Non-aqueous electrolyte secondary battery

• US 20070026313A1
• Filed: 07/27/2006
• Published: 02/01/2007
• Est. Priority Date: 07/27/2005
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Sano, Youko
• Granted Patent: US 7,297,444 B2
• Time in Patent Office: Days
• US Class Current: 429/217
• 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 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/621 Binders
• CPC Class Codes: H01M 4/622 being polymers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In a non-aqueous electrolyte secondary battery having a negative electrode containing Si as a negative electrode active material, a binder containing a non-crosslinked polyacrylic acid having a weight-average molecular weight of 300,000 to 3,000,000 is incorporated into a negative electrode molded article that constitutes the negative electrode, so as to prevent electrode decay resulting from expansion and contraction during charge/discharge, as well as to achieve high energy density and improved charge/discharge cycle characteristics.

Claims

1. A non-aqueous electrolyte secondary battery including:

a positive electrode capable of absorbing and desorbing lithium reversibly; and

a negative electrode comprising a porous molded article including a negative electrode active material comprising Si, a conductive material and a binder,

wherein said binder comprises a non-crosslinked polyacrylic acid having a weight-average molecular weight of 300000 to 3000000.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said negative electrode contains said binder in an amount of 2 to 40 wt %.

3. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said non-crosslinked polyacrylic acid has a weight-average molecular weight of 500000 to 2000000.

4. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said negative electrode active material comprises either Si or an alloy containing Si.

5. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said negative electrode active material comprises an alloy containing Si and a metal incapable of forming an alloy with Li.

6. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said negative electrode active material comprises a phase A containing Si and a phase B containing an intermetallic compound comprising a transition metal element and Si, and

said transition metal element is at least one selected from the group consisting of Ti, Zr, Fe, Co, Ni and Cu.

7. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said porous molded article has a thickness of 50 to 800 μ

m.

8. The non-aqueous electrolyte secondary battery in accordance with claim 1,

wherein said porous molded article has a porosity of 10 to 60%.