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International audience; Li3PS4 is an attractive solid-electrolyte material that possesses high RT ionic conductivity (10(-4) S.cm(-1) ) but the effects of specific synthesis parameters on the material's local structure and transport properties still demand clarifications. Herein, we highlight the substantial effects of cooling breaks in the mechanochemical synthesis procedure on the formation of a variety of PxSya- moieties and on the transport properties of Li3PS4, through Raman and impedance spectroscopy measurements. We show that ball-milled Li3PS4 (with no subsequent annealing), which is often regarded as ``amorphous/glass/glassy Li3PS4 ``, is not fully amorphous using X-ray diffraction and transmission electron microscopy. Upon subsequent annealing for 1 h above 190 degrees C, beta-Li3PS4 is crystallized and our P-31 magic angle spinning nuclear magnetic resonance spectra suggest that 3 distinct PS43- moieties form, which we refer to as amorphous-, beta-and gamma-type units. Herein, we present a hypothesis to explain the correlation between the ionic conductivity and the distinct PS43- units as a function of the annealing temperature. Our results consolidate the recent reports noting that crystallization of beta-Li3PS4 is not necessary to obtain a high conductivity in ball-milled Li3PS4. Finally, we introduce a phase mixture between beta-Li3PS4 and gamma-Li3PS4 synthesized at 200 degrees C, which is the lowest synthesis temperature yet for gamma-Li3PS4.

International audience; Mg 3 (BH 4) 4 (NH 2) 2 compound was synthesized through the investigation of the Mg(BH 4) 2-Mg(NH 2) 2 phase diagram; its crystal structure was solved in a tetragonal unit cell with the space group I4̅. Interestingly, Mg 3 (BH 4) 4 (NH 2) 2 has a high thermal stability with a decomposition temperature above 190°C and exhibits a high Mg 2+ ionic conductivity of 4.1 × 10 −5 S•cm −1 at 100°C with a low activation energy (0.84 eV). The reversible Mg deposition/stripping was demonstrated at 100°C when using Mg 3 (BH 4) 4 (NH 2) 2 as solid electrolyte. Thus, Mg 3 (BH 4) 4 (NH 2) 2 is a compound that could help to develop rechargeable Mg-ion solid-state batteries.

International audience; Na3PS4 is one of the most promising Na+ conductors, relevant for applications that can leverage its high ionic conductivity, such as solid-state batteries. Currently, two crystalline phases of the material have been identified, and it has been thought to melt above 500 degrees C. In contrast, based on diffraction, ab initio simulations, impedance spectroscopy, and thermal analysis, we show that Na3PS4 remains solid above this temperature and transforms to a third polymorph, gamma, exhibiting fast-ion conduction and an orthorhombic crystal structure. We show that the fast Na+-conduction is associated with rotational motion of the thiophosphate polyanions pointing to a plastic crystal. These findings are of major importance for the development and understanding of new polyanion-based solid electrolytes.

This paper describes the simple, highly reproducible, and robust synthesis of a new solid organic/inorganic electrolyte based on the ionic liquid (IL) 1-butyl-3-(carboxyundecyl)imidazolium bis(trif...

In parallel with the considerable investigations on renewable energy sources, electrical energy storage systems used to store the energy produced now and to provide it when needed have received much attention lately.1 Amongst them, lithium-ion batteries (LIB) are today the most employed in a huge range of purposes including cellphones, laptops or even electric vehicles. Current LIB consists in a planar arrangement (2D) in which the different parts of the battery (positive and negative electrodes, separator, current collectors) are rolled or stacked. Unfortunately, in this type of 2D configuration, lithium ions diffuse only along one dimension. Additive manufacturing (AM) technologies, also called 3D-printing processes, could enable the production of much more complex 3D architectures thus allowing diffusion of the lithium cations towards two or three-dimensions. Advantage of those 3D designs is that the electrochemical active surface area is expected to increase as well as the battery specific capacity and power.2 On the other hand, AM could also allow the direct incorporation of LIB within the final object, thus enabling the possibility to maximize the energy storage capabilities while reducing the dead volume and weight. Amongst the various AM available technologies, we focused our work on the Fused Deposition Modeling (FDM) process using a thermoplastic filament as material source for the 3D-printer. In this presentation, the formulation of composite PLA-based filaments specially designed to print each parts of the LIB (with liquid electrolyte) will be described.3,4 The active material composition within the negative and positive electrodes (graphite and lithium iron phosphate (LiFePO4) respectively), was increased as high as possible in order to enhance the electrochemical performances. Furthermore, the addition of a plasticizer was required to maintain enough mechanical strength while, in the meantime, carbon black was added to confer adequate electrical properties. The impact of ceramic additives on ionic conductivity in the separator was also investigated. From the optimized filaments compositions, stepwise and then “one-shot” 3D-printing of complete LiFePO4/graphite battery cells of any shapes were carried out (Figure 1). In order to prevent short-circuits, classical 3D-printing parameters such as the infill patterns and infill density were investigated for the LIB separator improvement. Finally, this presentation will introduce our latest results5 regarding the printability of a 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. This presentation, by combining both battery and 3D-printing understandings, will tackle various electrochemical (thickness, electronic and ionic conductivity, liquid electrolyte uptake) and 3D-printing parameters (infill density, infill pattern, perimeters, over and under-extrusion, retraction), which clearly paves the way for enhanced 3D-printed LIB. References: [1] Tarascon, J. M. & Armand, M. Issues and challenges facing rechargeable lithium batteries. Nature 414, 359-367, doi:10.1038/35104644 (2001). [2] Long, J. W., Dunn, B., Rolison, D. R. & White, H. S. Three-dimensional battery architectures. Chemical Reviews 104, 4463-4492, doi:10.1021/cr020740l (2004). [3] Maurel, A. et al. Highly Loaded Graphite-Polylactic Acid Composite-Based Filaments for Lithium-Ion Battery Three-Dimensional Printing. Chemistry of Materials 30, 7484-7493, doi:10.1021/acs.chemmater.8b02062 (2018). [4] Maurel, A. et al. Three-Dimensional Printing of a LiFePO4/Graphite Battery Cell via Fused Deposition Modeling. Scientific Reports 9, 18031, doi:10.1038/s41598-019-54518-y (2019). [5] Maurel, A. et al. Poly(Ethylene Oxide)−LiTFSI Solid Polymer Electrolyte Filaments for Fused Deposition Modeling Three-Dimensional Printing. Journal of The Electrochemical Society 167, 070536, doi:10.1149/1945-7111/ab7c38 (2020). Figure 1

The tortuosity factor of porous electrode microstructure is a crucial input parameter for numerical models of batteries as it strongly influences the electrode performance. As such, it is very important to have a method to determine this parameter accurately, based on a definition that reflects the design of the cell. Various experimental methods have been developed for either directly measuring or indirectly inferring the tortuosity factor; however, numerical approaches, based on 3D image data, are now gaining interest in the battery community, due to the advances in nanoscale tomographic imaging methods. The standard definition of the tortuosity factor solves the Fick diffusion equation at steady-state, i.e., between two parallel constant-value boundaries. Although this approach has been widely used for porous materials, including both electronic insulators (e.g., a battery separator), and electronic conductors (e.g., battery porous electrodes), it may be the case that the definition needs to be adjusted depending on the scenario being observed. In this study, we intend to give an insight into the appropriate way to determine the tortuosity factor of battery porous electrodes and the impact of various tortuosity determination methods is investigated. An additional module that relies on the symmetric cell method [1] [2] was implemented in the TauFactor software package [3] to compare with the already-implemented diffusion-based method [4]. This symmetric cell method refers to the measurement of the ionic current distribution inside the pores using AC impedance based on a symmetric cell setup. Figure 1 shows the workflow for tortuosity determination applied in this study. The integration of this module in TauFactor might be interesting for tortuosity determination at the microscale since it is the same method as at macroscopic scale observed in various experimental approaches. Figure 1 . Illustration of the workflow for tortuosity determination applied in this work. The module recently implemented in TauFactor allows calculation based directly on tomographic data in symmetric cell configuration, and generates a simulated impedance spectrum. A macroscopic model such as TLM or Newman’s model is used to extract the tortuosity value of the electrode. References: [1] Landesfeind, J. et al.; J. Electrochem. Soc. 2016, 163 (7), A1373–A1387 [2] Malifarge, S. et al.; J. Electrochem. Soc. 2017, 164 (11), E3329–E3334 [3] Cooper, S. J. et al.; SoftwareX 2016, 5, 203–210 [4] Cooper, S. J. et al.; Electrochimica Acta 251 (2017) 681–689 [5] Pouraghajan, F. et al.; J. Electrochem. Soc. 2018, 165 Figure 1

Reliable electrochemical models are necessary for performing numerical battery-related studies. These models must be comprehended with a number of input parameters. Many literature papers deal with the determination of electrolyte transport properties [1- 4] but only a minority of them proposes an exhaustive characterization (namely the determination of the transference number, the conductivity, the diffusion coefficient and the thermodynamic factor, for the simplest case of a binary electrolyte). Furthermore, when comparison can be made[5], it is often the case that data gathered from different sources for a same electrolyte are not in good quantitative agreement with each other [1,6]. The most commonly used experimental methods for a complete determination of the set of properties are: The Hittorf method [2,3] (for transference number), the restricted diffusion method [7] (for diffusion coefficient), the electrochemical impedance spectroscopy (for conductivity) and the concentration cell (for the activity coefficient). Back in 2016 [6], Farkhondeh and coworkers proposed to alleviate the tedious multi-experimental protocol by introducing a novel multi-electrode cell design, in which the potential between inner Li reference electrodes is measured during and after a current pulse applied between two outer Li working electrodes. The measured potential is free of any electrode polarization and can be fitted with a mathematical model of the electrolyte so that conductivity, salt diffusion coefficient, and lithium transference number are simultaneously determined in single experiment. Our current work builds on the prior art by Farkhondeh and coworkers. It deals with the use of a “multi-electrode electrochemical cell”. Different routes are being explored and will be discussed in the presentation, namely: Using more reference electrodes for the method to gain accuracy, and possibly to evaluate the composition dependence of parameters in a limited number of experiments (fig.1). Bypassing metallic-lithium-related problems by finding alternatives to be used as active electrodes. Theoretical and practical aspects will be discussed and LiPF6 dissolved in 1:1 weight proportions EC:DEC will be investigated as a benchmark electrolyte and compared with already-published data [1]. Our work aims at (i) showing how the parameters evaluation process could be simplified, and (ii) reduce drastically the number of experiments needed for fully characterizing a liquid electrolyte. This is an essential step towards the elaboration of an electrolyte-property database, supplying valuable information for modeling, as well as formulation-engineering, purposes. Fig. 1 : Representation of voltage measured between reference electrodes (blue red and orange crosses), during a current-pulse (black dashed line) of 1.9 A/m² and following relaxation. These experimental data were used to fit the electrolyte transport parameters using a mathematical model (in purple, green and cyan). Determined parameters are the following : . D = 2.85×10-10 m²/s , t+ 0 = 0.217 and κ eff = 0.602 S/m. The gradient-colored strip at the bottom highlights the parts of the signal where the different transport parameters have the largest sensivity. The multi-reference cell is represented in inset: (dark-grey: Li metal reference electrodes, dark grey: polyethylene spacers). References : [1] H. Lundgren, M. Behm, and G. Lindbergh, “Electrochemical Characterization and Temperature Dependency of Mass-Transport Properties of LiPF6 in EC:DEC,” J. Electrochem. Soc., vol. 162, no. 3, pp. A413–A420, 2014. [2] L. O. Valo̸en and J. N. Reimers, “Transport Properties of LiPF[sub 6]-Based Li-Ion Battery Electrolytes,” J. Electrochem. Soc., vol. 152, no. 5, p. A882, 2005. [3] T. Hou and C. W. Monroe, “Composition-Dependent Thermodynamic and Mass-Transport Characterisation of Lithium Hexafluorophosphate in Propylene Carbonate,” Manuscr. Submitt. Publ., p. 135085, 2019. [4] Yanping Ma, Marc Doyle, Thomas F Fuller, Marca M. Doeff, Lutgard C. De Jonghe, and John Newman. The measurement of a complete set of transport properties of a concentrated solid polymer electrolyte solution. Journal of The Electrochemical Society, 142(6):1859–1868, 1995 [5] A. Ehrl, J. Landesfeind, W. A. Wall, and H. A. Gasteiger, “Determination of Transport Parameters in Liquid Binary Electrolytes: Part II. Transference Number,” J. Electrochem. Soc., vol. 164, no. 12, pp. A2716–A2731, 2017. [6] FARKHONDEH, Mohammad, PRITZKER, Mark, FOWLER, Michael, et al. Transport property measurement of binary electrolytes using a four-electrode electrochemical cell. Electrochemistry Communications, 2016, vol. 67, p. 11-15.. [7] Herbert S. Harned and Douglas M. French. A conductance method for the determination of the diffusion coefficients of electrolytes. Annals of the New York Academy of Sciences, 46(1):267–284, 1945 Figure 1

Actual parallel-plate architecture of lithium-ion batteries consists of 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 is considered. With a view to build these complex three-dimensional (3D) battery architectures avoiding the electrodes interpenetration issues, this work is focused on fused deposition modeling (FDM). In this study, the formulation and characterization of a 3D-printable graphite/polylactic acid (PLA) filament, specially designed to be used as negative electrode in a lithium-ion battery and to feed a conventional commercially available FDM 3D printer, is reported. The graphite active material loading in the produced filament is increased as high as possible to enhance the electrochemical performance, while the addition of various amounts of plasticizers such as propylene carbonate, poly(ethylene glycol) dimethyl ether average Mn ∼ 2000, poly(ethylene glycol) dimethyl ether average Mn ∼ 500, and acetyl tributyl citrate is investigated to provide the necessary flexibility to the filament to be printed. Considering the optimized plasticizer composition, an in-depth study is carried out to identify the electrical and electrochemical impact of carbon black and carbon nanofibers as conductive additives. © 2018 American Chemical Society.

International audience; The use of good ionic conductors is a key point in various battery technologies such as Li-air Lithium-Sulfur (Li-S) and All-Solid-State batteries. The determination of the conduction properties as well as the structure in function of temperature and their electrochemical stability are paramount. At the same time, the manufacturing process of these solid electrolytes must be simplified in order to foster the emergence of these technologies. In this context, NASICON-type solid electrolytes LiZr2(PO4)(3) (LZP) and Li1.2Zr1.9Ca0.1(PO4)(3) (LCZP) were synthetized by a new sol-gel method to simplify the synthesis process compared to the solid-state reaction and to reduce the synthesis temperature from 1200 degrees C to 1100 degrees C. The influence of Ca-doping on crystal structure and transport properties was studied in function of temperature and for the first time the electrochemical stability determined. A method, the Phase Inflection Detection (PID), was developed to better determine the transport properties extracted from Electrochemical Impedance Spectroscopy. The ionic conductivity of LCZP is greater than that of LZP by about 2 decades at room temperature due to the stabilization of the high temperature phase at room temperature by Ca-doping, an increase in the number of lithium mobile ions and a better compactness compared with LZP. The impact of sintering temperature and grain boundaries on transport properties is clearly demonstrated and must be taken into account in the future studies of solid electrolytes. The LCZP material is not stable below 0.6 V vs. Li+/Li. It thus presents one of the best electrochemical stabilities, making it a potential candidate for various battery technologies.

International audience; Li4Ti5O12 (LTO) based batteries have severe gassing behavior during charge/discharge and storage process, due to interfacial reactions between active material and electrolyte solution. In the same time, the electronic and ionic conductivity of pristine LTO is very poor and induces the use of nanoparticles which increase the outgassing phenomena. The coating of LTO particles could be a solution. For this the LTO spinel particles are modified with ionic conductor Li3PO4 coating using a spray-drying method. For the first time a homogeneous thin dense layer phosphate based conductor is obtained without nanoparticles, as a thin film material. It is so possible to study the influence of ionic conductor deposited on the negative electrode material on performances by the controlled layer thickness. This coating was characterized by XRD, SEM, XPS and TEM. The electrochemical performance of Li3PO4 coated Li4Ti5O12 is improved at high C-rate by the surface modification (improvement of 30 mAh g(-1) at 5 C-rate compared to pristine LTO for 5 nm of coating), inducing by a modification of surface energy. An optimum coating thickness was studied. This type of coating allows a significant decrease of outgassing phenomena due the conformal coating and opens the way to a great number of studies and new technologies. (C) 2016 Elsevier B.V. All rights reserved.

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.

Solid electrolytes are crucial for next‑generation solid‑state batteries and Na3PS4 is one of the most promising Na+ conductors for such applications. At present, two phases of Na3PS4 have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na3PS4 based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na+ superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on ab initio molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes.

International audience; Nowadays, the development of rechargeable Mg batteries remains a challenge, especially due to the difficulty to find a non-corrosive liquid electrolyte with suitable ionic transport properties. A possible improvement could come from a solid electrolyte, such as Mg(BH 4)(NH 2), which has been recently reported as a solid-state Mg-ion conductor. In this

Despite some progress performed, state-of-the-art lithium ion batteries still require improvements in energy and power to extend the range of electric vehicles and reduce charging time. In this domain, all-solid-state batteries are viable alternatives to conventional batteries employing organic electrolytes because of their benefits, i.e., high power density, high energy density, long-life operation and safety. These advantages stem from the great features of inorganic solid electrolytes, which are single ion conductor, so a high lithium ion transport number, and no-liquid nature. In particular, the sulfide-based solid electrolytes possess favorable mechanical properties, allowing all-solid-state batteries to be easily prepared via simple mixing and cold-pressing processes, facilitating the scale-up. Sulfide-based solid-electrolytes can potentially be employed in conjunction with a lithium metal negative electrode and 5V-class high voltage positive electrode material. Indeed, lithium metal is believed to be the most promising negative electrode due to its specific large capacity (3862 mAh.g-1), low volumetric density (0.534 g.cm-3 at 20°C) and the lowest electrochemical potential (-3.03V vs ENH). Nevertheless, like most metal, lithium metal is morphologically dynamic. Its surface morphology is modified, since during the electrochemical cycling, a part of lithium migrates to the other electrode to react and is then plating on its surface heterogeneously, leading to a volume change and sometimes dendrite growth with potential internal short circuit and life-threatening accidents. Ceramic solid electrolytes have been considered to be the ideal solution to prevent dendrite growth because of their high shear modulus and high lithium transference number. In the same time, the chemical nature and composition of ceramic solid electrolyte can affect the dendrite growth by the interfacial chemical and electrochemical stability with lithium metal forming solid electrolyte interphase as a passivating layer. Since the lithium dendrites have to grow through this layer, its composition should play an important role in the dendrite formation. Moreover, it is known that the stack can be easily deformed because lithium dendrite growth with a high shear modulus, indicating that the solid electrolyte and its interface with lithium metal should be sufficiently strong to endure the pressure originating from lithium dendrite growth. The oxide–based ceramic solid electrolytes can be shaped by sintering at high temperature, leading to a grain and grain-boundary microstructure with some porosity, facilitating the lithium dendrite growth through grain boundaries. Due to the low density and plasticity of sulfide based inorganic solid electrolyte, the dendrite growth through the particle-particle contact can be reduced but still present. Different parameters can influence the lithium dendrite growth and the critical current density in ceramic all-solid-state configuration, such as the solid electrolyte chemical composition, particle size, and the compactness of ceramic solid electrolyte. The pressure effect on the electrochemical performances of sulfide electrolytes was investigated. The pressure affects resistive grain boundaries, contact between lithium metal and solid electrolyte and lithium plating. As, the kinetics of reaction is derived from thermodynamic parameters, the temperature can affect the plating/stripping phenomena. These different parameters and the relationship between them will be presented and explained through complete studies based on sulfide solid electrolytes with the combination of various chemical and electrochemical techniques.

Post Li-ion technologies such as Li-air, lithium sulphur or all-solid-state batteries have in common the use of lithium metal as negative electrode. Known from decades, dissolution and deposition of lithium induce the growth of inactive lithium moss or more critically the dendritic growth that can lead to short circuit phenomenon. Therefore, researchers try to tackle this problem by adding functional layers at the Li surface that may generate an improvement in capacity, lifetime and performances at high current rates. There are different ways to protect lithium such as ALD inorganic coating1,2, grafting of organic materials3,4,5, polymers6 or deposition of inorganic alloys7,8. In this work, by dip coating (a simple and cheap process) a lithium foil into a solution of glyme with phosphorus trichloride (DME-PCl3), we succeeded in obtaining a thin and protective phosphorus-based layer. Through electrochemical characterization techniques (EIS, GITT in 2 or 3 electrodes) and surface characterization techniques (SEM, and more importantly XPS), we were able to determine its morphology and chemical composition, its influence on the lithium plating and stripping processes and the mechanism of lithium diffusion through the protective layer. Cycling results in lithium symmetric cells but also full cells (Li-ion, Li-S) will be presented. Finally, since our results were very promising with lithium, we extended this type of protection to sodium since the reactivity of this metal with electrolyte is ever more pronounced. With the same methodology, we will demonstrate that our protection nicely improves the use of Na metal in liquid cells. 1 A. C. Kozen and al., Next-generation lithium metal anode engineering via Atomic Layer Deposition, acsnano, 2015, 9, 6, 5884-5892 2 C-F Lin, and al., ALD protection of Li-metal anode surfaces – Quantifying and preventing chemical and electrochemical corrosion in organic solvent, Adv. Mater. Interfaces, 2016, 3, 1600426 3 F. Marchioni and al., Protection of lithium metal surfaces using chlorosilanes, Langmuir, 2007, 23, 11598 - 11602 4 S. Neuhold and al., Effect of surface preparation and R-group size on the stabilization of lithium metal anode with silanes, Journal of Power Sources, 2012, 206, 295 -300 5 S. Neuhold and al., Enhancement in cycle life of metallic lithium electrodes protected with Fp-silanes, Journal of Power Sources, 2014, 254, 241-248 6 Y. Liu and al., Lithium-coated polymeric matrix as a minimum volume-change and dentrite-free lithium metal anode, Nature communications, 2016, 7, 10992 7 X. Liang and al., A facile surface chemistry route to a stabilized lithium metal anode, Nature Energy, 2017, 2, 17119 8 L-L. Kong and al., Lithium-Magnesium alloy as a stable anode for Lithium-sulfur battery, Adv. Funct. Mater., 2019, 29, 1808756 9 L. Lin and al., Lithium phosphide/lithium chloride coating on lithium for advanced lithium metal anode, J. Mater. Chem. A, 2018, 6, 15859

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.

The LiM(BH4)3Cl (M = La, Ce, Gd) compounds are prepared by ball-milling followed by annealing and their electrochemical stabilities are investigated. To validate the use of these compounds as solid-state electrolytes, their stabilities versus Li and Li-In alloy are tested in symmetrical cells and their electrochemical stability windows are studied by cyclic voltammetry. We show that LiCe(BH4)3Cl is the more stable phase without any formation of a resistive layer upon cycling. All-solid-state Li-S batteries using a carbon‑sulfur composite as the positive electrode material are then assembled using LiCe(BH4)3Cl as the electrolyte. Reversible electrochemical reaction between Li and sulfur takes place at 45 °C with an initial discharge capacity of 1186 mAh/g of S under a current density of 13 μA/cm2 (i.e. a rate of charge/discharge of C/100). The capacity retention is significant with still a value of 510 mAh/g after 9 cycles showing for the first time the possible use of LiCe(BH4)3Cl as solid electrolyte of Li-S batteries.

International audience; Among polyanionic-based electrode materials developed for Na-ion batteries, one of the most promising families turns out to be Na3V2(PO4)2F3–yOy (0 ≤ y ≤ 2). Here, we present the influence of the oxygen substitution for fluorine on the structural and transport properties of Na3V2(PO4)2F3–yOy, as a function of temperature, through the comparison of the two compositions y = 0 and y = 0.5. An order–disorder phase transition is observed, whatever the content in oxygen, in relation with changes in the ionic conductivity and thus with the mobility of the Na+ ions within the tunnels of the tridimensional structure. The richer the content in oxygen in Na3V2(PO4)2F3–yOy, the higher is the electronic conductivity, in relation with the mixed valence state V3+/V4+ within the bioctahedral units V2O8F3–yOy, and the better are the electrochemical performances in Na-ion batteries.

International audience; All-solid-state-batteries (ASSBs) are one of the most promising post-lithium-ion technologies that can increase the specific energy density and safety of secondary lithium batteries. Solid sulfide electrolytes are considered as promising candidates to be used in ASSBs owing to high ionic conductivities. In particular, solid electrolytes in the Li2S - P2S5 binary system have attracted considerable attention as they are composed of low-cost elements and they provide ionic conductivity values comparable to those of liquid electrolytes (> 10(-4) Scm(-1)). In this review, the structural properties and synthesis methods of materials in the binary system are summarized. Distinctions in local structures and Li-ion conduction properties between glassy, glass-ceramic, and crystalline materials are highlighted. Possible mechanisms are proposed for the fast ionic conduction observed in glass ceramics. Important parameters of each synthesis method are suggested and the relationships between structure, synthesis and material properties are discussed. The goals of this review are to provide greater understanding of the state-of-the-art in the field, and to point out the overlooked aspects for application.

Lithium superionic conductor (LISICON)-related compositions Li4±xSi1-xXxO4 (X = P, Al, or Ge) are important materials that have been identified as potential solid electrolytes for all solid state batteries. Here, we show that the room temperature lithium ion conductivity can be improved by several orders of magnitude through substitution on Si sites. We apply a combined computer simulation and experimental approach to a wide range of compositions (Li4SiO4, Li3.75Si0.75P0.25O4, Li4.25Si0.75Al0.25O4, Li4Al0.33Si0.33P0.33O4, and Li4Al1/3Si1/6Ge1/6P1/3O4) which include new doped materials. Depending on the temperature, three different Li+ ion diffusion mechanisms are observed. The polyanion mixing introduced by substitution lowers the temperature at which the transition to a superionic state with high Li+ ion conductivity occurs. These insights help to rationalize the mechanism of the lithium ion conductivity enhancement and provide strategies for designing materials with promising transport properties.

Secondary batteries capable of efficiently storing and delivering a large amount of electrical energy are essential elements to sustain the constantly increasing development of nomad and mobility technologies. Among the different energy storage systems, the most energetic storage systems which have flood the market are ions batteries (mainly lithium), however they suffer of one major drawback owing to overloads or short-circuits which may cause thermal runaway owing to the combustion of the liquid electrolyte. To make them safer both in use and after disposal, one possibility is to replace traditional liquid electrolyte by solid state electrolytes in the next generations of ion batteries [1]. All-solid-state batteries are capable to have longer life cycle, higher energy density and less requirements on packaging. One of key components that determines performance is solid electrolyte. In the past years many types have been investigated among which figures the types NASICON, perovskite, Argyrodite, anti-perovskite, garnet, LISICON, Li3N, sulfide and many more [2]. Nevertheless, an insufficient room-temperature ionic conductivity (10-5-10-3 σ.cm-1), lithium transport number, and poor electrode-electrolyte interface hinder the reality of these devices [3]. One other promising possibility is to use immobilized or grafted ionic liquids onto the surface of a nanometric material to ensure ion mobility [4]. These new types of hybrid materials, still modestly developed, offer mechanical strength comparable to that of solid polymer electrolytes and have been reported, by our group, to display lithium ion conductivity approaching the standards of liquid electrolytes [5]. Here we present the design of new organic/inorganic hybrid electrolytes based on nanometric zirconium and silicon dioxide and ionic liquid for ion conduction. Immobilization of the ionic liquid was realized using suitable function groups (carboxylic acid or organosilane) which formed with surface atoms a stable interaction. These new materials were carefully characterized by different techniques like FT-IR, TEM, TGA and N2-adsorption to ensure incorporation of the ionic liquid to prove the grafting and estimate the organic content of the synthesized hybrid materials. Additionally, ionic conductivity was measured by Electrochemical Impedance Spectroscopy using a specific new method specifically developed for this type of material and was completed with the determination of the electrochemical stability using cyclic voltammetry. Several parameters like material texture (particle diameter, porosity, shape…), anchoring type, molecular structure of ionic liquid fragments and surface density of the grafting were tuned to maximize ion mobility and so the conductivity. First trends linking hybrid materials structure/composition and ionic conductivity will be presented. [1] Fan, L. et al., Adv. Energy Mater., 2018, 8, 1702657. [2] Takada, K. Acta Mater., 2013, 61, 759–770. [3] Sun, C. et al., Nano Energy, 2017, 33, 363–386. [4] Lu, Y. et al., Adv. Mater., 2012, 24, 4430–4435. [5] Delacroix, S. et al., Chem. Mater., 2015, 27, 7926–7933. Fig 1. New organic/inorganic hybrid electrolytes based ionic liquids Figure 1

International audience; Microbatteries are energy sources well adapted to power various microsystems. To be considered as a microelectronic component, the microbatteries must be compatible with the solder-reflow treatment. During this industrial process, the temperature reaches 260 °C during few seconds. Having noticed an increase of the activation energy of the most used solid electrolyte lithium phosphate thin film (LiPON) after this type of thermal treatment, from 0.57 eV to 0.80 eV, we have investigated the correlations between composition, local structure (by XPS) and the electrical properties of lithium borophosphate solid electrolyte thin films. The lithium borophosphate thin films were prepared by radio-frequency sputtering using five different targets having the following compositions x LiBO2: (1 − x) Li3PO4 (x = 5, 10, 15, 20 and 25) in a pure argon discharge gas. In the absence of a thermal treatment, the addition of a small amount of boron (B/P ratio equal to 0.1) leads to an increase of the ionic conductivity (1.1 × 10− 6 S*cm− 1) and a decrease of the activation energy (0.52 eV) compared to a pure lithium phosphate. However, for B/P ratio higher than 0.12, the ionic conductivity decreases. The study of the local structure by X-ray photoelectron spectroscopy (XPS) shows that the borate groups have less reacted with the phosphate groups leading to a phase separation reducing the connectivity between phosphate and borophosphate networks and so the ionic conductivity. The solder-reflow type thermal treatment leads to an increase of the ionic conductivity. The best ionic conductivity, 1.9 × 10− 6 S*cm− 1, is obtained for a B/P ratio equal to 0.24 with an activation energy of 0.57 eV instead of 0.80 eV for the LiPON thin film. For a use of Li-ion microbattery at low temperature after the solder-reflow type thermal treatment, the lithium borophosphate solid electrolyte would be a potential candidate to replace LiPON with several industrial advantages.

PdAgAu alloy films were prepared on porous stainless steel supports by sequential electroless deposition. Two specific compositions, Pd83Ag2Au15 and Pd74Ag14Au12, were studied for their sulfur tolerance. The alloys and a reference Pd foil were exposed to 1000H2S/H2 at 623 K for periods of 3 and 30 h. The microstructure, morphology and bulk composition of both non-exposed and H2S-exposed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD and SEM analysis revealed time-dependent growth of a bulk Pd4S phase on the Pd foil during H2S exposure. In contrast, the PdAgAu ternary alloys displayed the same FCC structure before and after H2S exposure. In agreement with the XRD and SEM results, sulfur was not detected in the bulk of either ternary alloy samples by EDS, even after 30 h of H2S exposure. X-ray photoelectron spectroscopy (XPS) depth profiles were acquired for both PdAgAu alloys after 3 and 30 h of exposure to characterize sulfur contamination near their surfaces. Very low S 2p and S 2s XPS signals were observed at the top-surfaces of the PdAgAu alloys, and those signals disappeared before the etch depth reached ∼10 nm, even for samples exposed to H2S for 30 h. The depth profile analyses also revealed silver and gold segregation to the surface of the alloys; preferential location of Au on the alloys surface may be related to their resistance to bulk sulfide formation. In preliminary tests, a PdAgAu alloy membrane displayed higher initial H2 permeability than a similarly prepared pure Pd sample and, consistent with resistance to bulk sulfide formation, lower permeability loss in H2S than pure Pd. Fil: Braun, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Miller, James. University of Carnegie Mellon; Estados Unidos Fil: Gellman, Andrew J. University of Carnegie Mellon; Estados Unidos Fil: Tarditi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Fleutot, Benoit. University of Carnegie Mellon; Estados Unidos Fil: Kondratyuk, Petro. University of Carnegie Mellon; Estados Unidos Fil: Cornaglia, Laura Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Microbatteries are energy sources well adapted to power various microsystems. To be considered as a microelectronic component, the latters must be compatible with the solder-reflow process which reaches a temperature of 260 °C during few seconds. In this study, we have investigated the effect of a solder-reflow type thermal treatment on the composition, local structure and electrical performances of the most used solid electrolyte, a lithium phosphorus oxynitride (LiPON). Amorphous thin films of LiPON were prepared by radio-frequency magnetron sputtering from a Li 3 PO 4 target with a pure nitrogen discharge gas. Ionic conductivity increases from 3.0 × 10 − 6 S cm − 1 to 7.2 × 10 − 6 S cm − 1 with the thermal treatment at 260 °C. However, this treatment induces an increase of the activation energy from 0.57 eV to 0.80 eV which is detrimental for a use of the microbattery at low temperature. The study of the local structure by X-ray photoelectron spectroscopy (XPS) shows the break of Li + … − O–P ionic bond and the formation of two new type of species such as Li 2 O and a Li–O–P environment with a covalent bond between lithium and oxygen atoms. This induces a decrease of the charge carrier mobility and so an increase of the activation energy. Nevertheless, as the ionic conductivity is improved, we can expect an increase of the mobile charge carrier density.

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.

International audience; Amorphous thin solid films of lithium phosphorus oxynitride (LiPON) were prepared by radio-frequency sputtering from a Li3PO4 target by varying nitrogen flow rate. The aim of this study is to establish the correlations between deposition conditions, composition, local structure and the electrical properties of the electrolyte (ionic conductivity and activation energy). As expected, ionic conductivity of LiPON thin films increases with nitrogen flow rate reaching a maximum of 3.10−6 S cm−1 while the activation energy reaches a minimum of 0.57 eV. The use of three complementary techniques, X-ray photoelectron spectroscopy, Raman spectroscopy and Nuclear Magnetic Resonance has allowed a thorough investigation of the local structure of the LiPON thin films. The formation of phosphorus-nitrogen bonds in place of phosphorus-oxygen bonds involves two kinds of nitrogen atoms (N1: a nitrogen atom linked to two phosphorus atoms (-N=), and N2: a nitrogen atom linked to three phosphorus atoms (-N

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

International audience; Sputtered vanadium pentoxide thin films have been used as positive electrode in lithium microbatteries and extensively studied after cycling over the 31st galvanostatic cycles by two complementary techniques, especially well-adapted for thin films analysis: X-ray photoelectron spectroscopy and atomic force microscopy. This study is mainly focussed on the characterization of the surface film (solid electrolyte interface-type) which is formed during subsequent discharges and charges and especially on its composition and its morphology that are changing during cycling. First, the growth of a surface layer between the positive electrode and the liquid electrolyte has been evidenced upon the discharge as well as its partial dissolution upon the charge. Secondly, the chemical and topographic changes of this interfacial layer at various stages of cycling are discussed in correlation with the evolution of the discharge capacity over cycles.

The growing interest in hybrid and electric vehicles calls for the development of new safer batteries structures with little or no maintenance. Furthermore, specific requirements such as high temperature (> 100°C) stability in applications in measurement while drilling tools or during medical tools sterilization, force us to avoid the use of liquid electrolyte and to turn to all-solid-state systems. The major advantages of these all-solid-state massive batteries, and thus without solvent, are the thermal stability, the absence of leakage and pollution and the possibility to use high potential electrode materials. These batteries, shaped by Spark Plasma Sintering (SPS) technique, which allows the preparation of dense materials (without additives) at lower temperature, particularly in shorter time (few minutes) than by conventional technique, open the way to an industrial breakthrough. Recent works, particularly in the framework of ANR Ceralion and now within the framework of ANR Solibat including different French laboratories such as LRCS, CEMES, ICMCB, LCP and the SAFT company, showed the feasibility of such batteries with specific systems LiFePO4 (LFP) / Li1.5Al1.5Ge0.5(PO4)3 / Li3V2(PO4)3 (LVP) or LVP / LAGP / LVP. The use of other commercial electrode materials, like LiCoO2 (positive electrode LCO) or Li4Ti5O12 (negative electrode LTO), which is interesting due to its good cyclability at 1.5V vs Li+/Li and its small volume variation during the electrochemical process, proved complex because of their reactivity with the LAGP solid electrolyte. Moreover, the ANR Ceralion study has shown that the performances of these massive all-solid-state batteries are not only governed by the solid electrolyte electrical properties, but also by the properties of the electrode/electrolyte interfaces which can be modified during chemical and/or electrochemical reactions. Indeed, the need to activate the sintering process, despite short heat treatment, causes a detrimental reactivity between materials, as during the sintering of LTO with LAGP. To solve these problems and in particular to use the LTO as active material in the negative composite electrode, it is intended to stabilize the interfaces by limiting the incompatibility between electrode and electrolyte and/or implementation of coating with active materials selected to be chemically inert without introducing other limitations. A dedicated study of coating based insulating phosphate materials such as AlPO4 or Li3PO4 was undertaken as far as these materials result from the electrolyte decomposition with the electrode materials. As these decomposition materials used as coating agent are more stable than the initial materials, it is then possible to avoid the decomposition of certain materials such as LTO and the generation of detrimental interfaces. Different coating routes were tested such as hydrothermal or sol-gel route. Coated materials were characterized by XRD and TEM. Their impact on the active materials cyclability and performances were first tested in liquid electrolyte to optimize them before their integration in all-solid-state batteries. The first promising obtained results will be presented, opening the way for new generations of positive/negative composites combinations and so of all-solid-state batteries with commercial materials allowing the improvement of energy density as well as potential, and thus of aimed applications.

Implementing photovoltaic devices based on high efficiency thin-film technologies on cheap, light-weight and flexible polymeric substrates is highly appealing to cut down costs in industrial production and to accelerate very large scale deployment of photovoltaics in the upcoming years. Lift-off processes, which allow separating active layers from primary substrates and subsequent transfer onto an alternative substrate without modifying the upstream production process and without performance losses, are an emerging alternative to direct growth on polymeric substrates. This study concerns the feasibily of direct mechanical lift-off process for high efficiency Cu(In,Ga)Se2 (CIGS) thin film solar cells grown by coevaporation on glass/molybdenum substrates without performance losses. The study presents an in depth characterization (SEM,AFM,GIXRD,XPS) of samples leading to excellent lift-off properties. They are explained by a specific gallium rich CIGS graded interface structure according to the interfacial sequence glass/Mo/MoSe2/GaxSey/Ga-rich-CIGS. The interfacial layer, attributed to GaSe, has a layered structure and out performs the molybdenum diselenide layered layer which forms spontaneously at the interface Mo/CIGS. It allows a very easy lift-off process at the interface GaSe/CIGS thanks to Van-der-Waals adhesion mechanism in GaSe. Key physical-chemical parameters are identified and analyzed. After lift-off, an efficiency of 14.3%, higher than the initial reference CIGS solar cell efficiency (13.8%) is measured.

Composition spread alloy films (CSAFs) are materials libraries used for high throughput investigations of multicomponent materials such as alloys, AxByC1−x−y. CSAFs are prepared such that the alloy film has a lateral spatial gradient in its local composition; thus, they include a set of alloy samples with a distribution of compositions that spans a continuous region of composition space (x,y). A tool based on the shadow mask concept has been developed for generating composition gradients, but modified to allow rotation of the shadow mask during CSAF deposition. The tool allows deposition of CSAFs containing up to four elements with rotatable shadow masks between each of the four electron beam evaporation sources and the deposition substrate. This allows codeposition of any combination of up to four components. In the case of the ternary AxByC1−x−y CSAFs, the three components can be deposited such that the resulting CSAF spans the entire ternary alloy composition space (x = 0 → 1, y = 0 → 1 − x) and, furthermore, contains all three binary alloys AxB1−x, AxC1−x, and BxC1−x (x = 0 → 1) and all three pure components. The innovation of the rotatable shadow masks also allows preparation of CSAFs that magnify selected regions of the composition space (x = xmin → xmax, y = ymin → 1 − x). Herein, we describe the design and performance of this new CSAF deposition tool and assess its merits and limitations with respect to other methods for CSAF preparation.Composition spread alloy films (CSAFs) are materials libraries used for high throughput investigations of multicomponent materials such as alloys, AxByC1−x−y. CSAFs are prepared such that the alloy film has a lateral spatial gradient in its local composition; thus, they include a set of alloy samples with a distribution of compositions that spans a continuous region of composition space (x,y). A tool based on the shadow mask concept has been developed for generating composition gradients, but modified to allow rotation of the shadow mask during CSAF deposition. The tool allows deposition of CSAFs containing up to four elements with rotatable shadow masks between each of the four electron beam evaporation sources and the deposition substrate. This allows codeposition of any combination of up to four components. In the case of the ternary AxByC1−x−y CSAFs, the three components can be deposited such that the resulting CSAF spans the entire ternary alloy composition space (x = 0 → 1, y = 0 → 1 − x) and, furth...

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