Search

To overcome the challenges associated with the toxicity of the majority of organic solvents for the liquid phase synthesis of solid electrolytes toward the human body and environment, we demonstrate the synthesis of tin-based sulphide electrolytes using water, which is the most environmentally friendly solvent. ortho-Thiostannate, i.e., Li4SnS4, was obtained from a mixture of Li2S, Sn, and S using aqueous solution synthesis. Furthermore, Li10SnP2S12, a superionic conductor, was obtained by mixing an aqueous solution of Li4SnS4 and tetrahydrofuran suspension of Li3PS4, which exhibited the highest ionic conductivity (5.9 × 10−3 S cm−1 at 25 °C) in liquid-phase synthesis. This study successfully demonstrates that water can be efficiently used to synthesize sulphide electrolytes instead of conventional organic solvents. [ABSTRACT FROM AUTHOR]

Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all‐solid‐state batteries, a promising technology for electric vehicles. In this context, Li3PS4 glass, a promising solid electrolyte candidate, exhibits dynamic coupling between the Li+ cation mobility and the PS43− anion libration, which is commonly referred to as the paddlewheel effect. In addition, it exhibits a concerted cation diffusion effect (i.e., a cation–cation interaction), which is regarded as the essence of high Li ion transport. However, the correlation between the Li+ ions within the glass structure can only be vaguely determined, due to the limited experimental information that can be obtained. Here, this study reports that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyze the chemical bonds. It is found that three types of Li ions are present in Li3PS4 glass, and that the more mobile Li ions (i.e., the Li3‐type ions) exhibit a characteristic correlation at relatively long distances of 4.0–5.0 Å. Furthermore, reverse Monte Carlo simulations combined with deep learning potentials that reproduce X‐ray, neutron, and electron diffraction pair distribution functions showed an increase in the number of Li3‐type ions for partially crystallized glass structures with improved Li ion transport properties. Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences. Thus, considering the molecular vibrations in the glass during the evaluation of the Li ion valences is expected to lead to the development of new solid electrolytes. [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium‐sulfur batteries (ASSLSB), composed of sulfur cathode and lithium metal anode with high theoretical capacity, have a potentially higher energy density by weight than a typical lithium‐ion battery (LIB). However, due to insulating sulfur, a relatively large proportion of electronic (carbon) and ionic (solid electrolyte) conductors are mixed for cathode fabrication, leading to inferior practical capacity. Herein, we report a novel integrated cathode Li2S‐LiI‐MoS2 which has relatively high electronic and ionic conductivities (the order of 10−4 S cm−1) without any carbon and solid electrolyte. The ASSLSB with integrated Li2S‐LiI‐MoS2 cathode delivers a remarkably high energy density of 1020 Wh kg−1 at the cathode level at room temperature. By applying precise X‐ray diffraction, pair distribution function analysis and X‐ray computed tomography, it is found that the formation of an ionic conducting phase composed mainly of LiI during discharge is responsible for the high rate capability. Furthermore, X‐ray absorption fine structure (XAFS) has also revealed the charge compensation mechanism and ascertained the involvement of both Mo 3d and S 3p orbitals during the charging and discharging process. It is believed the strategy will pave the way for developing high practical energy density at room temperature for all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

The problem of lithium dendrites must be addressed for practical lithium metal all-solid-state batteries. Herein, three-dimensional morphological changes within Li3PS4 electrolyte away from the anode were observed using operando X-ray computed tomography. We revealed that the electronic conduction of decomposition and the electrolyte/void interface cause the lithium deposition within the Li3PS4. [ABSTRACT FROM AUTHOR]

Liquid-phase syntheses of sulfide materials are attractive for the mass production of solid electrolytes for all-solid-state batteries. In liquid-phase synthesis, the precursor of the solid electrolyte is obtained. The precursors are important for producing electrolytes of the same quality because they decompose into electrolytes by heat treatment. However, only a few studies have focused on the formation mechanism and structure of precursors. This study proposes a formation mechanism for Li3PS4 during liquid-phase synthesis using ethylenediamine (EDA) as a solvent and clarifies the crystal structure of Li3PS4·NH2CH2CH2NH2 (Li3PS4·EDA). Raman spectroscopy and nuclear magnetic resonance revealed that intermediate P2S62− units were generated in the EDA solution. Crystal structure analysis of Li3PS4·EDA showed that the terminal nitrogen atom of EDA coordinates with two lithium atoms. Ionic conductivity of Li3PS4·EDA was 2.8 × 10−9 S cm−1 at 25 °C. The analysis of precursors of solid electrolytes provides insight into the behavior of solvent molecules as ligands in the synthesis of sulfide electrolytes. Highlights: β-Li3PS4 is prepared using a precursor obtained from Li3PS4 and ethylenediamine. Intermediate P2S62− units are generated in the ethylenediamine solution. Tetrahedra of PS4 and LiS4 form a framework in the precursor. Ethylenediamine molecules coordinate to two lithium cations in the precursor. [ABSTRACT FROM AUTHOR]

The electrochemical window of solid electrolytes (SEs) plays a crucial role in designing active material–SE interfaces in high‐energy‐density all‐solid‐state batteries (ASSBs). However, the suitable electrochemical window for individual active materials is not yet investigated, as the electrochemical window of SEs is overestimated. In this study, the oxidation onset voltages (OOVs) of several SEs, namely those compatible with Li2S as a high‐capacity positive electrode material are determined. Results reveal that SEs with low OOVs decrease the capacity and increase the interfacial resistance of the corresponding ASSBs. The OOVs of SEs must exceed that of Li2S by more than 0.2 V to achieve high capacity, which in turn depends on SE ionic conductivity. Therefore, an Li2S positive electrode is combined with pseudobinary Li‐oxyacid salts as SEs, exhibiting high OOVs and ionic conductivities, to afford a high‐capacity (500 Wh kg−1) ASSB with high Li2S content. [ABSTRACT FROM AUTHOR]

Sulfide-based solid electrolytes (SEs) exhibiting high ionic conductivity are indispensable battery materials for next-generation all-solid-state batteries. However, sulfide-based SEs have a major drawback in their low chemical stability in air. When exposed to H2O or O2 gas, toxic H2S is generated, and their ionic conductivity considerably declines. However, their degradation mechanism caused by air exposure has not been understood yet. To clarify the degradation process, in this study, we developed a transmission electron microscope (TEM) system to evaluate the air stability of battery materials. Using a vacuum transfer double-tilt TEM holder with a gas-flow system, the in situ observation of the degradation process was conducted for a sulfide-based Li4SnS4 glass ceramic under an air-flow environment. Consequently, electron diffraction (ED) patterns and TEM images could clearly capture morphological changes and the amorphization process caused by air exposure. Moreover, based on the analysis of ED patterns, it is observed that Li4SnS4 is likely to decompose because of the reaction with H2O in air. Therefore, this airtight and air-flow TEM system should be effective in clarifying the process of the deterioration of sulfur-based SEs during exposure to air. [ABSTRACT FROM AUTHOR]

Composite quasi-solid electrolytes composed of Li3PS4 (LPS) glass and a carboxylate ester were prepared via planetary ball milling, and the influence of the molecular structure of the carboxylate esters on their ion-conduction was investigated. The results revealed that filling the voids in the solid electrolyte with a bulky carboxylate ester, which hardly reacted with the LPS glass, effectively maintains the high ionic conductivity of the LPS glass even when the relative density of LPS decreases. The use of this composite quasi-solid electrolyte is an effective approach to maintain the ion-conduction in not only an electrolyte separator layer but also a composite electrode layer in an all-solid-state battery. [ABSTRACT FROM AUTHOR]

The effect of the particle sizes of LiNi 1/3 Co 1/3 Mn 1/3 O 2 and Li 2 S–P 2 S 5 solid electrolytes (SEs) on the electrode morphology was investigated. Smaller-sized SE particles were advantageous in fabricating dense and homogeneous electrode layers with an effective lithium-ion conduction pathway and a large electrode–electrolyte interfacial contact area because of the unique mechanical properties of sulfide-based SEs. The homogeneous distribution of the SE is also effective in the suppression of cracking and fracturing of LiNi 1/3 Co 1/3 Mn 1/3 O 2 because of the favorable mechanical properties of the sulfide-based SEs. The capacity of the all-solid-state cells under high-rate operation was thus remarkably improved. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous Li2S–GeS2 solid electrolyte thin films were prepared using pulsed laser deposition (PLD) at the compositions of 67–83mol% Li2S. The ionic conductivities at room temperature increased with increasing Li2S contents and attained a maximum value of 1.8×10−4 Scm−1 at the composition of 78mol% Li2S. The obtained solid electrolyte thin film was applied to form an ideal electrode–electrolyte interface in all-solid-state batteries. The all-solid-state lithium cell using LiCoO2 coated with the solid electrolyte thin film operated as a lithium secondary battery at room temperature. [Copyright &y& Elsevier]

Abstract: Electrode–electrolyte composite materials were prepared by coating a highly conductive Li2S–P2S5 solid electrolyte onto LiCoO2 electrode particles using pulsed laser deposition (PLD). Cross-sections of the composite electrode layers of the all-solid-state cells were observed using a transmission electron microscope to investigate the packing morphology of the LiCoO2 particles and the distribution of solid electrolyte in the composite electrode. All-solid-state cells based on a composite electrode composed entirely of solid-electrolyte-coated LiCoO2 were fabricated, and their performance was investigated. The coating amounts of Li2S–P2S5 solid electrolytes on LiCoO2 particles and the conductivity of the coating material were controlled to increase the capacity of the resulting all-solid-state cells. All-solid-state cells using LiCoO2 with thick solid electrolyte coatings, grown over 120min, had a capacity of 65mAhg−1, without any addition of Li2S–P2S5 solid electrolyte particles to the composite electrode. The capacity of the all-solid-state cell increased further after increasing the conductivity of the Li2S–P2S5 solid electrolyte coating by heat treatment at 200°C. Furthermore, an all-solid-state cell based on a composite electrode using both a solid electrolyte coating and added solid electrolyte particles was fabricated, and the capacity of the resulting all-solid-state cell increased to 95mAhg−1. [Copyright &y& Elsevier]

Mechanical properties and ionic conductivities of solid electrolytes are important factors influencing the performance of all-solid-state batteries. This study investigates composite quasi-solid electrolytes composed of Li 2 S–P 2 S 5 glass and a phosphate ester, prepared via planetary ball milling, and the relative densities of the powder-compressed pellets, formed using the composite quasi-solid electrolytes. Dense pellets of the Li 2 S–P 2 S 5 glass electrolyte are obtained via addition of phosphate esters; the relative densities increase from 90.6% to 93.1%, without the ionic conductivities decreasing, upon addition of a small quantity of tris (2, 2, 2-trifluoroethyl) phosphate to the Li 3 PS 4 glass. The addition of small quantities of phosphate esters to sulfide solid electrolytes is effective in improving the formability of these solid electrolytes. • Quasi-solid electrolytes of Li 2 S-P 2 S 5 (LPS) glass and phosphate ester are prepared. • Relative density of the electrolytes increases by adding the ester to LPS glass. • Adding the ester increases formability and conductivity of the composites. [ABSTRACT FROM AUTHOR]

RT-NaMn 1/2 Sn 1/2 S 2 was prepared by mechanochemical synthesis from a mixture of Na 2 S, MnS, and SnS 2. The crystal structure was determined from X-ray powder diffraction data. The chemical composition was confirmed by energy dispersive X-ray spectroscopy, and the electrical conductivity was measured using electrochemical impedance spectroscopy. The RT-NaMn 1/2 Sn 1/2 S 2 sample crystallizes with rock salt-type structure, space group Fm 3 ‾ m , a = 5.4368(2) Å, V = 160.71(2) Å3, and Z = 2. This sample exhibits an irreversible phase transition. It transforms into a high temperature phase, HT-NaMn 1/2 Sn 1/2 S 2 which crystallizes with α-NaFeO 2 -type structure, space group R 3 ‾ m , a = 3.7523 (4) Å, c = 19.883 (2) Å, V = 242.44 (4) Å3, and Z = 3. The structure was determined from single crystal XRD data. The electrical conductivities of the RT- and HT-forms are 2.5 × 10−8 S cm−1 (E a = 0.58 eV) and 3.3 × 10−7 S cm−1 (E a = 0.42 eV) at 25 °C, respectively. [Display omitted] • The cubic NaMn 1/2 Sn 1/2 S 2 phase was prepared by mechanochemical synthesis route. • The rock salt structure of the NaMn 1/2 Sn 1/2 S 2 phase was solved from XRPD data. • Irreversible cubic to trigonal phase transition was observed at high temperature. • The trigonal NaMn 1/2 Sn 1/2 S 2 phase is crystallizes with the α-NaFeO 2 -type structure. • The ionic conductivity of the trigonal phase is higher than the cubic phase. [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium–sulfur batteries have attracted much attention because of their large capacity and long life. However, their rate capability is not sufficiently high, prompting a great demand for improvement. Herein, a sulfur‐based composite electrode is fabricated for the high‐rate operation of all‐solid‐state lithium–sulfur batteries. The electrode is made of a carbon material having a large number of "interconnected mesopores" with a diameter of 5 nm. The highly mesoporous structure is conducive to electrode reactions and the formation of conduction pathways. Consequently, the rate capability of the composite electrode is drastically improved compared with that of an electrode made of conventional conducting nanocarbon. The all‐solid‐state lithium–sulfur battery with this composite electrode shows a high capacity of 1100 mA h g−1 per sulfur after 400 cycles at a high current density of 1.3 mA cm−2 at 25 °C. These findings are expected to contribute toward the development of practical all‐solid‐state lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

Amorphous active materials have been developed for high-performance lithium and sodium secondary batteries to achieve a higher capacity, higher rate performance, and longer cycle life than those of crystalline active materials. In this study, a new function of amorphous active materials was explored through the heat treatment of pseudobinary amorphous materials (for example, LiCoO 2 –Li 2 SO 4). Additionally, active materials with crystalline/amorphous nanoheterostructures, in which the nano-LiCoO 2 domains were dispersed in a Li 2 SO 4 -rich matrix, were demonstrated. In all-solid-state batteries with sulfide solid electrolytes (SEs), the crystalline/amorphous active materials reduced the interface resistance of the active material and SE when compared with that of Li. High electrochemical performance was achieved using the Li 2 SO 4 -rich matrix, which served as an interfacial stabilizer. In summary, this paper reports a new strategy based on annealing amorphous materials for developing active materials with nanoheterostructures for high-performance energy storage devices. [Display omitted] • Electrode active materials with crystalline/amorphous nanostructures were developed.. • The active materials showed high electrode performance in all-solid-state batteries. • This study offers a new strategy for high-performance secondary batteries.. [ABSTRACT FROM AUTHOR]

Transparent needles-like single crystals of Na 2 MgP 2 S 6 were obtained by self-flux synthesis route from Na 2 S, Mg, and P 2 S 5. The crystal structure of the new compound was determined from single-crystal X-ray diffraction data [ wR (F 2) = 0.066, 1088 reflections, 58 variables]. The chemical composition was confirmed by energy dispersive X-ray spectroscopy (EDX), and the ionic conductivity was measured using electrochemical impedance spectroscopy (EIS). Na 2 MgP 2 S 6 crystallizes in the orthorhombic system, space group Pbcn (N° 60), a = 7.3629 (3) Å, b = 21.5547 (8) Å , c = 6.2155 (3) Å, V = 986.43 (7) Å3 and Z = 4. The sulfur atoms form a distorted hexagonal close packing within which the sodium, magnesium, and P-P dimer units are octahedrally coordinated and form a honeycomb-like structure. Two of the three sodium atomic positions are partially occupied. Na 2 MgP 2 S 6 exhibits an ionic conductivity of 8.8×10−7 S cm−1 (E a = 0.48 eV) at 29.6 °C. [Display omitted] • The crystallographic data of thiohypodiphosphate compounds were reviewed. • The single crystals of Na 2 MgP 2 S 6 were obtained by self-flux synthesis route. • The unique crystal structure of Na 2 MgP 2 S 6 was solved from single crystal XRD. • The structure of Na 2 MgP 2 S 6 is isostructural to the Na 2 MnP 2 S 6 -type. • The electrical conductivity of Na 2 MgP 2 S 6 is 8.8×10−7 S cm−1 at 29.6 °C. [ABSTRACT FROM AUTHOR]

All-solid-state sodium batteries are attracting attention as next-generation batteries, owing to their improved safety and abundance of sodium resources. To realize all-solid-state sodium batteries, solid electrolytes with high sodium-ion conductivities are required. In this study, Na 3 PS 4 electrolytes with partial substitution of P5+ with W6+ were investigated. The Na 3– x P 1– x W x S 4 sulfide-based solid electrolytes were prepared via a mechanochemical process and consecutive heat treatment. The Na 2.85 P 0.85 W 0.15 S 4 electrolyte with Na vacancies exhibited an ionic conductivity of 8.8 × 10−3 S cm−1 at 25 °C, which was higher than that of Na 3 PS 4 solid electrolyte. The all-solid-state batteries (Na-Sn/Na 2.85 P 0.85 W 0.15 S 4 /TiS 2) exhibited a reversible capacity of 140 mA h g−1 at a current density of 0.038 mA cm−2 and retained the capacity of 115 mAh g−1 for 40 cycles at 0.130 mA cm−2 at 25 °C. The Na 3– x P 1– x W x S 4 samples prepared via mechanochemistry are homogeneous electrolytes free of crystalline WS 2 impurities and are effective for application to all-solid-state sodium batteries. • Sulfide Na 3– x P 1– x W x S 4 electrolytes are prepared via a mechanochemical process. • Na 2.85 P 0.85 W 0.15 S 4 with Na vacancies shows a conductivity of 8.8 × 10−3 S cm−1. • All-solid-state cells exhibit a reversible capacity of 140 mAh g−1 of TiS 2 at 25 °C. [ABSTRACT FROM AUTHOR]

All-solid-state lithium‑sulfur batteries (ASSLSBs) based on sulfur or lithium sulfide (Li 2 S) as cathodes are one of the most promising candidates for next-generation energy storage devices due to their high theoretical energy density and good safety features. However, despite the promising outlook, the practical application of ASSLSBs is impeded due to the electronically and ionically insulating nature of S and Li 2 S. Consequently, even with carbon and solid state electrolytes (SSEs) addition, the electron and lithium-ion cannot transport smoothly through the cathode. Therefore, it is imperative to establish and tune effective electron/ion transport paths in the composite cathode to achieve high performance. In the present study, electronically/ionically dual conductive active material Li 2 S-LiI-MoS 2 and high ionically conductive Li 6 PS 5 Cl SSE were coupled and modified to control ionic and electronic paths in Li 2 S-based cathode composite. The optimized composite cathode possessed an overall gravimetric capacity of 423 mAh g−1 at 0.5C and 308 mAh g−1 at 2C with respect to the total mass of the cathode. The corresponding ASSLSBs achieved distinctively high energy with acceptable power density. The in-depth analysis by X-ray computed tomography revealed the three-dimensional conductive pathway in the composite cathode. • The Li 2 S-LiI-MoS 2 coupling with Li 6 PS 5 Cl as composite cathode. • The cathode shows balanced electronic and ionic conductivity approaching 10−3 S cm−1. • The optimized composite cathode exhibits good overall capacity of 423 mAh g−1 at 0.5C and 308 mAh g−1 at 2C. • X-ray CT reveals the microstructure of the cathode, including tortuosity and contact area. [ABSTRACT FROM AUTHOR]

Sulfide-based lithium ionic conductors show high conductivity. Many studies have focused on improving conductivity and understanding their migration mechanisms. Argyrodite-type Li 6 PS 5 X (X = Cl, Br, I) electrolytes with P cations are among the main subjects of research regarding the substitution of anions and cations. In this study, argyrodite-type thioantimonate electrolytes were prepared to extend the compositions of argyrodite-type electrolytes and study their mechanisms of ion conduction. An argyrodite-type crystal precipitated in the composition of Li 6 SbS 5 I, but was not obtained in the composition of Li 6 SbS 5 X (X = Cl, Br). This could be explained by the difference in size between the SbS 4 tetrahedra and halide anions. Argyrodite-type Li 6 SbS 5 I displayed a conductivity of 2.1 × 10−6 S cm−1 at 25 °C, which was higher than that of Li 6 PS 5 I. Comparing these crystal structures, only the lattice parameters differed, and the site positions and occupancies were almost identical. However, the pathways limiting 3D migration were intra-cage jumps within Li 6 SbS 5 I and inter-cage jumps within Li 6 PS 5 I, based on their bond valence-based energy landscapes. The bottleneck sizes for ionic conduction in Li 6 SbS 5 I is better than that of Li 6 PS 5 I. This difference was due to the lattice parameters derived from the SbS 4 and PS 4 tetrahedra. This study reveals a strategy to predict the producibilities and increase the conductivities of argyrodite-type electrolytes. • Argyrodite-type Li 6 SbS 5 X (X = Cl, Br, I) electrolytes are prepared. • Only Li 6 SbS 5 I exhibits an argyrodite-type structure. • The sizes of the MS 4 tetrahedra are critical in forming the argyrodite structure. • Li 6 SbS 5 I displays a higher ionic conductivity than that of Li 6 PS 5 I. • The different sizes of the MS 4 tetrahedra affect the ion migration pathways. [ABSTRACT FROM AUTHOR]

All-solid-state sodium batteries with sulfide-based solid electrolytes are attracting attention as next-generation energy storage systems to replace Li-ion batteries, owing to their improved safety and the abundant sodium resources. Na 3 PS 4 -based materials, which have relatively high conductivities and favorable mechanical properties, make promising Na-ion solid electrolytes for realizing all-solid-state sodium batteries. However, it is essential to establish a further simple and effective protocol for manufacturing such solid electrolytes and composite electrodes. In this study, Na 3- x PS 4- x Cl x (x = 0, 0.0625) was prepared by a liquid-phase (suspension) process from Na 2 S, P 2 S 5 , and NaCl using 1,2-dimethoxyethane as a reaction media. Na 3 PS 4 heated at 400 °C and Na 2.9375 PS 3.9375 Cl 0.0625 heated at 480 °C exhibited Na-ion conductivities of 2.6 × 10−4 and 4.3 × 10−4 S cm−1 at 25 °C, respectively. A homogenous composite electrode was prepared with TiS 2 active material and Na 3 PS 4 solid electrolyte via the simple liquid-phase process, resulting in large contact areas between electrode and electrolyte particles. The electrode obtained by liquid-phase provided an all-solid-state cell with higher reversible capacity of 161 mAh g−1 than a conventional mechanically mixed electrode. Suspension syntheses of Na 3- x PS 4- x Cl x are useful for the simple production of solid electrolytes and are highly applicable to all-solid-state sodium batteries. • Na 3- x PS 4- x Cl x (x = 0, 0.0625) electrolytes are prepared using 1,2-dimethoxyethane. • Na 3 PS 4 shows a high sodium-ion conductivity of 2.6 × 10−4 S cm−1. • Na 2.9375 PS 3.9375 Cl 0.0625 exhibits a superior conductivity of 4.3 × 10−4 S cm−1. • A TiS 2 –Na 3 PS 4 composite electrode is obtained by a simple liquid-phase process. • An all-solid-state cell using the electrode shows a high capacity of 161 mAh g−1. [ABSTRACT FROM AUTHOR]

Abstract All-solid-state cells are safe, and have high energy densities and power densities. Sulfide-based solid electrolytes (SEs) exhibit high ionic conductivities and favorable mechanical properties allowing for the facile preparation of all-solid-state cells via simple mixing and cold-pressing processes. For practical applications, it is necessary to produce SEs and all-solid-state cells more efficiently. Herein, a novel fabrication process for homogeneous composite electrodes used in all-solid-state cells was successfully demonstrated using an infiltration technique. The Li 4 Ti 5 O 12 and carbon nanotube (LTO@CNT) porous electrode was infiltrated with a precursor solution containing an argyrodite Li 6 PS 5 Br SE, and the solvent was removed by drying at 150 °C under vacuum to prepare an infiltrated SE-LTO@CNT electrode. The process without conventional mixing formed an electrochemically active interface with a large contact area and favorable conduction pathways. The all-solid-state cell with the SE-LTO@CNT electrode showed an improved capacity of 163 mAh g−1 compared to those prepared with the dry-mixed electrodes at 25 °C, and the high capacity was maintained for 500 cycles. Moreover, the cell with the SE-LTO@CNT electrode showed a reversible capacity of 100 mAh g−1 or more at 4 C-rate and 100 °C. Thus, the infiltration process is effective for the practical fabrication and application of all-solid-state cells. Highlights • Li 4 Ti 5 O 12 -CNT-Li 6 PS 5 Br electrode is prepared by an infiltration technique. • The infiltration process is effective in achieving electrode-electrolyte interface. • An all-solid-state cell with the electrode shows a high capacity of 163 mAh g−1. • The cell operates with high rate and good cycle performances at 100 °C. [ABSTRACT FROM AUTHOR]

The ternary oxide glasses in the system of Li 3 BO 3 -Li 2 SO 4 -Li 2 CO 3 were prepared by mechanical milling. By heating the glasses to crystallize, the glass-ceramics were obtained. The 90Li 3 BO 3 ·7Li 2 SO 4 ·3Li 2 CO 3 (mol%) glass-ceramic electrolyte showed the conductivity of 1.0 × 10 − 5 S cm − 1 at room temperature, which was higher than that of the 90Li 3 BO 3 ·10Li 2 SO 4 glass-ceramic electrolyte. At the 33Li 3 BO 3 ·33Li 2 SO 4 ·33Li 2 CO 3 composition, a cold-pressed pellet at 720 MPa of the glass exhibited excellent formability with the relative density of 90%, which was comparable to that of sulfide glass electrolytes. By heating the glass, a metastable phase was precipitated and the glass-ceramic exhibited the conductivity of 1.8 × 10 − 6 S cm − 1 at room temperature. To obtain a denser pellet, hot-pressing at around its glass-transition temperature and consecutive crystallization were conducted. The hot-pressed pellet of the glass-ceramic was transparent and showed the conductivity of 2.3 × 10 − 6 S cm − 1 at room temperature. From the ultrasonic pulse-echo measurement, the bulk modulus of the glass was 44 GPa, which was lower than that of 68 GPa of the 90Li 3 BO 3 ·10Li 2 SO 4 glass. From the galvanostatic cycling test, the 33Li 3 BO 3 ·33Li 2 SO 4 ·33Li 2 CO 3 glass-ceramic electrolyte was kinetically stable against lithium metal negative electrode. The 33Li 3 BO 3 ·33Li 2 SO 4 ·33Li 2 CO 3 glass-ceramic electrolyte is therefore a promising material with both conductivity and ductility for the application to all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Sulfide-based solid electrolytes have gained attention for application in solid-state lithium batteries, due to their high ionic conductivities, suitable mechanical properties, and wide electrochemical windows. However, the sulfide in these materials is very hygroscopic, and can react with traces of water, thus generating toxic H 2 S gas. This reduces the lithium-ion conductivity, which plays an important role in solid state batteries. On the contrary, it has also been found that the conductive performance of a sulfide solid electrolyte exposed to water can be partially recovered by a suitable heat treatment. In this study, multiple spectroscopic analyses using X-ray photoelectron spectroscopy, Raman spectroscopy, nuclear magnetic resonance spectroscopy, and diffuse reflectance infrared Fourier-transform spectroscopy were performed on an argyrodite-type sulfide solid electrolyte to elucidate the degradation mechanism under a small amount of moisture, as in a dry room, as well as the recovery mechanism of a degraded sample by vacuum heat treatment. We found that the degradation behavior of the PS 4 3− unit and the adsorption/desorption of water molecules on the surface of the electrolyte were correlated with the lithium-ion conductivity. [Display omitted] • Water durability of an argyrodite-type sulfide-based solid electrolyte in a low dew point air was investigated by using XPS, Raman, NMR, and DRIFTS. • The decomposed species and the adsorbed H 2 O were observed on the SE surface. • It was directly confirmed that the adsorbed H 2 O was desorbed by vacuum heating, and the conductivity recovered partially. [ABSTRACT FROM AUTHOR]

The development of all-solid-state capacitors (ASSCs) based on inorganic solid electrolytes (SEs) with high thermal stability is desired. However, because of their high cell resistance, such capacitors have lower capacitances and rate capabilities than conventional electric double-layer capacitors (EDLCs) that use aqueous solutions and organic liquid electrolytes. The high resistance is caused by the mechanical and electrochemical properties of the SE. In this study, a highly deformable Li-ion conducting oxide SE was investigated to improve the electrochemical performance of ASSCs. Bulk-type symmetric ASSCs, with a 33Li 3 BO 3 ·33Li 2 SO 4 ·33Li 2 CO 3 (LBSC) SE layer between two electrode layers of an LBSC-CNT composite, showed low resistance and were operable at 100–300 °C. Additionally, the highest capacitance at the highest current reported for ASSCs till date was achieved. The highly deformable SE will facilitate the design of ASSCs and expand the potential range of applications of EDLCs. [Display omitted] • Thermally stable all-solid-state capacitor with oxide electrolyte is developed. • Highly-deformable electrolyte and carbon nanotube are mixed to obtain electrode. • The fabricated capacitor is operable at 100–300 °C with high capacity. [ABSTRACT FROM AUTHOR]

A promising method to increase the energy density of all-solid-state batteries (ASSBs) featuring lithium ions as carriers is to employ Li metal as the anode. However, this has been accompanied by safety problems like flammable accidents associated with lithium dendrites originating from reactions with the solid electrolyte, leading to reduced battery performance. To overcome this issue toward the commercialization of ASSBs, various approaches have been proposed by many researchers. Among the suggested solutions, the use of lithium-halide-doped Li 3 PS 4 , to suppress lithium dendrite formation, has attracted attention. LiI-doped Li 3 PS 4 has shown the highest lithium dendrite growth suppression among lithium-halide-doped systems, but the reason for this is unclear. Thus, we attempted to clarify the cause of this suppression by comparing LiBr-doped Li 3 PS 4 with LiI-doped Li 3 PS 4. Investigation using various methods such as electrochemical evaluation, X-ray absorption spectroscopy, X-ray computed tomography, and pair distribution function analysis revealed that two factors affect the suppression of Li dendrite growth: the suppression of the current density distribution by improving the ionic conductivity and the stable interfacial layer. This is the main reason LiI-doped Li 3 PS 4 shows excellent Li dendrite suppression. • The structural properties and ability to lithium dendrite suppression of LiBr–doped Li 3 PS 4 were investigated by pair distribution function (PDF) analysis and critical current density (CCD) test in relation to the ionic conductivity. • The PDF analysis revealed that the LiBr–doped Li 3 PS 4 solid electrolyte has a structure in which bromine is inserted between the PS 4 3− anions. • Although Interfacial layer between LiBr-doped Li 3 PS 4 and Li metal is stable, the interfacial resistance is relatively high. [ABSTRACT FROM AUTHOR]

Graphite–solid electrolyte (SE) composite anode, prepared by spark-plasma-sintering (SPS) process, was applied to all-solid-state lithium secondary batteries with lithium sulfide (Li2S) positive electrode. The electrochemical tests demonstrated that the graphite–SE/Li2S cells showed the discharge capacity of ca. 750mAh·g−1-Li2S with the average voltage of ca. 1.98V. Although the discharge capacity was lower than that of the In/Li2S cells (ca. 920mAh·g−1-Li2S), the estimated energy density was higher than that (ca. 1490 and 1220mWh·g−1-Li2S for graphite–SE/Li2S and In/Li2S cells, respectively), due mainly to its higher average voltage. The graphite–SE/Li2S cells showed improved rate capability as compared with the cells with the graphite+SE blended powder, which was attributable mainly to the reduced interfacial resistance between the graphite and SE particles caused by the SPS process. [ABSTRACT FROM AUTHOR]

A positive electrode containing Li 3 PS 4 (LPS) glasses and LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) is a promising candidate for sulfide-based all-solid-state lithium batteries owing to its excellent charge–discharge cycle characteristics. However, sulfide-based solid electrolytes exhibit low chemical stability in air. This disadvantage affects process cost and thermal stability of all-solid-state cells. To resolve these issues, in this study, we focus on solid electrolytes, Li 4 SnS 4 (LSS), that do not generate H 2 S gas in air. The thermal behavior and microstructure of LSS–NMC positive electrode composites before and after the initial charge–discharge cycle are investigated. The initially charged LSS–NMC composites exhibit several exothermal reactions above 250 °C. However, pristine and initially discharged samples do not show any considerable exothermal reactions. For LPS–NMC composites, by contrast, exothermal reactions are detected regardless of the charging and discharging state. To clarify the exothermic factors of initially charged LSS–NMC composites, we performed ex situ transmission electron microscopy observation and X-ray diffraction measurements. It is determined that SnS 2 , transition metal sulfides, and metal oxides are formed above 300 °C, which is attributable to LSS and NMC decomposition reactions. On the basis of the relation between thermal behavior and corresponding structural changes, exothermic factors and thermal stability of LSS–NMC composites are discussed in comparison with LPS–NMC composites. • Li 4 SnS 4 –LiNi 1/3 Mn 1/3 Co 1/3 O 2 positive electrode composites are synthesized. • Exothermic factors and thermal stability of the composites are investigated. • The reactivity of Li 4 SnS 4 and LiNi 1/3 Mn 1/3 Co 1/3 O 2 during heating is low. • Li 4 SnS 4 –LiNi 1/3 Mn 1/3 Co 1/3 O 2 composites exhibit excellent thermal stability. [ABSTRACT FROM AUTHOR]

In this study, we present a dry coating process to produce a core-shell composite particle for an all-solid-state lithium battery, where a single particle of the active material is coated with solid electrolytes. LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) and Li 3 PS 4 (LPS), which are typical cathode active material and sulfide solid electrolyte, were used. A dry impact-blending device was employed for the dry coating process. We demonstrated that a single particle of NCM was uniformly coated with a continuous layer of LPS by the dry coating process without any breakage or attrition of NCM, to produce an NCM@LPS core-shell particle. The charge-discharge cycling tests showed that the rate and cycle performances of an all-solid-state half-cell prepared with the NCM@LPS core-shell particles significantly improved. The three-dimensional internal structure of the composite cathode was subsequently analyzed using FIB-SEM with an image reconstruction technique. The results revealed that the composite cathode prepared with the NCM@LPS core-shell particles had a (i) high interfacial contact area between NCM and LPS and (ii) well-percolated ion transport pathway. In conclusion, the core-shell composite particle contributed to the structure of the composite cathode, thus resulting in improved cell performance. Image 1 • Dry coating was used to produce a core-shell composite particle for an all-solid-state battery. • A single particle of NCM was uniformly coated with a continuous layer of Li 3 PS 4. • The cell performance significantly improved when using the core-shell composite particles. • A high NCM-Li 3 PS 4 contact area and well-percolated ion transport path were formed. [ABSTRACT FROM AUTHOR]