Solid electrolyte with low-symmetry garnet-related structure and lithium-ion secondary battery

Patent metadata

Field	Value
Publication number	US-10763544-B1
Application number	US-201716304231-A
Country	US
Kind code	B1
Filing date	May 2, 2017
Priority date	May 26, 2016
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A solid electrolyte material having high ion conductivity and a all-solid-state lithium-ion secondary battery using this solid electrolyte material are provided. The solid electrolyte material has a garnet-related structure crystal represented by the chemical composition Li7−x−yLa3Zr2−x−yTaxNbyO12 (0.05≤x+y≤0.2, x≥0, y≥0), which belongs to an orthorhombic system and a space group belonging to Ibca. The solid electrolyte material has lithium-ion conductivity at 25° C. of at least 1.0×10−4 S/cm. Also, in this solid electrolyte material, the lattice constants are 1.29 nm≤a≤1.32 nm, 1.26 nm≤b≤1.29 nm, and 1.29 nm≤c≤1.32 nm, and three 16f sites and one 8d site in the crystal structure are occupied by lithium-ions. The all-solid-state lithium-ion secondary battery has a positive electrode, a negative electrode, and a solid electrolyte, the solid electrolyte comprising this solid electrolyte material.

First claim

The invention claimed is:

1. A garnet-related structure crystal represented by the chemical composition Li 7−x−y La 3 Zr 2−x−y Ta x Nb y O 12 (0.05≤x+y≤0.2, x≥0, y≥0), the crystal structure being an orthorhombic system.

2. The garnet-related structure crystal according to claim 1 , wherein the space group showing symmetry in the crystal structure belongs to Ibca.

3. The garnet-related structure crystal according to claim 1 , wherein lattice constants a, b and c in the crystal structure satisfy 1.29 nm≤a≤1.32 nm, 1.26 nm≤b≤1.29 nm, and 1.29 nm≤c≤1.32 nm, respectively.

4. The garnet-related structure crystal according to claim 1 , wherein at least four sites in the crystal structure are occupied by lithium-ions.

5. The garnet-related structure crystal according to claim 1 , wherein the lithium-ion conductivity at 25° C. is at least 1.0×10 −4 S/cm.

6. The garnet-related structure crystal according to claim 1 , wherein the relative density is at least 99%.

7. The garnet-related structure crystal according to claim 6 , wherein the relative density is 100%.

8. A garnet-related structure sintered compact comprising: the garnet-related structure crystal according to claim 1 ; and a crystal having a cubic garnet-related structure crystal represented by the chemical composition Li 7−x−y La 3 Zr 2−x−y Ta x Nb y O 12 (0.2<x+y≤0.6, x≥0, y≥0).

9. An all-solid-state lithium-ion secondary battery comprising: a positive electrode, a negative electrode, and a solid electrolyte containing the garnet-related structure crystal according to claim 1 .

10. An all-solid-state lithium-ion secondary battery comprising: a positive electrode, a negative electrode, and the garnet-related structure sintered compact according to claim 8 .

11. A method for manufacturing a garnet-related structure crystal belonging to an orthorhombic system represented by the chemical composition Li 7−x−y La 3 Zr 2−x−y Ta x Nb y O 12 (0.05≤x+y≤0.2, x≥0, y≥0), the method comprising melting at least a portion of a raw material represented by the chemical composition Li (7−x−y)z La 3 Zr 2−x−y Ta x Nb y O 12 (0.05≤x+y≤0.2, x≥0, y≥0, 1<z≤2) to form a molten portion for crystal growth; moving the molten portion for crystal growth to an uncrystallized raw material at a traveling rate of at least 8 mm/h; and conducting crystal growth.

Assignees

• Aist

Inventors

• HAMAO Naoki
• Kataoka Kunimitsu
• Akimoto Junji

Classifications

• C04B2235/3203

  Lithium oxide or oxide-forming salts thereof · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• C04B2235/764

  Garnet structure A3B2(CO4)3 · CPC title

• C01P2002/78

  by stacking-plane distances or stacking sequences · CPC title

• H01M10/0562 Primary

  Solid materials · CPC title