Secondary battery

Patent metadata

Field	Value
Publication number	US-11728519-B2
Application number	US-202117470114-A
Country	US
Kind code	B2
Filing date	Sep 9, 2021
Priority date	Sep 17, 2020
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

The secondary battery includes: a square battery case; and a wound electrode body accommodated in the battery case. The wound electrode body has a positive electrode sheet and a negative electrode sheet overlapping with each other to be wound about a winding axis to have a rectangular shape when seen from a winding axis direction. The wound electrode body has corner parts positioned at four corners of the wound electrode body when seen from the winding axis direction. The positive electrode sheet has a positive electrode collector and a positive electrode active material layer. The negative electrode sheet has a negative electrode collector and a negative electrode active material layer. Folding grooves are formed along the winding axis direction at portions of the positive electrode active material layer or portions of the negative electrode active material layer that are positioned at the corner parts.

First claim

What is claimed is:

1. A secondary battery comprising:
a square battery case; and
a wound electrode body accommodated in the battery case, wherein
the wound electrode body has a positive electrode sheet and a negative electrode sheet at least overlapping with each other to be wound about a winding axis to have a rectangular shape when seen from a winding axis direction,
the wound electrode body has corner parts positioned at four corners of the wound electrode body when seen from the winding axis direction,
the positive electrode sheet has a positive electrode collector and a positive electrode active material layer formed on the positive electrode collector,
the negative electrode sheet has a negative electrode collector and a negative electrode active material layer formed on the negative electrode collector, and
folding grooves are formed along the winding axis direction in at least one of the positive electrode active material layer and the negative electrode active material layer at positions corresponding to the corner parts about the winding axis in the positive electrode sheet and the negative electrode sheet.

2. The secondary battery according to claim 1 , wherein
the positive electrode active material layer has
an inside positive electrode active material layer formed on a surface of the positive electrode collector on the winding axis side, and
an outside positive electrode active material layer formed on a surface of the positive electrode collector on an opposite side thereof to the winding axis, and
the folding grooves have
an inside positive electrode folding groove formed on the inside positive electrode active material layer, and
an outside positive electrode folding groove formed on the outside positive electrode active material layer.

3. The secondary battery according to claim 2 , wherein
a width of the inside positive electrode folding groove is greater than a width of the outside positive electrode folding groove.

4. The secondary battery according to claim 2 , wherein
the width of the inside positive electrode folding groove is same as or greater than a thickness of the inside positive electrode active material layer.

5. The secondary battery according to claim 2 , wherein
a cross-sectional shape of the inside positive electrode folding groove is different from a cross-sectional shape of the outside positive electrode folding groove.

6. The secondary battery according to claim 1 , wherein
the folding grooves are formed on the positive electrode active material layer,
when an axis passing through the winding axis and extending in a reference direction crossing the winding axis direction is defined as a reference axis when seen from the winding axis direction, the corner parts have a first corner part and a second corner part positioned on one side of the reference axis when seen from the winding axis direction, and
when an folding groove of the folding grooves that is formed at a portion of the positive electrode active material layer at a position corresponding to the first corner part about the winding axis is defined as a first positive electrode folding groove and an folding groove of the folding grooves that is formed at a portion of the positive electrode active material layer at a position corresponding to the second corner part about the winding axis is defined as a second positive electrode folding groove, an interval between the first positive electrode folding groove and the second positive electrode folding groove reduces gradually toward the winding axis.

7. The secondary battery according to claim 1 , further comprising:
a nonaqueous electrolyte solution accommodated in the battery case.

Assignees

• Prime Planet Energy & Solutions Inc

Inventors

• Kadoi Masafumi
• Sakurai Takahiro
• Sakashita Yasuhiro

Classifications

• H01M10/0587 Primary

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

• H01M4/38

  of elements or alloys · CPC title

• H01M10/0431

  Cells with wound or folded electrodes (H01M10/045 takes precedence) · CPC title

• H01M10/0585

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

• H01M50/103

  prismatic or rectangular (H01M50/109, H01M50/11 take precedence) · CPC title