Mechanical properties of sulfide glasses in all-solid-state batteries

Abstract

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.

Correlating Macro and Atomic Structure with Elastic Properties and Ionic Transport of Glassy Li2S‐P2S5 (LPS) Solid Electrolyte for Solid‐State Li Metal Batteries

“…[ 20 ] This value would be anticipated to be even higher for a 75‐25 composition as observed with sulfide glasses as the glass modifier concentration is increased. [ 21 ] The higher moduli observed in oxide glasses compared to sulfide glasses lies in the higher bonding dissociation energies resulting in a more rigid glass network (P‐S: 442 kJ mol −1 , Li‐S: 313 kJ mol −1 , P‐O: 589 kJ mol −1 , Li‐O: 341 kJ mol −1 ), in addition to a higher packing density. [ 22 ]…”

Favorable composite electrodes for all-solid-state batteries

“…24) The ultrasonic pulse echo method is particularly useful because it does not require a large-scale apparatus, and even small samples (10 mm diameter, ³2 mm thickness) can be measured with relatively high accuracy. Figure 4 shows the relationship between mean atomic volume and Young's modulus; 25) in general, these quantities are strongly correlated. 25),26) Oxide glasses have higher Young's moduli and smaller mean atomic volumes.…”

“…The properties of sulfide solid electrolytes are intermediate between the oxide and other chalcogenide glasses. 25) Further details have been summarized in previous papers. 12), 25) 3.…”

“…25) Further details have been summarized in previous papers. 12), 25) 3. Design of composite electrodes…”

“…The blue area depicts the properties of sulfide solid electrolytes. 25) lytes. 27)30) The introduction of a oxide solid electrolyte such as LiNbO 3 can considerably decrease this interfacial resistance, 27)35) as first reported by Takada and Ohta et al Similar results have been observed in all-solid-state batteries using polymer electrolytes.…”