[en] Metal binary sulfides (TiS₂, FeS₂), in either powder or thin film forms, were the first studied Li insertion electrodes for rechargeable lithium batteries, with thin films made mainly by sputtering. Here we exploit the equilibrium solubility of molecular sulfur into ionic liquids at its melting point (120 °C), which we estimated to be at a maximum level of 80 mM by both electrochemical and microwave studies, to prepare thin films of both Co₉S₈ and FeS_x showing initial capacities of 559 mAh g⁻¹ and 708 mAh g⁻¹ versus lithium in coin cells, respectively. We demonstrate that the growth of Co₉S₈ films involves the reaction of soluble sulfur with the electrodeposited Co metallic layer, while the formation of FeS_x films enlists a precipitation between the reduced Fe(II) cations and the electrochemically produced S_x^y− species in the ionic liquid bath. Such findings, namely the solubility of sulfur into ionic liquids, open opportunities to electrodeposit sulfur-based compounds as well as capture sulfur from various media enabling a better environment

[en] As it is commonly stated that it would be possible to massively developed renewable energies in order to de-carbonate our energy system by getting rid of fossil and nuclear energies, the authors recall and discuss some facts. They outline that the solution depend on geographical and climatic constraints which are proper to each country, that renewable energies only represents about a quarter of our consumption and raise the problem of intermittency. Moreover, the present status of energy storage technology does not provide a viable and possible solution, and is still to be further developed. They also outline problems faced in Germany where coal fired plants had to be created to solve issues of electricity availability. They outline that France is one of the less carbon-emitting country, due to the importance of nuclear energy. Thus, they outline that realistic scenarios must be proposed in which nuclear will still have its role in a de-carbonated system, and with investments in basic, technological and industrial research on various fields (nuclear wastes and safety, energy storage, CO_2 capture and sequestration)

[en] Intermetallic phases Li-Sn were synthesized by ball-milling and characterized for their structures and electrochemical performances. All phases in Li-Sn binary phase diagram were identified by ¹¹⁹Sn Moessbauer spectroscopy, used as reference materials for the study of lithium insertion into tin-based electrode materials. The observed spectra show two distinct environments of tin; the Sn-rich phases and the Li-rich phases. An example of electrochemical properties of these phases is proposed for Li₂₂Sn₅. Irreversibility of the first cycle is related to the structural change (3D^→2D) of this phase.

[en] Li-rich layered chalcogenides have recently led to better understanding of the anionic redox process and its associated high capacity while providing ways to overcome its practical limitations of voltage fade and irreversibility. This study reports on the feasibility of triggering anionic activity in Li${}_2$TiS${}_3$, through anionic substitution (Se for S) or cationic substitution (Fe for Ti). Herein, the chalcogenide chemical space is further explored to prepare mono-substituted Li${}_{1.7}$Ti${}_{0.85}$Mn${}_{0.45}$Ch${}_3$ (Ch = S/Se) and doubly substituted cationic and anionic phases (Li${}_{1.7}$Ti${}_{0.85}$Fe${}_{0.45}$S${}_{3-<!--\; ???\; -->z}$Se${}_z$) which crystallize either in the O3- or O1-type structures depending upon substituents. All series show a bell-shape capacity variation as function of the transition metal (TM) substitution degree with values up to 240 mAh g${}^{-<!--\; ???\; -->1}$. For specific compositions, a structural O3 to O1 phase transition is observed upon Li removal, which is not reversible upon Li re-insertion due to kinetic limitations and negatively affects long-term cycling performance. Density functional theory (DFT) calculations confirm the O3/O1 relative stability along the different series and point subtle electronic differences in the TM-doping, rationalizing the structural and electrochemical behaviors of these phases upon cycling. These findings provide further insights into the link between structural and electronic stability, which is of key importance for designing chalcogenide-based anionic redox compounds. (© 2023 Wiley‐VCH GmbH)

[en] Aiming at improving the durability of anodic electrochromic nickel oxide thin films, Ni-M-O (M = Co, Ta) thin films were grown by pulsed laser deposition (PLD), using optimized conditions, namely room temperature and 10^-1 mbar oxygen pressure. For low Co and Ta contents (<5%), both additions lead to a loss of the [1 1 1] preferred orientation of the NiO rock-salt structure followed by a film amorphization with increasing Ta amount. Among the two series of metal additions (M ≤ 20%), the Ni-Co-O (5% Co) and Ni-Ta-O (10% Ta) thin films show the highest electrochemical performances especially in respect of improved durability. If the enhanced properties are associated with a limited dissolution of the oxidized phase for the Ni-Ta-O system, the opposite trend is observed for the Ni-Co-O system as compared to pure NiO

[en] Ion and electron transport is of paramount importance for solid-state technology and its limitation presently prevents the access to liquid cells performance. Herein, this work tackles this issue by proposing an easily implementable cell design enabling to follow the cathode composite's electronic conductivity evolution, in situ and during cycling. For proof of concept, distinct active material (AM) based composites are studied, namely LiCoO${}_2$ (LCO), LiNiO${}_2$, LiNi${}_{0.9}$Co${}_{0.1}$O${}_2$ (NC 9010), NMC 811, NMC 622, NMC 111 (NMC family: LiNi${}_{1-<!--\; ???\; -->y}$Mn${}_y$Co${}_y$O${}_2$), and Li${}_4$Ti${}_5$O${}_{12}$ (LTO) mixed with Li${}_6$PS${}_5$Cl solid electrolyte (SE). This work shows the feasibility to track AM's phase transitions associated with changes in the material's electronic transport properties. Moreover, this work demonstrates the impact of the Ni content in the various layered oxides, on the interparticle loss of contact at high state-of-charge affecting electronic transport. Lastly, by tuning LTO particle size and morphology, this work shows the effect of primary and secondary particle size on the specific metal-insulator transition pertaining to this material. Altogether, this new testing cell opens-up a broad spectrum of experimental possibilities aiming to access in situ mode key metrics to benefit the optimization of solid-state batteries research. (© 2023 Wiley-VCH GmbH)

[en] Iron fluoride thin films were successfully grown by Pulsed Laser Deposition (PLD), and their physico-chemical properties and electrochemical behaviours were examined by adjusting the deposition conditions, such as the target nature (FeF₂ or FeF₃), the substrate temperature (T _s ≤ 600 deg. C), the gas pressure (under vacuum or in oxygen atmosphere) and the repetition rates (2 and 10 Hz). Irrespective of the FeF₂ or FeF₃ target nature, iron fluoride thin films, deposited at 600 deg. Cunder vacuum, showed X-ray diffraction (XRD) patterns corresponding to the FeF₂ phase. On the other hand, iron fluoride thin films deposited at room temperature (RT) from FeF₂ target were amorphous, whereas the thin films deposited from FeF₃ target consisted of a two-phase mixture of FeF₃ and FeF₂ showing sharp and broad diffraction peaks by XRD, respectively. Their electrochemical behaviour in rechargeable lithium cells was investigated in the 0.05-3.60 V voltage window. Despite a large irreversible capacity on the first discharge, good cycling life was observed up to 30 cycles. Finally, their electrochemical properties were compared to the ones of iron oxide thin films

[en] To secure its future and that of the planet, humanity must find alternatives to oil. But this vital transition toward renewable energy (currently the subject of a national debate in France), is highly dependent on the development of efficient storage solutions. Today's technologies make it relatively easy to produce electricity, heat, and even hydrogen, but their long-term storage remains a daunting scientific and technical challenge-a high priority for CNRS researchers

[en] Solid-state batteries are enjoying a regained interest owing to the discovery of sulfide-based solid electrolytes with ionic conductivities comparable to their liquid counterparts. Among them, the metastable β-Li${}_3$PS${}_4$ polymorph has attracted great attention given its high room temperature ionic conductivity (≈0.15 mS cm${}^{-<!--\; ???\; -->1}$) when synthesized via a solvent-mediated route. However, the origin of such a high conductivity together with its structural interplay remains unclear. Herein, an in-depth study of the THF-synthesized nanoporous β-Li${}_3$PS${}_4$ is reported. Synchrotron X-ray diffraction, NMR, and Raman spectroscopy confirm the presence of β-Li${}_3$PS${}_4$ as the only crystalline phase and also reveal an additional amorphous phase and remnant THF. Moreover, a clear dependence of the ionic conductivity of the material on the relative content of its phases is found, the amorphous one being the most conductive. Lastly, high chemical reactivity is found for the nanoporous β-Li${}_3$PS${}_4$ and other phosphosulfide electrolytes toward Li metal, evidenced in the spontaneous ignition when mixed together and further investigated by XRD and XPS. This study, which unveils a hidden side of the THF-synthesized β-Li${}_3$PS${}_4$ and other sulfide solid electrolytes, provides a new insight to the battery community when selecting a proper electrolyte for practical all-solid state batteries. (© 2021 Wiley-VCH GmbH)

[en] To secure its future and that of the planet, humanity must find alternatives to oil. But this vital transition toward renewable energy (currently the subject of a national debate in France), is highly dependent on the development of efficient storage solutions. Today's technologies make it relatively easy to produce electricity, heat, and even hydrogen, but their long-term storage remains a daunting scientific and technical challenge - a high priority for CNRS researchers