project PTDC/EEA-ELC/114713/2009, strategic Project PEst-C/FIS/UI607/2013, PEst-C/QUI/UI0686/2013 and UID/EEA/04436/2013, first author scholarship SFRH/BD/78217/2011 and third author scholarship SFRH/BPD/95905/2013.

(BiFeO3)(1−x)Λ/(LaFeO3)xΛ superlattices (SLs) have been grown using pulsed laser deposition and studied by X‐ray diffraction, transmission electron microscopy (TEM), and Raman spectroscopy. The composition is varied, 0.30 ≤ x ≤ 0.85, while the modulation period Λ is kept constant at about 10 nm. Unit cell doubling signatures typical of orthorhombic Pnma symmetry for x = 0.80 and 0.85 SLs and ¼{011} antiferroelectric PbZrO3‐like reflections in SLs with 0.30 ≤ x ≤ 0.7 are detected by TEM showing a complex structural mixture at the nanoscale level. The Raman spectra confirm these observations and show a change in the SLs from a Pnma LaFeO3‐like spectra for LaFeO3‐rich period to a PbZrO3‐like spectra for BiFeO3‐rich period. Electron–phonon interactions and resonant‐like excitations are also observed in the SLs. A temperature‐dependent X‐ray diffraction investigation shows a large shift of the paraelectric‐antiferroelectric phase transition scaling with the BiFeO3 thickness. This shift is correlated with the strain state and can be explained by a strong interplay between octahedral rotation/tilt and antipolar Bi displacement. Thickness–temperature phase diagram is constructed and differs from previous report showing the extreme sensitivity of the BiFeO3 phase stability to strain effects and rotation/tilt degrees of freedom.

International audience; Tavorite-type compositions offer rich crystal chemistry for positive electrodes in rechargeable batteries, among which LiVIIIPO4F has the highest theoretical energy density (i.e. 655 Wh kg−1). In this article, we report for the first time the synthesis of the related Na-based phase crystallizing in the Tavorite-like structure. Its in-depth structural and electronic characterization was conducted by a combination of several techniques, spanning electron and X-ray powder diffraction as well as infrared and X-ray absorption spectroscopy. The magnetic susceptibility measurement reveals an average oxidation state for vanadium slightly higher than V3+. This slight oxidation is supported by infrared and X-ray absorption spectroscopies which highlight the presence of V4+[double bond, length as m-dash]O vanadyl-type defects leading to an approximated NaVIII0.85(VIVO)0.15(PO4)F0.85 composition. In this material, the profile of the diffraction lines is governed by a strong strain anisotropic broadening arising from the competitive formation between the ionic V3+–F and the covalent V4+[double bond, length as m-dash]O bonds. This material shows a limited extraction of sodium, close to 15% of the theoretical capacity. Indeed, its electrochemical properties are strongly inhibited by the intrinsic low sodium mobility in the Tavorite framework.

International audience; All-solid-state Li/LiPONB/TiOS microbatteries were manufactured at the pilot scale on silicon substrate. In a first attempt, the characterization of the active materials constituting the microbattery was achieved in order to determine their accurate composition, structure and morphology. Finally, a thorough electrochemical characterization was carried out on all-solid-state cells. Excellent performances were noted in terms of cycle life (with more than 1000 cycles), efficiency and self-discharge (less than 5% per year). In addition, the positive electrode highlighted a high volumetric capacity close to 90 μAh cm−2 μm−1 when cycled at 100 μA cm−2 between 1 V and 3 V vs. Li+/Li.

Actual parallel-plate architecture of lithium-ion batteries consists in lithium ion diffusion in one dimension between the electrodes. To achieve higher performances in terms of specific capacity and power, configurations enabling lithium ion diffusion in two or three dimensions have been considered (1-5). With a view to build these complex 3D battery architectures avoiding the electrodes interpenetration issues, this work was focused on the Fused Deposition Modeling (FDM). In this presentation, the formulation and characterization of a 3D-printing graphite/polylactic-acid (PLA) filament, specially designed to be used as negative electrode in a lithium-ion battery, and to feed a conventional FDM 3D-printer will be described (6). Graphite loading into the produced filament was increased as high as possible (up to 62.5%wt) to enhance the electrochemical performances while maintaining sufficient mechanical strength to be printed. Formulation process is displayed in Fig. 1a. With such a high ratio of active material, the graphite/PLA filament was found to be very brittle. To overcome this problem, a plasticizer has been added to the PLA matrix to improve its ductility and decrease its stiffness. Influence of the amount of various plasticizers such as propylene carbonate (PC), poly(ethylene glycol) dimethyl ether average Mn~2000 (PEGDME2000), poly(ethylene glycol) dimethyl ether average Mn~500 (PEGDME500) and acetyl tributyl citrate (ATBC) was investigated by performing both differential scanning calorimetry and tensile mechanical tests. On the other hand, printability behavior of the extruded composite filaments was tested by using a commercially available 3D printer. From the optimized plasticizer composition, two-dimensional discs but also high resolution complex three-dimensional structures, such as a semi-cube lattice and a “3Dbenchy” boat, were successfully 3D-printed. Finally, considering this optimized composite, an in-depth study was carried out to identify the electronic percolation (Fig. 1b) and electrochemical impact of carbon black SuperP and carbon nanofibers as conductive additives; electrical conductivities were determined from impedance measurements performed at various stabilized temperatures ranging from 20ºC to 50°C and, in parallel, capacity retention was investigated in detail at different current densities after the different elaboration steps (film before extrusion and disc after printing). Significant progress has been achieved regarding the capacity retention as compared to Foster et al. (7) who was the first group to use FDM technology to 3D-print a negative electrode disc. They were aware that the low specific capacity values reported (15.8 mAh.g-1 at current density of 10 mA.g-1) were unfortunately caused by the use of a filament containing only 8%wt of graphene as active material and 92%wt of PLA. In this work, by increasing the graphite loading up to 62.5%wt, a reversible capacity of 201 mAh.g- 1 at current density of 4 mA.g-1 was achieved for the 3D-printed negative electrode disc by using the most printable filament (Fig. 1c). References: J. W. Long, B. Dunn, D. R. Rolison and H. S. White, Chemical Reviews, 104, 4463 (2004). S. Ferrari, M. Loveridge, S. D. Beattie, M. Jahn, R. J. Dashwood and R. Bhagat, Journal of Power Sources, 286, 25 (2015). H. S. Min, B. Y. Park, L. Taherabadi, C. L. Wang, Y. Yeh, R. Zaouk, M. J. Madou and B. Dunn, Journal of Power Sources, 178, 795 (2008). L. Taberna, S. Mitra, P. Poizot, P. Simon and J. M. Tarascon, Nature Materials, 5, 567 (2006). K. Sun, T. S. Wei, B. Y. Ahn, J. Y. Seo, S. J. Dillon and J. A. Lewis, Advanced Materials, 25, 4539 (2013). A. Maurel, M. Courty, B. Fleutot, H. Tortajada, K. Prashantha, M. Armand, S. Grugeon, S. Panier and L. Dupont, Advanced Energy Materials, (submitted April 2018). C. W. Foster, M. P. Down, Y. Zhang, X. B. Ji, S. J. Rowley-Neale, G. C. Smith, P. J. Kelly and C. E. Banks, Scientific Reports, 7 (2017). Figure 1

The behavior of Li 3 PO 4 and Li 2 MSiO 4 ( M = Mn, Co) compounds under high pressure/high temperature is investigated. Pmn2 1 -Li 3 PO 4 remains stable up to the higher experimental limit of 80 kbar (900 °C). A sample of Li 2 MnSiO 4 consisting of a mixture of Pn2 1 and Pmnb polymorphs converts upon high pressure/high temperature treatment into the Pmn2 1 polymorph; the latter being stable at 80 kbar and 900 °C. A sample of Li 2 CoSiO 4 - P2 1 /n transforms to the denser Pmn2 1 polymorph at 40 kbar/900 °C, but decomposes at higher pressure (60 kbar/900 °C). No evidence on any novel Li 2 MSiO 4 polymorph is detected in any of the high-pressure products.

Electrochemical lithium insertion into two isostructural titanium-based oxides, K 2 Ti 6 O 13 and Na 2 Ti 6 O 13 has been investigated. Although the two compounds differ mainly from their particle size and cell volume, pronounced differences in the insertion mechanism have been evidenced. They can accommodate about three Li per formula unit at relatively low potentials (1.5–0.9 V versus Li reference), which qualifies them as potential alternatives to Li 4 Ti 5 O 12 . The main limitations are their rate capabilities and capacity retention related to large particles and parasitic electrolyte decomposition, respectively.

Rutile type TiO2 nanoparticles (10 nm × 200 nm in size) were prepared using a precipitation method in aqueous solution. Their lithium reactivities were followed using both classical galvanostatic insertion and in situ XRD measurements, and compared to that of a bulk and commercial nano-sized (50 nm) rutile TiO2 sample so as to stress the interlink between Li insertion electrochemical capacity and crystallite size. For the highly divided material, we obtained a reversible capacity of 0.5 Li ion per formula unit after a first reduction step during which, the material is irreversibly transformed. Such a reduction step is shown to enlist two solid solution domains followed by the formation of a rocksalt type phase LiTiO2. Such a specific reactivity of nano-sized rutile TiO2 is explained in terms of better lattice strains accommodation during the insertion of lithium. Keywords: Rutile TiO2, Nanotextured, Li batteries

Analytical high resolution transmission electron microscopy has been used to clearly evidence the electrochemical reactivity of Cr2O3 thin films versus lithium. We showed that during the reduction process, chromium sesquioxide (+III) transforms first into chromium monoxide (+II) and then into metallic chromium nanoparticles embedded into a Li2O matrix at 0 V. On the subsequent recharge up to 3 V, we did not convert back to Cr2O3, but only to a chromium monoxide implying a partial re-oxidation process, thus explaining the irreversibility measured during the first cycle. We extended this study to the comprehension of the electrochemical performances of Cr2O3-based electrodes obtained by thermal treatment, under different atmospheres, of chromium rich stainless steel disks. In addition to the characterization of the particles forming the so-obtained electro-active layers, we showed, using nano-probe EDS, that a mixed “Fe–Cr–O” oxide could react versus lithium, through a conversion reaction mechanism, leading to alloyed metallic nanoparticles upon reduction and nanograins of mixed oxide during the following oxidation.

Nanocrystalline Ce1-xTixO2 (0 ≤ x ≤ 0.4) and Ce1-x-yTixPtyO2-δ (x = 0.15, y = 0.01, 0.02) solid solutions crystallizing in fluorite structure have been prepared by a single step solution combustion method. Temperature programmed reduction and XPS study of Ce1-xTixO2 (x = 0.0−04) show complete reduction of Ti4+ to Ti3+ and reduction of ∼20% Ce4+ to Ce3+ state compared to 8% Ce4+ to Ce3+ in the case of pure CeO2 below 675 °C. The substitution of Ti ions in CeO2 enhances the reducibility of CeO2. Ce0.84Ti0.15Pt0.01O2-δ crystallizes in fluorite structure and Pt is ionically substituted with 2+ and 4+ oxidation states. The H/Pt atomic ratio at 30 °C over Ce0.84Ti0.15Pt0.01O2-δ is 5 and that over Ce0.99Pt0.01O2-δ is 4 against just 0.078 for 8 nm Pt metal particles. Carbon monoxide and hydrocarbon oxidation activity are much higher over Ce1-x-yTixPtyO2 (x = 0.15, y = 0.01, 0.02) compared to Ce1-xPtxO2 (x = 0.01, 0.02). Synergistic involvement of Pt2+/Pt° and Ti4+/Ti3+ redox couples in addition to Ce4+/Ce3+ due t...

International audience; We report the electrochemical study of cubic and monoclinic NiP2 polymorphs toward Li, as a candidate for anodic applications for Li-ion batteries. We found that the monoclinic form is the most attractive one performance-wise. Monoclinic NiP2 can reversibly uptake 5 lithium per formula unit, leading to reversible capacities of 1000 mAh/g at an average potential of 0.9 V vs Li+/Li°. From complementary X-ray diffraction (XRD) and HRTEM (high-resolution transmission electron microscopy) measurements, it was shown that, during the first discharge, the cubic phase undergoes a pure conversion process (NiP2 + 6 Li+ + 6e- f Ni° + 2Li3P) as opposed to a sequential insertion-conversion process for monoclinic NiP2. Such a different behavior rooted in subtle structural changes was explained through electronic structure calculations. Once the first discharged is achieved, both phases were shown to react with Li through a classical conversion process. More importantly, we report a novel way to design NiP2 electrodeswith enhanced capacity retention and rate capabilities. It consists in growing the monoclinic NiP2 phase,through a vapor-phase transport process, on a commercial Ni-foam commonly used in Ni-based alkaline batteries. These new self-supported electrodes, based on chemically made interfaces, offer new opportunities to fully exploit the capacity gains provided by conversion reactions

LiMn2O4 spinels were studied with the aim of assessing the role of different types and amounts of defects in blocking the phase transition from spinel to double hexagonal that is associated with anomalous 4.5 and 3.3/3.95 V redox steps. The influence of the type of MnO2 precursor (β or γ, both with diverse amounts of stacking faults), the effect of introducing defects in the final spinel by ball milling or of cationic subsitutions on the spinel 16d sites (Al or Li) were examined. Electrochemical experiments performed on all these defective samples indicate that defects block the phase transition to a certain extent. The introduction of either Li or Al in spinel 16d sites proved to be the most effective to prevent the structural transformation, and thus eliminate the anomalous redox steps that are detrimental to the electrochemical performances of LiMn2O4.

A brief review of our fundamental studies of the reversible reactivity mechanism of vanadates towards lithium is presented. This mechanism totally differs from the classical one based either on reversible insertion/deinsertion of lithium into host structures or on Li alloying reactions, and has led to the thought of using nanosized transition metal oxides as possible negative electrode materials for rechargeable Li-ion batteries. Electrochemical capacities, as high as 700 mAh/g with a 100% capacity retention up to 100 cycles and high rates, can be achieved with optimized metal oxides (MO, M=Co, Cu, Ni, Fe, etc.) powders. By combining transmission electron microscope (TEM), infrared (IR) and magnetic measurements we directly proved the formation of 10–50 A metal nanoparticles dispersed into a lithia (Li2O) matrix during the reduction step of MO with Li. Upon oxidation, the metal nanoparticles were shown to convert back to MO while Li2O was decomposed. The new opportunities provided by these metal oxides systems based on the reversible formation/decomposition of Li2O are discussed together with the positive attributes that nanoparticles could have to the field of energy storage.

Thin films of composition belonging to the In2O3–ZnO binary system were made by pulsed laser deposition, and characterized by means of X-ray and transmission electron microscopy (TEM) measurements to obtain phase purity and textural/microstructural information. Collected TEM images together with their analysis clearly show that three different types of films could be obtained, depending on the In2O3–ZnO target composition and film growth parameters. The first type, obtained from indium-rich pellets, is made of polyhedral grains having a bixbyite-type structure. The second type, obtained from zinc-rich pellets, presents a classic columnar texture consisting of grains having a wurtzite-type structure, occasionally faulted. The last type of thin films is made of a multitude of ZnkIn2Ok+3 polytypes forming a fibrous texture. The overall EDS analysis evidences that the composition is nearly constant between the target and the film, except for the Zn amount that is always slightly lower in the films. High-resolution electron microscopy studies on films formed of polytypes enable, after a complete image analysis, a simulation of the X-ray diffraction patterns that fit well with the experimental patterns, justifying the validity of our random intergrowth model.

Transmission electron microscopy (TEM) measurements were performed on electrochemically partially delithiated prepared spinel Li 1− x Mn 2 O 4 samples. The potential–composition profile of LiMn 2 O 4 exhibits (besides the two plateaus at 4.05 and 4.1 V) two additional redox steps of identical capacity at 4.5 and 3.3/3.95 V. We found by TEM studies that these extra steps are the signature of a reversible phase transition between LiMn 2 O 4 spinel type structure and a new Li 1− x Mn 2 O 4 double hexagonal (DH) type structure ( a ≈5.8 A, c ≈8.9 A, P 6 3 mc ). The latter is isotypic with DH LiFeSnO 4 . Selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) made it possible to identify the mechanism by which this cubic–DH phase transition occurs within a particle. Based on the structural findings the origin as well as the similar electrochemical capacity of the 3.3/3.95 and 4.5 V anomalies are explained.

With respect to lithium batteries, vanadate-based electrodes display large electrochemical capacities that rapidly decay during the cycling. A full study of the 3d-metal(M)-based vanadates performed using in situ DRX, XAS and TEM has enabled to pinpoint the important role of the 3d-metal cations, and has motivated the study of simple metal oxides MO, (M=Co, Ni, Cu, Fe) in rechargeable Li cells. We found that these materials could reversibly react with a large amount of lithium leading to capacities as high as 800 mAh/g. The reactivity mechanism totally differs from the well established one based on Li insertion-deinsertion or Li alloying reactions but mainly involves the formation of highly reactive metallic nanoparticles that favor Li2O formation-decomposition. Besides, we gave experimental evidence of an electrochemically driven polymerization-dissolution process at low potential, which is highly reversible, and emphasized the importance of the role of the electrolyte on such a process. Finally, the universality of this mechanism to account for the large Li reactivity at low voltage in many 3d-metal (Co, Ni, Fe, Cu, Mn)-based oxides is discussed together with the urgent issues to be solved for such oxide anodes to stand as serious alternative candidates for today’s carbon anodes in Li-ion cells.

We report on the synthesis of an electrochemically active Mg0.9Y0.1Ni polynanocrystalline phase by mechanical alloying. This alloy presents an initial capacity of 323 mAh/g that decreases upon cycling to reach a stable value of 220 mAh/g after 30 complete charge/discharge cycles (e.g. 62% capacity retention). Such an increase in capacity retention with respect to pure MgNi alloy (62% instead of 24%) is due to the addition of yttrium that enhances the resistance of the alloy against corrosion in concentrated alkaline media.

Mixed vanadium-molybdenum oxide hydrates (H x V x Mo 1− x O 3 ·0.26H 2 O with 0.06≤ x ≤0.18) have been synthesized by a soft chemistry method. The phase transitions from one of these hydrates ( x =0.13) to the final product MoO 3 have been studied by thermal analysis, X-ray powder diffraction, and transmission electron microscopy techniques. Both metastable and stable oxides have been observed. H 0.13 V 0.13 Mo 0.87 O 3 ·0.26H 2 O possesses a structure related to hexagonal MoO 3 . Dehydration of the precursor leads to a metastable phase H 0.13 V 0.13 Mo 0.87 O 3 , with a structure similar to that of the hydrate. At 500°C this phase transforms into the metastable V 0.13 Mo 0.87 O 2.935 , with a structure related to the orthorhombic MoO 3 structure. The heating of this last phase above 500°C induces a change from the metastable system to the stable binary (V 2 O 5 –MoO 3 ) one. In agreement with this binary, a liquid phase and a solid phase with a composition closest to MoO 3 , are formed during the phase segregation at 600°C. Models for explaining these phase transitions are proposed.

A mixed vanadium–tungsten oxide hydrate (H0.27V0.27W0.73O3· 1 3 H2O) has been synthesized by a soft chemistry method, and the phase transitions from the hydrate (precursor) to the final product V0.27W0.73O2.865have been studied by thermal analysis, X-ray powder diffraction, and high-resolution electron microscopy (HREM) techniques. Supermetastable, metastable, and stable oxides have been observed. H0.27V0.27W0.73O3· 1 3 H2O possesses a structure related to WO3· 1 3 H2O. Dehydration of the precursor leads to a supermetastable phase, H0.27V0.27W0.73O3, with a structure similar to that of the hydrate. At 350°C this phase transforms to the metastable H0.27V0.27W0.73O3, with a structure isotypic with WO3(hex). The phase transition between the hydrate and H0.27V0.27W0.73O3is both pseudomorphous and topotactic. Removal of hydrogen and oxygen from the metastable oxide induces a second phase transition at 500°C to a more stable phase, V0.27W0.73O2.865, with an oxygen-deficient WO3-type structure. The monoclinic symmetry of the latter oxide increases at higher temperature, first to orthorhombic and then to tetragonal. This transition is not pseudomorphous but of a topotactic nature. The obtained results suggest that the hydrogen content stabilizes the WO3(hex)-related structure of the metastable phase. A hypothetical model based on HREM observations is proposed for the structural transformation H0.27V0.27W0.73O3→V0.27W0.73O2.865.

An investigation of the Nb-Tl-O system has allowed the synthesis of a new phase, Tl{sub 8}Nb{sub 27.2}O{sub 72}. This phase is structurally and chemically close to a Tl-Nb-O phase previously described as a builtup hexagonal bronze with a {approx} 7.4 {angstrom}, b {approx} 13 {angstrom}, c {approx} 7.6 {angstrom}, and an orthorhombic C-type lattice. The electron diffraction study evidences a doubling of the c parameter with regard to the C cell, resulting in an orthorhombic I-type lattice with, in addition, the observation of a second superstructure and twinned microdomains. A structural determination of the mean orthorhombic I-type cell was successfully carried out by combining energy dispersion spectroscopy (EDS) and single-crystal XRD studies and leads to a = 7.534(7) {angstrom}, b = 12.992(12) {angstrom}, c = 15.555(12) {angstrom}, Z = 8, space group Im2m, R = 0.097, and R{sub w} = 0.099 from 995 independent reflections. A chemical formula for this thallium niobate, Tl{sub 8}Nb{sub 27.2}O{sub 72}, consistent with EDS results, was deduced by structure refinement. HREM investigations on this phase clearly show irregular occupancy of the supplementary crystallographic positions by niobium atoms together with a monocommensurate modulated structure and twinned microdomains.

From acid solutions obtained by dissolution of molybdenum or tungsten metal and V2O5in hydrogen peroxide solution, pure and well-crystallized phases have been prepared under the general formula HxVxMo1−xO3·0.3H2O (0.06 ≤x≤ 0.18) and H0.27V0.27W0.73O3·1/3H2O. The former presents an hexagonal structure (for instance, whenx= 0.13,a= 10.6129(5) A,c= 3.7045(3) A, and space groupP63) and the latter is isostructural with orthorhombic WO3·1/3H2O (a= 7.272(1) A,b= 12.573(2) A,c= 7.728(1) A, and space groupFmm2). These phases have been characterized by classic solid state techniques and their thermal behavior has also been studied.

The carbon/electrolyte interface was characterized during galvanostatic cycling at different current densities by means of impedance spectroscopy, semi-in situ transmission microscopy and Fourier-transform infrared spectroscopy (FT–IR). These techniques, carried-out in an inert atmosphere, showed that the formation rate strongly influences both the chemical nature and thickness of this interface; its growth will be detailed using a rate corresponding to the intercalation of one lithium in 20 h.

Mesoporous single crystal (PSC) oxides have been reported as presenting higher electrochemical performances than bulk materials in lithium ion batteries operating via intercalation processes. Here, we extend this study to the electrochemical behaviour of mesoporous Cr 2 O 3 versus Li + /Li 0 . We confirm that the Cr 2 O 3 reacts towards Li through a conversion reaction mechanism leading, upon discharge, to the formation of large metallic chromium nanoparticles (10 nm); the latter are embedded into a Li 2 O matrix together with, in this specific case, a copious amount of polymeric materials coming from electrolyte degradation, surrounding the particles, and filling the pores. During the following charge, re-oxidation of the nanoparticles occurs with the formation of CrO 1− x , with the main difference, as opposed to bulk Cr 2 O 3 electrodes, being the preservation of the polymeric layer at the end of the charge. We believe the material mesoporosity, via capillary effects, to be at the origin of such a difference. These electrolyte degradation products are shown to help in maintaining the material mesoporosity for a great number of cycles; and interestingly they are not detrimental to the cell performance in terms of capacity retention while presenting great advantages in terms of charge transfer by reducing diffusion lengths, namely for Li + ions. The positive attributes of mesoporous material-based electrodes noticed for insertion reactions can then be extended to conversion reaction electrodes as long as we can master their synthesis while controlling their mesoporosity through either soft or hard templating techniques.

International audience; We report on the Li electrochemical reactivity of amorphous and crystalline VP2, synthesized by ball-milling and by 600 °C heat treatment of a ball-milled sample, respectively. The amorphous sample can reversibly react with 3.5 Li per formula unit as compared to solely 2.5 for the crystalline one. However in both cases there is a rapid capacity decay upon cycling that is more pronounced in the case of the crystalline sample. Complementary X-rays, HTREM and NMR tend to show that the Li reactivity mechanism differs from the classical conversion reactions since neither V nanoparticles nor the formation of Li3P were detected, as opposed to some of the other MP2 compounds (M = Ni or Cu). Besides structural phase variations within the 3d metal-based binary phosphide series, the possibility of a change in the nature of the redox centre upon lithiation from cation (M) to anion (P) is evoked.

A multilayer physical vapour DEPOSITION (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD DEPOSITION techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 Ω μm was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour DEPOSITION(CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber., This work was financially supported by FEDER/COMPETE and FCT funds with the projects PTDC/EEA-ELC/114713/2009, PEST-C/QUI/UI0686/2013 and UID/EEA/04436/2013, first author scholarship SFRH/BD/78217/2011, fourth author scholarship SFRH/BPD/95905/2013, and CRUP AI TC-09_14.

Nanocrystalline Ce(1)(-)(x)Ti(x)O(2) (0or = xor = 0.4) and Ce(1-)(x)(-)(y)Ti(x)Pt(y)O(2)(-)(delta) (x = 0.15, y = 0.01, 0.02) solid solutions crystallizing in fluorite structure have been prepared by a single step solution combustion method. Temperature programmed reduction and XPS study of Ce(1)(-)(x)Ti(x)O(2) (x = 0.0-04) show complete reduction of Ti(4+) to Ti(3+) and reduction of approximately 20% Ce(4+) to Ce(3+) state compared to 8% Ce(4+) to Ce(3+) in the case of pure CeO(2) below 675 degrees C. The substitution of Ti ions in CeO(2) enhances the reducibility of CeO(2). Ce(0.84)Ti(0.15)Pt(0.01)O(2)(-)(delta) crystallizes in fluorite structure and Pt is ionically substituted with 2+ and 4+ oxidation states. The H/Pt atomic ratio at 30 degrees C over Ce(0.84)Ti(0.15)Pt(0.01)O(2)(-)(delta) is 5 and that over Ce(0.99)Pt(0.01)O(2)(-)(delta) is 4 against just 0.078 for 8 nm Pt metal particles. Carbon monoxide and hydrocarbon oxidation activity are much higher over Ce(1-)(x)(-)(y)Ti(x)Pt(y)O(2) (x = 0.15, y = 0.01, 0.02) compared to Ce(1)(-)(x)Pt(x)O(2) (x = 0.01, 0.02). Synergistic involvement of Pt(2+)/Pt degrees and Ti(4+)/Ti(3+) redox couples in addition to Ce(4+)/Ce(3+) due to the overlap of Pt(5d), Ti(3d), and Ce(4f) bands near E(F) is shown to be responsible for improved redox property and higher catalytic activity.

International audience; The Li5.5Mn2.5P4 and Li7MnP4 phases having a tetragonal structure (P4/nmm, a ) b ) 4.176(1) Å andc ) 5.978(1) Å) and a cubic structure (Fm3hm a ) 5.968(3) Å) were synthesized by a two-step process consisting in ball milling Li, Mn, and P powders followed by annealing at 800 °C under argon in a sealed stainless steel tube. The resulting materials were tested on Li cells between 0.01 and 2 V. Bothof them can reversibly react with Li, leading to reversible capacities as high as 1000 mAh/g, but only the Li5.5Mn2.5P4 electrode can nicely maintain its initial capacity upon cycling. The origin of such a difference was found in the partial decomposition of Li7MnP4 in Li3P and Mn nanoparticles at low potential, as deduced by in situ X-ray diffraction measurements. In contrast, no decomposition was shown to occur for the Li5.5Mn2.5P4 electrode that shows the best capacity retention among of ternary LixMyP4 (M ) Ti, V) so far studied

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

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