JP2003272569A - Lithium ion secondary battery case and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery case cover with mass production capability and a thin sheet metal outer covering with strong damage resistance. <P>SOLUTION: An aluminum thin plate 6 is press-molded into a half case cover, which is an original form of an outer covering of the lithium ion secondary battery 1. The half case cover with an external periphery 4e rising, and a folding part 4g is produced by press molding of the periphery 4e. A joint part is formed by injection molding of the external periphery 4e of the half case cover using a synthetic resin body 7, and the half cases 4a and 4b are placed opposite each other, a lithium ion secondary battery main unit 2 is inserted inside, and the joint part is bonded by ultrasonic welding. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a case for enclosing a main body of a lithium ion secondary battery and a method for manufacturing the case. More specifically, the present invention relates to a lithium ion secondary battery case having a structure in which a thin metal plate and a synthetic resin are combined, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, the exterior of a battery is hermetically covered with a case-like body such as aluminum or plastic, or is injection-molded with a thermoplastic resin to be packaged. It has been known. It is also known that a heat-shrinkable tube made of polyvinyl chloride is used as a heat-shrinkable synthetic resin for coating a battery.

The use of a stretched tube made of a mixed composition containing an olefinic ionomer resin as a main component is also disclosed. What is generally used as an exterior cover is an exterior that is covered with a plastic mold case molded of synthetic resin by injection molding. It is used by connecting a protection circuit.

[0004]

However, the conventional methods do not solve all the demand requirements, and still have many problems. Particularly in terms of thinning and packaging, in conventional injection molding, there is a limit because the flow becomes worse and the flow becomes worse due to the flow of the molten resin. Further, if the heat-shrinkable synthetic resin is thin, it may cause wrinkles, and there is still a manufacturing problem in producing a product of stable quality.

The exterior is intended to prevent the lithium ion secondary battery main body from being damaged by accidental troubles such as dropping and impact, and from leaking out the electrolytic solution and the like from the above-mentioned conventional synthetic resin. Those are not necessarily strong to prevent damages due to external impacts, etc., and if the structure is particularly thin, the concern increases. Therefore, as long as the current molding method is used, PBT (polybutylene terephthalate) cannot be reduced to a predetermined thickness dimension or less, and there is a limit. Further, these synthetic resin case covers must be PBT and have chemical resistance, and must be highly productive.

The present invention has been made based on such a technical background, and the case cover is made of a metal plate,
It is manufactured in combination with a synthetic resin to achieve the following objects. An object of the present invention is to provide a case cover of a lithium-ion secondary battery and a manufacturing technique thereof, in which the side surface exterior of the lithium-ion secondary battery is made of metal such as aluminum which is thinly reinforced, and the joint portion is made of synthetic resin. It is in. Another object of the present invention is to provide a case cover for a lithium-ion secondary battery, which is suitable for mass production and easy to manufacture, and a manufacturing technique thereof. Still another object of the present invention is to provide a case cover for a lithium ion secondary battery, which can form an exterior with an excellent design, and a manufacturing technique thereof.

[0007]

[Means for Solving the Problems] To solve the above problems, the following means are adopted. The lithium ion secondary battery case of the present invention 1 is a case for packaging a lithium ion secondary battery, and is a rectangular first side surface plate formed of a metal plate material and having an outer peripheral edge portion in a rising shape, and the first side plate. A rectangular second side plate, which is arranged parallel to the face plate and is formed of a metal plate and has an outer peripheral edge portion in a rising shape, and a synthetic resin integrally provided on the outer peripheral edge portion of the first side plate. When the first outer peripheral portion, the second outer peripheral portion made of synthetic resin integrally provided on the outer peripheral edge portion of the second side plate, and the first outer peripheral portion and the second outer peripheral portion face each other and are joined together It is composed of an integrally joined portion.

In the lithium ion secondary battery case of the second aspect of the present invention, in the first aspect of the present invention, the metal plate material may be aluminum or an aluminum alloy. It can be light and thin. In the lithium ion secondary battery case of the third aspect of the present invention, in the first aspect of the present invention, a deformed portion may be provided on the outer peripheral edge portions of the first side plate and the second side plate. It is possible to adopt a structure in which the synthetic resin coated on the outer peripheral edge portion cannot be removed. A lithium ion secondary battery case according to a fourth aspect of the present invention is the same as the first aspect of the present invention, wherein the joint portions may have uneven portions. The joining force is strengthened.

A method for manufacturing a lithium ion secondary battery case of the present invention 5 is a method for manufacturing a case for packaging a lithium ion secondary battery, in which a metal plate material is pressed to form an outer peripheral edge portion and formed into a box shape. Then, the molded metal plate material is inserted into an injection molding die, and a molten synthetic resin is injected into the injection molding die, and the outer peripheral edge portion is covered with the synthetic resin to form the metal plate material as a half case cover. It is a method of manufacturing a lithium-ion secondary battery case by facing and joining the outer peripheral edge portions of the two half case covers.

In the method for manufacturing a lithium ion secondary battery case of the present invention 6, in the invention 5, press working may be added to the press working for providing a deformed portion on the outer peripheral edge portion of the metal plate material. . It is possible to adopt a structure in which the synthetic resin coated on the outer peripheral edge portion cannot be removed. In the method for manufacturing a lithium ion secondary battery case of the present invention 7, in the invention 5, the outer peripheral edge portions may be opposed to each other and bonded by ultrasonic welding. The finish is beautiful,
The welding time is short and it is efficient and effective for small products.
A method for manufacturing a lithium ion secondary battery case according to an eighth aspect of the present invention is the method for producing the lithium ion secondary battery case according to the fifth aspect, in which the outer peripheral edge portions are formed into concavo-convex joint portions, and the half case covers are joined to face each other. May be. The joining force is strengthened.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 shows an external view of a lithium ion secondary battery 1 to which the present invention is applied, and FIG. 2 shows an exploded view of the lithium ion secondary battery 1 in an exploded manner. In the figure, the lithium ion secondary battery main body 2 is a battery that can be repeatedly charged, and has recently been used as a battery for mobile phones, digital cameras, and the like. It is characterized by high energy density, light weight and compact size, high operating voltage, and high safety.

The principle of the lithium ion secondary battery main body 2 is that current is caused to flow by moving the lithium ions to the negative electrode during charging and to the positive electrode during discharging. The basic structure of the lithium-ion secondary battery main body 2 is a three-layer structure in which a sheet-shaped positive electrode plate and a negative electrode plate are provided and a resin-based separator is sandwiched therebetween. Cobalt acid lithium or the like is used for the positive electrode, and graphite or the like is used for the negative electrode.

The resin-based separator is, for example, a polymer porous film. These are housed in, for example, a deep-drawn metal case 3, covered with a lid, filled with an electrolytic solution, and sealed by laser welding or the like. In a general prismatic structure, a positive electrode terminal 2a is provided on the upper portion of the lithium ion secondary battery main body 2, and the metal case 3 serves as a negative electrode terminal 2b. The negative electrode terminal 2b may be provided as a terminal in the lower part of the metal case 3 or may be provided in parallel on the positive electrode side, depending on the form.

In the embodiment, the lithium ion secondary battery main body 2 has a structure in which the negative electrode side output terminal is provided on the positive electrode side via the lead wire. Between the lead wire and the output terminal on the negative electrode side, a protection circuit 2d insulated from the main body is provided. A safety valve 2c is provided on the positive electrode terminal 2a side,
If the pressure inside the battery rises, the gas inside the battery is released to the outside to ensure safety. Lithium ion secondary battery main body 2 having such a configuration
The case cover 4 is externally mounted for protection.

The present invention relates to this case cover 4, and in the present embodiment, it is a thin half case cover (first side body) 4a and the other half case cover (second side body). ) 4b, the lithium ion secondary battery main body 2 is sandwiched between the two half case covers 4a and 4b for interior mounting. The completed lithium ion secondary battery 1 is a product in which the lithium ion secondary battery main body 2 and the case cover 4 are integrated. A product name, a manufacturing company name, etc. are displayed on the surface of the case cover 4 by a label 5 or the like. The basic material of the case cover 4 is a metal plate material such as aluminum or aluminum alloy.

Conventionally, a plastic mold case made of synthetic resin has been used as described above. However, although this synthetic resin product can be manufactured into a complicated shape by injection molding, there is a limit to how thin it can be made. On the other hand, the metal plate material such as aluminum or aluminum alloy is light and is metal, so that it is less likely to be scratched than synthetic resin and can be thinly processed.

The case cover 4 of the present invention makes use of such characteristics of the material, and uses aluminum or an aluminum alloy for the exterior of the wide area portion 4c of the lithium ion secondary battery 1, and the outer peripheral edge portion 4d thereof. The synthetic resin is injected and coated, and the two half case covers are opposed to each other and joined to each other, thereby facilitating the manufacture.

Next, a method of manufacturing the case cover 4 will be described. FIG. 3 shows an aluminum thin plate 6 forming the main part of the case cover. This aluminum thin plate 6
Has a thickness of 0.4 mm or 0.5 mm, for example. As shown in FIG. 4, this is combined with plastic working such as punching by press working, bending, cutting and drawing. By this press, the wide area portion 4 which is a flat plate portion which covers the main portion of the lithium ion secondary battery main body 2
The box-shaped half case covers 4a and 4b are formed by forming c and its outer peripheral edge portion 4e.

The outer peripheral edge portion 4e of the half case covers 4a and 4b has a width which is half the thickness of the lithium ion secondary battery main body 2. One surface of the outer peripheral edge portion 4e is provided with an electrode terminal. A cutout portion 4f for exposing the safety valve is provided. Next, the outer peripheral edge portion 4e of the half case covers 4a and 4b.
When is molded, the outer peripheral edge portion 4e is partially provided with a plurality of bent portions 4g as shown in FIG.

This is for preventing the synthetic resin body 7 described later from coming off. For details, as shown in FIG. 6 (a), the bent portion 4g partially deforms the outer peripheral edge portion 4e. It is a thing. The bent portion 4g is formed by partially pressing a protrusion having a predetermined shape toward the inside of the case cover by press molding. The protrusion size is a little, for example, 0.3 mm. Further, the bent portion 4g may be continuously provided on the entire surface of the outer peripheral edge portion 4e.
It may be up to 3 places.

As a result, a part of the outer peripheral edge portion 4e in the flat state is bent to form a hook portion for the synthetic resin body 7. The bent portion 4g is the bent portion 4g.
Alternatively, as shown in FIG. 6 (b), the hole 4h may be opened, or the bent portion 4g may be cracked. It may be something with some deformation.

As a result, the mechanical joining strength between the two is increased. This pressed original case cover 4
If the shape of the cutout portion 4f of the outer peripheral edge portion 4e is evenly arranged, then the two half-split case covers 4a and 4b to be joined are the same in both cases, and as a press-formed product. One kind is good.

A method of injection-molding the original case cover 4 of the aluminum thin plate 6 thus press-molded with a synthetic resin on the outer peripheral edge portion 4e of the original case cover will be described. FIG. 7 partially shows a mold configuration for molding the synthetic resin body 7. The original case cover 4 is installed on the fixed-side mold 8 at a predetermined position. On the other hand, a mold for injection molding the outer peripheral edge portion 4e is movably installed as a movable mold 9 at a predetermined position above the original case cover 4. The movable side mold 9 shown in the figure has the mold shape of the half case cover 4a.

FIG. 8 shows a state in which the movable mold 9 is attached to the fixed mold 8 and is closed. The outer peripheral edge portion 4e of the case cover 4 constitutes the cavity 10 space. The hard synthetic resin body 7 is injected into the space of the cavity 10 to mold the half case cover 4a. The runner 11 for this injection has a fixed side mold 8 and a movable side mold 9 as shown in the figure.
It is provided on the dividing surface. The runner 11 serves as a passage for guiding the synthetic resin body 7 for molding from the sprue to the cavity 10. Although FIG. 8 shows a state in which a single case cover 4 is molded, such injection molding is generally performed on a plurality of products at the same time. The molten synthetic resin body 7 is simultaneously injected via the.

FIG. 9 shows one of the molded half case covers 4a. In this half case cover 4a, the joint portion of the synthetic resin body 7 of the outer peripheral edge portion 4e constitutes a recess 7a. The shape of this joint is determined by the relation of joining with the other side. Even if the joining portion has a flat shape, it can be joined by heat fusion, but if it has an uneven shape, the joining force can be enhanced. Further, the molded synthetic resin body 7 covers the bent portion 4g on the original case cover 4 of the aluminum thin sheet 6 and is fusion-cured, so that the synthetic resin body 7 is formed on the outer peripheral edge portion of the thin aluminum sheet 6. It does not peel off from 4e.

FIG. 10 shows the other half case cover 4b. The half case cover 4b has an outer peripheral edge portion 4
The joint portion of the synthetic resin body 7 of e forms the convex portion 7b. The convex portion 7b has a shape matching the concave portion 7a of the mating half case cover 4a. Although not shown, the mold of the movable side mold in this case is matched with the half case cover 4b. Therefore, when the two molded half case covers 4a and 4b are joined so as to face each other, the concavo-convex portion 7a,
The two half case covers 4a and 4b are brought into close contact with each other by joining 7b. Since the original case cover 4 is the same, the difference between the half case covers 4a and 4b is due to the difference between the uneven portions 7a and 7b.

Next, a method of joining the uneven portions 7a and 7b will be described. The joining method is ultrasonic welding. The principle of ultrasonic welding is to apply ultrasonic vibration to the joint surface of two synthetic resins to weld them by frictional heat. That is, when one of the two synthetic resin molded products to be welded is brought into contact with the horn to which ultrasonic vibration is applied, the ultrasonic vibration energy transmitted from the tip of the horn to the molded product causes the joining of the two molded products. Changes to mechanical vibration (called hammering effect).
Then, frictional heat is generated over the entire joint surface, the portion is melted, and the joint surface is instantaneously welded.

FIG. 11 shows a form in which two case covers 4a and 4b, which are molded products, are butted and joined to each other. More specifically, a triangular protrusion 7c is provided at the joint of the protrusion 7b of the case cover 4b. The protrusion 7c is a welded portion called a ridge, and ultrasonic energy is transmitted to the ridge, that is, the protrusion 7c.
If the concentration is concentrated on, the temperature rise of the joint surface of the synthetic resin body 7 becomes faster, and the welding is completed.

In this way, the two case covers are abutted and joined in the direction of the arrow as shown in FIG. In this ultrasonic welding, the finish of the joint is clean and the welding time is short. The application to the case cover of the present invention is effective because the product is small and can be processed efficiently.
Since this joint cannot be disassembled once it is butt-joined, it is actually butt-joined and integrated after the main body 2 of the lithium ion secondary battery, the protection circuit and the like are incorporated.

Although the drawing of this embodiment is shown schematically for the purpose of explanation, in reality, both the aluminum and the synthetic resin body are extremely thin and very light. As described above, the case cover of the present invention is a metal body and exhibits an excellent effect in terms of design, and the lithium ion secondary battery as a product can be made into a product with sensitivity and high quality. . Also, since labels and the like can be easily attached, various designs can be applied.

The structure and manufacturing method of the case cover for the lithium ion secondary battery have been described above. However, since this packaging method can be applied to various product forms, it is not limited to the configuration described above. For example, although the case cover has been described as an aluminum or aluminum alloy, it goes without saying that other light metals may be used and the case cover is not limited to the embodiment.

[0032]

As described above in detail, the lithium ion secondary battery case and the method for manufacturing the same according to the present invention include a lithium ion secondary battery outer casing, a thin metal plate material such as aluminum in the lithium ion secondary battery main body. Since the case cover configuration is such that the joint part is integrated with the synthetic resin part so that it is externally attached to the base, the exterior of the lithium-ion secondary battery is thinly sealed and there is no risk of damage. It was Further, the manufacturing method is not complicated and can be mass-produced. Furthermore, it became a product with excellent design.

[Brief description of drawings]

FIG. 1 is an external view showing a lithium-ion secondary battery.

FIG. 2 is an explanatory view showing a disassembled state of the lithium ion secondary battery.

FIG. 3 is an external view showing an aluminum thin plate.

FIG. 4 is an external view showing a state where an aluminum thin plate is press-molded.

5 is an external view showing a state in which a bent portion is press-molded to the aluminum thin plate molded product shown in FIG.

6 is a cross-sectional view taken along the line AA of FIG.
(A) has shown the bending structure. FIG. 6B shows a perforated structure as another method.

FIG. 7 is a partial cross-sectional view showing a structure for injection molding the outer peripheral edge portion of the case cover.

FIG. 8 is a partial cross-sectional view showing a state in which the mold is closed to form a cavity in the configuration of FIG.

FIG. 9 is a cross-sectional view showing one of the molded half case covers.

FIG. 10 is a cross-sectional view showing the other half of the molded half case cover.

FIG. 11 is a cross-sectional view showing a state in which two half case covers are butted and joined together to be integrated.

[Explanation of symbols]

1 ... Lithium ion secondary battery 2 ... Lithium ion secondary battery body 4 ... Case cover 4a, 4b ... Half case cover 4e ... outer peripheral portion 4g ... Bent part 6 ... Aluminum thin plate 7 ... Synthetic resin body 7a ... Recess 7b ... convex portion 8 ... Fixed side mold 9 ... Movable mold 10 ... Cavity

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Claims (8)

[Claims] 1. A case for enclosing a lithium-ion secondary battery, comprising: a rectangular first side plate formed of a metal plate and having an outer peripheral edge portion in a rising shape; A rectangular second side surface plate that is arranged and is formed of the metal plate material and has an outer peripheral edge portion in a rising shape; and a first outer peripheral portion made of synthetic resin integrally provided on the outer peripheral edge portion of the first side surface plate, A second outer peripheral portion made of synthetic resin integrally provided on an outer peripheral edge portion of the second side plate; and a joint portion which is integrated when the first outer peripheral portion and the second outer peripheral portion are opposed and joined to each other. Lithium ion secondary battery case consisting of. 2. The lithium-ion secondary battery case according to claim 1, wherein the metal plate material is aluminum or an aluminum alloy. 3. The lithium ion secondary battery case according to claim 1, wherein a deformed portion is provided on the outer peripheral edge portions of the first side plate and the second side plate. Secondary battery case. 4. The lithium-ion secondary battery case according to claim 1, wherein the joint portions have concavo-convex portions. 5. A method of manufacturing a case for packaging a lithium-ion secondary battery, wherein the metal plate material is formed into a box-like shape by pressing the outer peripheral edge portion of the metal plate material, and the molded metal plate material is formed into an injection mold. Inserting, injecting molten synthetic resin into the injection molding die, covering and molding the outer peripheral edge portion with the synthetic resin to make the metal plate material into a half case cover, and the outer peripheral edge portions of the two half case covers. And a method for manufacturing the lithium ion secondary battery case, wherein the lithium ion secondary battery case is assembled by facing each other. 6. The method for manufacturing a lithium-ion secondary battery case according to claim 5, wherein press working is performed to provide a deformed portion on the outer peripheral edge portion of the metal plate material. And a method for manufacturing a lithium-ion secondary battery case. 7. The method of manufacturing a lithium ion secondary battery case according to claim 5, wherein the outer peripheral edge portion is joined by ultrasonic welding. Method. 8. The method for manufacturing a lithium ion secondary battery case according to claim 5, wherein the outer peripheral edge portions are formed into a joint portion having an uneven shape,
A method for manufacturing a lithium-ion secondary battery case, characterized in that the half case covers are joined so as to face each other.