Electrode assembly having high flexibility and battery cell including the same

Patent metadata

Field	Value
Publication number	US-12002922-B2
Application number	US-201715767541-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Mar 31, 2016
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

The present invention provides an electrode assembly having a one directionally spiral-wound structure with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet, wherein the electrode assembly has a horizontal length (x) equal to or more than three times a vertical length (y), and both side end portions of the electrode assembly are bent together in the same direction by a curvature radius (R) satisfying the following Equation 1:

S [{1/ln( x/y )}* t]=R   1

wherein t is an average thickness (mm) of the spiral-wound electrode assembly, x is the horizontal length of the electrode assembly, and y is the vertical length of the electrode assembly, and S is a constant of 8 or more, and ln(x/y)≥1.

First claim

The invention claimed is:

1. An electrode assembly having a one directionally spiral-wound structure with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being wound about a winding axis extending in first and second opposite vertical directions,
wherein the spiral-wound structure of the electrode assembly has a length (x) in a horizontal direction perpendicular to the winding axis and a height (y) in the first vertical direction, and the spiral-wound structure of the electrode assembly has first and second opposite ends that are separated by the length (x) in the horizontal direction, and a center that is equidistant between the first and second opposite ends,
wherein the spiral-wound structure of the electrode assembly is configured to be bent about a bending axis extending in the first and second opposite vertical directions, the bending axis being parallel to the winding axis, the spiral-wound structure having a naturally curved shape having a curvature radius (R) naturally formed without additional external force, the curvature radius (R) relative to the bending axis satisfying the following Equation 1:
S[{ 1/ln( x/y )}* t]=R   1

wherein t is an average thickness (mm) of the spiral-wound electrode assembly in radial directions extending perpendicularly from the bending axis toward the spiral-wound structure and S is a constant of 8 or more, and
wherein the spiral-wound structure of the electrode assembly is configured to be repeatedly movable between two positions including a position in which opposing sides of the electrode assembly have a planar shape parallel to one another and in which the first and second opposite ends of the spiral-wound structure of the electrode assembly are spaced apart from the bending axis by a first distance that is greater than the curvature radius (R) and the center is spaced apart from the bending axis by a second distance that is equal to the curvature radius (R), and a position having the naturally curved shape in which the spiral-wound structure of the electrode assembly is bent about the bending axis according to the Equation 1 and in which the first and second opposite ends and the center of the spiral-wound structure of the electrode assembly are spaced apart from the bending axis by a second distance that is equal to the curvature radius (R).

2. The electrode assembly of claim 1 , wherein the curvature radius (R) is 5 mm to 20 mm.

3. The electrode assembly of claim 1 , wherein the length (x) in the horizontal direction perpendicular to the winding axis is 50 mm to 500 mm.

4. The electrode assembly of claim 1 , wherein a positive electrode lead and a negative electrode lead protrude side by side from the spiral-wound structure of the electrode assembly in the first vertical direction.

5. The electrode assembly of claim 1 , wherein S is a constant of 9 to 12.

6. The electrode assembly of claim 1 , wherein the electrode assembly has a structure having relatively increased flexibility for deformation into a curved shape by dispersing stress in a direction of the relatively long horizontal length.

7. The electrode assembly of claim 1 , wherein the spiral-wound structure of the electrode assembly includes winding of the positive electrode sheet and the negative electrode sheet about the winding axis five times or less.

8. A battery cell having a structure in which an electrode assembly is stored in a flexible battery case together with an electrolyte solution,
wherein the electrode assembly has a one directionally spiral-wound structure with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being wound about a winding axis extending in first and second opposite vertical directions,
wherein the spiral-wound structure of the electrode assembly has a length (x) in a horizontal direction perpendicular to the winding axis and a height (y) in the first vertical direction, and the spiral-wound structure of the electrode assembly has first and second opposite ends that are separated by the length (x) in the horizontal direction, and a center that is equidistant between the first and second opposite ends,
wherein the spiral-wound structure of the electrode assembly is configured to be bent about a bending axis extending in the first and second opposite vertical directions, the bending axis being parallel to the winding axis, the spiral-wound structure having a naturally curved shape having a curvature radius (R) naturally formed without additional external force, the curvature radius (R) relative to the bending axis satisfying the following Equation 1:
S[{ 1/ln( x/y )}* t]=R   1

wherein t is an average thickness (mm) of the spiral-wound electrode assembly in radial directions extending perpendicularly from the bending axis toward the spiral-wound structure and S is a constant of 8 or more,
wherein the spiral-wound structure of the electrode assembly is configured to be repeatedly movable between two positions including a position in which opposing sides of the electrode assembly have a planar shape parallel to one another and in which the first and second opposite ends of the spiral-wound structure of the electrode assembly are spaced apart from the bending axis by a first distance that is greater than the curvature radius (R) and the center is spaced apart from the bending axis by a second distance that is equal to the curvature radius (R), and a position having the naturally curved shape in which the spiral-wound structure of the electrode assembly is bent about the bending axis according to the Equation 1 and in which the first and second opposite ends and the center of the spiral-wound structure of the electrode assembly are spaced apart from the bending axis by a second distance that is equal to the curvature radius (R), and
wherein a curved surface is formed on an outer surface of the flexible battery case when the spiral-wound structure is in the naturally curved shape.

9. A method of forming a flexible battery cell comprising an electrode assembly stored in a flexible battery case, the method comprising:
forming a spiral-wound structure of the electrode assembly having a one directionally spiral-wound structure with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet, the spiral-wound structure having a length (x) in a horizontal direction perpendicular to a winding axis and a height (y) in the first vertical direction, the spiral-wound structure being configured to be repeatedly moved between two positions including a first position and a second position having a naturally curved shape in which the spiral-wound structure is bent about a bending axis extending in the first and second opposite vertical directions, the bending axis being parallel to the winding axis;
before the forming of the spiral-wound structure, selecting the length (x) and the height (y) such that the spiral-wound structure in the stably curved position has a curvature radius (R) relative to the bending axis satisfying the following Equation 1:
S[{ 1/ln( x/y )}* t]=R   1

wherein t is an average thickness (mm) of the spiral-wound electrode assembly in radial directions extending perpendicularly from the bending axis toward the spiral-wound structure and S is a constant of 8 or more; and
inserting the spiral-wound structure into the flexible battery case together with an electrolyte solution, the flexible battery case being configured such that an outer surface of the flexible battery cell has a curved shape when the spiral-wound structure is in the naturally

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• You Min Kyu
• Kang Sung Joong
• Kim Ji Young

Classifications

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M10/0431 Primary

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

• H01M10/0436

  Small-sized flat cells or batteries for portable equipment · CPC title

• H01M10/0587

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

• H01M50/105 Primary

  Pouches or flexible bags · CPC title