Search

US-20260128323-A1 - SULFIDE SOLID ELECTROLYTE POWDER AND ELECTRODE MIXTURE

US20260128323A1US 20260128323 A1US20260128323 A1US 20260128323A1US-20260128323-A1

Abstract

A sulfide solid electrolyte powder includes a crystal phase. A value represented by [(strain value−0.001)/specific surface area (m 2 /g)]×100 is 0.010 to 0.070, and the crystal phase comprises an argyrodite crystal structure. The sulfide solid electrolyte powder may further include an amorphous phase, and a content ratio of the amorphous phase may be 5 mass % or more.

Inventors

  • Naoki Fujii
  • Yasuhiro Kunisa

Assignees

  • AGC Inc.

Dates

Publication Date
20260507
Application Date
20251219
Priority Date
20230705

Claims (7)

  1. 1 . A sulfide solid electrolyte powder comprising a crystal phase, wherein a value represented by [(strain value−0.001)/specific surface area (m 2 /g)]×100 is 0.010 to 0.070, and the crystal phase comprises an argyrodite crystal structure.
  2. 2 . The sulfide solid electrolyte powder according to claim 1 , further comprising an amorphous phase, wherein a content ratio of the amorphous phase is 5 mass % or more.
  3. 3 . The sulfide solid electrolyte powder according to claim 1 , wherein the argyrodite crystal structure comprises two or more kinds of halogen elements as constituent elements.
  4. 4 . The sulfide solid electrolyte powder according to claim 3 , wherein the halogen elements comprise Br, and a content ratio of Br to the halogen elements is 0.1 to 0.9.
  5. 5 . The sulfide solid electrolyte powder according to claim 1 , wherein the argyrodite crystal structure is represented by a composition formula Li a MZ b Ha c , in the composition formula, M is at least one element selected from Na, K, and elements present as a divalent to quinquevalent cation in the crystal structure, Z is at least one element selected from elements present as a divalent anion in the crystal structure, and Ha is at least one element selected from the group consisting of F, Cl, Br, and I, and the composition formula satisfies relationships of 5≤a≤7, 4≤b≤6, and 1<c≤2.
  6. 6 . The sulfide solid electrolyte powder according to claim 1 , having a composite elastic modulus of 5 GPa to 20 GPa.
  7. 7 . An electrode mixture comprising the sulfide solid electrolyte powder according to claim 1 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This is a bypass continuation of International Application No. PCT/JP2023/037116 filed on Oct. 12, 2023, and claims priority from Japanese Patent Application No. 2023-110732 filed on Jul. 5, 2023, the entire content of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates to a sulfide solid electrolyte powder and an electrode mixture containing the same. BACKGROUND ART Lithium ion secondary batteries are widely used in portable electronic devices such as a mobile phone and a notebook computer. In the related art, a liquid electrolyte has been used in a lithium ion secondary battery, but a lithium ion all-solid-state battery (hereinafter, also referred to as a solid battery) in which a solid electrolyte is used as an electrolyte of the lithium ion secondary battery has attracted attention from the viewpoint that improvement of safety and high-speed charging and discharging can be expected. The solid electrolytes are roughly classified into a sulfide solid electrolyte and an oxide solid electrolyte. Among them, the sulfide solid electrolyte exhibits high ion conductivity since the sulfide solid electrolyte contains sulfide ions having high polarizability. As the sulfide solid electrolyte, there has been known LGPS crystals such as Li10GeP2S12, argyrodite crystals such as Li6PS5Cl, LPS crystallized glasses such as a Li7P3S11 crystallized glass, and the like. When producing an all-solid-state battery such as a lithium ion battery using the sulfide solid electrolyte as described above, it is necessary to use a high restraining pressure in order to maintain interface contact between a positive electrode active material or a negative electrode active material and the solid electrolyte during charging and discharging. This is to prevent deterioration of the interface contact due to a volume change caused by expansion and contraction of the positive electrode active material or the negative electrode active material accompanying the charging and discharging of the all-solid-state battery. Patent Literature 1: WO2021/085239 SUMMARY OF INVENTION In order to realize such a high restraining pressure, it is necessary to use a large restraining jig. In addition, even when an all-solid-state battery is obtained at a high restraining pressure, as a charging and discharging cycle is repeated, good interface contact cannot be maintained due to the volume change, and a battery capacity decreases. Therefore, an object of the present invention is to provide a sulfide solid electrolyte powder capable of maintaining good interface contact with an active material even at a low restraining pressure when formed into an all-solid-state battery, and an electrode mixture containing the same. Patent Literature 1 discloses a solid electrolyte including a crystal phase having an argyrodite crystal structure, and discloses that a lattice strain of a compound having the crystal phase is less than 0.10% and that lithium ion conductivity is improved as the lattice strain is smaller. With respect to this, as a result of intensive studies, the present inventors have found that the above problems can be solved by imparting a certain strain to a crystal phase constituting a sulfide solid electrolyte powder and having a certain relationship with a specific surface area, and have completed the present invention. That is, the present invention relates to the following. [1]A sulfide solid electrolyte powder including a crystal phase,in which a value represented by [(strain value−0.001)/specific surface area (m2/g)]×100 is 0.010 to 0.070, andthe crystal phase includes an argyrodite crystal structure.[2] The sulfide solid electrolyte powder according to [1], further including an amorphous phase,in which a content ratio of the amorphous phase is 5 mass % or more.[3] The sulfide solid electrolyte powder according to [1] or [2],in which the argyrodite crystal structure includes two or more kinds of halogen elements as constituent elements.[4] The sulfide solid electrolyte powder according to [3],in which the halogen elements include Br, anda content ratio of Br to the halogen elements is 0.1 to 0.9.[5] The sulfide solid electrolyte powder according to any one of [1] to [4],in which the argyrodite crystal structure is represented by a composition formula LiaMZbHac,in the composition formula, M is at least one element selected from Na, K, and elements present as a divalent to quinquevalent cation in the crystal structure, Z is at least one element selected from elements present as a divalent anion in the crystal structure, and Ha is at least one element selected from the group consisting of F, Cl, Br, and I, andthe composition formula satisfies relationships of 5≤a≤7, 4≤b≤6, and 1<c≤2.[6] The sulfide solid electrolyte powder according to any one of [1] to [5], having a composite elastic modulus of 5 GPa to 20 GPa.[7] An electrode mixture including the sulfide solid electrolyte powder