Lithium ionic conductor and fabrication method therefor, and all-solid lithium secondary battery

• US 9,142,861 B2
• Filed: 02/03/2014
• Issued: 09/22/2015
• Est. Priority Date: 08/17/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Homma, Kenji, Yamamoto, Tamotsu, Tanaka, Tsutomu
• Primary Examiner(s): DOVE, TRACY MAE
• Application Number:
  US14/170,860
• Publication Number:
  US 20140147753A1
• Time in Patent Office: 596 Days
• Field of Search: 429/188, 429/322
• US Class Current: 1/1
• CPC Class Codes: H01B 1/06 mainly consisting of other non-metallic substances
• CPC Class Codes: H01B 1/10 sulfides
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 2300/0068 inorganic
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A lithium ionic conductor (solid electrolyte) contains lithium (Li), phosphorus (P), boron (B) and sulfur (S) as constituent elements and has a crystal structure that boron (B) is substituted for part of phosphorus (P) in the β structure of Li₃PS₄.

Claims

1. A lithium ionic conductor, comprising lithium (Li), phosphorus (P), boron (B) and sulfur (S) as constituent elements and comprising a crystal structure that boron (B) is substituted for part of phosphorus (P) in a β

structure of Li₃PS₄.

2. The lithium ionic conductor according to claim 1, wherein a composition of the lithium ionic conductor is represented by Li_3+3/4xB_xP₁₋

3/4xS₄ (0.2≦

x≦

1.0).

3. The lithium ionic conductor according to claim 1, wherein the β

structure of Li₃PS₄ is a crystal structure in which six-coordinated octahedrons centering on lithium (Li) are located in such a manner as to share an edge.

4. The lithium ionic conductor according to claim 1, wherein the β

structure of Li₃PS₄ is a crystal structure in which one half of apexes of a plurality of four-coordinated tetrahedrons centering on boron (B) or phosphorus (P) face an opposite direction in a unit cell.

5. The lithium ionic conductor according to claim 1, wherein the β

structure of Li₃PS₄ is a crystal structure in which a four-coordinated tetrahedron centering on boron (B) or phosphorus (P) and a four-coordinated tetrahedron centering on lithium (Li), a four-coordinated tetrahedron centering on boron (B) or phosphorus (P) and a six-coordinated octahedron centering on lithium (Li), and a four-coordinated tetrahedron centering on lithium (Li) and a six-coordinated octahedron centering on lithium (Li) are located in such a manner as to share an edge.

6. An all-solid lithium secondary battery, comprising:

a positive electrode;

a negative electrode; and

a solid electrolyte provided between the positive electrode and the negative electrode, and containing lithium (Li), phosphorus (P), boron (B) and sulfur (S) as constituent elements, the solid electrolyte having a crystal structure that boron (B) is substituted for part of phosphorus (P) in a β

structure of Li₃PS₄.

7. The all-solid lithium secondary battery according to claim 6, wherein the solid electrolyte has a composition represented by Li_3+3/4xB_xP₁₋

3/4xS₄ (0.2≦

x≦

1.0).

8. The all-solid lithium secondary battery according to claim 6, wherein the β

structure of Li₃PS₄ is a crystal structure in which six-coordinated octahedrons centering on lithium (Li) are located in such a manner as to share an edge.

9. The all-solid lithium secondary battery according to claim 6, wherein the β

structure of Li₃PS₄ is a crystal structure in which one half of apexes of a plurality of four-coordinated tetrahedrons centering on boron (B) or phosphorus (P) face an opposite direction in a unit cell.

10. The all-solid lithium secondary battery according to claim 6, wherein the β

structure of Li₃PS₄ is a crystal structure in which a four-coordinated tetrahedron centering on boron (B) or phosphorus (P) and a four-coordinated tetrahedron centering on lithium (Li), a four-coordinated tetrahedron centering on boron (B) or phosphorus (P) and a six-coordinated octahedron centering on lithium (Li), and a four-coordinated tetrahedron centering on lithium (Li) and a six-coordinated octahedron centering on lithium (Li) are located in such a manner as to share an edge.

11. A fabrication method for a lithium ionic conductor, comprising:

mixing lithium (Li), phosphorus (P), boron (B) and sulfur (S), melting the mixture by heating and then cooling the mixture to form a burned body; and

reducing the burned body to powder and then burning the powder again at a temperature at which the powder does not melt to fabricate a lithium ionic conductor having a crystal structure that boron (B) is substituted for part of phosphorus (P) in a β

structure of Li₃PS₄.