NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

• US 20090017375A1
• Filed: 01/26/2007
• Published: 01/15/2009
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Takezawa, Hideharu
• Granted Patent: US 7,736,808 B2
• Time in Patent Office: Days
• US Class Current: 429/207
• CPC Class Codes: H01M 10/0566 Liquid materials
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 6/162 characterised by the electrolyte
• CPC Class Codes: H01M 6/166 by the solute
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A non-aqueous electrolyte secondary battery of the present invention includes a positive electrode including a positive electrode material mixture, a negative electrode including a negative electrode material mixture, and a non-aqueous electrolyte including a non-aqueous solvent and a first lithium salt and a second lithium salt dissolved in the non-aqueous solvent. The negative electrode material mixture includes a material capable of absorbing and desorbing lithium ions, and carbon nanofibers. The material capable of absorbing and desorbing lithium ions has a ratio A/B of a volume A in a charged state to a volume B in a discharged state of 1.2 or more. The first lithium salt is at least one selected from the group consisting of LiBF₄ and LiB(C₂O₄)₂. The second lithium salt is a salt other than the first lithium salt. The first lithium salt is included in the non-aqueous electrolyte at a weight ratio of 10⁻⁴ or more relative to the carbon nanofibers. The first lithium salt included in the non-aqueous electrolyte has a concentration of 0.05 mol/dm³ or less.

Claims

1. A non-aqueous electrolyte secondary battery including:

a positive electrode including a positive electrode material mixture;

a negative electrode including a negative electrode material mixture; and

a non-aqueous electrolyte including a non-aqueous solvent, and a first lithium salt and a second lithium salt dissolved in said non-aqueous solvent, wherein

said negative electrode material mixture includes a material capable of absorbing and desorbing lithium ions, and carbon nanofibers,

said material capable of absorbing and desorbing lithium ions has a ratio A/B of a volume A in a charged state to a volume B in a discharged state of 1.2 or more,

said first lithium salt is at least one selected from the group consisting of LiBF₄ and LiB(C₂O₄)₂,

said second lithium salt is a salt other than said first lithium salt,

said first lithium salt is included in said non-aqueous electrolyte at a weight ratio of 10<sup>−

4</sup> or more relative to said carbon nanofibers, and

said first lithium salt included in said non-aqueous electrolyte has a concentration of 0.05 mol/dm³ or less.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said carbon nanofibers are carried on a surface of said material capable of absorbing and desorbing lithium ions, and a catalyst for promoting a growth of said carbon nanofibers is also carried on the surface of said material capable of absorbing and desorbing lithium ions.

3. The non-aqueous electrolyte secondary battery in accordance with claim 2, wherein a ratio of said carbon nanofibers to a total of said carbon nanofibers, said material capable of absorbing and desorbing lithium ions, and said catalyst is 10 to 50% by weight.

4. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said material capable of absorbing and desorbing lithium ions contains at least one element selected from the group consisting of Si and Sn.