Negative electrode for lithium ion secondary battery, method for producing the same, and lithium ion secondary battery

• US 20080020281A1
• Filed: 07/18/2007
• Published: 01/24/2008
• Est. Priority Date: 07/24/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Ugaji, Masaya, Kogetsu, Yasutaka
• Granted Patent: US 7,964,307 B2
• Time in Patent Office: Days
• US Class Current: 429/231.5
• CPC Class Codes: C23C 14/226 in order to form films with columnar structure
• 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 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/66 Selection of materials
• CPC Class Codes: H01M 4/664 Ceramic materials
• CPC Class Codes: H01M 4/667 in the form of layers, e.g. coatings
• 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 negative electrode for a lithium ion secondary battery includes a current collector, an intermediate layer formed on a surface of the current collector, and an active material layer formed on the intermediate layer. The current collector includes a metal capable of being alloyed with silicon. The active material layer includes an active material including silicon. The intermediate layer includes silicon and oxygen. The intermediate layer prevents the metal capable of being alloyed with silicon from diffusing into the active material layer. The diffusion of the constituent element of the current collector into the active material layer is suppressed.

Claims

1. A negative electrode for a lithium ion secondary battery, comprising a current collector, an intermediate layer formed on a surface of said current collector, and an active material layer formed on said intermediate layer,

wherein said current collector comprises a metal capable of being alloyed with silicon,

said active material layer comprises an active material comprising silicon,

said intermediate layer comprises silicon and oxygen, and

said intermediate layer prevents said metal capable of being alloyed with silicon from diffusing into said active material layer.

2. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said intermediate layer comprises SiO_x where 0.1≦

x<

2.

3. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said active material layer further includes oxygen, nitrogen, or titanium.

4. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said metal capable of being alloyed with silicon is copper or nickel.

5. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said metal capable of being alloyed with silicon diffuses into said intermediate layer to form a mixed layer, and said mixed layer has a thickness of 1 μ

m or less.

6. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said active material forms a plurality of columnar particles.

7. The negative electrode for a lithium ion secondary battery in accordance with claim 6, wherein said columnar particles are inclined relative to the direction of the normal to the surface of said current collector.

8. The negative electrode for a lithium ion secondary battery in accordance with claim 6, wherein said columnar particles include a plurality of subparticles, and said subparticles are laminated and grown slantwise relative to the direction of the normal to the surface of said current collector.

9. The negative electrode for a lithium ion secondary battery in accordance with claim 8, wherein said subparticles are grown in different directions.

10. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said active material layer has a thickness of 0.1 μ

m to 100 μ

m.

11. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein said current collector has a thickness of 1 μ

m to 50 μ

m.

12. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein the surface of said current collector carrying said intermediate layer has a surface roughness Rz of 0.1 μ

m to 100 μ

m.

13. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein the surface of said current collector carrying said intermediate layer has asperities of a regular pattern.

14. The negative electrode for a lithium ion secondary battery in accordance with claim 5, wherein said mixed layer contains copper and at least one element X selected from the group consisting of chromium, carbon, and hydrogen, and the content of said element X is 10 mol % or less of the copper contained in said mixed layer.

15. The negative electrode for a lithium ion secondary battery in accordance with claim 1, wherein lithium has been provided on said active material layer by vapor deposition, thereby causing a reaction between said lithium and said active material.

21. A lithium ion secondary battery comprising a positive electrode, the negative electrode as recited in claim 1, a separator interposed between said positive electrode and said negative electrode, and an electrolyte.

16. A method for producing a negative electrode for a lithium ion secondary battery, comprising the steps of:

forming an intermediate layer including silicon and oxygen on a current collector comprising a metal capable of being alloyed with silicon, said intermediate layer being provided for preventing diffusion of said metal; and

forming an active material layer on said intermediate layer,

wherein during a process of forming at least one of said intermediate layer and said active material layer, said current collector has a temperature of 300°

C. to 700°

C.

17. The method for producing a negative electrode for a lithium ion secondary battery in accordance with claim 16, further comprising the step of depositing lithium on said active material layer,

wherein during a process of depositing said lithium, said current collector has a temperature of 300°

C. to 700°

C.

18. The method for producing a negative electrode for a lithium ion secondary battery in accordance with claim 16, further comprising the step of heating said current collector, said intermediate layer, and said active material layer at the same time,

wherein said heating is performed at a temperature of 300°

C. to 700°

C.

19. The method for producing a negative electrode for a lithium ion secondary battery in accordance with claim 16, wherein said intermediate layer is formed by vapor deposition or sputtering.

20. The method for producing a negative electrode for a lithium ion secondary battery in accordance with claim 19, wherein said intermediate layer is formed at a speed of 10 nm to 700 nm per second in thickness.