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]

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]

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]

Highly safe all-solid-state batteries are constructed using oxide electrolytes because of their high chemical and electrochemical stabilities. Previously, we have developed various Li 3 BO 3 -based glass-ceramic electrolytes with high ductility and conductivity. In this study, we focus on the importance of electrode/electrolyte interfacial contacts in all-solid-state batteries. All-oxide solid-state cells (Li-In/LiNi 1/3 Mn 1/3 Co 1/3 O 2) with Li 3 BO 3 -based glass-ceramic electrolytes, are fabricated simply by pressing at room temperature. Furthermore, the effects of the ductility and ionic conductivity of glass-ceramic electrolytes on the charge-discharge properties of all-solid-state batteries are investigated. The 33Li 3 BO 3 ·33Li 2 SO 4 ·33Li 2 CO 3 (mol%) glass-ceramic electrolyte shows lower ionic conductivity and better ductility than the 90Li 3 BO 3 ·10Li 2 SO 4 electrolyte. The all-solid-state cells using these electrolytes operate as secondary batteries at 100 °C. However, better cycle performance is obtained with cells using the former electrolyte. Formation of well-contacted electrode/electrolyte interfaces when using highly ductile electrolytes leads to enhanced electrochemical performance of bulk-type all-solid-state batteries. • All-solid-state cells using Li 3 BO 3 -based glass-ceramic electrolytes are fabricated. • The cell with highly ductile electrolyte shows better charge-discharge performance. • Electrode-electrolyte interfacial formation is important for good cyclability. [ABSTRACT FROM AUTHOR]

(100 − x)(0.75Li2S·0.25P2S5)·xLiBH4 (0 ≤ x (mol%) ≤ 33) glass electrolytes were prepared from 75Li2S·25P2S5 (mol%) glass and LiBH4 crystal by a mechanical milling technique. The effects of the addition of LiBH4 on the structures and properties of the glass electrolytes were examined. The DSC curves of the prepared glasses with LiBH4 did not have the endothermic peak attributable to the phase transition of LiBH4 crystal. The Raman spectra of the glasses indicated that the glasses included PS4 3− and BH4 − ions. The conductivities of the glasses increased with increasing the LiBH4 content. The glass at the composition of x = 33 showed the highest lithium-ion conductivity of 1.6 × 10−3 S cm−1 at room temperature. The glass had a wide electrochemical window up to 5 V vs. Li+/Li. An all-solid-state Li/TiS2 cell using the glass as an electrolyte successfully operated as a secondary battery at 25 °C. [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]

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]

Abstract All-solid-state batteries comprising sulfide solid electrolytes are promising for energy storage in electric vehicles because of their safety record. There is a high demand for batteries in the form of stackable compact sheets with high cell-based energy density that are mass fabricated in a scalable process. A slurry coating is advantageous for fabricating sheet-type batteries, improves productivity, and allows control of the layer thickness. Here we present a slurry-mixing method for fabricating homogeneously dispersed composite sheets containing micrometer-sized silicon particles. Subsequent removal of the volatile binder from the stacked-sheet cells is demonstrated to reduce their internal resistance. The silicon composite sheets exhibit high initial Coulombic efficiencies of 95%, with practical areal capacities of 2.0–4.4 mAh cm−2 at the 47th cycle under 0.30 mA cm−2, a reversible specific capacity of 2300 mAh g−1 after 100 cycles, and long-term cycling stability (specific capacity above 1700 mAh g−1 after 375 cycles). Cracks that are vertical to the silicon composite layer after cycling buffer the internal strain originating from silicon volume changes, providing excellent cycling stability. These results can assist the rational design of silicon anodes for high-cell-performance all-solid-state batteries. Graphical abstract Image 1 Highlights • Slurry mixing assisted by ZrO 2 balls forms good ionic/electronic conduction paths. • The binder is removed from the sheet-type cell to minimize its resistance. • The μm-Si-composite sheet with practical areal capacity has excellent performance. • Strain from Si volume changes is buffered by vertical cracks in the composite layer. • The slurry overcoating of solid electrolyte leads to high cell-based energy density. [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-sulfur (Na/S) batteries are promising next-generation batteries with high safety and high energy density. Sodium sulfide (Na 2 S) has application as active material in positive electrodes owing to its advantages such as low cost, low toxicity, and a large theoretical capacity. However, the electronic and sodium ion conductivities of Na 2 S are significantly low, and ascertaining the entire contribution of the active materials to cell capacities is challenging. Therefore, facilitating an electronic and ionic conduction path in the positive electrode is essential. In this study, Na 2 S was mixed with sodium iodide (NaI) via a mechanochemical process and was used as an active material in an all-solid-state Na/S battery. Consequently, a Na 2 S–NaI solid solution was formed, and the ionic conductivity of Na 2 S–NaI increased by five orders of magnitude compared to that of Na 2 S. Na 2 S–NaI showed large charge–discharge capacities and cycle capability. In particular, 90Na 2 S·10NaI showed a large capacity and high cycle efficiency, and 94% of Na 2 S acted as an active material. The result of this study leads to the development of all-solid-state Na/S batteries with high capacities, high rates, and high cycles. • Na 2 S–NaI solid solution was synthesized via mechanochemical process. • Na 2 S–NaI showed five orders of magnitude higher ionic conductivity than that of Na 2 S. • Na 2 S–NaI showed large charge–discharge capacities and cycle capability. [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]

White opaque single crystals of Na 6 Ge 2 S 6 O were obtained serendipitously during the preparation of Na 4 GeS 4. Then, pure glass and ceramic Na 6 Ge 2 S 6 O samples were synthesized from Na 2 S, GeS 2 , and GeO 2 reagents. The crystal structure was determined from powder and single crystal X-ray diffraction data. The physical properties were characterized by TG-DTA, SEM-EDX, Raman spectroscopy and electrochemical impedance spectroscopy. Na 6 Ge 2 S 6 O crystallizes with a new type of structure in the non-centro-symmetric space group P 2 1 2 1 2 1 , a = 6.96882 (6) Å, b = 7.04159 (6) Å, c = 26.7069 (2) Å, V = 1310.55 (2) Å3 and Z = 4. The asymmetric unit is built up of six Na+ cations surrounding a bi-tetrahedral complex anion, [S 3 GeOGeS 3 ]6−, which adopts a staggered conformation. The strongly distorted sodium polyhedra share edges and/or faces. The electrical conductivities of Na 6 Ge 2 S 6 O glass and ceramic at 25 °C are 2.9 × 10−5 S cm−1 (E a = 0.47 eV) and 1.8 × 10−7 S cm−1 (E a = 0.43 eV), respectively. [Display omitted] • The ternary system Na 2 S-GeO 2 -GeS 2 was investigated by solid state synthesis. • Glass and ceramic forms of the new Na 6 Ge 2 S 6 O compound were prepared. • Single crystals of Na 6 Ge 2 S 6 O were isolated after melting the Na 4 GeS 4 composition. • The new crystal structure was solved from powder and single crystal XRD data. • The electrical conductivity of amorphous Na 6 Ge 2 S 6 O is 2.9 × 10−5 S cm−1 at 25 °C. [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]

The Na 2 S-Na 4 GeS 4 section of the binary system Na 2 S-GeS 2 has been studied and the crystal structure of the Na 4 GeS 4 compound was determined from single-crystal X-Ray diffraction data. The physical properties of Na 4 GeS 4 were characterized by X-ray powder diffraction, TG/DTA, SEM-EDX, Raman spectroscopy and electrochemical impedance spectroscopy. Na 4 GeS 4 crystallizes with a new type of structure in the non-centro-symmetric space group Im , a = 10.9822(9) Å, b = 29.652(2) Å, c = 20.0391(16) Å, β = 105.77(1) (°), V = 6279.96(90) Å3 and Z = 30. The Na 4 GeS 4 asymmetric unit that contains 76 atoms is made up of 10 isolated GeS 4 tetrahedra. The 31 sodium atoms are located between these tetrahedra. The distorted NaS 6 octahedra, NaS 5 trigonal bipyramids, NaS 5 square pyramids and NaS 4 tetrahedra share corners, edges or faces. The electrical conductivity [2.7 × 10−5 S cm−1 (E a = 0.41 eV) at 25 °C] of the Na 4 GeS 4 glass phase, prepared by mechanochemical synthesis, is two orders of magnitude higher than that of the glass-ceramic phase, prepared by the combination of mechanochemical and solid-state synthesizes [9.8 × 10−8 (E a = 0.65 eV) at 25 °C]. [Display omitted] • The binary system Na 2 S-GeS 2 was reinvestigated by solid state synthesis. • Amorphous Na 4 GeS 4 was prepared by mechanochemical synthesis. • Single crystals of Na 4 GeS 4 were isolated after melting the Na 6 GeS 5 composition. • The unique crystal structure of Na 4 GeS 4 was solved from single crystal XRD. • The electrical conductivity of amorphous Na 4 GeS 4 is 2.7 × 10−5 S cm−1 at 25 °C. [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]

A new lithium-ion conducting oxide, hexagonal Li 4 GeO 4 , with a space group of P 6 3 /mmc , was prepared by mechanochemical treatment and subsequent heat treatment at 250 °C. The crystal structure was found in sulfide Li 4 SnS 4 , and this is the first study to report an oxide system. In addition, (100- x)Li 4 GeO 4 · x Li 2 MO 4 (M = S or W; x = 10, 20, 30, and 40 mol%) glass-ceramic electrolytes with the hexagonal phase were prepared by crystallization of their mother glasses. The formability of the electrolytes improved as the quantity of Li 2 SO 4 increased, and the 90Li 4 GeO 4 ·10Li 2 SO 4 glass-ceramic electrolyte showed the highest ionic conductivity of 2.9 × 10−6 S cm−1 at 25 °C. Compared with the experimental results, the bond valence sum (BVS) analysis results indicated that ionic conduction paths are easily connected along the c -axis in the hexagonal phase, suggesting that the relatively small lattices in the a - and b -axes are more advantageous for three-dimensional ionic conduction. • Li 4 GeO 4 -based glass electrolytes are prepared via a mechanochemical process. • The addition of Li 2 SO 4 improves the formability of the electrolytes. • A hexagonal metastable phase is formed by crystallization of Li 4 GeO 4 -based glasses. • The 90Li 4 GeO 4 ·10Li 2 SO 4 glass-ceramic has the highest conductivity of 2.9 × 10−6 S cm−1. [ABSTRACT FROM AUTHOR]

Liquid-phase synthesis for solid electrolytes has received considerable attention owing to its shape control, with the potential to produce particles easily on a large scale, and its low cost and energy consumption. However, solid electrolytes prepared through liquid-phase synthesis have been shown to have lower ionic conductivity than solid electrolytes prepared through the mechanical milling method. Recently, following various efforts, our group found that the crystallinity and remaining intermediate are the reasons for the low ionic conductivity of these materials. By using tetrahydrofuran (THF), we successfully improved the ionic conductivity of Li 3 PS 4 to 1.85 × 10−4 S cm−1 at 25 °C, higher than that afforded by ethyl propionate, which was reported to produce the highest ionic conductivity among the solvents used for liquid-phase synthesis. High-energy X-ray diffraction (XRD) measurements coupled with pair distribution function (PDF) analysis were employed to analyze the synthesized materials in order to determine why the ionic conductivity was higher than that of a sample prepared using ethyl propionate. The PDF analysis revealed that the crystallization of Li 3 PS 4 can be suppressed using THF, which has a lower boiling point than ethyl propionate. Moreover, it was revealed that the solvent could not be removed completely when the material has an amorphous structure, and thus, the ionic conductivity was lower than that of a material prepared using the solid-phase synthesis method. • By using tetrahydrofuran (THF) for liquid-phase synthesis, we prepared for Li3PS4 with relatively high ionic conductivity. • The Li 3 PS 4 structure was analyzed by high-energy X-ray diffraction coupled with pair distribution function (PDF) analysis. • The PDF analysis revealed that the crystallization of Li3PS4 can be suppressed using THF because of its low boiling point. • The THF could not be removed completely when the Li3PS4 has an amorphous structure, reducing the ionic conductivity. [ABSTRACT FROM AUTHOR]