JP2020129514A - Laminated battery - Google Patents

Abstract

To provide a laminated battery capable of appropriately suppressing the impact of a foreign object that may be generated when collector tabs are bonded to external terminals.SOLUTION: A laminated battery 1 comprises a power generation element, collector tabs 12A and 12B, external terminals 20A and 20B, and a laminate outer package body 30. The power generation element includes an electrode body 10. The collector tabs 12A and 12B extend outward from the electrode body 10. The external terminals 20A and 20B are bonded to the collector tabs 12A and 12B, respectively. The laminate outer package body 30 comprises a first outer package part 31 and a second outer package part 36. The first outer package part 31 internally seals the power generation element with the collector tabs 12A and 12B partially sandwiched by a first seal part 32. The second outer package part 36 internally seals bonding parts 15A and 15B between the collector tabs 12A and 12B, and the external terminals 20A and 20B with the external terminals 20A and 20B partially sandwiched by a second seal part 37.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminate type battery in which a power generation element is sealed inside a laminate exterior body.

Batteries such as lithium-ion secondary batteries are widely used as portable power sources for personal computers, mobile terminals, etc., or power sources for driving vehicles such as EVs (electric vehicles), HVs (hybrid vehicles), PHVs (plug-in hybrid vehicles). There is.

As an example of a battery, a laminated battery is known in which a power generation element is sealed inside a film-shaped laminate outer package. For example, in the battery disclosed in Patent Document 1, a current collecting tab (tongue piece portion) and an external terminal (positive electrode tab and negative electrode tab) are joined by ultrasonic joining. After that, the electrode body including the current collecting tab and the external terminal is sealed inside the laminate exterior body.

JP, 2008-176215, A

When the current collecting tab and the external terminal are joined by resistance welding, laser welding, ultrasonic joining, or the like, foreign matter (for example, fine metal powder) may occur. In the battery described in Patent Document 1, foreign matter generated at the time of joining may be mixed in the power generation element such as the electrode body, and the mixed foreign matter may cause a defect such as a short circuit.

A typical object of the present invention is to provide a laminated battery capable of appropriately suppressing the influence of foreign matter that may occur when joining the current collecting tab and the external terminal.

In order to achieve such an object, a laminate-type battery according to one embodiment disclosed herein is joined to a power generating element including an electrode body, a current collecting tab extending outward from the electrode body, and the current collecting tab. A laminate outer body that is formed into a film and is welded in a state where the wide surfaces are opposed to each other by being externally electrically connected to the current collecting tab, thereby sealing at least the power generating element inside. The laminate outer body seals the power generating element inside by being welded in such a manner that the electrode body side of the current collecting tab with respect to the tip end portion is sandwiched by the first seal portion. The first exterior portion and the tip portion of the external terminal are projected outward, and at least a part of the external terminal is welded in a state of being sandwiched by the second seal portion, so that the first exterior portion has the above-mentioned structure. It is characterized in that it is provided with a second exterior portion that seals the joint portion of the current collecting tab protruding outward from the first seal portion and the external terminal.

In the laminated battery having the above configuration, the first seal portion shields between the joint portion joining the current collecting tab and the external terminal and the power generation element sealed by the first exterior portion. Therefore, even if foreign matter is generated from the joint portion, it is difficult for the generated foreign matter to mix into the power generation element. Therefore, the influence of foreign matter that may occur from the joint portion is appropriately suppressed.

FIG. 3 is a front view of the laminated battery 1 in a state in which the laminated exterior body 30 on the front side of the paper surface is omitted. FIG. 2 is a partial sectional view taken along line AA in FIG. 1. FIG. 3 is a front view of the laminate type battery 2 in a state where the laminate exterior body 300 on the front side of the paper surface is omitted.

Hereinafter, one of exemplary embodiments in the present disclosure will be described in detail with reference to the drawings. Matters other than the matters particularly referred to in the present specification and necessary for implementation can be grasped as design matters of a person skilled in the art based on conventional technology in the field. The present invention can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the field. In addition, in the following drawings, the same reference numerals are given to members and portions that have the same effect. Further, the dimensional relationship (length, width, thickness, etc.) in each drawing does not reflect the actual dimensional relationship.

In the present specification, the “battery” is a term that generally refers to an electricity storage device that can take out electrical energy, and is a concept that includes a primary battery and a secondary battery. The term "secondary battery" generally refers to an electricity storage device that can be repeatedly charged and discharged, and includes so-called storage batteries (that is, chemical batteries) such as lithium-ion secondary batteries, nickel-hydrogen batteries, and nickel-cadmium batteries, and electric double-layer capacitors. Includes capacitors (ie physical batteries). Hereinafter, the laminate type battery according to the present disclosure will be described in detail by exemplifying a case where the lithium ion secondary battery is configured as a laminate type battery. However, the laminated battery according to the present disclosure is not intended to be limited to those described in the following embodiments. For example, the laminate type battery may be an all-solid-state battery using a solid electrolyte, or may be a power storage element such as an electric double layer capacitor.

The configuration of the laminated battery 1 of this embodiment will be described with reference to FIGS. 1 and 2. The laminated battery 1 of the present embodiment includes an electrode body 10, an electrolyte (not shown), external terminals 20 (a positive electrode external terminal 20A and a negative electrode external terminal 20B), and a laminated outer package 30. The electrode body 10 and the electrolyte serve as a power generation element of the laminated battery 1. The electrode body 10 and the electrolyte are sealed inside the laminate exterior body 30.

The structure of the electrode body 10 may be the same as that of a conventionally known battery, and is not particularly limited. The electrode body 10 of the present embodiment is a laminated type electrode body, and includes one or more sheet-shaped positive electrode bodies 11A and negative electrode bodies 11B, typically, a plurality of each. The positive electrode body 11A and the negative electrode body 11B are alternately laminated while being insulated from each other. The configuration of the electrode body 10 can be changed. For example, the electrode body 10 may be a wound type electrode body in which the stacked positive electrode body 11A and negative electrode body 11B are wound.

The positive electrode body 11A typically includes a positive electrode current collector and a positive electrode active material layer formed on the surface thereof. Aluminum is used for the positive electrode current collector of this embodiment. The positive electrode active material layer contains a positive electrode active material (for example, lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide). Negative electrode body 11B typically includes a negative electrode current collector and a negative electrode active material layer formed on the surface thereof. Copper is used for the negative electrode current collector of this embodiment. The negative electrode active material layer contains a negative electrode active material (for example, a carbon material such as graphite). A separator may be arranged between the positive electrode body 11A and the negative electrode body 11B. The separator insulates the positive electrode active material layer and the negative electrode active material layer. As the separator, for example, a resin sheet such as polyethylene (PE) or polypropylene (PP) can be used.

The structure of the electrolyte may be the same as that of a conventionally known battery, and is not particularly limited. The electrolyte may be in a liquid state, a polymer state (gel state), or a solid state. As an example, the electrolyte of the present embodiment contains a non-aqueous solvent and a supporting salt such as a lithium salt that forms a charge carrier.

The electrode body 10 is provided with a current collecting tab 12 (a positive electrode current collecting tab 12A and a negative electrode current collecting tab 12B). Specifically, the positive electrode current collector tab 12A extends outward from the positive electrode body 11A (specifically, the positive electrode current collector). The negative electrode current collector tab 12B extends outward from the negative electrode body 11B (specifically, the negative electrode current collector). The current collecting tabs 12A and 12B are exposed without including an active material layer (a positive electrode active material layer or a negative electrode active material layer). As an example, in the present embodiment, the positive electrode current collector tab 12A and the negative electrode current collector tab 12B extend from different positions of the electrode body 10 in the same direction (upward in FIG. 1). However, the configurations of the positive electrode current collecting tab 12A and the negative electrode current collecting tab 12B can be changed. For example, the positive electrode current collector tab 12A and the negative electrode current collector tab 12B may extend in different directions (for example, in opposite directions).

The external terminals 20A and 20B are electrically connected to the current collecting tabs 12A and 12B by being joined to the current collecting tabs 12A and 12B. Specifically, the positive electrode external terminal 20A extends further outward (upward in FIG. 1) from the vicinity of the tip of the positive electrode current collector tab 12A, and projects outward from the laminate outer casing 30. The positive electrode external terminal 20A of this embodiment is a thin aluminum plate. The negative electrode external terminal 20B extends further outward (upward in FIG. 1) from the vicinity of the tip portion of the negative electrode current collector tab 12B, and projects outward from the laminate outer casing 30. The negative electrode external terminal 20B of this embodiment is a thin copper plate.

The positive electrode external terminal 20A and the positive electrode current collecting tab 12A are joined to each other at the joining portion 15A. Further, the negative electrode external terminal 20B and the negative electrode current collecting tab 12B are joined to each other at the joining portion 15B. As an example, in the present embodiment, resistance welding is used as a method of joining the external terminals 20A, 20B and the current collecting tabs 12A, 12B at the joints 15A, 15B. However, the external terminals 20A and 20B and the current collecting tabs 12A and 12B may be joined by a joining method other than resistance welding (for example, laser welding or ultrasonic joining).

The laminated outer package 30 is formed in a film shape, and is formed in a bag shape by being welded with the wide surfaces facing each other. As a result, the power generation element (electrode body 10 and electrolyte) is sealed in the internal space. As an example, in the present embodiment, the two laminated outer casings 30 formed in a film shape are attached to each other to form a bag shape. However, it is also possible to change the configuration of the laminated outer package 30. For example, one laminated outer body formed in a film shape may be folded in two, and the portions other than the folds may be welded to form a bag shape. Further, it may be formed in a bag shape by laminating three or more laminated outer casings formed in a film shape. In addition, in the present embodiment, the first exterior part 31 and the second exterior part 36, which will be described later, may be separated before manufacturing the laminated battery 1.

The laminated exterior body 30 of the present embodiment has a laminated structure. Specifically, the film-shaped laminated outer package 30 includes a protective layer, a metal layer, and a sealant layer in order from the outside. The protective layer is formed of, for example, nylon or the like, and improves the durability and impact resistance of the laminated outer package 30. The metal layer is formed of, for example, aluminum or the like, and improves the gas barrier property and the moistureproof property of the laminated outer package 30. The sealant layer is formed of a member having a heat-welding property (for example, polypropylene (PP) or the like) and seals the gap. It is also possible to change the configuration of the laminated outer package 30. For example, a material other than aluminum (such as iron) may be used as the metal layer. Further, the number of layers of the laminated outer package 30 is not limited to three.

With reference to FIGS. 1 and 2, a method of sealing the power generation element and the like with the laminate outer casing 30 will be described. The laminated exterior body 30 of the present embodiment includes a first exterior portion 31 and a second exterior portion 36. The 1st exterior part 31 seals a power generation element (electrode body 10 and electrolyte) inside. The second exterior portion 36 seals the joint portions 15A, 15B of the current collecting tabs 12A, 12B and the external terminals 20A, 20B inside. The details will be described below.

The first exterior portion 31 includes a first seal portion 32 and a first outer peripheral seal portion 33. The first seal portion 32 is located on the electrode body 10 side (specifically, on the electrode body 10 side of the joint portions 15A and 15B) of the current collecting tabs 12A and 12B with respect to the tip end portions thereof on both sides in the thickness direction of the laminated battery 1. It is welded in a state that it is sandwiched between. The 1st seal part 32 of this embodiment is formed in the shape of a straight line which traverses two current collection tabs 12A and 12B. However, the shape of the first seal portion 32 is not limited to the linear shape. In addition, a first seal portion that sandwiches the positive electrode current collector tab 12A and a first seal portion that sandwiches the negative electrode current collector tab 12B may be separately provided.

The first outer peripheral seal portion 33 is welded to a portion of the outer periphery of the power generation element other than the first seal portion 32. The power generation element is sealed in a sealed space surrounded by the first seal portion 32 and the first outer peripheral seal portion 33. The tip portions of the two current collecting tabs 12A and 12B are in a state of protruding outward (upward in FIG. 1) from the first seal portion 32. As described above, in the present embodiment, the two laminated outer casings 30 formed in a film shape are attached to each other to form a bag shape. Therefore, the first outer peripheral seal portion 33 of the present embodiment has a substantially U shape in a front view. However, the shape of the first outer peripheral seal portion 33 can also be changed.

In the first seal portion 32, a tab film (for example, pre-attached) formed of a heat-welding material (for example, polypropylene (PP)) between the current collecting tabs 12A and 12B and the sealant layer of the laminate outer casing 30. Resin) may be provided. In this case, the sealing property between the current collecting tabs 12A and 12B and the laminate outer casing 30 is further improved.

The second exterior portion 36 includes a second seal portion 37 and a second outer peripheral seal portion 38. The second seal portion 37 projects a part of the external terminals 20A, 20B outward (upward in FIGS. 1 and 2), and at the same time, a part of the external terminals 20A, 20B (specifically, the tip portions of the external terminals 20A, 20B). And the joint portions 15A and 15B) are sandwiched from both sides in the thickness direction of the laminated battery 1 and are welded. The second seal portion 37 of the present embodiment is formed in a linear shape that crosses the two external terminals 20A and 20B. However, the shape of the second seal portion 37 is not limited to the linear shape. Further, the second seal part that sandwiches the positive electrode external terminal 20A and the second seal part that sandwiches the negative electrode external terminal 20B may be separately provided. In addition, in the second seal portion 37 of the present embodiment, the tab films 40A and 40B formed of a material having a heat-welding property are provided between the external terminals 20A and 20B and the sealant layer of the laminated exterior body 30, , 20B from both sides in the thickness direction. As a result, the sealing property between the external terminals 20A and 20B and the laminated outer package 30 is further improved. However, the tab films 40A and 40B can be omitted.

The second outer peripheral seal portion 38 is welded to a portion other than the first seal portion 32 and the second seal portion 37 on the outer periphery of the joint portions 15A and 15B. As a result, the joint portions 15A and 15B projecting outward (upward in FIGS. 1 and 2) from the first exterior portion 31 are sealed inside the second exterior portion 36. In the present embodiment, the joint portions 15A and 15B are sealed in the hermetically sealed space formed inside the second exterior portion 36.

In the present embodiment, the first outer casing 31 and the second outer casing 36 are not separated before the laminated battery 1 is manufactured. That is, in the present embodiment, the two sheet-shaped laminated exterior parts 30 together form the first exterior part 31 and the second exterior part 36. However, the first outer casing 31 and the second outer casing 36 may be separated before the laminated battery 1 is manufactured.

A method for manufacturing the laminated battery 1 of this embodiment will be described. The method for manufacturing the laminated battery 1 includes a first exterior portion welding step, an external terminal joining step, and a second exterior portion welding step. In the first exterior portion welding step, the electrode body 10 is sealed inside the first exterior portion 31 in a state before the external terminals 20A and 20B are joined to the current collecting tabs 12A and 12B. Next, in the external terminal joining step, the external terminals 20A and 20B are joined to the current collecting tabs 12A and 12B protruding outward from the first exterior portion 31. Next, in the second exterior portion welding step, the joint portions 15A and 15B of the current collecting tabs 12A and 12B and the external terminals 20A and 20B are sealed inside the second exterior portion 37.

In the laminated battery 1 of the present embodiment, the joining portions 15A and 15B joining the current collecting tabs 12A and 12B and the external terminals 20A and 20B, and the power generation element sealed inside the first exterior portion 31 are provided. The gap is blocked by the first seal portion 32. Therefore, even if foreign matter is generated from the joint portions 15A and 15B, it is difficult for the generated foreign matter to mix into the power generation element. Therefore, the influence of foreign matter that may be generated from the joint portions 15A and 15B is appropriately suppressed.

Further, in general, the current collecting tabs 12A and 12B are often thinly formed, so that the current collecting tabs 12A and 12B easily become high in temperature when energized. However, in the laminated battery 1 of the present embodiment, the energization tabs 12A and 12B are in contact with the laminated outer casing 30 at the first seal portion 32. Therefore, the heat generated from the energizing tabs 12A and 12B is easily dissipated to the laminate outer casing 30. Therefore, the temperature rise of the energization tabs 12A and 12B is also suppressed.

Further, the internal pressure of the closed space enclosing the power generation element may fluctuate. In the conventional laminated battery, it was also considered that when the internal pressure of the sealed space fluctuates, the shape of the laminated outer casing is deformed, and the thin collector tab is damaged. However, in the laminated battery 1 of this embodiment, a part of the current collecting tabs 12A and 12B is sealed by the first seal portion 32. Therefore, even if the internal pressure in the first exterior portion 31 fluctuates and the shape of the first exterior portion 31 is deformed, the current collecting tabs 12A and 12B are not easily damaged.

The technology disclosed in the above embodiments is merely an example. Therefore, it is possible to change the technique exemplified in the above embodiment. With reference to FIG. 3, a laminated battery 2 which is one modification of the above-described embodiment will be described. Among the configurations of the laminated battery 2 illustrated in FIG. 3, the configurations other than the second seal portion 370 of the second exterior portion 360 can be the same as the configurations of the laminated battery 1 of the above-described embodiment. Therefore, in the following description, the same reference numerals as those of the laminate-type battery 1 are used for the same components as those of the laminate-type battery 1 of the above embodiment, and the description thereof will be omitted. The laminated exterior body 300 illustrated in FIG. 3 includes the first exterior portion 31 and the second exterior portion 360, as in the above embodiment. The second seal portion 370 of the second exterior portion 360 is welded with the external terminals 20A and 20B protruding outward while sandwiching the external terminals 20A and 20B from both sides in the thickness direction. Here, unlike the second exterior portion 36 of the above-described embodiment, the second exterior portion 360 illustrated in FIG. 3 is welded in a state in which no gap is created between the joint portions 15A and 15B. That is, the second seal portion 370 is welded without a gap so that no space is created around the joint portions 15A and 15B. In this case, the amount of water that permeates the second seal portion 370 is reduced, and the strength around the joint portions 15A and 15B is increased. In the example shown in FIG. 3, for convenience, the second seal portion 370 and the second outer peripheral seal portion 38 are shown separately. However, in the laminated battery 2 illustrated in FIG. 3, the second seal portion 370 and the second outer peripheral seal portion 38 may be integrated.

Further, in the above embodiment, both the positive electrode current collecting tab 12A and the negative electrode current collecting tab 12B extend in the same direction (upward in FIG. 1). Both the positive electrode current collecting tab 12A and the negative electrode current collecting tab 12B are sealed by one first seal portion 32. However, the positive electrode collector tab 12A and the negative electrode collector tab 12B may extend in different directions (for example, to the left and right in FIG. 1). In this case, the first seal portion that seals the positive electrode current collector tab 12A and the first seal portion that seals the negative electrode current collector tab 12B may be provided separately. Even in this case, as in the laminated battery 2 illustrated in FIG. 3, the second seal portion may be welded so that no space is created around the joint portions 15A and 15B.

1, 2 Laminated battery 10 Electrode body 12A Positive electrode current collecting tab 12B Negative electrode current collecting tab 15A, 15B Joint part 20A Positive electrode external terminal 20B Negative electrode external terminal 30,300 Laminate exterior body 31 First exterior part 32 First seal part 36, 360 Second exterior part 37, 370 Second seal part

Claims (1)

A power generation element including an electrode body,
A current collecting tab extending outward from the electrode body,
An external terminal electrically connected to the current collecting tab by being joined to the current collecting tab,
A laminate outer body that is formed into a film and is welded in a state where the wide surfaces are opposed to each other, thereby sealing at least the power generating element inside,
Equipped with
The laminate exterior body,
A first exterior portion that seals the power generating element inside by welding the current collecting tab on the side of the electrode body with respect to the tip end portion with being sandwiched by the first seal portion.
While the tip end portion of the external terminal is projected outward, at least a part of the external terminal is welded in a state of being sandwiched by the second seal portion, so that the external terminal is removed from the first seal portion of the first exterior portion. A second exterior part for sealing the joint part of the current collecting tab protruding in one direction and the external terminal inside;
Laminated battery, comprising:

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