JP2020129515A - Laminated battery - Google Patents

Abstract

To provide a laminated battery capable of preventing breakage of a laminate outer package body and removal of a seal even when external force is applied to external terminals.SOLUTION: A laminated battery 1 comprises external terminals 20A and 20B, a laminate outer package body 30, and tab films 40A and 40B. The laminate outer package body 30 internally seals an electrode body 10 with the external terminals 20A and 20B exposed outward from a welded seal part. The tab films 40A and 40B are disposed between the external terminals 20A and 20B, and the laminate outer package body 30 so as to be welded together with the seal part. The external terminals 20A and 20B respectively have deformed parts 25A and 25B in portions covered by the seal part. In the deformed parts 25A and 25B, the width in the width direction becomes narrower toward the outer side in a penetration direction of the external terminals 20A and 20B.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, of the external terminals (electrode tabs) electrically connected to the power generation element (electrical device element), a portion sealed by the laminate outer body is provided outside in the width direction. A thin portion is provided so that the plate thickness gradually decreases. As a result, it is possible to suppress the generation of a gap between the portion welded for sealing and the external terminal.

JP, 2006-164784, A

In the battery described in Patent Document 1, when an external force is applied to the external terminal, the stress is likely to be concentrated on the outer end portion of the joint portion between the portion welded for sealing and the external terminal. As a result, there is a possibility that the outer end portion of the joint portion becomes a starting point and the laminate outer casing is broken or the seal is peeled off.

A typical object of the present invention is to provide a laminate-type battery capable of suppressing breakage of a laminate outer package and peeling of a seal even when an external force is applied to an external terminal.

In order to achieve such an object, a laminated battery according to one embodiment disclosed herein is in a state in which a plate-shaped external terminal electrically connected to an electrode body is formed in a film shape and wide surfaces are opposed to each other. And the outer end of the external terminal is exposed to the outside from the welded seal portion, and a laminate outer body for sealing the electrode body inside, and a heat-welding material. A tab film that is formed and is welded together with the seal portion in a state of being disposed between at least a part of the external terminal and the seal portion of the laminate outer package, and is parallel to the plate surface of the external terminal. Among the different directions, when the direction in which the external terminal penetrates the seal part is the penetrating direction, and the direction intersecting the penetrating direction is the width direction, the external terminal is in a portion covered by the seal part. It is characterized by including a deforming portion whose width in the width direction becomes narrower toward the outside in the penetrating direction.

In the laminated battery having the above structure, the deformable portion having a width that narrows outward in the penetrating direction is provided at a portion of the external terminal covered by the seal portion. Therefore, when an external force is applied to the external terminal, stress is likely to concentrate on the deformed portion covered by the seal portion. As a result, stress is less likely to be concentrated on the outer end of the joint between the welded portion and the external terminal, which tends to be the starting point of breakage and peeling of the laminate outer package. Therefore, even when an external force is applied to the external terminal, breakage of the laminate outer package and peeling of the seal are appropriately suppressed.

FIG. 3 is a front view of the laminate type battery 1 in a state where the laminated outer package 30 and the tab films 40A and 40B on the front side of the paper are omitted. FIG. 2 is a partial sectional view taken along line AA in FIG. 1. It is a perspective view of 20 A of external terminals. It is a front view of external terminals 201-206 concerning a modification.

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 formed in a plate shape. 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 is exposed to the outside 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 of the negative electrode current collecting tab 12B, and is exposed to the outside from the laminate outer casing 30. The negative electrode external terminal 20B of this embodiment is a thin copper plate. Detailed configurations of the external terminals 20A and 20B will be described later with reference to FIG.

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.

As shown in FIG. 2, the laminated exterior body 30 of the present embodiment has a laminated structure. Specifically, the film-shaped laminate outer package 30 includes a protective layer 31, a metal layer 32, and a sealant layer 33 in order from the outside. The protective layer 31 is made of, for example, nylon or the like, and improves the durability and impact resistance of the laminated outer package 30. The metal layer 32 is formed of, for example, aluminum or the like, and improves the gas barrier property and the moisture proof property of the laminate outer casing 30. The sealant layer 33 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 32. 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. First, the external terminals 20A and 20B are joined to the current collecting tabs 12A and 12B extending from the electrode body 10. Next, the tab films 40A and 40B are sandwiched from both sides in the thickness direction of the laminated battery 1 so as to cover the deformed portions 25A and 25B (see FIG. 1) described later with respect to the external terminals 20A and 20B, respectively. The tab films 40A and 40B are formed of a material having a heat-welding property (for example, polypropylene (PP) or the like).

Next, the laminated outer package 30 is arranged so as to cover the entire electrode body 10, the external terminals 20A and 20B, and the tab films 40A and 40B from both sides in the thickness direction. That is, as shown in FIG. 2, on both sides in the thickness direction of the external terminal 20A and the tab films 40A and 40B, the wide surfaces of the film-shaped laminate exterior body 30 face each other so that the sealant layer 33 is located inside. Are arranged.

Next, the sealant layer 33 is welded to the outer peripheral portion of the laminated outer casing 30 so that a bag-shaped closed space is formed between the laminated outer casings 30 that face each other. As a result, the electrode body 10 is sealed inside the laminate exterior body 30. As shown in FIG. 1, in the present embodiment, the sealant layer 33 on the outer peripheral portion of the laminate outer casing 30 is welded to form the external terminal seal portion 35 and the peripheral edge seal portion 36. The external terminal seal portion 35 seals the external terminals 20A and 20B in a state where the tip portions of the external terminals 20A and 20B are exposed to the outside. Here, when the external terminal sealing portion 35 is welded, the tab films 40A and 40B arranged between the laminate outer package 30 and the external terminals 20A and 20B are also welded. Therefore, the sealability of the external terminals 20A and 20B is improved.

Further, the peripheral edge seal portion 36 is formed on a portion of the outer peripheral portion of the laminate exterior body 30 other than the external terminal seal portion 35. As described above, in the present embodiment, the two bag-shaped laminated outer casings 30 are bonded together to form a bag-shaped closed space. Therefore, the peripheral edge seal portion 36 of the present embodiment has a substantially U shape in a front view. However, the shape of the peripheral seal portion 36 can be changed.

In the following description, of the directions parallel to the plate surfaces of the external terminals 20A and 20B, the direction in which the external terminals 20A and 20B penetrate the external terminal seal portion 35 (direction A in FIGS. 1 to 4) is penetrated. The direction is A. Further, of the directions parallel to the plate surfaces of the external terminals 20A and 20B, the direction (the direction B in FIGS. 1, 3, and 4) that intersects the penetration direction A (vertically intersects in this embodiment) is defined as The width direction B of the terminals 20A and 20B is assumed. The thickness direction of the laminated battery 1 is a direction (direction C in FIGS. 2 and 3) that intersects both the penetration direction A and the width direction B.

The configuration of the external terminals 20A and 20B in this embodiment will be described in detail with reference to FIG. Note that the positive external terminal 20A and the negative external terminal 20B may have the same structure. Therefore, the configuration of the positive electrode external terminal 20A will be mainly described below, and the detailed description of the negative electrode external terminal 20B will be omitted.

As shown in FIG. 3, the external terminal 20A of this embodiment includes a wide portion 21A and a narrow portion 22A. The width in the width direction B of the wide portion 21A is larger than that of the narrow portion 22A. The narrow portion 22A is located on the outer side (upper side in FIG. 3) in the penetrating direction A than the wide portion 21A. In the present embodiment, the wide portion 21A and the narrow portion 22A have the same thickness in the thickness direction C. However, the wide portion 21A and the narrow portion 22A may have different thicknesses.

The external terminal 20A includes a thin portion 23A. The thin portion 23A is a portion where the plate thickness gradually decreases toward the outside in the width direction B. The thin portion 23A of the present embodiment has a symmetrical shape in the thickness direction C. However, the thin portion 23A may be formed by making one surface of the external terminal 20A in the thickness direction C a flat surface and inclining the other surface. The thin portion 23A is formed on at least a part of a portion of the external terminal 20A that is covered by the external terminal seal portion 35 (see FIGS. 1 and 2). As an example, in this embodiment, the thin portion 23A is formed over the wide portion 21A and the narrow portion 22A. However, it is also possible to change the position where the thin portion 23A is formed. For example, the thin portion 23A may be formed on only one of both ends in the width direction B. Further, the thin portion 23A may be formed only in the central portion of the external terminal 20A in the penetrating direction A. By forming the thin portion 23A, a gap is less likely to occur between the external terminal 20A and the tab film 40A and the external terminal seal portion 35. Therefore, the sealing property is improved.

The external terminal 20A includes a deforming portion 25A. The deforming portion 25A is a portion whose width in the width direction B becomes narrower toward the outside in the penetrating direction A (upper side in FIG. 3). As described above, the deformable portion 25A is formed in the portion of the external terminal 20A that is covered by the external terminal seal portion 35 (see FIGS. 1 and 2). As an example, the deforming portion 25A of the present embodiment is a step portion at a right angle between the wide portion 21A and the narrow portion 22A.

If the external terminal 20A is not provided with the deforming portion 25A and an external force in the width direction B is applied to the external terminal 20A, stress is likely to be concentrated at, for example, the position P1 in FIG. The position P1 is defined by a portion to be welded for sealing the external terminal 20A (tab film 40A and external terminal seal portion in the present embodiment) and external terminal 20A (specifically, thin portion 23A in the present embodiment). It is an outer end of the joining portion in the penetrating direction A. When the stress concentrates on the position P1, the position P1 may serve as a starting point and the laminate exterior body 30 may be broken or the seal may be peeled off.

On the other hand, in the laminated battery 1 of the present embodiment, stress is likely to be concentrated on the deformed portion 25A (for example, the position P2 in FIG. 1) covered by the external terminal seal portion 35. Therefore, stress is less likely to be concentrated at the position P1 which is likely to be a starting point of breakage or peeling. Therefore, even when an external force is applied to the external terminal 20A, the occurrence of breakage of the laminate outer casing 30 and peeling of the seal are appropriately suppressed.

The technology disclosed in the above embodiments is merely an example. Therefore, it is possible to change the technique exemplified in the above embodiment. For example, you may change the structure of the deformation|transformation part of an external terminal. FIG. 4 is a front view of the external terminals 201 to 206 according to the modification. As shown in FIGS. 4(A), (B), and (C), the external terminals 201, 202, and 203 are wider than the wide portions 211, 212, and 213 in the penetrating direction A (downward in FIG. 4). It further includes a narrow portion whose width in the direction B is smaller than that of the wide portions 211, 212, 213. In this case, not only the deformed portions 251, 252, 253 are formed outside the wide portions 211, 212, 213, but also the deformed portions are formed inside the wide portions 211, 212, 213. Therefore, it becomes more difficult for stress to concentrate. Further, as shown in FIGS. 4C and 4E, of the deformed portions 253 and 255 of the external terminals 203 and 205, the surface facing the outside in the penetrating direction A (upper side in FIG. 4) is in the penetrating direction A. It is not vertical, but inclined. Even in this case, the stress is properly distributed. In addition, as shown in FIGS. 4B, 4D, and 4F, of the deformed portions 252, 254, and 256 of the external terminals 202, 204, and 206, the surface facing outward in the penetrating direction A is the thickness direction. It is curved from the perspective. Even in this case, the stress is properly distributed.

DESCRIPTION OF SYMBOLS 1 Laminated battery 10 Electrode body 20A, 20B, 201-206 External terminal 25A, 25B, 251-256 Deformation part 30 Laminate exterior body 35 External terminal seal part 40A, 40B Tab film

Claims (1)

A plate-shaped external terminal electrically connected to the electrode body,
It is formed in a film shape and is welded with the wide surfaces facing each other, so that the electrode body is sealed inside with the tip of the external terminal exposed to the outside from the welded seal portion. A laminated exterior body to stop,
A tab film formed of a material having a heat-welding property, which is welded together with the seal portion in a state of being disposed between at least a part of the external terminal and the seal portion of the laminate outer casing,
Equipped with
In the direction parallel to the plate surface of the external terminal, the direction in which the external terminal penetrates the seal part is the penetrating direction, and the direction intersecting the penetrating direction is the width direction,
The laminate battery according to claim 1, wherein the external terminal includes a deformable portion in a portion covered by the seal portion, the deforming portion having a width that narrows in the width direction toward the outside in the penetrating direction.

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