JP2022014715A - Secondary battery - Google Patents

Abstract

To provide a secondary battery in which the movement of a protection member can be restricted, in a laminate battery housing the protection member inside an outer package.SOLUTION: A secondary battery 1 disclosed herein includes an electrode body 10 including a terminal connection part, an outer package 20 including a welding part, an electrode terminal 30, a main holder 40, a side holder 70, and resin 80. The main holder 40 is disposed to have the electrode terminal 30 held between the electrode body 10 and the outer package 20 from a lamination direction. The side holder 70 having a structure of fitting the main holder 40 thereto is attached to both end parts of a side surface including the terminal connection part of the electrode body 10. By fitting the main holder 40 and the side holder 70 to each other, the movement of the main holder 40 can be restricted.SELECTED DRAWING: Figure 2

Description

The present invention relates to a secondary battery in which an electrode body is housed in an outer body made of a laminated film.

Since secondary batteries such as lithium-ion secondary batteries are lightweight and can obtain high energy density, they are portable power sources such as personal computers and mobile terminals, or EVs (electric vehicles), HVs (hybrid vehicles), and PHVs (plug-in hybrids). It is widely used as a power source for driving vehicles such as automobiles. An example of a secondary battery is a secondary battery (hereinafter, also referred to as “laminated battery”) in which an electrode body is housed inside an outer body made of a laminated film. In order to construct such a laminated battery, the laminated film around the accommodating portion is welded while the electrode body is accommodated in the laminated film. As a result, an exterior body having a welded portion is formed, and the electrode body is housed inside the exterior body in a sealed state.

By the way, in a secondary battery, the internal pressure of the battery may change due to depressurization treatment during the manufacturing process, gas generation due to charging / discharging, and the like. In a laminated battery, the exterior body may be deformed such as expansion and contraction due to such a change in the internal pressure of the battery. If the secondary battery that exceeds the warranty period is used for a long time, the amount of deformation of the exterior body becomes large, and the welded portion of the exterior body may be cleaved due to the stress at the time of deformation. For this reason, in laminated batteries, it has been proposed to accommodate a protective member inside the exterior body, which regulates deformation of the exterior body due to a change in internal pressure and prevents cleavage of the welded portion. Patent Document 1 discloses a laminated battery provided with such a protective member (deformation regulating member).

Japanese Unexamined Patent Publication No. 2005-317312

However, if a protective member as in Patent Document 1 is provided inside the exterior body, the frequency of manufacturing a battery with significantly reduced battery performance increases, and a decrease in production efficiency due to disposal of defective products becomes a problem. was there. The reason for this is that in the manufacture of secondary batteries, when the inside of the exterior body is evacuated to a vacuum, the protective member moves toward the electrode body and comes into contact with the electrode body, resulting in damage to the electrode body. Was considered.

Therefore, the present invention has been made in view of the above problems, and a main object thereof is to provide a secondary battery in which the movement of the protective member can be restricted in a laminated battery in which the protective member is housed inside the exterior body. Is.

The secondary battery disclosed herein is a secondary battery including an electrode body, an exterior body, and an electrode terminal, and the electrode body is a separator having a positive electrode and a negative electrode having a substantially rectangular wide surface. The positive electrode and the negative electrode are each provided with a current collector foil and a mixed material layer coated on the surface of the current collector foil, respectively. There is a collector foil exposed portion on which the composite material layer is not formed, and a part of the current collector foil exposed portion extends from the long side or the short side of the wide surface, and is described above. In each of the laminated positive electrode and the negative electrode, a part of the extended current collector foil exposed portion is bonded to each other in the stacking direction on the same electrode side to form a terminal connection portion. Of the side surfaces existing between the two outer surfaces formed of the wide surface of the electrode body, the side surface having no terminal connection portion is sealed with resin, and the exterior body is formed of a laminated film. It has an accommodating portion for accommodating the electrode body and a welding portion surrounding the accommodating portion in a sealed state, and one end of the electrode terminal is connected to the terminal connecting portion. The other end is exposed to the outside of the exterior body, and a main holder in a state where the electrode terminals are sandwiched between the electrode body and the exterior body from the stacking direction is arranged in the housing portion. A side holder having a structure that fits with the main holder is attached to both ends in the long side or the short side direction on the side surface having the terminal connection portion.

With such a configuration, the side holder attached to the electrode body and the main holder which is a protective member are aligned and fixed, and the movement of the main holder in the exterior body can be restricted. As a result, even if the internal pressure of the battery changes, the movement of the main holder can be restricted, and damage to the electrode body due to contact with the main holder can be prevented.

It is a top view which shows typically the secondary battery which concerns on one Embodiment of this invention. It is a perspective view which shows typically the structure when the exterior body is removed from the secondary battery which concerns on one Embodiment of this invention. It is an exploded perspective view which shows the assembly of the upper holder and the lower holder of the secondary battery which concerns on one Embodiment of this invention. It is an exploded perspective view which shows the assembly of the main holder and the side holder of the secondary battery which concerns on one Embodiment of this invention. It is a top view schematically showing the lower holder of the secondary battery which concerns on one Embodiment of this invention. It is a top view schematically showing the upper holder of the secondary battery which concerns on one Embodiment of this invention. It is a perspective view which shows typically the side holder of the secondary battery which concerns on one Embodiment of this invention. It is a perspective view which shows typically the side holder shown in FIG. 7 from the opposite direction.

Hereinafter, as one of the embodiments of the present invention, a lithium ion secondary battery will be described in detail with reference to the drawings. The secondary battery disclosed here is not limited to the lithium ion battery, and may be, for example, a nickel hydrogen battery or the like. In addition, matters other than those specifically mentioned in the present specification and necessary for implementation are grasped as design matters of those skilled in the art based on the prior art in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.

In the drawings shown here, the members / parts having the same action are described with the same reference numerals. In addition, the dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensions. The reference numeral X in each figure indicates the “long side direction”, the reference numeral Y indicates the “short side direction”, and the reference numeral Z indicates the “thickness direction”. Here, the "long side" and "short side" refer to the long side and the short side of the wide surface of the electrode body, respectively. These directions are defined for convenience of explanation, and are not intended to limit the installation mode of the secondary battery disclosed herein.

FIG. 1 is a plan view schematically showing the secondary battery 1 according to the present embodiment, and FIG. 2 is a perspective view schematically showing the structure when the exterior body 20 is removed from the secondary battery 1 according to the present embodiment. It is a figure. As shown in FIGS. 1 and 2, the secondary battery 1 includes an electrode body 10, an exterior body 20, an electrode terminal 30, a main holder 40, a side holder 70, and a resin 80.

As shown in FIG. 2, the assembly 90 is composed of an electrode body 10, an electrode terminal 30, a main holder 40 (a combination of a lower holder 50 and an upper holder 60), a side holder 70, and a resin 80. Has been done. As shown in FIG. 3, the lower holder 50 and the upper holder 60 are sandwiched between the electrode terminal 30 from the thickness direction Z, and the protrusion 56 provided in the lower holder 50 and the matching hole 66 provided in the upper holder 60. The main holder 40 is formed by arranging the above. Then, as shown in FIG. 4, the assembly 90 is formed by aligning the protrusion 68 of the main holder 40 with the alignment hole 78 of the side holder 70. As shown in FIG. 1, the assembly 90 is housed inside the exterior body 20 so that a part of the electrode terminals 30 is exposed to the outside of the exterior body 20. Thereby, the secondary battery 1 can be manufactured. Hereinafter, each member will be described in detail.

The electrode body 10 includes an electrode sheet including a positive electrode and a negative electrode. Although detailed illustration is omitted, the electrode body 10 is configured by laminating a plurality of positive electrode sheets and negative electrode sheets in a state of being insulated by a separator. The electrode sheets of the positive electrode and the negative electrode have wide surfaces having a substantially rectangular shape, and the wide surfaces are laminated so as to face each other. Here, the stacking direction of the electrode body 10 is the thickness direction Z. Further, in the electrode body 10, the surface existing between the two outer surfaces configured by the wide surface is hereinafter also referred to as a “side surface”.
The electrode sheets of the positive electrode and the negative electrode each include a current collector foil, which is a foil-shaped metal member, and a mixed material layer coated on the surface of the current collector foil. Further, on the long side or the short side of the wide surface of each electrode sheet, a current collector foil exposed portion where the current collector foil is exposed without being coated with the mixture layer extends. In this embodiment, the current collector exposed portion extends from the short side. The electrode sheets are laminated so that the exposed parts of the current collector foil extending from the electrode sheets of the positive electrode and the negative electrode have the same side surface, and the exposed part of the current collector foil of the positive electrode and the exposed part of the current collector foil of the negative electrode are formed. The electrode body 10 is formed by laminating so as not to overlap in the thickness direction Z. Then, the terminal connection portions 12 of the positive electrode and the negative electrode are formed by joining the current collector foil exposed portions extending from the respective electrode sheets in a bundle shape to each other on the same electrode side in the stacking direction (thickness direction Z). ..

As the material of each member (for example, a current collector foil, a mixture layer, etc.) constituting the electrode body 10, any material that can be used for this type of secondary battery can be used without particular limitation.
As the current collecting foil for the positive electrode, for example, an aluminum foil or the like can be used. Further, as the positive electrode active material contained in the mixed material layer of the positive electrode, for example, a lithium transition metal oxide, a lithium transition metal phosphoric acid compound, or the like can be used.
As the current collecting foil for the negative electrode, for example, a copper foil or the like can be used. Further, as the negative electrode active material contained in the mixture layer of the negative electrode, for example, graphite or the like can be used.

Further, the secondary battery 1 includes an electrolyte (not shown) inside the exterior body 20.
When the secondary battery 1 is a liquid-based lithium ion secondary battery, a solution obtained by dissolving a lithium salt such as LiPF ₆ in a non-aqueous solvent such as carbonates can be used as the electrolytic solution. Further, as a separator, for example, a porous polyolefin sheet is arranged between the electrode sheets of the positive electrode and the negative electrode to insulate the positive electrode and the negative electrode.
When the secondary battery 1 is an all-solid-state battery, a solid electrolyte layer is arranged between the positive electrode and the negative electrode. The solid electrolyte layer serves as a separator and an electrolyte in a liquid-based secondary battery. Examples of the solid electrolyte contained in the solid electrolyte layer include various compounds having lithium ion conductivity (eg, amorphous sulfide, crystalline sulfide, amorphous oxide, crystalline oxide, crystalline acid). Nitride, crystalline nitride, crystalline amorphous, etc.) can be used.

The exterior body 20 is formed of a laminated film 22, and has an accommodating portion for accommodating the electrode body 10 and a welding portion 24 surrounding the accommodating portion for enclosing the accommodating portion in a sealed state. In addition to the electrode body 10, the main holder 40, the side holder 70, and the resin 80 are housed in the housing portion.
In the present embodiment, as shown in FIG. 1, a welded portion 24 to which the laminated film 22 is welded is formed on the outer peripheral edge portion of the exterior body 20, and one end of the electrode terminal 30 is exposed to the outside of the exterior body 20. As such, the assembly 90 is housed in a sealed state. The laminating film 22 may be formed in a bag shape in advance, or the outer peripheral edge portion may be welded after arranging the electrode body between the two laminated films.

The material constituting the laminated film 22 is not particularly limited, and typically, a material in which a foil-shaped metal and a resin sheet are laminated can be used. For example, for the purpose of imparting heat resistance, sealing strength, impact resistance, etc. to the surface of a non-stretched polypropylene film (CPP) for heat welding, a metal layer such as aluminum and PET, polyamide (PA), or nylon A laminated film having a three-layer structure in which an external resin layer such as a film-making film is bonded to each other can be used.

The electrode terminal 30 is a plate-shaped conductive member, and as shown in FIG. 3, one end of the electrode terminal 30 is connected to the terminal connection portion 12. Further, as shown in FIG. 1, the other end of the electrode terminal 30 is exposed to the outside of the exterior body 20. At the portion where the electrode terminal 30 penetrates the exterior body 20, the electrode terminal 30 is sandwiched between the laminating film 22, and the laminating film 22 is welded to the surface of the electrode terminal 30. A welding film is applied to the portion where the electrode terminal 30 is sandwiched by the laminating film 22, and the surface of the electrode terminal 30 is subjected to a welding treatment so that the welding film and the outer peripheral edge portion of the laminating film 22 overlap each other. The laminated film 22 can be preferably welded to the surface.

As shown in FIG. 3, the electrode terminal 30 may have a recess 34 formed in the short side direction Y. The concave portion 34 can be combined with the convex portion 54 that can be formed on the lower holder 50 to form the engaging portion E. By forming the engaging portion E, the alignment between the electrode terminal 30 and the lower holder 50 can be facilitated.

The resin 80 is formed so as to seal the side surface of the electrode body 10 that does not have the terminal connection portion 12. The resin 80 fixes the side holders 70 attached to both ends of the side surface of the electrode body 10 having the terminal connection portion 12 in the short side direction Y to the electrode body 10.
The material of the resin 80 is not particularly limited, but for example, a thermosetting resin such as an epoxy resin or a phenol resin can be used.

The method for forming the resin 80 is not particularly limited, but for example, the resin 80 can be molded using a mold. However, if the resin 80 is formed on the side surface having the terminal connection portion 12, a defect may occur in the joining process between the terminal connection portion 12 and the electrode terminal 30. Therefore, by attaching the side holder 70 to both ends of the side surface of the electrode body 10 having the terminal connection portion 12 in the short side direction Y, it is possible to prevent the resin 80 from flowing into the side surface having the terminal connection portion 12.
Further, by using a mold, the resin 80 having good dimensional accuracy can be formed. Therefore, when the assembly 90 is housed in the exterior body 20, the laminating film 22 and the electrode body 10 and the resin 80 can be housed in closer contact with each other.

The main holder 40 is formed by combining the lower holder 50 and the upper holder 60. The main holder 40 is arranged between the exterior body 20 and the electrode body 10 in a state where the electrode terminal 30 is sandwiched from the thickness direction Z in the accommodating portion. As a result, even if the internal pressure of the secondary battery 1 changes due to decompression processing during the manufacturing process, gas generation due to charging / discharging, etc., deformation of the exterior body 20 due to this can be regulated, and the welding portion 24 can be controlled. Cleavage can be prevented.
The lower holder 50 and the upper holder 60 constituting the main holder 40 are preferably made of a resin material having a predetermined strength, for example, a thermoplastic resin such as polypropylene, polyethylene, polyphenylene sulfide, a phenol resin, an epoxy resin, or the like. The thermosetting resin of the above can be preferably used.

The lower holder 50 is a member constituting the main holder 40, and is arranged below the electrode terminal 30 in the accommodating portion. As shown in FIG. 5, the lower holder 50 is provided with a stepped portion 52 on the surface in contact with the upper holder 60. Since the step portion 52 is thinner than both ends in the short side direction Y, it is possible to form a terminal insertion hole through which the electrode terminal 30 is inserted when combined with the upper holder 60.

Further, the lower holder 50 may be formed with a convex portion 54 protruding from the step portion 52. As described above, since the convex portion 54 can be fitted with the concave portion 34 of the electrode terminal 30 to form the engaging portion E, the alignment of the electrode terminal 30 can be facilitated. The shape of the convex portion 54 and the concave portion 34 is not particularly limited as long as they can be engaged with each other. Here, the lower holder 50 is provided with a convex portion 54 and the electrode terminal 30 is provided with a concave portion 34. For example, the lower holder 50 may be provided with a concave portion and the electrode terminal 30 may be provided with a convex portion.

Further, the lower holder 50 is provided with a protrusion 56 on the surface in contact with the upper holder 60. The main holder 40 can be formed by aligning the protrusion 56 with the matching hole 66 provided on the surface of the upper holder 60 in contact with the lower holder 50 shown in FIG. The number of protrusions 56 and aggregating holes 66 is not particularly limited, and may be one or a plurality of two or more.

The upper holder 60 is a member constituting the main holder 40, and is arranged above the electrode terminal 30 in the accommodating portion. As shown in FIG. 6, the upper holder 60 is provided with a protrusion 68 protruding in the long side direction X. Specifically, the protrusion 68 is provided on each surface of the side holder 70 shown in FIG. 7 in contact with the front side surface 72. The protrusion 68 can be aligned by being inserted into the alignment hole 78 of the side holder 70. As a result, after the lower holder 50 and the upper holder 60 are combined to form the main holder 40, the side holder 70 and the main holder 40 can be fixed by a combination.
Due to such fixing, the main holder 40 moves in the direction of the electrode body 10 (here, the long side direction X) even when the inside of the exterior body 20 is evacuated in the manufacturing of the secondary battery 1. It is possible to prevent the electrode body 10 and the resin 80 from coming into contact with each other, and it is possible to prevent the electrode body 10 and the resin 80 from being damaged.

The side holder 70 has a structure that fits with the main holder 40, and is attached to both ends of the side surface of the electrode body 10 having the terminal connection portion 12 in the short side direction Y. The side holder 70 is fixed to the electrode body 10 by the resin 80. As shown in FIG. 7, the side holder 70 is provided with a matching hole 78 on the front side surface 72 in contact with the main holder 40. As described above, the matching hole 78 is fitted by inserting the protrusion 68 of the upper holder 60, and the main holder 40 can be fixed to the side holder 70. The number of protrusions 68 and 78 is not particularly limited, and may be one or more than one. Further, in the present embodiment, the protrusion 68 provided on the upper holder 60 and the matching hole 78 are aligned with each other. For example, a protrusion is provided on the surface of the lower holder 50 in contact with the side holder 70, and the side holder 70 is provided. May be provided with a matching hole 78 that fits with the protrusion.

The matching hole 78 may be formed so as to penetrate the rear side surface 74. However, in that case, when the resin 80 is formed on the side surface of the electrode body 10 that does not have the terminal connection portion 12, the resin 80 may enter the matching hole 78. Therefore, as shown in FIG. 8, it is preferable to attach a tape 75 for closing the through hole 78 to the rear side surface 74. Further, by attaching the tape 75 from the rear side surface 74 to the second middle side surface 76a, the side holder 70 can be temporarily fixed to the electrode body 10. As a result, when the resin 80 is formed, the position of the side holder 70 can be fixed, so that the resin 80 can be more reliably prevented from flowing into the side surface of the electrode body 10 having the terminal connection portion 12.

The first middle side surface 76 of the side holder 70 shown in FIG. 8 is a surface in contact with the side surface of the electrode body 10 having the terminal connection portion 12, and the second middle side surface 76a is adjacent to the side surface of the electrode body 10 having the terminal connection portion 12. It is the surface that comes into contact with the side surface. Therefore, as long as the first middle side surface 76 and the second middle side surface 76a are in contact with the above side surface of the electrode body 10, this shape is not particularly limited. For example, if the electrode body 10 has a structure in which rectangular electrode sheets are laminated, the first middle side surface 76 and the second middle side surface 76a have a shape in which they are in contact with each other at a right angle.

Further, as shown in FIG. 8, one or more grooves 77 may be formed from the rear side surface 74 of the side holder 70 to the second middle side surface 76a. As a result, when the resin 80 is formed on the electrode body 10, the resin 80 flows into the groove 77, the contact area between the resin 80 and the side holder 70 increases, and the side holder 70 and the electrode body 10 are more firmly fixed. be able to.

The side holder 70 is preferably made of a resin material having predetermined strength and heat resistance. For example, a thermoplastic resin such as polypropylene, polyethylene or polyphenylene sulfide, or a thermosetting resin such as a phenol resin or an epoxy resin can be preferably used.

The technique disclosed herein can be applied to secondary batteries having various structures without particular limitation. That is, the technique disclosed herein applies to any of an all-solid-state battery that uses a solid electrolyte as an electrolyte, a polymer battery that uses a polymer electrolyte, and a non-aqueous electrolyte secondary battery that uses a non-aqueous electrolyte. be able to.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

1 Rechargeable battery 10 Electrode body 12 Terminal connection part 20 Exterior body 22 Laminated film 24 Welding part 30 Electrode terminal 34 Recessed part 40 Main holder 50 Lower holder 52 Stepped part 54 Convex part 56, 68 Protrusion 60 Upper holder 66, 78 70 Side holder 72 Front side surface 74 Rear side surface 75 Tape 76 First middle side surface 76a Second middle side surface 77 Groove 80 Resin 90 Assembly E Engagement part

Claims (1)

Electrode body, exterior body, electrode terminal,
It is a secondary battery equipped with
The electrode body is composed of a plurality of positive electrodes and negative electrodes having a substantially rectangular wide surface laminated via a separator.
The positive electrode and the negative electrode are each
The current collector foil, the mixture layer coated on the surface of the current collector foil, and
Equipped with
The current collector foil has an exposed portion of the current collector foil on which the mixture layer is not formed.
A part of the exposed part of the current collector foil extends from the long side or the short side of the wide surface.
In each of the laminated positive electrode and the negative electrode, a part of the extended current collector foil exposed portion is bonded to each other in the stacking direction on the same electrode side to form a terminal connection portion.
Of the side surfaces of the electrode body existing between the two outer surfaces formed of the wide surface, the side surface having no terminal connection portion is sealed with resin.
The exterior body is made of a laminated film, and has an accommodating portion for accommodating the electrode body and a welding portion for enclosing the accommodating portion in a sealed state around the accommodating portion.
One end of the electrode terminal is connected to the terminal connection portion, and the other end is exposed to the outside of the exterior body.
In the accommodating portion, a main holder in a state where the electrode terminals are sandwiched between the electrode body and the exterior body from the stacking direction is arranged.
A side holder having a structure that assembles with the main holder is attached to both ends in the long side or short side direction on the side surface having the terminal connection portion.
Secondary battery.

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