Amorphous thin film materials in the LiPON ( 1 ) or LiSiPON ( 2 ) systems have been prepared for the first time in the early 1990s using magnetron sputtering. Since then, LiPON materials have been used as state-of-the-art solid electrolytes into all-solid-state thin film micro-batteries thanks to their outstanding properties (electrochemical stability vs Li°, wide electrochemical stability window of ~[4-0] V vs. Li + /Li 0 , isotropic and homogeneous medium, beneficial mechanical properties (3) , very low electronic conductivity). The ionic conductivity of LiPON prepared from Li 3 PO 4 targets remains rather moderate, reaching a maximum of 3.10 -6 S.cm -1 at room temperature. However, it has recently been demonstrated that the introduction of SiO 2 as a second glass former can increase this value up to 2.10 -5 S.cm -1 , and also that the ionic conductivity of these compounds does not increase steadily with their Li content. (4) This highlights the convoluted effects of mixed formers ( 5 ) (Si, P, B...), mixed anions (6) (O, N, S...) and Li concentration on the ionic conductivity. Nevertheless, the latter are usually observed on limited series of compositions, and barely not studied on large sets of samples, which can limit the understanding of composition-structure-conductivity relationships. In this context the aim of our work was to build a High Throughput Screening (HTS) approach to explore the Li x Si y P z O u N w system as a case study (Fig.1). Indeed, HTS approaches aim to accelerate material breakthrough discovery, and to understand beyond the material mechanisms. In material science, the goal is to accelerate the discovery of new keys organic, inorganic or composite materials. It may also bring beyond ‘classical’ iterative method regarding the study of complex systems (ternary, quaternary...) ( 7 ) . To do so, wide ranges of material libraries are synthesized, prior to be tested through an automated characterization workflow. Our specific approach starts with the preparation of material libraries by combinatorial synthesis using magnetron co-sputtering with tilted targets, then goes through automated and fast characterizations targeting specific properties, relevant to its application as ionic conductor. Deposition of thin films displaying composition and thickness gradients at the surface of a 4’’ silicon substrate is achieved by co-sputtering three target materials in a pure Ar or N 2 atmosphere. Deposition through a shadow mask allows to discretize the continuum and to prepare a library of 76 separate Li x Si y P z O u N w samples in one experiment. Then, by tuning the sputtering parameters (i.e discharge gas, gas pressure, incident power, target tilt, target-to-substrate distance,...) different compositional domains can be explored. Relevant automated characterization techniques are then applied to the material library spread on the 4’’ substrate. For the assessment of these amorphous ionic conducting films, dimensional (thickness), physical-chemical (composition & local structure) and functional properties (ionic/electronic conductivities) are studied.In this sequence, determining the composition of the thin film is a real challenge due to a number of requirements :(i) light elements analysis, especially lithium; (ii) need of localized analysis (mapping) on few mm² over large substrate (4” wafer); (iii) scarce material quantity available (~ μg) and finally (iv) fast analysis. Over lab-scale techniques available, only Laser Induced Breakdown Spectroscopy technique (LIBS) seems to fulfil all these requirements. To this purpose, LIBS is developed as a HTS mapping technique for chemical analysis. A sample calibration approach is implemented through coupling with robust chemical analysis techniques (RBS, NRA, ICP-OES, SEM-EDS). In short, this specific HTS procedure will be discussed and results about composition-structure-conductivity relationships in the LiSiPON system will be presented (Fig.2). References J. B. Bates et al. , J. Power Sources . 43 , 103–110 (1993). N. J. Dudney, J. B. Bates, J. D. Robertson, J. Vac. Sci. Technol. A . 11 , 377–389 (1993). A. S. Westover et al. , Chem. Mater. 35 , 2730–2739 (2023). T. Famprikis, J. Galipaud, O. Clemens, B. Pecquenard, F. Le Cras, ACS Appl. Energy Mater. 2 , 4782–4791 (2019). Y. Su et al. , Phys. Status Solidi B . 254 , 1600088 (2017). N. Mascaraque, J. L. G. Fierro, A. Durán, F. Muñoz, Solid State Ion. 233 , 73–79 (2013). E. J. Amis, X.-D. Xiang, J.-C. Zhao, MRS Bull. 27 , 295–300 (2002). Figure 1

Li-rich layered oxide (Li[LixM1-x]O2, (M = Mn, Ni, Co,...) positive electrode materials are considered as a key component for next generation lithium ion batteries, as they display outstanding specific energy originating from a combination of additional lithium de-intercalation and the unusual oxidation of oxygen anions. Recently we have extended these studies to the homologous titanium sulfides belonging to the LiTiS2 – Li2TiS3 system. Layered Li2TiS3 was obtained for the first time by direct reaction of Li2S on TiS2. Its structure is similar to the Li2MnO3 one, with a small amount of stacking faults. Overlithiated compositions (Li[LitTi1-t]S2, (0 < t ≤ 0.33)) were synthesized by direct synthesis from Li2TiS3 and LiTiS2 and structurally characterized. While LiTiS2 exhibits the O1 type sulfur packing, all compositions with ~0.08 < t ≤ 0.33 exhibit the O3 type sulfur packing like the homologous oxides. High resolution HAADF images recorded for the Li2TiS3 end-member reveal that lithium and titanium are fully ordered within the [Li1/3Ti2/3]S2 slabs of the typical honeycomb lattice usually observed for Li-rich layered oxides. Nevertheless, stacking faults are observed along the hexagonal C axis. In the Li[LitTi1-t]S2, (0.08 < t ≤ 0.33) solid solution the honeycomb ordering is observed only in some domains thank to the departure from the ideal ratio required for the ordering. The electrochemical studies shows that up to 1.1 Li per Li[LitTi1-t]S2 can be reversibly cycled with a negligible irreversibility. The high capacity (≈240 mAh/g) and the shape of the charge curves suggest that Ti3+ ions are oxidized in a first step and the S2- ions in a second step to form S2 2- ions. The very small irreversibility results from the easy oxidation of S2- ions, which does not induce any sulfur release from the particle surface and subsequent structural densification. The XPS study of the deintercalated material confirms the formation of S2 2- species. Contrary to oxides, there is a very small fading and voltage decay upon cycling. This behavior suggests that there is no significant structure modification as it is observed in lithium-rich oxides. In a particular composition range, they exhibit high electrochemical performance with a reversible capacity and an energy density exceeding respectively 265 mAh·g-1 and 600 Wh·kg-1, a very low irreversible capacity in the first cycle, fast activation and a limited voltage decay. Their operation potential within the electrochemical stability window of sulfide-based fast ionic conductors makes them promising cathode materials for all-solid-state lithium and Li-ion batteries.

Over the last decades, the development and the miniaturization of portable electronic devices have stimulated many researches in the field of micro power sources. In this context, all-solid-state microbatteries have been developed and are currently commercialized for room temperature applications [1]. The thermal stability of the LiPON ceramic electrolyte used in these microbatteries suggests that they could be used for powering autonomous sensors located in harsh environment, and particularly those exposed to high temperatures (typically 200 °C) [2]. In order to estimate the sustainability of standard microbatteries LiCoO2/LiPON/Li at high temperature, the thermal stability of the positive electrode material and its compatibility with the LiPON electrolyte have been studied. Lithium cobalt oxide is the most used material for positive electrode in microbatteries. Its thermal stability was investigated for the first time by Dahn et al. [3] who showed that LixCoO2 materials start to decompose above 200 °C. Ever since, only few studies have evaluated their intrinsic thermal stability, i.e. without electrolyte and in airtight conditions, but never over extended periods of time and at lower temperatures. Here, LixCoO2 compounds with various compositions (0.452 powder using a NO2BF4 [4]. ICP-OES and XPS were used to determine the Li/Co ratio and the oxidation state of cobalt respectively. XRD and Raman spectroscopy analyses, conducted in air-tight cells, were achieved to characterize the structural evolution of the pristine delithiated samples. Their thermal stability was firstly evaluated by DSC in sealed crucible. For all the delithiated phases, an exothermic peak linked to the decomposition of the structure accompanied by oxygen loss is observed above 200 °C [3,5]. Long term thermal stability under argon atmosphere was assessed for temperatures ranging from 100 °C to 200 °C, by XRD and Raman spectroscopy. LixCoO2 compounds start to evolve from 100 °C to form a HT-LiCoO2 phase and a spinel Co3O4-like one. In situ XRD temperature analyses were achieved under helium atmosphere to study the decomposition mechanism of the LixCoO2 compounds. The kinetics of the decomposition reaction was followed by in situ XRD isothermal measurements. Kinetics parameters and model function were determined by conventional [6] and Coats-Redfern methods [7]. Identification of decomposition products at 200 °C was carried out by combining XRD, TEM, Raman, XPS and 7Li NMR spectroscopies. All these results suggest that the spinel phase is partially lithiated in this temperature range (100-200°C), whereas HT-LiCoO2 and Co3O4 were clearly identified as decomposition products at higher temperature (600 °C) in agreement with prior studies [3]. The decomposition mechanism appears therefore more complex than the previously reported one. The presence of lithium vacancies destabilizes to the layered structure which collapses locally to form a spinel-like phase due to cobalt moving into the vacancies. Given the ionic radius of cobalt, its presence in the interslab space traps some lithium in the spinel-like phase. At the same time, the major part of remaining lithium tends to segregate in other parts of the crystals where it re-stabilizes the layered scaffold. Raman spectroscopy analyses carried out on LixCoO2 films prepared by magnetron sputtering and delithiated in coin cells, showed that thin films exhibit the same thermal behaviour as bulk compounds. In parallel, LiCoO2/LiPON interface was studied before and after annealing at 200 °C. Thin film bilayers of LiCoO2 (5 µm)/LiPON (3 µm) were prepared by magnetron sputtering. GD-OES and ToF-SIMS analyses were achieved post deposition and after high temperature annealing under argon atmosphere. For pristine bilayers, a 500 nm lithium-rich interphase is observed [8,9]. A marked growth of this interphase, accompanied by phosphorous diffusion into the latter is highlighted for annealed samples. References: [1] Y. Wang et al., J. Power Sources, 286 (2015) 332 [2] L. Li et al., Ionics, 23 (2017) 1451 [3] J. Dahn et al., Solid State Ionics, 69 (1994) 265 [4] D. Mohanty et al., Solid State Ionics, 194 (2011) 41 [5] Y. Baba et al., Solid State Ionics, 148 (2002) 311 [6] A. Khawam et D. R. Flanagan, J. Pharma. Sci., 95 (2006) 472 [7] A. W. Coats and J. P. Redfern, Nature, 201 (1964) 68 [8] M. Fingerle et al., Chem. Mater., 29 (2017) 7675 [9] A. Uhart et al., Appl. Mater. Interfaces, 9 (2017) 33238 Figure 1

Among the different cutting-edge solutions currently under investigation, lithium metal technologies have received a renewed interest. Thorough research work is currently carried out to enhance the safety and cyclability of the lithium metal electrode, targeting high energy post-Li-ion systems such as the lithium/sulfur technology. This study aims at investigating different inorganic protective layers that could be placed at the surface of the lithium metal electrode in a lithium/sulfur system, in order to prevent the detrimental interactions with polysulfide species and electrolyte components. The chemical stability of the selected inorganic materials (amorphous thin films, crystalline ceramics and glass-ceramics) towards ether-based (polysulfides-containing) electrolytes was studied. Although being crucial for long term cycling of Li/S cells, this issue has not been addressed so far. The chemical composition and morphology of the different materials after immersion in different electrolytes were characterized by X-ray diffraction, XPS and SEM, and the most promising materials were evaluated in Li/S cells.

In the context of efforts to develop at the same time high energy density cathode materials for lithium-ion batteries with low content of critical elements such as cobalt and new cell chemistries for all-solid-state batteries, a novel family of lithium-rich layered sulfides (Li[LitTi1-t]S-2, 0 < t <= 0.33) belonging to the LiTiS2 - Li2TiS3 system was investigated as intercalation materials. These sulfides, in which both cations and anions are involved in the redox process, display common features with isotype Li-rich layered oxides (Li[LixM1-x]O-2, M = Mn, Ni, Co,center dot center dot center dot). In a particular composition range, they exhibit high electrochemical performance with a reversible capacity and an energy density exceeding respectively 265 mAh.g(-1) and 600 Wh.kg(-1), a very low irreversible capacity in the first cycle, fast activation and a limited voltage decay. Their operation potential within the electrochemical stability window of sulfide-based fast ionic conductors makes them promising cathode materials for all-solid-state lithium and Li-ion batteries.

The current commercial standard thin film electrolyte LiPON is the limiting factor for the further development of microbatteries due to its low Li (+) ionic conductivity (2 X 10(-6) S/cm). In order to produce more conductive electrolytes and elucidate the synthesis-properties interrelation for this system, we sputtered thin films from single-phase ceramic targets of composition Li3+xSixP1-xO4 under Ar and N-2 atmospheres. The amorphous thin films produced under Ar (LiSiPO) are more conducting than the crystalline target materials (amorphization effect). Furthermore, the fact that the resulting amorphous films contain both phosphate and silicate building units (mixed-former effect) increases the conductivity to approximately the values of LiPON (10(-6) S/cm). Reactive sputtering under N-2 leads to oxynitride (LiSiPON) thin films with a maximum Li+ ionic conductivity of 2.06 X 10(-5) S/cm (E-a = 0.45 eV), about 1 order of magnitude higher than LiPON, in accordance with previous works. These results are discussed in the context of available literature in order to elucidate the effect of Si:P and Li:(Si + P) compositional ratios on ionic conductivity. Finally, we expose a target-dependent effect of nonstoichiometric, Li-deficient depositions that is a current impediment to sputtering of highly Li+-conductive targets.

Current all-solid-state thin film lithium batteries available on the market are using glassy lithium phosphorus oxynitride (LiPON) as the electrolyte. This ionic conducting material has been considered so far an optimal trade-off in terms of ionic conductivity (10 S·cm at 25°C), chemical reactivity, compatibility with the Li metal anode, and processability for microbattery applications [1]. Recent evolutions towards Li-ion systems and insisting demands for less resistive cells have motivated renewed studies about more conductive (~10 S·cm), but a priori less electrochemically stable materials such as LiSiPO(N) glasses [2-3]. This work reports for the first time the preparation of such materials by radio-frequency magnetron sputtering of single-phase crystalline Li3+xSixP1-xO4 targets (-Li3PO4 Li4SiO4 system [4-5]). Resulting amorphous thin film electrolytes exhibit an enhanced conductivity close to the value of LiPON, due to the presence of both phosphate and silicate building units (mixedformer effect). Reactive sputtering under N2 leads to oxynitride (LiSiPON) thin films with a maximum Li conductivity of 2.1·10 S·cm (Ea=0.42 eV), about one order of magnitude higher than LiPON. The present results are considered in the framework of available literature in order to determine the influence of Si:P and Li:(Si+P) compositional ratios on the ionic conductivity. Parallel to these considerations, the use of highly Li conductive Li3+xSixP1-xO4 targets has revealed significant accumulation of Li3P and Li2O on their surface under the form of thick dark rings, during the sputtering process. The potential origins of this particular phenomenon, its influence on film composition are discussed. Finally, possible variations of the present sputter deposition process to get a better monitoring and stability are proposed.

Solid-state thin film batteries utilize electrode and electrolyte components which are nanometers or micrometers thick, enabling the production of novel devices with new form factors. Here, in situ X-ray diffraction is used to carry out the first study of a solid-state thin film lithium-ion battery containing a solid-state LiPON electrolyte and Bi negative electrode. The structure-electrochemistry relationships in the Li-Bi system are revealed and details of cell construction, data collection, and data analysis is presented to guide for research.

With the aim of developing 3V all-solid-state lithium microbatteries, Fe-2(MoO4)(3) thin films were prepared by radiofrequency magnetron sputtering from a home-made Fe-2(MoO4)(3) target using optimized sputtering conditions. In addition to elemental analyses, Mossbauer spectroscopy and XPS analyses, showing that Mo6+ and Fe3+ are the main detected species, confirmed the stoichiometric character of the films. Post-deposition annealing was necessary to form well-crystallized thin films. The best electrochemical performance was obtained with those annealed at 500 degrees C which were able to deliver a stable reversible capacity close to the theoretical one, i.e. 2 Li+ per Fe-2(MoO4)(3) formula unit. The corresponding voltage curve displays a plateau with a low hysteresis located at 3.0 V/Li+/Li and related to the Fe-2(MoO4)(3) - Li2Fe2(MoO4)(3) two-phase system. Therefore, it was demonstrated for the first time the possible use of Fe-2(MoO4)(3) thin films as positive electrodes for 3 V lithium microbatteries. (C) 2017 Elsevier B.V. All rights reserved.

Iron molybdate thin films are studied here as a possible electrode material for future Li and Na microbatteries working in a lower potential range than currently used systems. Monoclinic Fe2(MoO4)3 thin films are successfully deposited using radio frequency (RF) sputtering and an annealing treatment. The electrochemical behaviour of the obtained electrodes against Li and Na is then studied in a coin cell configuration with liquid electrolytes. The redox processes ruling the insertion/deinsertion of Li+ and Na+ are investigated by means of XPS (X-ray Photoelectron Spectroscopy). The results highlight a different behaviour depending on the alkali, with a better redox reversibility for sodium at the end of the first charge. For subsequent cycles however, improved capacity retention is evidenced for cycling versus lithium as compared to sodium which was attributed to the properties of the SEI layer.

Lithium-rich spinel Li1.2Mn1.8O4 thin film electrodes operated at 3 ViLi(+)/Li are studied by means of X-ray photoelectron spectroscopy (XPS), mainly on the basis of the evolution of the Mn2p XPS peak during the electrode cycling. The analysis of this core peak has long been debated in literature given its complex character. Based on manganese oxide references, MnO (Mn2+), Mn2O3(Mn3+) and Li2MnO3(Mn4+), we propose a deconvolution method to identify each Mn oxidation state. This method is then used for the deconvolution of Mn2p XPS peaks of bulk lithium-rich spinels Li1+xMn2-xO4 (0 <= x <= 0.25) for validation before proceeding to the study of cycled Li1.2Mn1.8O4 thin film electrodes. Electrochemical measurements exhibit significant capacity loss during the first cycle. Based on XPS analyses, this phenomenon could be explained by mechanical breakup of parts of the electrode. A stable behavior during subsequent cycles is then observed. The presence of Mn2+ species (XPS) at the most top surface of the electrode and the significant polarization observed during the discharge illustrate the kinetical limitation of the two-phase reaction, despite the reduced thickness of the electrode material. (C) 2017 Elsevier B.V. All rights reserved.

The current sustained demand for "smart" and connected devices has created a need for more miniaturized power sources, hence for microbatteries. Lithium-ion or "lithium-free" all-solid-state thin-film batteries are adapted solutions to this issue. The capability to carry out spatially resolved chemical analysis is fundamental for the understanding of the operation in an all-solid-state microbattery. Classically cumbersome and not straightforward techniques as TEM/STEM/EELS and FIB preparation methods could be used to address this issue. The challenge in this work is to make the characterization of Li-based material possible by coupling ion-milling cross section preparation method and AES techniques to characterize the behavior of a LiCoO2 positive electrode in an all solid state microbattery. The surface chemistry of LiCoO2 has been studied before and after LiPON deposition. Modifications of the chemical environments characteristic of the positive electrode have been reported at different steps of the electrochemical process. An original qualitative and a semiquantitative analysis has been used in this work with the peak deconvolution method based on real, certified reference spectra to better understand the lithiation/delithiation process. This original coupling has demonstrated that a full study of the pristine, cycled, and post mortem positive electrode in a microbattery is also possible. The ion-milling preparation method allows access to a large area, and the resolution of Auger analysis is highly resolved in energy to separate the lithium and the cobalt signals in an accurate way.

Over the past 25 years, intense research efforts were focused on lithium-ion batteries due to their advantages such as high energy density, high operating voltage and low self-discharge rate. However, their gravimetric energy density that reaches 250 Wh.kg-1 today is still insufficient to meet some requirements, in particular for electric cars and electrified aircrafts. Among possible alternatives, Li/S system seems to be very promising. Indeed, elemental sulfur is characterized by a high theoretical specific capacity of about 1675 mAh.g-1 of sulfur material [1]. The discharge potential is around 2.1 V (vs. Li+/Li), and the complete Li/S system should allow to reach a gravimetric energy density close to 500 Wh.kg-1. Moreover, elemental sulfur is readily available and non-toxic, advantages that should allow to manufacture cheap and safe high energy batteries requirements for instance. However, despite actual progress, this promising system still suffers from several limitations: low discharge capacity, poor cycle life, low coulombic efficiency, high self-discharge and the compulsory use of the highly reactive lithium metal negative electrode, which may lead to dendrites formation, short-circuits and explosions [2]. Most of research works have been devoted to the positive electrode and the electrolyte and in particular to sulfur/carbon composites [3-6] or to the optimization of ether-based electrolyte compositions [7-9]. Regarding inorganic or organic protective coatings on the lithium metal electrode, numerous efforts were achieved on protective coating of lithium metal electrode either for Li/ion batteries or more recently for Li/air secondary batteries. The proposed solutions are mainly dealing with surfactants, polymers and inorganic materialsto protect the electrode and/or to better control the SEI formation. Hence, the use of polyether surfactants such as PEGDME significantly suppresses the inactivation of deposited lithium. Among inorganic materials, LiPON is commonly used to protect the battery electrodes such as lithium [10]. This material is widely used as electrolyte in all-solid-state thin film batteries [11]. The deposition of LiPON on lithium electrode leads to the formation of a stable electrolyte interface which effectively improves the reaction between lithium and the liquid electrolyte, as impedance measurements indicate that LiPON layer is more ionically conductive than the film formed by electrolyte decomposition. Quite recently, LiPON was associated with LATP in Li/air batteries [12-13]. The use of this glass-ceramic electrolyte allows fast ion conduction but necessitates the use of a LiPON interlayer to protect LATP from metallic lithium, the ceramic being not stable in contact with lithium. Only few studies are related to negative electrode in Li/S batteries [14]. This study aims at developing inorganic layers to protect for lithium metal negative electrode in order to prevent the dendrites formation as well as to improve the system performances (increase of the discharge capacity, reduction of self-discharge and shuttle mechanism). Several ceramic electrolyte materials have been developed and tested to prevent the formation of dendrites as well as the contact of lithium metal electrode with the dissolved active materials. Thorough physico-chemical characterizations were carried out on pristine ceramic materials as well as on ceramic after immersion in the liquid electrolyte to check the chemical stability of the latters (ICP, DRX, SEM, impedance measurements, XPS). Finally, the effect of the multilayered inorganic electrolyte on the electrochemical behavior of Li/S cells will be presented. [[1]] B.L. Ellis, K.T. Lee, L.F. Nazar, Chem. Mater. 22 (2010) 691-714 [2] F. Orsini, A. Du Pasquier, B. Beaudoin, J.M. Tarascon, M. Trentin, N. Langenhuizen, E. De Beer, P. Notten, J. Power Sources 76 (1998) 19-29 [3] X. Ji, L.F. Nazar, J. Mater. Chem. 20 (2010) 9821-9826 [4] H. Schneider, A. Garsuch, A. Panchenko, O. Gronwald, N. Janssen, P. Novak, J. Power Sources 205 (2012) 420-425 [5] G. He, X. Ji, L. Nazar, Energy Environ. Sci. 4 (2011) 2878-2883 [6] R. Elazari, G. Salitra, A. Garsuch, A. Panchenko, D. Aurbach, Adv. Mater. 23 (2011) 5641-5644 [7] WO 00/46870, Y.S. Nimon, S.J. Visco, M.Y. Chu, PolyPlus, (2000) [8] J.Z. Wang, L. Lu, M. Choucair, J.A. Stride, X. Xu, H.K. Liu, J. Power Sources 196 (2011) 7030-7034 [9] US 2008/0193835, Y.V. Mikhaylik, Sion Power, (2008) [[1]0] X. Yu, J.B. Bates, G.E. Jellison, F.X. Hart, J. Electrochem. Soc. 144 (1997) 524 [11] F. Le Cras, B. Pecquenard et al., Adv. Energy Mater., 5 (2015) 1501061 [12] S. Hasegawa, N. Imanishi, T. Zhang, J. Xie, A. Hirano, Y. Takeda, O. Yamamoto, J. Power Sources 189 (2009) 371-377 [13] WO 2011/039449, G. Toussaint, P. Stevens, G. Caillon, P. Viaud, C. Cantau, P. Vinatier, (2011) [14] US 08/0113261, C.L. De Jonghe, S.J. Visco, Y.S. Nimon, A.M. Sukeshini, PolyPlus, (2008)