Ether-functionalized ionic liquid electrolytes (ILEs) with fluorinated anions enhance Li+ mobility through the cation's influence on the Li solvation. Herein, we examine how the cationic oxygen position affects its interactions with Li+ at high concentrations of lithium bis(fluorosulfonyl)imide. Advanced nuclear magnetic resonance spectroscopy techniques are employed to probe Li-cation interactions, local oxygen environments, and ion mobilities. In acyclic ether cations, the N-(3-methoxypropyl)-N-methylpyrrolidinium [C3O1mpyr] exhibits more selective coordination and enhanced Li+ diffusivity and transport number relative to 1-methyl-1-(2-methoxyethyl)pyrrolidinium. On the other hand, cyclic ether cations show that Li+ remains closest to the ring oxygen, with 3-ethyl-3-methyl-oxazolidinium [C2moxa] displaying interactions across both the cyclic ether and alkyl chain, whereas 4-ethyl-4-methylmorpholinium presents more localized interactions. Faster Li+ transport was observed in [C3O1mpyr] and [C2moxa], consistent with stronger Li-cation coordination. These results demonstrate that variations in cation structure can have a strong impact on Li+ interactions and ion transport in ILEs.

Halide-enriched lithium argyrodite superionic conductors are considered as promising candidates for all-solidstate batteries due to their soft structure and high ionic conductivity. Challenges remain, including chemical instability and incompatibility with anode materials, and in addition a deeper understanding of the fundamental aspects of ionic transport and performance is required. In this study, we investigated two argyrodite mixed-halide series of compositions, Li6_xPS5_xBrClx and Li5.5PS4.5Br1.5_ xClx. By employing a range of techniques including Xray diffraction (XRD), neutron diffraction, nuclear magnetic resonance (NMR) spectroscopy, electrochemical impedance spectroscopy and machine learning based molecular dynamics, we found that increasing the halide substitution enhances ionic conductivity. Notably, the Li5.4PS4.4BrCl0.6 composition achieves an ionic conductivity of 10 mS/cm, demonstrates superior air stability compared to conventional lithium argyrodites and allows for the fabrication of well-performing all solid-state batteries. Our results reveal that in lithium-poor compositions the lithium environments in the 4a and 4d cages become more alike, facilitating fast long-range lithium-ion transport. This work paves the way for the development of air-stable, high-conductivity sulfide electrolytes, advancing the practical implementation of solid-state batteries.

Over the last decade, anti-perovskites have drawn significant attention as potential solid-electrolytes for solid-state batteries. Due to the increase in consumption of lithium, there has been a push towards next generation batteries, including sodium-ion batteries. The first representative of the material class of sulphate hydride anti-perovskites, Na3SO4H, was synthesized by solid-state methods as a possible electrolyte for sodium solid-state batteries. Structural characterization confirms the results reported in literature with P4/nmm space group Thermal measurements (DSC and TGA) reveal the stability of the material up to 633 K with H2 release beginning shortly after. Here were report the first electrochemical measurements of this new sulphate hydride anti-perovskite with room temperature conductivity of 4.0 x 10-7 S/cm. Similarly, the electronic conductivity was also measured by Direct Current (DC) experiments to understand a non-linear Arrhenius plot of the conductivity. From the EIS and DC measurements, it is suggested that the electronic and ionic conductivities of this material fall in the same range at room temperature. Upon heating, the material becomes a mainly ionic conductor, explaining the change in the activation energy values in the Arrhenius plot (0.83 eV at low T and 0.24 eV at high T). Solid-state NMR hints at defects in the structure that correspond to Na1 and Hb-c-d dynamics.

NMR (Nuclear Magnetic Resonance) spectroscopy is a common analytical technique for analysing electrode materials. Most of these analyses are ex situ NMR measurements, a post mortem analysis of the cell. Yet, development of in situ and operando NMR considerably increased. Since the first in situ measurement reported by Gerald et al [1] in 2000, a large variety of operando NMR approaches have been developed and applied to batteries [2–5].Two levers of improvement remain for operando NMR: the battery-casing design, usually home-made, and the geometry of the NMR resonator used to detect the spectrum. Battery-casing goes from flexible cells in a clear pouch to capsule, Swagelok or coin cells. Home-made casings are usually used to avoid distortion and sensitivity loss in the NMR measurement, attributed to the conductive casings. Another way of improvement is the type of NMR resonator to fit a larger variety of cell geometries. Solenoids, saddle coil, hairpin coil or parallel plates are currently used. Electrochemistry is sensitive to cell fabrication, so home-made cells are intrinsically less reproducible than commercial cells. To increase the repeatability for a higher number of cycles and from one cell to another, we collaborate with a cell maker to get industrial pouch cells and we use commercial protocols. Nevertheless, studying such cells implies new challenges. First, strong and controlled pressure must be applied on the cell. An innovative pressure system was created to be compatible with the NMR requirements, mainly low available space and the absence of magnetic or strongly paramagnetic materials. It also involved adapting the resonator to the commercial cell geometry. The second challenge is the attenuation and distortion of the NMR signal by conductors (skin effect for radio-frequency fields). Recently, Walder [6]. arose our interest with their report on operando NMR measurement for a stainless steel coin cell. We will present measurements that quantify the influence of the components of a commercial battery (casing material, electrodes, current collector and number of stacks). This development and these measurements will lead in close future to performing operando NMR of commercial cells in fast charging conditions (for example on silicon Li-ion batteries). [1] R. E. Gerald et al., J. Power Sources 89, 237 (2000). [2] X. Liu et al., Adv Mater 33, 2005878 (2021). [3] O. Pecher et al., Chem. Mater. 29, 213 (2017). [4] K. Gotoh et al., J. Mater. Chem. A 8, 14472 (2020). [5] K. J. Sanders et al., Carbon 189, 377 (2022). [6] B. J. Walder et al., Sci. Adv. 7, eabg8298 (2021).

Lithium-ion batteries are at the core of the democratisation of electric transportation and portative electronic devices. However, fast and/or low temperature charge induce performance loss, mainly through lithium plating, a degrading mechanism. In this report, 7Li operando Nuclear Magnetic Resonance spectroscopy is used to detect the onset of metastable lithium deposits in an NMC622/graphite cell at 0 degrees C and fast charge. An operando setup, compatible with low temperatures, was developed with special attention to the pressure applied on the electrodes/separator stack and noise reduction to enable early detection and good time-resolution. Direct detection of metallic lithium enables drawing correlations between lithium plating and electrochemical data.

Nuclear Magnetic Resonance (NMR) is a powerful technique to probe the local environment of atoms bearing a nuclear spin. Interfaces in a rechargeable battery, within multi-component electrode or electrolytes or between the electrodes and the electrolyte, are key to its function and lifetime. NMR spectroscopy of the solid phases in the battery participate in the understanding of the processes at these interfaces. The solid-state NMR community is still highly active for ex situ measurements. Dynamic Nuclear Polarization attracted interest thanks to its enhanced sensitivity. In situ spectroscopy and imaging prospered in the context of metallic Li or Na deposition, either as an ageing process in conventional Li or Na batteries, or as the primary process in a metal battery.

Lithium and sodium-ion batteries have become the focal point of interest for the energy transition due to their promising applications for electric cars and energy grid storage. Operando characterization of batteries is critical to understand the degradation processes and increasing their electrochemical performance, especially in abusive conditions like during fast charges. Knowledge of the redox state of each electrode is essential to identify the origins of capacity loss in full batteries. Among the methods used for these investigations, operando Nuclear Magnetic Resonance (NMR) methods are promising since, without destroying the battery, they enable monitoring in real-time the electrochemical processes and the formation of short-lived metastable or reactive phases [1,2]. Up to now, most operando NMR studies have focused on 7Li NMR spectroscopy to follow the lithiation and degradation processes in the solid electrodes of lithium-ion batteries. However, the large shifts and broadenings of the NMR spectra, which result from the redox-active paramagnetic ions (Ni2/3+, Co4+, Mn3/4+) or from the metallicity of the electrodes [3], complicate operando NMR spectra acquisition and interpretation for full batteries. Herein, we demonstrate that the 1H operando NMR signal of the liquid electrolyte solvent can be used to spy on the positive electrode evolution while benefitting from the high sensitivity of 1H liquid-state NMR compared to 7Li NMR. So far, operando NMR using the liquid electrolyte signal was mainly exploited to follow electrolyte decomposition [4] or to image indirectly dendrite formation [5]. Contrary to the lithium or sodium atoms composing the electrodes, hydrogen atoms in the electrolyte solvent are not a direct probe of the state of charge of the electrode. We demonstrate that the 1H NMR signal of the electrolyte molecules in the battery is, however, highly sensitive to the magnetic susceptibility (and therefore the redox state) of the neighboring particles of positive electrode active material. The state-of-charge (SOC) of the positive electrodes in the charging battery can be tracked indirectly through distortion in the spectrum of the dimethyl carbonate (DMC) solvent near the positive electrode. The effect of the other battery components such as current collectors, separators, or even negative electrodes is shown to be negligible compared to the perturbations induced by the positive electrode. We define specific descriptors to track the changes in the distorted 1H NMR spectrum of the battery and we correlate these changes with the state-of-charge of the positive electrode inside the battery as it is charged and discharged. This approach will enable measuring, operando, the redox state of positive electrodes in batteries, even when their 7Li signals cannot be detected by NMR. Exact knowledge of the redox state will contribute to a better exploitation of the electrochemical curves in full batteries. [1] Bagheri, K.; Deschamps, M.; Salager, E. Nuclear Magnetic Resonance for Interfaces in Rechargeable Batteries. Current Opinion in Colloid & Interface Science 2023, 64, 101675. https://doi.org/10.1016/j.cocis.2022.101675. [2] Liu, X.; Liang, Z.; Xiang, Y.; Lin, M.; Li, Q.; Liu, Z.; Zhong, G.; Fu, R.; Yang, Y. Solid‐State NMR and MRI Spectroscopy for Li/Na Batteries: Materials, Interface, and in Situ Characterization. Advanced Materials 2021, 33 (50), 2005878. https://doi.org/10.1002/adma.202005878. [3] Grey, C. P.; Dupré, N. NMR Studies of Cathode Materials for Lithium-Ion Rechargeable Batteries. Chemical Reviews 2004, 104 (10), 4493–4512. https://doi.org/10.1021/cr020734p. [4] Wiemers-Meyer, S.; Winter, M.; Nowak, S. NMR as a Powerful Tool to Study Lithium Ion Battery Electrolytes. Annual Reports on NMR Spectroscopy 2019, 121–162. https://doi.org/10.1016/bs.arnmr.2018.12.003. [5] Ilott, A. J.; Mohammadi, M.; Chang, H. J.; Grey, C. P.; Jerschow, A. Real-Time 3D Imaging of Microstructure Growth in Battery Cells Using Indirect MRI. Proceedings of the National Academy of Sciences 2016, 113 (39), 10779–10784. https://doi.org/10.1073/pnas.1607903113.

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.

The synthesis and characterization of novel alkaline-rich transition-metal chalcogenides is an intriguing task for solid-state chemists and battery researchers. This class of materials allures by its rich compositional variety, high theoretical capacities, and sometimes surprising electrochemistry. Using electrochemically inactive O3-type Li2TiS3 as a starting point, we embark on the synthesis and electrochemical characterization of five novel chalcogenides: Na2TiS3, Na2TiSe3, Na2ZrS3, Na2ZrSe3, and finally Na1.5[Li0.5Ti]S3. All compounds crystallize in the layered O3 structure type but show different electrochemical activities. In particular, Na2TiS3 proves to be an interesting cathode material: the exchange of Li for Na unlocks electrochemical activity and allows for sustained electrochemical cycling of up to 1.8 Na per formula unit. We elucidate the structural evolution of the NaxTiS3 framework during cycling and find a reversible structural transformation from O3 to O1 stacking of the TiS3 octahedral layers. These findings could help understand the origin of anionic redox activity in the materials based on d0 transition metals while opening another direction toward cathode materials comprising solely abundant elements.

Li 3 PS 4 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 P x S ya-moieties and on the transport properties of Li 3 PS 4 , through Raman and impedance spectroscopy measurements. We show that ball-milled Li 3 PS 4 (with no subsequent annealing), which is often regarded as “amorphous/glass/glassy Li 3 PS 4 ”, is not fully amorphous using X-ray diffraction and transmission electron microscopy. Upon subsequent annealing for 1 hour above 190 ° C, β-Li 3 PS 4 is crystallized and our 31 P magic angle spinning nuclear magnetic resonance spectra suggest that 3 distinct PS 43-moieties form, which we refer to as amorphous-, β-and ϒ -type units. Herein, we present a hypothesis to explain the correlation between the ionic conductivity and the distinct PS 43-units as a function of the annealing temperature. Our results consolidate the recent reports noting that crystallization of β-Li 3 PS 4 is not necessary to obtain a high conductivity in ball-milled Li 3 PS 4 . Finally, we introduce a phase mixture between β-Li 3 PS 4 and ϒ -Li 3 PS 4 synthesized at 200 ° C, which is the lowest synthesis temperature yet for ϒ -Li 3 PS 4 .

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(BH4)(NH2), which has been recently reported as a solid-state Mg-ion conductor. In this study, its synthesis parameters are carefully investigated. The formation of an additional phase is reported, whose amount is decreased by optimizing the synthesis parameters and especially by increasing the ball-milling speed. For the first time, B MAS-NMR spectroscopy is applied to this Mg-B-N-H system: it reveals that an additional phase is always present even in an amorphous state. Interestingly, it strongly influences the ionic conduction properties. Indeed, the as-obtained borohydride-amide composite exhibits a high conductivity of 3.10 S.cm at 100°C, one of the highest ever-reported ionic conductivity for a Mg solid conductor at such low temperature.

Monitoring the formation of dendrites or filaments of lithium is of paramount importance for Li-based battery technologies, hence the intense activities in designing in situ techniques to visualize their growth. Herein we report the benefit of correlating in situ electron paramagnetic resonance (EPR) spectroscopy and EPR imaging to analyze the morphology and location of metallic lithium in a symmetric Li/LiPF 6 /Li electrochemical cell during polarization. We exploit the variations in shape, resonance field and amplitude of the EPR spectra to follow, operando, the nucleation of sub-micrometric Li particles (narrow and symmetrical signal) that conjointly occurs with the fragmentation of bulk Li on the opposite electrode (asymmetrical signal). Moreover, in situ EPR correlated spectroscopy and imaging (spectral-spatial EPR imaging) allows the identification (spectral) and localization (spatial) of the sub-micrometric Li particles created by plating (deposition) or stripping (altered bulk Li surface). We finally demonstrate the possibility to visualize, via in situ EPR imaging, dendrites formed through the separator in the whole cell. Such a technique could be of great help in mastering the Li-electrolyte interface issues that plague the development of solid-state batteries.

Expanding the chemical space for designing novel anionic redox materials from oxides to sulfides has enabled to better apprehend fundamental aspects dealing with cationic-anionic relative band positioning. Pursuing with chalcogenides, but deviating from cationic substitution, we here present another twist to our band positioning strategy that relies on mixed ligands with the synthesis of the Li 2 TiS 3-x Se x solid solution series. Through the series the electrochemical activity displays a bell shape variation that peaks at 260 mAh/g for the composition x = 0.6 with barely no capacity for the x = 0 and x = 3 end members. We show that this capacity results from cumulated anionic (Se 2− /Se n− ) and (S 2− /S n− ) and cationic Ti 3+ /Ti 4+ redox processes and provide evidence for a metal-ligand charge transfer by temperature-driven electron localization. Moreover, DFT calculations reveal that an anionic redox process cannot take place without the dynamic involvement of the transition metal electronic states. These insights can guide the rational synthesis of other Li-rich chalcogenides that are of interest for the development of solid-state batteries.

Li-7,P-31, and(19)F solid-state nuclear magnetic resonance (NMR) spectroscopy was used to investigate the local arrangement of oxygen and fluorine in LiVPO(4)F(1-y)O(y)materials, interesting as positive electrode materials for Li-ion batteries. From the evolution of the 1D spectra versus y, 2D(7)Li radiofrequency-driven recoupling (RFDR) experiments combined, and a tentative signal assignment based on density functional theory (DFT) calculations, it appears that F and O are not randomly dispersed on the bridging X position between two X-VO4-X octahedra (X = O or F) but tend to segregate at a local scale. Using DFT calculations, we analyzed the impact of the different local environments on the local electronic structure. Depending on the nature of the VO(4)X(2)environments, vanadium ions are either in the +III or in the +IV oxidation state and can exhibit different distributions of their unpaired electron(s) on the d orbitals. Based on those different local electronic structures and on the computed Fermi contact shifts, we discuss the impact on the spin transfer mechanism on adjacent nuclei and propose tentative signal assignments. The O/F clustering tendency is discussed in relation with the formation of short V-IV(sic)O vanadyl bonds with a very specific electronic structure and possible cooperative effect along the chain.

The growing hydrogen-economy requires accelerating the hydrogen evolution reaction. The water dissociation step (Volmer step) has been proposed as a main kinetic limitation, but the mechanisms at play in the electrochemical double-layer are poorly understood. This is due to the ambivalent role of water: it acts both as a reactant and as a solvent. Here we propose to confine water inside an organic liquid matrix in order to isolate the sole role of water as a reactant. We observe the formation of aqueous-rich nanodomains, which size can be tuned by changing the supporting electrolyte, and found that the reactivity of the system significantly varies with its nanostructure. Depending on the conditions, it is dominated by either the strength of short-range cation-water interactions or the formation of long chains of water molecules. This understanding paves the way toward the development of more efficient and selective electrocatalysts for the water, CO2, O2 or N2 reduction.

Magnetic Resonance in ChemistryVolume 58, Issue 11 p. 987-987 SPECIAL ISSUE EDITORIAL Advances of solid-state NMR spectroscopy in material sciences Anuji Abraham, Corresponding Author Anuji Abraham [email protected] orcid.org/0000-0003-3811-7071 Materials Science and Engineering, Drug Product Development, Bristol Myers Squibb, New Brunswick, NJ, USA Correspondence Anuji Abraham, Materials Science and Engineering, Drug Product Development, Bristol Myers Squibb, 1 Squibb Dr, New Brunswick, NJ 08903, USA. Email: [email protected]Search for more papers by this authorElodie Salager, Elodie Salager orcid.org/0000-0002-5443-9698 CNRS, CEMHTI UPR3079, University Orléans, Orléans, FranceSearch for more papers by this authorDamodaran Krishnan, Damodaran Krishnan orcid.org/0000-0001-8170-9000 Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USASearch for more papers by this authorYongchao Su, Yongchao Su orcid.org/0000-0001-5063-3218 Pharmaceutical Sciences, Preclinical Development, Merck & Co, Inc., Rahway, NJ, USASearch for more papers by this author Anuji Abraham, Corresponding Author Anuji Abraham [email protected] orcid.org/0000-0003-3811-7071 Materials Science and Engineering, Drug Product Development, Bristol Myers Squibb, New Brunswick, NJ, USA Correspondence Anuji Abraham, Materials Science and Engineering, Drug Product Development, Bristol Myers Squibb, 1 Squibb Dr, New Brunswick, NJ 08903, USA. Email: [email protected]Search for more papers by this authorElodie Salager, Elodie Salager orcid.org/0000-0002-5443-9698 CNRS, CEMHTI UPR3079, University Orléans, Orléans, FranceSearch for more papers by this authorDamodaran Krishnan, Damodaran Krishnan orcid.org/0000-0001-8170-9000 Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USASearch for more papers by this authorYongchao Su, Yongchao Su orcid.org/0000-0001-5063-3218 Pharmaceutical Sciences, Preclinical Development, Merck & Co, Inc., Rahway, NJ, USASearch for more papers by this author First published: 01 October 2020 https://doi.org/10.1002/mrc.5086Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume58, Issue11Special Issue: Solid‐State NMRNovember 2020Pages 987-987 RelatedInformation

Organic–inorganic tin(II) halide perovskites have emerged as promising alternatives to lead halide perovskites in optoelectronic applications. While they suffer from considerably poorer performance and stability in comparison to their lead analogues, their performance improvements have so far largely been driven by trial and error efforts due to a critical lack of methods to probe their atomic-level microstructure. Here, we identify the challenges and devise a 119Sn solid-state NMR protocol for the determination of the local structure of mixed-cation and mixed-halide tin(II) halide perovskites as well as their degradation products and related phases. We establish that the longitudinal relaxation of 119Sn can span 6 orders of magnitude in this class of compounds, which makes judicious choice of experimental NMR parameters essential for the reliable detection of various phases. We show that Cl/Br and I/Br mixed-halide perovskites form solid alloys in any ratio, while only limited mixing is possible for I/Cl compositions. We elucidate the degradation pathways of Cs-, MA-, and FA-based tin(II) halides and show that degradation leads to highly disordered, qualitatively similar products, regardless of the A-site cation and halide. We detect the presence of metallic tin among the degradation products, which we suggest could contribute to the previously reported high conductivities in tin(II) halide perovskites. 119Sn NMR chemical shifts are a sensitive probe of the halide coordination environment as well as of the A-site cation composition. Finally, we use variable-temperature multifield relaxation measurements to quantify ion dynamics in MASnBr3 and establish activation energies for motion and show that this motion leads to spontaneous halide homogenization at room temperature whenever two different pure-halide perovskites are put in physical contact.

Monitoring the formation of dendrites or filaments of lithium is of paramount importancefor Li-based battery technologies, hence the intense activities in designing in situ techniquesto visualize their growth. Herein we report the benefit of correlating in situ electron para4 magnetic resonance (EPR) spectroscopy and EPR imaging to analyze the morphology andlocation of metallic lithium in a symmetric Li/LiPF6/Li electrochemical cell during polariza6 tion. We exploit the variations in shape, resonance field and amplitude of the EPR spectrato follow, operando, the nucleation of sub-micrometric Li particles (narrow and symmetricalsignal) that conjointly occurs with the fragmentation of bulk Li on the opposite electrode(asymmetrical signal). Moreover, in situ EPR correlated spectroscopy and imaging (spectral10 spatial EPR imaging) allows the identification (spectral) and localization (spatial) of the sub11 micrometric Li particles created by plating (deposition) or stripping (altered bulk Li surface).We finally demonstrate the possibility to visualize, via in situ EPR imaging, dendrites formedthrough the separator in the whole cell. Such a technique could be of great help in masteringthe Li-electrolyte interface issues that plague the development of solid-state batteries.