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The sulfide solid electrolyte x LiCl·(25- x)LiBr·75Li 3 PS 4 was synthesized by a two-step glass-ceramic method. In the first step, amorphous precursors were obtained by a high-energy ball-milling method, and in the second step, the obtained precursors were heated up to a temperature in the range of 165 to 180 °C in order to obtain crystalline samples. The LGPS-like crystalline phase was precipitated in the heat-treated samples in the 0 < x < 12.5 composition range. The glass-ceramic samples showed high ion conductivities of 3 × 10−3 to 4 × 10−3 S cm−1 at 25 °C. A charge-discharge test was conducted on an all-solid-state test cell using the 7.5LiCl·17.5LiBr·75Li 3 PS 4 (mol%) glass-ceramic sample as a separator. The cathode composite of the test cell was a mixture of LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) active materials, the solid electrolyte, and acetylene black. The test cell exhibited high electrochemical stability and the electrochemical capacity based on NMC active materials was 145 mAhg−1. • The sulfide solid electrolyte xLiCl·(25-x)LiBr·75Li3PS4 was synthesized by a two-step glass-ceramic method. • The LGPS-like crystalline phase was precipitated in the heat-treated samples. • The glass-ceramic samples showed high ion conductivities of 3 × 10–3 to 4 × 10–3 Scm-1 at 25 °C. • An all-solid-state test cell with the glass ceramics exhibited good charge-discharge performance. [ABSTRACT FROM AUTHOR]

Lithium-ion conducting glass-ceramic electrolyte in the composition 75Li2S·5P2S3 ·20P2S5 (mol%) was prepared by heat treatment of an amorphous precursor. The amorphous precursor was obtained by a high-energy ball-milling process. The glass ceramic showed high ion conductivity 2.0×10−3 Scm−1 at room temperature. Raman scattering measurements suggested that the glass ceramic essentially composed of thio-phosphate anions, PS4 3− and P2S6 4−, as structural units. A laboratory-scale all-solid-state battery was also assembled by use of the glass ceramic as solid electrolytes and LiNi1/3Mn1/3Co1/3O2 powders as positive electrode materials. The all-solid-state battery showed good charge–discharge cycle performance at room temperature under a constant current density of 0.1 mAcm−2. [ABSTRACT FROM AUTHOR]

Abstract: LiAlO2-coated LiNi1/3Mn1/3Co1/3O2 powders were prepared by a sol–gel method associated with ultra-sonication, and the obtained LiAlO2-coated LiNi1/3Mn1/3Co1/3O2 was investigated as positive electrode materials for all-solid-state batteries with sulfide-based solid electrolytes. All-solid-state lithium batteries were assembled with the obtained LiAlO2-coated LiNi1/3Mn1/3Co1/3O2 powders and with amorphous Li3PS4 as solid electrolytes. The charge–discharge cycle performance of the all-solid-state cells was improved by the LiAlO2-coating on LiNi1/3Mn1/3Co1/3O2 powders. The LiAlO2 coating was effective in suppressing an increasing of the interfacial resistance between the LiNi1/3Mn1/3Co1/3O2 electrode material and the sulfide based solid electrolyte, Li3PS4, during charge–discharge cycling. The battery with the 1.0mol% LiAlO2-coated LiNi1/3Mn1/3Co1/3O2 showed an initial discharge capacity of 134 mAhg−1 and the battery retained the capacity more than 124 mAhg −1 even after 400 charge–discharge cycles at a current density of 11 mAg −1 at room temperature. [Copyright &y& Elsevier]

Abstract: All-solid-state lithium batteries were fabricated by use of LiNi1/3Mn1/3Co1/3O2 powders coated with ZrO2 as positive electrode materials and amorphous Li3PS4 as solid electrolytes. The ZrO2-coated powders were prepared by a sol–gel method associated with ultrasonic irradiation. The charge–discharge cycle performance of the all-solid-state cells was improved by use of the ZrO2-coated LiNi1/3Mn1/3Co1/3O2 powders. The ZrO2 coating was effective in suppressing an increasing of the interfacial resistance between the LiNi1/3Mn1/3Co1/3O2 electrode material and the sulfide based solid electrolyte, a-Li3PS4, during charge–discharge cycling. The battery with the ZrO2-coated LiNi1/3Mn1/3Co1/3O2 showed an initial discharge capacity of 115mAhg−1 and good capacity retention even after 50cycles at a current density of 0.1mAcm−2 at room temperature. [Copyright &y& Elsevier]

Abstract: Lithium-ion conducting solid electrolytes in the composition (100-x)Li3PS4·xLiAlS2 (mol%) were prepared by the use of a high-energy ball-milling process at room temperature. Amorphous samples were obtained in the composition range of x=0 to x=13.1. In the composition of x≥18.2, a crystalline Al2S3 phase remained in the samples which were ball-milled for 35h. The lithium ion conductivity at 298K of the obtained amorphous samples was increased with an increase in the compositional parameter x and showed the maximum at the compositional parameter x=13.1 (86.9Li3PS4·13.1LiAlS2: σ298K =6.0×10−4Scm−1 at 298K). [Copyright &y& Elsevier]

Abstract: We have analyzed the transfer efficiency of ballistic electron emission microscopy (BEEM), taking the finite spot size of the emitted electron beam from scanning probes into account. Three-dimensional diffraction from an aperture at a surface–metal/air interface is introduced to model an effect caused by the finiteness of spot size. As a general trend, the diffraction decreases BEEM transfer efficiency. The diffraction effect increases as the spot size decreases and the air-gap distance increases. In a Au/GaAs sample, BEEM transfer efficiency markedly deteriorates down to 6% of the value derived from a conventional planar tunneling theory when a spot size of 0.2nm, an air-gap distance of 0.6nm, and an electron energy of 0.2eV, measured from the bottom of the GaAs conduction band, are assumed. BEEM transfer efficiency is markedly dependent on the spot size of the emitted hot electron. This result indicates that the BEEM current depends on the spatial resolution of the scanning probe, that is, the condition of the tip apex. [Copyright &y& Elsevier]

Abstract: Preparation of lithium ion conducting solid electrolytes in the composition 75Li2S·xP2S3·(25−x)P2S5 (mol%) was attempted by use of a high-energy ball-milling process at room temperature. Amorphous samples were obtained in the composition range of x=0 to x=5. In the samples with x ≥ 8.3, a crystalline Li2S phase was remained after the ball milling for 50 h. The lithium ion conductivity at 298 K of the amorphous samples was increased with an increase in x, and the amorphous sample with x=5 showed the highest lithium ion conductivity of 6.2×10−4 S·cm−1 at 298 K among the obtained samples. A laboratory-scale all-solid-state lithium battery using the amorphous sample with x=5 showed good discharge–charge performance at room temperature. [Copyright &y& Elsevier]

Abstract: Amorphous solid electrolytes containing large amount of Li2S were prepared in the system Li2S–GeS2–P2S5 by a high-energy ball-milling process. The region of amorphous-sample formation by the ball-milling process is much wider than the glass-forming region by a conventional melt-quenching method. The addition of a second network-forming sulfide, GeS2, to the Li2S–P2S5 system caused an enhancement of ion conductivities of the amorphous samples. The 95Li3PS4·5Li4GeS4 amorphous sample showed the highest lithium-ion conductivity 4.0×10−4 S cm−1 at room temperature among the obtained amorphous samples in the system Li2S–GeS2–P2S5. DC polarization measurements suggested that lithium-ion transport number of the 95Li3PS4·5Li4GeS4 sample was almost unity. [Copyright &y& Elsevier]

Abstract: Sulfur was investigated as positive electrode materials for all-solid-state lithium batteries with an inorganic solid electrolyte a-60Li2S·40SiS2 (mol%). The sulfur (54 mass%) was ball-milled with metallic copper (42.8 mass%) and acetylene black (3.2 mass%) for 10 h and the obtained composite was used as the positive electrode materials of the solid-state battery. The composite worked as reversible positive electrode materials with a large electrochemical capacity. The capacity that was calculated on the base of the weight of sulfur was larger than 980 mAhg−1. The all-solid-state lithium cell showed a successive reversibility with the large specific capacity. [Copyright &y& Elsevier]

Abstract: Li4.4GexSi1−x alloys were prepared by use of a high-energy ball-milling process. The Li4.4GexSi1−x alloys formed a solid solution over the whole composition range of 0≤x≤1. Those alloys were isomorphic with an Li15Ge4 crystalline phase that had a D86 structure belonging to a space group I4¯3d. The lattice constants of the alloys were increased with an increase in the compositional parameter x. The Li4.4GexSi1−x alloys were investigated as negative electrode materials for all-solid-state lithium batteries with an inorganic solid electrolyte a-60Li2S·40SiS2 (mol%). Among the obtained alloys, the Li4.4Ge0.67Si0.33 alloy showed the largest specific capacity of 190 mA h g−1 and good charge–discharge reversibility. [Copyright &y& Elsevier]

Amorphous fine powders in the system AgI–Ag2PO3.5 were obtained over a wide composition range of 20–70 mol% AgI by a high-energy ball-milling process. While an amorphous sample was not obtained of the composition 80AgI · 20Ag2PO3.5 (mol%) by the ball-milling process, the amorphous sample-forming region by the high-energy ball-milling process was very similar to the glass-forming region by a conventional melt-quenching method. The 60AgI · 40Ag2PO3.5 (mol%) composition, at which an amorphous sample was obtained by ball milling to 48 h, was the most easily amorphous-forming composition in the system AgI–Ag2PO3.5. Ball-milled samples showed high ion conductivities at room temperature. The σ298 of the 60AgI·40Ag2PO3.5 sample changed with the ball-milling time. The σ298 steeply increased with an increase in the milling time and showed a maximum of 7.3×10−1 Sm−1 at around 20 h. It was noted that the maximum conductivity was higher than the conductivity of the melt-quenched glass with the same chemical composition. The σ298 of the samples ball-milled for longer than 30 h decreased with an increase in the milling time, and had a similar value as that of a melt-quenched glass. [Copyright &y& Elsevier]

We have examined microstructures induced by pulsed-laser-melting for the Mn ion implanted Si using transmission electron microscopy. Single crystalline Si(0 0 1) wafers were irradiated with 65 keV and 120 keV Mn ions to a fluence of 1.0 × 10 16 /cm 2 at room temperature. The ion beam-induced amorphous layers in the as-implanted samples were melted and resolidified by pulsed YAG laser irradiation. After laser irradiation with appropriate laser fluence, the surface amorphous layers recrystallize into the single crystalline Si. The Mn concentration becomes higher in the near-surface region with increasing the number of laser shots. The migrated Mn atoms react with Si atoms and form the amorphous Mn–Si in the Si matrix. [ABSTRACT FROM AUTHOR]

Abstract: The sulfide-based solid electrolyte (Li2S)7(P2S5)3 has large ionic conductivity, and thus is an important candidate for application to solid-state lithium rechargeable batteries. In lithium solid conductors, a small lithium ion (Pauling ionic radius of 60pm) migrates in space composed of standing anions, and such situations are not yet well understood experimentally as well as theoretically. Lithium ion migration for the crystalline (Li2S)7(P2S5)3 was observed over short observation times using the pulsed-gradient spin-echo (PGSE) 7Li nuclear magnetic resonance (NMR) techniques. Diffusive diffraction effects were apparent in the echo attenuation profiles indicating that motion of lithium ions was in some way constrained to a certain (i.e., ‘characteristic’) length scale. Prior to being diffracted, the lithium ions rapidly migrate similar to lithium ions in liquids. The diffractive behavior depends on observation time and the strength of the applied pulsed magnetic field gradient (PFG), which suggests that the diffusing lithium ions are distributed. The diffraction patterns give a longer characteristic distance for faster moving lithium ions. Diffusing lithium ions collide with obstacles such as standing anions many times at longer time intervals, which consequently results in slow migration. We believe that our findings will contribute to understand conduction mechanisms in solid conductors. [Copyright &y& Elsevier]

Abstract: Sulfur–carbon composites were investigated as positive electrode materials for all-solid-state lithium ion batteries with an inorganic solid electrolyte (amorphous Li3PS4). The elemental sulfur was mixed with Vapor-Grown Carbon Fiber (VGCF) and with the solid electrolyte (amorphous Li3PS4) by using high-energy ball-milling process. The obtained sulfur–VGVF–solid electrolyte composite was used as positive electrode materials of the all-solid-state battery. The composite showed good electrochemical properties as positive electrode materials. The capacity that was calculated on the base of the weight of sulfur was about 1300mAhg−1 at room temperature, when the all-solid-state battery was discharged and charged in the voltage range of 0.9 to 2.6V at a constant current density of 0.1mAcm−2. The battery kept the capacity more than 1200mAhg−1 even after 50 discharge–charge cycles. [Copyright &y& Elsevier]

In this paper, highly oriented nanocrystals of Fe3Si with a D03 structure are fabricated on SiO2 using ultrathin Si on insulator substrate. First, (001) oriented Si nanocrystals are formed on the SiO2 layer by solid state dewetting of the top Si layer. Then, Fe addition to the Si nanocrystals is performed by reactive deposition epitaxy and post-deposition annealing at 500°C. The structures of the Fe–Si nanocrystals are analyzed by cross-sectional transmission electron microscopy and nanobeam electron diffraction. We observe that Fe3Si nanocrystals with D03, B2, and A2 structures coexist on the 1-h post-annealed samples. Prolonged annealing at 500°C is effective in obtaining Fe3Si nanocrystals with a D03 single phase, thereby promoting structural ordering in the nanocrystals. We discuss the formation process of the highly oriented D03-Fe3Si nanocrystals on the basis of the atomistic structural information. [ABSTRACT FROM AUTHOR]

Abstract: Atomistic structures of high-fluence Mn ion implanted Si were examined using transmission electron microscopy (TEM). Si(001) single crystals were irradiated at cryogenic temperature with 120keV Mn ions to a fluence of 3.0×1017/cm2. Cross-sectional TEM observations revealed that an amorphous bilayer consisting of amorphous Mn–Si and amorphous Si is formed on the topmost layer of the Si substrate. Atomic pair-distribution functions extracted from electron diffraction patterns indicated that short-range order of the amorphous Mn–Si thin layer is similar to the local atomic configuration of higher manganese silicides. The amorphous Mn–Si layer crystallized to Mn4Si7 polycrystalline layer by thermal annealing. [Copyright &y& Elsevier]

Concentration of conducting ions is known to be a main factor affecting ionic conductivities of glasses. Therefore, the melt-quenched Ag2S–SiS2 glasses reported by Pradel et al. (J. Non-Cryst. Solids 188 (1995) 75) were difficult to show high ionic conductivity owing to the low Ag2S content of 40–50 mol.%. We recently reported that 60Ag2S·40SiS2 amorphous sample showed electrochemical potential window of more than 2.5 V vs. Ag/Ag+ electrode and silver ion conductivity of 7×10−2 Sm−2 at room temperature (J. Mater. Chem. 12 (2002) 1094). The ionic conductivity is somewhat low for practical uses. In order to further increase the ion conductivity, we tried to prepare high Ag2S-containing amorphous samples in the system Ag2S–SiS2 by employing the high-energy ball-milling process. Our results proved that amorphous samples containing 70 and 80 mol.% Ag2S can be synthesized in a suitable milling time range, and that the amorphous samples partially transformed into Ag8SiS6 crystalline phases with further milling. The high Ag2S-containing amorphous samples showed high ionic conductivity, and the highest ion conductivity of 2.1×100 Sm−1 was obtained at 298 K for the 80Ag2S·20SiS2 amorphous sample. Those samples, however, showed very poor electrochemical stability. [Copyright &y& Elsevier]

7 Li spectra were observed for amorphous and crystalline Li 3 PS 4 to study the structure of lithium ions. Lithium migration was studied using pulsed-gradient spin-echo 7 Li NMR between 30 °C and 120 °C. The lithium diffusion behavior depended on the observation time and the pulsed-field gradient strength, and was quite different from the lithium diffusion in liquid electrolytes. Amorphous Li 3 PS 4 showed higher ionic conductivity than crystalline Li 3 PS 4 , and similarly, the lithium diffusion rate was faster in amorphous samples. The lithium diffusion behavior in both conductors was not uniform and was distributed widely in time and space. [ABSTRACT FROM AUTHOR]

A new class of sulfide electrolytes, (1-x)LiCl-xLiBr-2Li 3 PS 4 (x = 0, 0.25, 0.50, 0.75, and 1.0), was synthesized, and characterized their stable temperature range, ionic-conductivity and applicability for all-solid-state lithium metal battery. The optimal heat-treatment temperature of the synthesis process is relatively low, i.e., 200 °C. Ionic conductivity of the electrolyte increases with increasing LiBr ratio, and maximum ionic conductivity at 25 °C is 1.7 mScm−1 with x = 0.75. At higher heat-treatment temperature, above 250 °C, a low-ionic-conduction crystalline phase appears in the electrolyte, and at that time, ionic conductivity decreases to a similar value to that of the amorphous precursor used in the synthesis process. Since the electrolyte does not contain a transition metal, it is applicable to the lithium-metal secondary system. A reversible lithium deposition-stripping reaction was demonstrated by cyclic voltammogram, the results of which indicate that the electrolyte is applicable to a typical 4-V rechargeable lithium-metal secondary system. The Coulombic efficiency of the first charge-discharge cycle is approximately 75%, and reversible capacity of 185 mAhg−1 was verified by a Li/0.25LiCl-0.75LiBr-2Li 3 PS 4 /NCA pelletized-cell test. It is concluded from these results that the proposed low-temperature-synthesized sulfide electrolytes will reduce energy consumption for material production, and such a low-carbon-footprint process meets the demand of the future sustainable society. • A new class of LiX (X = Cl, Br)-Li 3 PS 4 solid electrolytes are synthesized by using conventional solid reaction process. • 0.25LiCl-0.75LiBr-2Li 3 PS 4 solid electrolyte shows a high Li+ conductivity of 1.7mScm−1 at 25 °C. • All-solid-state cells exhibits a discharge capacity of 185 mAhg−1 -NCA at 25 °C. [ABSTRACT FROM AUTHOR]

A crystalline solid electrolyte, Li 7 P 3 S 11 , was synthesized by a liquid-phase reaction of Li 2 S and P 2 S 5 in an organic solvent. A precursor, which was a mixture of solvated Li 3 PS 4 and Li 4 P 2 S 7 , was prepared by mixing Li 2 S and P 2 S 5 powders in 1,2-dimethoxyethane (DME) solvent. After a vacuum drying of the precursor, the crystalline phase of Li 7 P 3 S 11 was obtained by heat treatment at 250 °C for 1 h in Ar atmosphere. The Li 7 P 3 S 11 sample showed high ionic conductivity of 2.7 × 10 −4 S cm −1 at room temperature. The liquid-phase synthesis of the solid electrolyte has advantages for mass-production of all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Abstract: An all-solid-state lithium-ion battery (ASSB) using non-flammable solid electrolytes is a candidate for a next-generation battery. Although the excellent cycle performance and its high energy density are suggested in the literature, a practical size battery has not been appeared yet. In this paper, we have adopted a sulfide based electrolyte, Li2S–P2S5 (80:20 mol%) to a rocking chair type lithium ion battery. The electrochemical cell consists of a Li2O–ZrO2 coated LiNi0.8Co0.15Al0.05O2 (NCA) cathode, an artificial graphite anode and the sulfide based electrolyte without any organic and inorganic liquids. The cathode charge transfer resistance is significantly reduced by the Li2O–ZrO2 coating. The total cell resistance of the Li2O–ZrO2 (LZO) coated NCA adopted cell is approximately one quarter of non-treated one. A standard type single cell with the nominal capacity of 100 mAh at 25 °C is fabricated by wet printing process, and its capacity retention is approximately 80% at 100 cycles. Also, a 1 Ah class battery was constructed by stacking the single cells, and demonstrated. [Copyright &y& Elsevier]