Lithium secondary battery

• US 20030124423A1
• Filed: 01/24/2003
• Published: 07/03/2003
• Est. Priority Date: 07/27/2000
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Nakano, Hideyuki, Sasaki, Tsuyoshi, Ukyo, Yoshio, Kohzaki, Masao
• Granted Patent: US 7,189,475 B2
• Time in Patent Office: Days
• US Class Current: 429/221
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0563 Liquid materials, e.g. for Li-SOCl2 cells
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/581 Chalcogenides or intercalation compounds thereof
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The present invention provides a secondary battery which is less expensive, whose safety is extremely high, which is of large capacity as well as good cyclic characteristic, and which uses an aqueous solution for the electrolytic solution. A lithium secondary battery according to the present invention is constituted by including a positive electrode, formed by binding a positive-electrode raw-material mixture including a positive electrode active material, a negative electrode, formed by binding a negative-electrode raw-material mixture including a negative electrode active material, and an electrolytic solution, comprising an aqueous solution in which a lithium salt is dissolved, said positive electrode active material including at least one of a layered structure lithium-manganese composite oxide whose basic composition is LiMnO₂ and an olivine structure lithium-iron composite phosphorus oxide whose basic composition is LiFePO₄. The present lithium secondary battery can be used in the fields of communication appliances and information-related appliances, and as an electric source for electric automobiles and the like.

Claims

1. A lithium secondary battery comprising:

a positive electrode formed by binding a positive-electrode raw-material mixture including a positive electrode active material,

a negative electrode formed by binding a negative-electrode raw-material mixture including a negative electrode active material, and

an electrolytic solution comprising an aqueous solution in which a lithium salt is dissolved, wherein

said positive electrode active material comprising at least one of a layered structure lithium-manganese composite oxide whose basic composition is LiMnO₂ and an olivine structure lithium-iron composite phosphorus oxide whose basic composition is LiFePO₄.

2. The lithium secondary battery set forth in claim 1, wherein said positive electrode active material is a layered structure lithium-manganese composite oxide whose basic composition is LiMnO₂.

3. The lithium secondary battery set forth in claim 2, wherein said layered structure lithium-manganese composite oxide has a hexagonal layered rocksalt structure.

4. The lithium secondary battery set forth in claim 1, wherein said positive electrode active material is an olivine structure lithium-iron composite phosphorus oxide whose basic composition is LiFePO₄.

5. The lithium secondary battery set forth in claim 1, wherein said negative electrode active material comprises a lithium-vanadium composite oxide.

6. The lithium secondary battery set forth in claim 5, wherein said lithium-vanadium composite oxide has, in an X-ray diffraction pattern by means of CuKα

ray, the highest intensity peak at 2θ

=13.9°

±

1°

(θ

being diffraction angle), and the intensity of the peak is 5 times or more compared to the intensities of all of the other peaks.

7. The lithium secondary battery set forth in claim 6, wherein said lithium-vanadium composite oxide is expressed by a composition formula Li_xV₃O_y (1.2<

x<

1.6;

7.5≦

y≦

8.25).

8. The lithium secondary battery set forth in claim 5, wherein said lithium-vanadium composite oxide is a spinel structure lithium-vanadium composite oxide whose basic composition is LiV₂O₄.

9. The lithium secondary battery set forth in claim 1, wherein said negative electrode active material comprises a transition metal chalcogenide.

10. The lithium secondary battery set forth in claim 9, wherein said transition metal chalcogenide is at least one selected from the group consisting of TiS₂, MoS₂, NbS₂ and VS₂.