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Mechanical properties of solid electrolytes are important as well as ionic conductivity to achieve all-solid-state batteries with large capacities and long cycle life. In this study, it is shown that Li2S–P2S5 glasses with lithium halides, especially LiI, exhibit both high ionic conductivity and favorable mechanical properties. Mechanical properties, such as Young’s modulus and formability at powder compaction, are evaluated for the solid electrolytes. The addition of lithium halides decreases the Young’s modulus of the electrolytes. In addition, fewer pores and grain boundaries were observed in the powder-pressed pellets of Li2S–P2S5 glasses with lithium halides. All-solid-state batteries using Si electrodes and glass electrolytes with lithium halides exhibited a larger capacity of 20 cycles compared to those without lithium halides. These results provide guidelines for the construction of all-solid-state batteries from the viewpoint of the mechanical properties of solid electrolytes.

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Summary C‐Glycosides are characterized by their C–C bonds in which the anomeric carbon of the sugar moieties is directly bound to the carbon atom of aglycon. C‐Glycosides are remarkably stable, as their C–C bonds are resistant to glycosidase or acid hydrolysis. A variety of plant species are known to accumulate C‐glycosylflavonoids; however, the genes encoding for enzymes that catalyze C‐glycosylation of flavonoids have been identified only from Oryza sativa (rice) and Zea mays (maize), and have not been identified from dicot plants. In this study, we identified the C‐glucosyltransferase gene from the dicot plant Fagopyrum esculentum M. (buckwheat). We purified two isozymes from buckwheat seedlings that catalyze C‐glucosylation of 2‐hydroxyflavanones, which are expressed specifically in the cotyledon during seed germination. Following purification we isolated the cDNA corresponding to each isozyme [FeCGTa (UGT708C1) and FeCGTb (UGT708C2)]. When expressed in Escherichia coli, both proteins demonstrated C‐glucosylation activity towards 2‐hydroxyflavanones, dihydrochalcone, trihydroxyacetophenones and other related compounds with chemical structures similar to 2′,4′,6′‐trihydroxyacetophenone. Molecular phylogenetic analysis of plant glycosyltransferases shows that flavonoid C‐glycosyltransferases form a different clade with other functionally analyzed plant glycosyltransferases.

To evaluate ideal interfaces between Li metal and Li 2 S-P 2 S 5 solid electrolytes, bulk-type cells were fabricated using thin Li metal films prepared by vacuum-evaporation. The symmetric cell of Li/75Li 2 S ･ 25P 2 S 5 /Li showed a high utilization of Li metal (about 40%), though abrupt decrease of the utilization was observed after 5 cycles. A high utilization of Li metal (about 25%) was retained for 5 cycles by inserting Au thin film at the interface between Li metal and Li 2 S-P 2 S 5 solid electrolytes. Morphology of Li metal after dissolution/deposition cycles for the cell with Au thin film became more uniform compared to the cell without Au thin film. .

Sulfide glasses are considered to be promising electrolytes for all-solid-state batteries because of their high ionic conductivities and favorable mechanical properties. In this paper, comprehensive studies of the mechanical properties of sulfide glasses were carried out based on the Li 2 SP 2 S 5 system, and we evaluated the effects of changing the glass former and modifier on the elastic moduli and formability of these glasses. Young's moduli of Li 2 SP 2 S 5 glasses increased when the glass former P was replaced with Ge or Si. Moreover, the Young's moduli of Li 2 SP 2 S 5 glasses also increased when substituting S with O. Irrespective of the glass modifier, the Young's moduli of R x S y P 2 S 5 glasses (R = Li, Na, Ag, Mg, or Sn) increased with the increase in content of each modifier. The measured Young's moduli are correlated with the mean atomic volumes of the glasses. We evaluated the formability of the sulfide glasses in powder-compaction tests at room temperature. Sulfide glasses with lower bonding energy, larger free volume, and more isolated structure exhibited higher densification ability. Pugh's ratio (B/G) (B is the bulk and G the shear modulus) was used to evaluate the ductile-brittle property of materials. The glasses with a larger B/G ratio, meaning higher ductility, tended to show a higher relative density. It is suggested that plastic deformation contributes to the densification. This study will provide valuable results for glass science, and will be useful for developing all-solid-state batteries.

Mechanical properties such as formability and elastic moduli of solid electrolytes are important for the fabrication of all-solid-state batteries and retention of their charge-discharge capacities. In this paper, xNa 2 S$(100 À x)P 2 S 5 (mol%) sulfide glass electrolytes (x ¼ 50, 67, and 75) were prepared and their formability and elastic moduli were evaluated by an ultrasonic pulse-echo technique and a compression test under uniaxial pressing. The glasses were better densified and showed lower Young's moduli (15-19 GPa) than the Li 2 S-P 2 S 5 glasses.