Electricity storage device

Patent metadata

Field	Value
Publication number	US-10490795-B2
Application number	US-201314400709-A
Country	US
Kind code	B2
Filing date	May 30, 2013
Priority date	Jun 1, 2012
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A rechargeable battery includes positive and negative electrodes and first and second separator portions. The positive electrode includes a positive metal foil and a positive active material layer. A positive active material-free portion is formed on a first end of the positive electrode. The positive active material layer extends to a second end. The negative electrode includes a negative metal foil and a negative active material layer. A negative active material-free portion is formed on a third end of the negative electrode. The negative active material layer extends to a fourth end. Each of the first and second separator portions includes a strong bonding portion and a weak bonding portion. The strong bonding portion is located proximate to the first end and extends along the first end. The weak bonding portion is located proximate to the second end and extends along the second end.

First claim

The invention claimed is:

1. An electricity storage device comprising:
a first electrode including a first metal foil and a first active material layer formed by applying a first active material to the first metal foil, wherein the first electrode includes a first end portion and a second end portion located at an opposite side of the first end portion, the first end portion is free from the first active material and defines a first active material-free portion that exposes the first metal foil, and the first active material layer extends from a border of the first active material layer and the first active material-free portion to the second end portion;
a first separator portion that covers a first surface of the first electrode;
a second separator portion that covers a second surface of the first electrode located at an opposite side of the first surface in a thicknesswise direction;
a second electrode including a second metal foil and a second active material layer formed by applying a second active material to the second metal foil, wherein the second electrode includes a third end portion corresponding to the first end portion and a fourth end portion corresponding to the second end portion, which is located at an opposite side of the third end portion, the third end portion is free from the second active material and defines a second active material-free portion that exposes the second metal foil, and the second active material layer extends from a border of the second active material layer and the second active material-free portion to the fourth end portion, wherein
the first electrode, the second electrode, the first separator portion, and the second separator portion are overlapped in a layered manner to form an electrode assembly,
the first separator portion and the second separator portion include a strong bonding portion and a weak bonding portion that bond the first separator portion and the second separator portion to each other, the strong bonding portion and the weak bonding portion unifies the first separator portion and the second separator portion, and the strong bonding portion has a bonding strength that is strong relative to a bonding strength of the weak bonding portion so that a thermal contraction of the first separator portion and the second separator portion causes delamination from the weak bonding portion,
wherein the first active material-free portion further includes a first electrode tab projecting from the first end portion,
the strong bonding portion corresponds to a portion in which the first separator portion and the second separator portion are continuously welded to each other, and is located in the first separator portion and the second separator portion at a section proximate to the first end portion and extends in a longitudinal direction (TD direction) along the first end portion excluding a position overlapped with the first electrode tab, and
the weak bonding portion is located in the first separator portion and the second separator portion at a section proximate to the second end portion and extends in the longitudinal direction (TD direction) along the second end portion,
wherein a total length L2 of the weak bonding portion extends in the longitudinal direction (TD direction), and a total length L1 of the strong bonding portion extends in the longitudinal direction (TD direction), wherein L1=L2−L3, wherein L3 is a length of the position overlapped with the first electrode tab where the strong bonding portion is not formed,
wherein a width W2 of the weak bonding portion extends in a horizontal direction (MD direction) and is less than a width W1 of the strong bonding portion that extends in the horizontal direction (MD direction), wherein the total length L1 of the strong bonding portion is formed with the width W1, and
wherein a total bonding area of the weak bonding portion is defined as L2×W2 and is smaller than a total bonding area of the strong bonding portion which is defined as L1×W1.

2. The electricity storage device according to claim 1 , wherein
the strong bonding portion is strip-shaped,
the weak bonding portion is strip-shaped.

3. The electricity storage device according to claim 1 , wherein the first separator portion and the second separator portion are manufactured by cutting a sheet of a separator material, wherein the sheet of a separator material is formed from a polyolefin fine porous material including openings so that a predetermined degree of porosity is obtained, and the first separator portion and the second separator portion cover the first electrode so that a machine direction when manufacturing the first separator portion and the second separator portion extends in the first direction, which extends from the second end portion toward the first end portion.

4. The electricity storage device according to claim 1 , wherein
the second active material-free portion further includes a second tab projecting from the third end portion,
the first tab and the second tab each project in the first direction, which extends from the second end portion toward the first end portion, and
the strong bonding portion and the weak bonding portion extend opposing each other in the first direction.

5. The electricity storage device according to claim 1 , wherein the electricity storage device is a rechargeable battery.

6. The electricity storage device according to claim 1 , wherein
the weak bonding portion includes a first bonding portion, and
the strong bonding portion includes the first bonding portion and a second bonding portion, of which type of bonding differs from the first bonding portion.

7. An electricity storage device comprising:
a first electrode including a first metal foil and a first active material layer, wherein the first metal foil includes first sheet surfaces located at opposite sides of the first metal foil in a thicknesswise direction, a first active material layer is formed by applying a first active material to the first sheet surfaces, wherein each of the first sheet surfaces includes a first end portion and a second end portion located at an opposite side of the first end portion, the first end portion is free from the first active material and defines a first active material-free portion including a first active material-free edge, the first active material-free edge exposes the first metal foil and extends along the first end portion, and the first active material layer extends from a border of the first active material layer and the first active material-free edge to the second end portion;
a first separator portion that covers one first sheet surface of the first electrode;
a second separator portion that covers the other first sheet surface of the first electrode;
a second electrode including a second metal foil and a second active material layer, wherein the second metal foil includes second sheet surfaces located at opposite sides of the second metal foil in a thicknesswise direction, a second active material layer is formed by applying a second active material to the second sheet surfaces, wherein each of the second sheet surfaces includes a third end portion corresponding to the first end portion and a fourth end portion corresponding to the second end portion, which is located at an opposite side of the third end portion, the third end portion is free from the second active material and defines a second active material-free portion including a second active material-free edge, includes a second active material-free edge, the second active material-free edge exposes the second metal foil and extends along the third end portion, and the second active material layer extends from a border of the second active material layer and the second active material-free edge to the fourth en

Assignees

• Toyota Jidoshokki Kk

Inventors

• MINAGATA Atsushi

Classifications

• H01M10/058

  Construction or manufacture · CPC title

• H01G11/72

  specially adapted for integration in multiple or stacked hybrid or EDL capacitors · CPC title

• H01G11/52 Primary

  Separators · CPC title

• H01M10/0585

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

• H01M10/0463

  Cells or batteries with horizontal or inclined electrodes · CPC title