Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-9257717-B2
Application number	US-201214233149-A
Country	US
Kind code	B2
Filing date	Apr 3, 2012
Priority date	Jul 22, 2011
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

In a wound electrode group, a positive electrode includes positive electrode active material layers formed on both surfaces of a band-like positive electrode current collector, and a negative electrode includes negative electrode active material layers on both surfaces of a band-like negative electrode current collector. Charge capacity of the negative electrode falls within a range of 83-99% of theoretical capacity of the negative electrode in a full charge state of a nonaqueous electrolyte secondary battery. An active material mass M1 per unit area of a negative electrode active material layer formed on an outer circumference of the negative electrode current collector, and an active material mass M2 per unit area of a negative electrode active material layer formed on an inner circumference satisfy a relational expression of M1/M2<(R1+t/2)/(R1−t/2), where the electrode group has an innermost diameter of R1, and the negative electrode has a thickness of t.

First claim

The invention claimed is:

1. A nonaqueous electrolyte secondary battery comprising:
an electrode group formed by winding a positive electrode and a negative electrode with a porous insulating layer interposed therebetween, wherein
the positive electrode includes positive electrode active material layers on both surfaces of a band-like positive electrode current collector,
the negative electrode includes negative electrode active material layers on both surfaces of a band-like negative electrode current collector,
charge capacity of the negative electrode falls within a range of 83-99% of theoretical capacity of the negative electrode in a full charge state of the nonaqueous electrolyte secondary battery, and
an active material mass M1 per unit area of one of the negative electrode active material layers, which is formed on an outer circumference of the negative electrode current collector, and an active material mass M2 per unit area of the other of the negative electrode active material layers, which is formed on an inner circumference of the negative electrode current collector, satisfy a relational expression of
M 1/ M 2<( R 1+ t/ 2)/( R 1− t/ 2),

where the electrode group has an innermost diameter of R1, and the negative electrode has a thickness of t.

2. The nonaqueous electrolyte secondary battery of claim 1 , wherein
the active material mass M1 per unit area of the one of the negative electrode active material layers, which is formed on the outer circumference of the negative electrode current collector, and the active material mass M2 per unit area of the other of the negative electrode active material layers, which is formed on the inner circumference of the negative electrode current collector, satisfy a relational expression of
( R 2+ t/ 2)/( R 2− t/ 2)< M 1/ M 2,

where the electrode group has an outermost diameter of R2.

3. The nonaqueous electrolyte secondary battery of claim 1 , wherein
the nonaqueous electrolyte secondary battery is a lithium-ion secondary battery,
a negative electrode active material is carbon, and
the charge capacity of the negative electrode falls within a range from 310 mAh/g to 372 mAh/g in the full charge state of the nonaqueous electrolyte secondary battery.

4. The nonaqueous electrolyte secondary battery of claim 1 , wherein
the negative electrode active material layers formed on the both surfaces of the band-like negative electrode current collector have the same active material density, and
a thickness T1 of the one of the negative electrode active material layers, which is formed on the outer circumference of the negative electrode current collector, and a thickness T2 of the other of the negative electrode active material layers, which is formed on the inner circumference of the negative electrode current collector, satisfy a relation of
T 1/ T 2<( R 1+ t/ 2)/( R 1− t/ 2).

5. The nonaqueous electrolyte secondary battery of claim 1 , wherein
an active material mass per unit area of one of the positive electrode active material layers, which is formed on an inner circumference of the positive electrode current collector, is smaller than the active material mass per unit area of the other of the positive electrode active material layers, which is formed on the outer circumference of the positive electrode current collector.

6. The nonaqueous electrolyte secondary battery of claim 2 , wherein
the relation between the masses M1 and M2 satisfies a relational expression of
M 1/ M 2=[( R 1+ R 2)/2+ t/ 2]/[( R 1+ R 2)/2− t/ 2].

Assignees

• Muraoka Yoshiyuki
• Ugaji Masaya
• Aoyama Takahiro
• Nakai Haruya
• Panasonic Ip Man Co Ltd

Inventors

• Muraoka Yoshiyuki
• Ugaji Masaya
• Aoyama Takahiro
• Nakai Haruya

Classifications

• Y02E60/122

  Cross-Sectional Technologies · mapped topic

• H01M10/0587

  of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators · CPC title

• H01M4/13 Primary

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/70

  characterised by shape or form · CPC title