Understanding Lithium-ion conduction mechanisms is key to develop new solid-state electrolytes. However, Li-ion dynamics in glassy electrolytes are intricate and remain unclear due to the challenges in understanding the local structures of glasses. In this work, we probe the Li-ion conduction mechanism in Li2S-P2S5 binary glassy system using the combination of variable-temperature 7Li and 31P NMR relaxometry. The temperature-dependent 31P NMR spin-lattice relaxation measurements show that dynamics of thiophosphate dimers are sluggish in 67Li2S-33P2S5 and 70Li2S-30P2S5 glasses while in 75Li2S-25P2S5 glass, the anionic dynamics are enhanced significantly due to the increased amounts of isolated PS43- units. The energy barrier for 31P rotation is decreased by a factor of ∼2, indicating drastic enhancement in 31P dynamics. We find that the cation and anion motion is highly cooperative in the glassy electrolyte system. The long-range Li-ion diffusion barrier decreases from 0.30 eV in 67Li2S-33P2S5 glass to 0.14 eV in 75Li2S-25P2S5 glass. It is clear that the rapid PS43- rotation can speed up Li-ion migration. Moreover, a large amount of PS43- ions break the rigid networks formed by thiophosphate dimers. This may loosen the glass matrix, expanding Li-ion percolation channels in the 75Li2S-25P2S5 glass.

InP/ZnSe/ZnS core/shell/shell quantum dots are the most investigated quantum dot material for commercial applications involving visible light emission. The inner InP/ZnSe interface is complex since it is not charge balanced, and the InP surface is prone to oxidation. The role of oxidative defects at this interface has remained a topic of debate, with conflicting reports of both detrimental and beneficial effects on the quantum dot properties. In this study we probe the structure of the InP/ZnSe interface at the atomic level using 31P, 77Se and 17O ssNMR and HAADF-STEM. We observe clear differences in Se NMR spectra and crystal orientation of core and shell when the InP/ZnSe is oxidized on purpose. High levels of interface oxidation result in an amorphous phosphate layer at the interface, which inhibits epitaxial growth of the ZnSe shell.

Polymer-in-ceramic composite solid electrolytes (PIC-CSEs) provide important advantages over individual organic or inorganic solid electrolytes. In conventional PIC-CSEs, the ion conduction pathway is primarily confined to the ceramics, while the faster routes associated with the ceramic-polymer interface remain blocked. This challenge is associated with two key factors: (i) the difficulty in establishing extensive and uninterrupted ceramic-polymer interfaces due to ceramic aggregation; (ii) the ceramic-polymer interfaces are unresponsive to conducting ions because of their inherent incompatibility. Here, we propose a strategy by introducing polymer-compatible ionic liquids (PCILs) to mediate between ceramics and the polymer matrix. This mediation involves the polar groups of PCILs interacting with Li+ ions on the ceramic surfaces as well as the interactions between the polar components of PCILs and the polymer chains. This strategy addresses the ceramic aggregation issue, resulting in uniform PIC-CSEs. Simultaneously, it activates the ceramic-polymer interfaces by establishing interpenetrating channels that promote the efficient transport of Li+ ions across the ceramic phase, the ceramic-polymer interfaces, and the intervening pathways. Consequently, the obtained PIC-CSEs exhibit high ionic conductivity, exceptional flexibility, and robust mechanical strength. A PIC-CSE comprising poly(vinylidene fluoride) (PVDF) and 60 wt % PCIL-coated Li3Zr2Si2PO12 (LZSP) fillers showcasing an ionic conductivity of 0.83 mS cm(-1), a superior Li+ ion transference number of 0.81, and an elongation of similar to 300% at 25 degrees C could be produced on meter-scale. Its lithium metal pouch cells show high energy densities of 424.9 Wh kg(-1) (excluding packing films) and puncture safety. This work paves the way for designing PIC-CSEs with commercial viability.

Nanocomposites of complex metal hydrides and oxides are promising solid state electrolytes. The interaction of the metal hydride with the oxide results in a highly conducting interface layer. Up until now it has been assumed that the interface chemistry is independent of the nanoconfinement method. Using Si-29 solid state NMR and LiBH4/SiO2 as a model system, we show that the silica surface chemistry differs for nanocomposites prepared via melt infiltration or ball milling. After melt infiltration, a SiHBH3 complex is present on the interface, together with silanol and siloxane groups. However, after ball milling, the silica surface consists of Si- H sites, and silanol and siloxane groups. We propose that this change is related to a redistribution of silanol groups on the silica surface during ball milling, where free silanol groups are converted to mutually hydrogen-bonded silanol groups. The results presented here help to explain the difference in ionic conductivity between nanocomposites prepared via ball milling and melt infiltration.

Boosting the transport and selectivity properties of membranes based on polymers of intrinsic microporosity (PIMs) toward one specific working analyte of interest is challenging. In this work, a novel family of PIM membranes, prepared by casting and exhibiting optima mechanical properties and high thermal stability, was synthesized from 4,4 '-(2,2,2-trifluoro-1-phenylethane-1,1-diyl) bis(benzene-1,2-diol) and two tetrafluoro-nitrile derivatives. Gas permeability measurements evidenced a CO2/CH4 selectivity up to 170% relative to the reference polymer, PIM-1, in agreement with their calculated fractional free volume and the analysis of the textural properties by N-2 and CO2 gas adsorption. Besides, the chemical modification by acid hydrolysis of the PIM membranes favored the permeability for lithium ions (LiCl 2M, 6 x 10(-9) cm(2)s(-1)) compared to other alkali metal analogs such as sodium (NaCl 2M, 7.38 x 10(-10) cm(2)s(-1)) and potassium (KCl 2M, 1.05 x 10(-9) cm(2)s(-1)). Moreover, the complete mitigation of the crossover of redox species with higher molecular sizes than the ions from alkali metal salts was confirmed by using in-line benchtop NMR methods. Additionally, the modified PIM membranes were measured in a symmetric electrochemical flow cell using an aqueous electrolyte by combining lithium ferro/ferricyanide redox compounds and lithium chloride. The electrochemical tests showed low polarization, high-rate capability, and capacity retention values of 99% when cycled at 10 mAcm(-2) for over 50 cycles. Based on these results, these polymers could be used as highly selective and conducting membranes in electrodialysis for lithium separation and lithium-based redox flow batteries and as a protective layer in high-energy density lithium metal batteries.

Easy-to-manufacture Li 2 S-P 2 S 5 glass ceramics are the key to large-scale all-solid-state lithium batteries from an industrial point of view, while their commercialization is greatly hampered by the low room temperature Li + conductivity, especially due to the lack of solutions. Herein, we propose a nanocrystallization strategy to fabricate super Li + -conductive glass ceramics. Through regulating the nucleation energy, the crystallites within glass ceramics can self-organize into hetero-nanodomains during the solid-state reaction. Cryogenic transmission electron microscope and electron holography directly demonstrate the numerous closely spaced grain boundaries with enriched charge carriers, which actuate superior Li + -conduction as confirmed by variable-temperature solid-state nuclear magnetic resonance. Glass ceramics with a record Li + conductivity of 13.2 mS cm −1 are prepared. The high Li + conductivity ensures stable operation of a 220 μm thick LiNi 0.6 Mn 0.2 Co 0.2 O 2 composite cathode (8 mAh cm −2 ), with which the all-solid-state lithium battery reaches a high energy density of 420 Wh kg −1 by cell mass and 834 Wh L −1 by cell volume at room temperature. These findings bring about powerful new degrees of freedom for engineering super ionic conductors.

We investigate the impact of Al incorporation on the structure and dynamics of Al-doped lithium thiophosphates (Li3-3xAlxPS4) based on β-Li3PS4. 27Al and 6Li magic-angle spinning NMR spectra confirm that Al3+ ions occupy octahedral sites in the structure. Quantitative analyses of 27Al NMR spectra show that the maximum Al incorporation is x = 0.06 in Li3-3xAlxPS4. The ionic conductivity of β-Li3PS4 is enhanced by over a factor 3 due to Al incorporation. Further increase of the Al doping level leads to the formation of a more complicated material consisting of multiple crystalline and distorted phases as indicated by 31P NMR spectra and powder X-ray diffraction. Consequently, novel Li ion diffusion pathways develop leading to a very high ionic conductivity at room temperature. NMR relaxometry shows that the activation barrier for long-range Li ion diffusion in β-Li3PS4 hardly changes upon Al incorporation, but the onset temperature for motional narrowing comes down significantly due to Al doping. The activation barrier in the subsequently formed multiphase material decreases significantly, however, indicating a different more efficient Li ion conduction pathway.

Chloride based solid electrolytes are considered interesting candidates for catholytes in all-solid-state batteries due to their high electrochemical stability, which allows the use of high-voltage cathodes without protective coatings. Aliovalent Zr(IV) substitution is a widely applicable strategy to increase the ionic conductivity of Li3M(III)Cl6 solid electrolytes. In this study, we investigate how Zr(IV) substitution affects the structure and ion conduction in Li3-xIn1-xZrxCl6 (0 ≤ x ≤ 0.5). Combined refinement of x-ray and neutron diffraction is used to make a structural model based on both scattering contrasts, and AC-impedance measurements and solid-state NMR relaxometry measurements at multiple Larmor frequencies are used to study the Li-ion dynamics. Hereby the diffusion mechanism and its correlation with the structure are explored and compared to previous studies, advancing the understanding of these complex and difficult to characterize materials. It is found that the diffusion in Li3InCl6 is most ikely anisotropic considering the crystal structure and two distinct jump processes found by solid-state NMR. Zr-substitution improves ionic conductivity by tuning the charge carrier concentration, accompanied by small changes in the crystal structure which affect ion-transport even on short timescales, likely reducing the anisotropy.

Indium phosphide quantum dots are the main alternative for toxic and restricted Cd-based quantum dots for lighting and display applications, but in the absence of protecting ZnSe and/or ZnS shells, InP quantum dots suffer from low photoluminescence quantum yields. Traditionally, HF treatments have been used to improve the quantum yield of InP to ∼50%, but these treatments are dangerous and not well understood. Here, we develop a postsynthetic treatment that forms HF in situ from benzoyl fluoride, which can be used to strongly increase the quantum yield of InP core-only quantum dots. This treatment is water-free and can be performed safely. Simultaneous addition of the z-type ligand ZnCl2 increases the photoluminescence quantum yield up to 85%. Structural analysis via XPS as well as solid state and solution NMR measurements shows that the in situ generated HF leads to a surface passivation by indium fluoride z-type ligands and removes polyphosphates, but not PO3 and PO4 species from the InP surface. With DFT calculations it is shown that InP QDs can be trap-free even when PO3 and PO4 species are present on the surface. These results show that both polyphosphate removal and z-type passivation are necessary to obtain high quantum yields in InP core-only quantum dots. They further show that core-only InP QDs can achieve photoluminescence quantum yields rivalling those of InP/ZnSe/ZnS core/shell/shell QDs and the best core-only II-VI QDs.

Complex metal hydride/oxide nanocomposites are a promising class of solid-state electrolytes. They exhibit high ionic conductivities due to an interaction of the metal hydride with the surface of the oxide. The exact nature of this interaction and composition of the hydride/oxide interface is not yet known. Using 1H, 7Li, 11B, and 29Si NMR spectroscopy and lithium borohydride confined in nanoporous silica as a model system, we now elucidate the chemistry and dynamics occurring at the interface between the scaffold and the complex metal hydride. We observed that the structure of the oxide scaffold has a significant effect on the ionic conductivity. A previously unknown silicon site was observed in the nanocomposites and correlated to the LiBH4 at the interface with silica. We provide a model for the origin of this silicon site which reveals that siloxane bonds are broken and highly dynamic silicon-hydride-borohydride and silicon-oxide-lithium bonds are formed at the interface between LiBH4 and silica. Additionally, we discovered a strong correlation between the thickness of the silica pore walls and the fraction of the LiBH4 that displays fast dynamics. Our findings provide insights on the role of the local scaffold structure and the chemistry of the interaction at the interface between complex metal hydrides and oxide hosts. These findings are relevant for other complex hydride/metal oxide systems where interface effects leads to a high ionic conductivity.

The development of commercial solid-state batteries has to date been hindered by the individual limitations of inorganic and organic solid electrolytes, motivating hybrid concepts. However, the room-temperature conductivity of hybrid solid electrolytes is still insufficient to support the required battery performance. A key challenge is to assess the Li-ion transport over the inorganic and organic interfaces and relate this to surface chemistry. Here we study the interphase structure and the Li-ion transport across the interface of hybrid solid electrolytes using solid-state nuclear magnetic resonance spectroscopy. In a hybrid solid polyethylene oxide polymer–inorganic electrolyte, we introduce two representative types of ionic liquid that have different miscibilities with the polymer. The poorly miscible ionic liquid wets the polymer–inorganic interface and increases the local polarizability. This lowers the diffusional barrier, resulting in an overall room-temperature conductivity of 2.47 × 10−4 S cm−1. A critical current density of 0.25 mA cm−2 versus a Li-metal anode shows improved stability, allowing cycling of a LiFePO4–Li-metal solid-state cell at room temperature with a Coulombic efficiency of 99.9%. Tailoring the local interface environment between the inorganic and organic solid electrolyte components in hybrid solid electrolytes seems to be a viable route towards designing highly conducting hybrid solid electrolytes. NMR measurements show that the interface between the inorganic and organic components can be tailored to design a highly conducting hybrid solid electrolyte.

Development of commercial solid-state batteries so far been hindered by the individual limitations of inorganic and organic solid-electrolytes, motivating hybrid concepts. However, room-temperature performance of hybrid-solid electrolytes is still insufficient in terms of ion conductivity, where especially the role and impact of the inorganic and organic interphases is largely unexplored. A key challenge is to assess the Li-ion transport over the interfaces directly and relate this to the surface chemistry. Here the lithium-ion conductivity in hybrid-solid electrolytes, the interface structure and Li + interface transport was investigated by state-of-art solid-state nuclear magnetic resonance methodologies. In a hybrid-solid Polyethylene oxide polymer – inorganic electrolyte, two representative types of ionic liquids, having a different miscibility with the polymer, were used as a benchmark to tailor the local environment at the interface between the inorganic and organic solid electrolytes species. The poor miscibility ionic liquid wets the polymer-inorganic interface and raises the local polarizability, thereby lowering the diffusional barrier, which activates the high conductivity of the inorganic solid-electrolyte, resulting in and overall room temperature conductivity of 0.25 mS/cm. A very high critical current density of 0.25 mA/cm 2 versus a Li-metal anode is achieved, demonstrating improved stability, and a LiFePO 4 – Li-metal full solid-state cell can be cycled at room temperature at an Coulombic efficiency of 99.9%. The local interface environment between the solid electrolyte phases in hybrid solid electrolytes, is thus demonstrated to be the bottleneck and tailoring the interface properties appears a viable route towards the design of highly conducting hybrid-solid electrolyte concepts.

The use of polymeric nanoparticles (NPs) as therapeutics has been steadily increasing over past decades. In vivo imaging of NPs is necessary to advance the therapeutic performance. F-19 Magnetic Resonance Imaging (F-19 MRI) offers multiple advantages for in vivo imaging. However, design of a probe for both biodistribution and degradation has not been realized yet. We developed polymeric NPs loaded with two fluorocarbons as promising imaging tools to monitor NP biodistribution and degradation by F-19 MRI. These 200 nm NPs consist of poly(lactic-co-glycolic acid) (PLGA) loaded with perfluoro-15-crown-5 ether (PFCE) and PERFECTA. PERFECTA/PFCE-PLGA NPs have a fractal sphere structure, in which both fluorocarbons are distributed in the polymeric matrix of the fractal building blocks, which differs from PFCE-PLGA NPs and is unique for fluorocarbon-loaded colloids. This structure leads to changes of magnetic resonance properties of both fluorocarbons after hydrolysis of NPs. PERFECTA/PFCE-PLGA NPs are colloidally stable in serum and biocompatible. Both fluorocarbons show a single resonance in F-19 MRI that can be imaged separately using different excitation pulses. In the future, these findings may be used for biodistribution and degradation studies of NPs by F-19 MRI in vivo using "two color" labeling leading to improvement of drug delivery agents. (C) 2019 Published by Elsevier Inc.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The development of high-performance all-solid-state batteries relies on charge transport in solid electrolytes, where transport across grain boundaries often limits their bulk conductivity. The argyrodite Li6PS5X (X = Cl, Br) solid electrolyte has a high conductivity; however, macroscopic diffusion in this material involves complex jump processes, which leads to an underestimation of the activation energy. Using a comprehensive frequency- and temperature-dependent analysis of the spin-lattice relaxation rates, a complete estimation of Li self-diffusion is demonstrated. Another experimental challenge is quantifying the impact of grain boundaries on the total bulk conductivity. Li6PS5Cl and Li6PS5Br have identical crystalline structures, but with Li-6 MAS NMR, their resonance peaks have different chemical shifts. Exploiting this with two-dimensional Li-6-Li-6 exchange NMR on a mixture of Li6PS5Br and Li6PS5Cl, we observe Li exchange between particles of these two materials across grain boundaries, allowing direct and unambiguous quantification of this often limiting process in solid-state electrolytes.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

After years of controversy over the solid state structure of the essential amino acid L-phenylalanine, four different polymorphic forms were published recently. The common form I has symmetry P21 with four molecules in the asymmetric unit (Z′ = 4), similar to form III, but with a different arrangement of molecular bilayers. Form II, obtained from the hydrate at very low humidity, is unrelated to forms I and III, as is the high-density form IV. The present investigation demonstrates that this prototype aromatic amino acid has two additional high-temperature phases Ih and IIIh obtained from form I and form III above 458 and 440 K, respectively, when flipping between two alternative side-chain conformations becomes dynamic and causes pairs of molecules, initially crystallographically independent, to become equivalent above a sharp transition temperature. These abrupt and reversible phase changes occur with a reduction of Z′ from 4 (low T) to 2 (high T) and modified crystal symmetry. We furthermore experienced an example of disappearing polymorph for form I which after growing form III in one of our laboratories could no longer be crystallized at room temperature. In contrast, form III crystals may be irreversibly converted to form I crystals as a result of sliding of molecular bilayers in the crystal at elevated temperature. No conversions between the high-temperature forms Ih and IIIh were found. The remarkable crystallographic results are here corroborated by Molecular Dynamics and metadynamics simulations of the form I − form III system.

The Cover Feature shows emission in oxidized and reduced carbon dots. The interaction between oxidized carbon dots (upper left) with UV light results in green emission whereas in the case of reduced carbon dots (lower right) mainly photo-assisted thermal relaxation is detected. Such different phenomena occurring within the exited states of hydrothermal carbon dots are controlled by different structural features, with oxidized carbon dots containing more oxygen functionalities and reduced carbon dots having mainly conjugated domains. More information can be found in the Full Paper by H. Luo et al. on page 4432 in Issue 19, 2019 (DOI: 10.1002/cssc.201901795).

The increasing demand for high capacity yet safe storage of renewable energy calls for the development of all-solid-state batteries. A major hurdle in this development is the identification of new suitable types of solid-state electrolytes. Nanoconfined lithium borohydride is a solid-state electrolyte candidate due to its high lithium-ion mobility at ambient temperatures. The origin of the high lithium-ion mobility is not fully understood, however. We studied nanocomposites of lithium borohydride and nanoporous silica Santa Barbara Amorphous-15 (SBA-15) with different pore sizes, using H-1, Li-6,Li-7, and B-11 solid-state NMR at various temperatures, to get in-depth insights into the phase behavior and ion dynamics of lithium borohydride in the silica pores. The results allow us to formulate a detailed dynamic model for lithium borohydride confined in SBA-15; bulklike LiBH4 is separated from the pore walls by an amorphous, highly dynamic LiBH4 fraction displaying both Li+ and BH4- diffusion even at ambient temperatures. As shown by B-11 temperature-jump exchange NMR, this dynamic fraction increases as a function of temperature. Li+ exchange between the bulklike and "dynamic" LiBH4 fraction is slow at ambient temperatures, but at elevated temperatures (>= 90 degrees C), above the phase transition of the bulklike fraction, lithium ions rapidly diffuse through both LiBH4 fractions and exchange between these confined fractions at rates approaching the megahertz time scale.

The high Li-ion conductivity of the Li7P3S11 sulfide-based solid electrolyte makes it a promising candidate for all-solid-state lithium batteries. The Li-ion transport over electrode-electrolyte and electrolyte-electrolyte interfaces, vital for the performance of solid-state batteries, is investigated by impedance spectroscopy and solid-state NMR experiments. An all-solid-state Li-ion battery is assembled with the Li7P3S11 electrolyte, nano-Li2S cathode and Li-In foil anode, showing a relatively large initial discharge capacity of 1139.5 mAh/g at a current density of 0.064 mA/cm(2) retaining 850.0 mAh/g after 30 cycles. Electrochemical impedance spectroscopy suggests that the decrease in capacity over cycling is due to the increased interfacial resistance between the electrode and the electrolyte. 1D exchange Li-7 NMR quantifies the interfacial Li-ion transport between the uncycled electrode and the electrolyte, resulting in a diffusion coefficient of 1.70(3)x10(-14) cm(2)/s at 333K and an energy barrier of 0.132 eV for the Li-ion transport between Li2S cathode and Li7P3S11 electrolyte. This indicates that the barrier for Li-ion transport over the electrode-electrolyte interface is small. However, the small diffusion coefficient for Li-ion diffusion between the Li 2 S and the Li7P3S11 suggests that these contact interfaces between electrode and electrolyte are relatively scarce, challenging the performance of these solid-state batteries. (C) 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.