JP2004022480A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thinned battery pack by suppressing the volume increase of a thinned battery. <P>SOLUTION: A PTC unit 26 is equipped to a step 6 formed on the battery 1 in which a battery case that houses a power generation element and formed in a half shell body is closed by a lid and thinly made, and a frame 25 is made to cover the battery by covering the step 6 and a short side face, and an insulation sheet 27 is wound. From a positive electrode terminal aperture 31 and a negative electrode terminal aperture 32 formed in the frame, a position where external connectors of the positive electrode and the negative electrode are placed is exposed outside. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery pack configured by utilizing the characteristics of a thinly formed battery.
[0002]
[Prior art]
Mobile electronic devices, such as mobile phones and PDAs, have been significantly reduced in size and thickness as well as becoming more sophisticated. Batteries applied to them have been required to be smaller, thinner and have higher energy densities. As a result, the demand for flat-shaped lithium ion secondary batteries is increasing. The recent trend of portable electronic devices is to reduce the thickness rather than reduce the size, and it is easy to put them in pockets and bags, and it does not impair ease of use.
[0003]
In order to achieve the reduction in the thickness of the device, it is required to reduce the thickness of the battery, which is the power source of the device. Since the battery case is formed by drawing or handling, the smaller the opening area with respect to the depth in the processing direction, the more difficult the processing becomes, and the more difficult it is to insert the electrode plate group into the battery case. In order to further reduce the thickness of the current flat prismatic battery, it is necessary to fundamentally change the structure of the battery case.The battery case is formed in a half-shell, and after the electrode group is housed, the flat plate or A battery structure in which a battery case is closed by a half-shell lid has been developed.
[0004]
[Problems to be solved by the invention]
When a battery pack is formed using such a thin battery, the thin battery cannot be utilized unless the thin battery is not damaged. The inventors of the present application have developed a thin battery in which a power generation element is housed in a half-shell battery case, and have devised a structure in consideration of forming a battery pack.
[0005]
It is an object of the present invention to provide a battery pack configured to minimize the increase in volume by utilizing the characteristics of a thin battery structure.
[0006]
[Means for Solving the Problems]
A battery pack according to the present invention for achieving the above object has a battery case formed in a half-shell by providing a flange around an opening of a recess formed by providing a step portion having a reduced depth at an end. The electrode plate group is accommodated in the concave portion, the positive electrode terminal and the negative electrode terminal are formed by being connected to the electrode plate group at the stepped portion, and the lid plate and the flange are arranged such that the peripheral portion is overlapped with the flange. A frame is provided to cover the short side surface and the step portion of the battery with respect to the battery formed by bonding between the two, and the external connection terminal is externally exposed from an opening formed in the frame. It is characterized by the following.
[0007]
According to the above configuration, since the frame is disposed so as to cover the short side surface and the step portion of the battery, the frame is accommodated under the flange portion for joining the lid to the battery case, and the step portion and the frame are provided. The components of the battery pack are housed in the space between the body and the battery pack, so that the increase in volume from the battery is small.
[0008]
In the above configuration, the configuration of the external connection terminal of the battery pack is such that a battery case is formed of metal, a positive electrode plate or a negative electrode plate of an electrode plate group is connected to the battery case, and a part of the battery case is externally exposed from the opening. Thus, a positive or negative external connection terminal can be formed.
[0009]
If a thermosensitive element is connected to the positive or negative terminal on the outer surface of the step, a function to protect the battery from a short circuit or a high temperature condition can be provided. The electrode plate of the element can be exposed to the outside from the opening and used for external connection.
[0010]
In addition, when a circuit board is arranged on the outer surface of the step portion by connecting to the positive terminal and the negative terminal, and a battery circuit such as a protection circuit for protecting the battery from overcharging or overdischarging is formed on the circuit board, the protection of the battery is improved. In this case, the external connection terminal can be used for external connection by externally exposing the land formed on the circuit board or the metal plate bonded to the land from the opening. .
[0011]
In addition, when the external connection terminal is configured to externally expose the terminal member joined to the required portion from the opening, the external connection terminal can be provided at an arbitrary position.
[0012]
In addition, by winding the battery and the frame body and attaching the insulating sheet, it is possible to suppress an increase in volume and improve the appearance, and to print the product number, precautionary notes, and the like on the insulating sheet.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0014]
FIG. 1 shows an external view of a battery pack 20 according to the present embodiment. A flat battery secondary battery 1 described below is covered with a frame 25 and an insulating sheet 27, and a positive electrode terminal formed on the frame 25 is shown in FIG. The positive electrode external connection terminal is externally exposed from the opening 31, and the negative electrode external connection terminal is externally exposed from the negative terminal opening 32.
[0015]
FIG. 2 shows a configuration of the battery 1 applied to the battery pack 20, which is formed as a lithium ion secondary battery. In the battery 2, as shown in FIG. 2, the electrode group 4 is accommodated in a battery case 2 formed in a half-shell, and an open portion of the battery case 2 is covered with a lid 3. It is configured to be sealed.
[0016]
As shown in FIG. 2, the battery case 2 is formed by pressing a metal plate to form a concave portion 5 having a stepped portion 6 at an end, and providing a welding margin 8 in a flange shape around the concave portion 5. Is done. A rivet 10 which is insulated from the battery case 2 by an outer gasket 11 and an inner gasket 12 and secures airtightness and serves as a positive electrode terminal is fastened and fixed to a terminal hole 7 formed in the step portion 6. Further, an injection port 14 for the electrolyte is formed in the step portion 6.
[0017]
An electrode group 4 in which a positive electrode plate and a negative electrode plate are wound via a separator is accommodated in the concave portion 5 of the battery case 2. The positive electrode lead 15 pulled out from the positive electrode plate of the electrode plate group 4 is joined to the rivet 10, and the negative electrode lead 16 pulled out from the negative electrode plate is joined on the step 6, and the battery case 2 is used as a negative electrode terminal. As shown in FIG. 8, the electrode plate group 4 winds the positive electrode plate and the negative electrode plate in the longitudinal direction with a separator interposed therebetween, pulls out the positive electrode lead 15 from the terminal end (winding end) of the positive electrode plate, and pulls out the negative electrode lead 16. It can also be drawn out from the terminal end (winding end) of the negative electrode plate and configured as an electrode plate group 4a, and the bonding of the positive electrode lead 15 to the rivet 10 and the bonding of the negative electrode lead 16 to the step 6 are easy, and the connection is secure Performance can be improved. The cover plate 3 is put on the open portion of the battery case 2 accommodating the electrode plate groups 4 and 4a, and the periphery of the cover plate 3 and the welding margin 8 are seam-welded, so that the battery The recess 5 of the case is sealed by the cover plate 3. A predetermined amount of electrolyte is injected into the sealed recess 5 from the injection port 14, and after the injection is completed, a plug 13 is inserted into the electrolyte injection port 14, and the plug 13 is welded to the step. Thereby, the inside of the concave portion 5 is sealed.
[0018]
The battery 1 manufactured by the above manufacturing procedure has a rivet 10 formed on the stepped portion 6 as a positive electrode external connection terminal as shown in FIG. 1, and an outer surface of the stepped portion 6 as a negative electrode external connection terminal for external connection. Can be offered. Since the external connection terminals of the positive electrode and the negative electrode are formed on the stepped portion 6, the leads connected to the external connection terminals can be processed within the thickness of the battery 1. Further, even when the battery 1 is contact-connected to the external connection terminal, the contact structure can be formed within the thickness of the battery 1. Therefore, the battery 1 can be mounted on a device without impairing the characteristics of the thin battery 1.
[0019]
When applied to the battery pack 20 according to the present embodiment, a PTC element (heat sensitive element) 33 is mounted on the outer surface of the step 6 when the rivet 10 of the battery 1 is fastened. FIG. 4 shows an example of mounting the PTC element 33, which is mounted on the step 6 as the PTC unit 26. The PTC holder 34 and the PTC element 33 are fixed on the outer surface of the stepped portion 6 by fastening the rivet 10 while being insulated from the stepped portion 6 by the lower gasket 11 and the upper gasket 35, and the opening of the PTC holder 34 is a holder. The plate 36 is closed by welding.
[0020]
In the configuration of the present embodiment, since the positive electrode lead 15 drawn from the electrode plate group 4 is welded to the rivet 10, the upper electrode plate 33 b of the PTC element 33, the conductive polymer 33 a, A positive electrode circuit is formed on the lower electrode plate 33c, the PTC holder 34, and the holder plate 36.
[0021]
As shown in FIG. 5, the battery 1 with the PTC unit 26 attached thereto has a frame 25 formed by resin molding so that the outer dimensions are the same as the cover plate 3. Covered and covered. That is, by making the outer peripheral edge of the lid plate 3 coincide with the outer peripheral edge of the frame 25, the battery pack can be configured with a minimum increase in volume. When the frame 25 is put on the battery 1, the holder plate 36 is externally exposed from the positive terminal opening 31 formed in the frame 25 as a positive external connection terminal, and can be used for positive external connection. Further, the negative electrode external connection terminal can be used for negative electrode external connection by exposing one end of the battery case 2 where the step portion 6 is not formed to the outside through the negative electrode terminal opening 32.
[0022]
Examples of the material of the frame 25 include thermoplastic resins such as polyethylene resins, polyolefin resins such as polypropylene resins, polyethylene terephthalate resins, polyether ether ketone resins, polyphenylene sulfide resins, polyarylate resins, polyamide resins, and polyimide resins. These resins can be used alone or as a blended or modified resin, and can also be used after adding a filler such as glass fiber, talc, or silica.
[0023]
When the battery 1 is covered with the frame 25, the battery case 2 and the cover plate 3 serving as the negative electrode are exposed to the outside, which is not preferable from the viewpoint of insulation. When the insulating sheet 27 is wound around the frame 25 and the peripheral surface of the battery 1, a battery pack 20 as shown in FIG. 1 can be formed. A product number, a precautionary statement, and the like can be printed on the surface of the insulating sheet 27, and the battery pack 20 can be used for convenience. Although the material of the insulating sheet 27 is not particularly limited, polytetrafluoroethylene (PTFE), ethylene tetrafluoride / hexafluoropropylene copolymer (FEP), and ethylene tetrafluoride / perfluoroalkoxy ethylene may be used. A material comprising a heat-resistant base material such as a fluororesin such as a polymer (PFA), a polyethylene terephthalate resin, or a polyimide resin and a glue such as a natural rubber, isobutyl rubber, styrene butadiene rubber, or an acrylic resin, or polyethylene terephthalate It is a heat-shrinkable material such as resin or polyethylene resin, and its thickness is preferably 20 μm to 60 μm.
[0024]
In the above configuration, the external connection terminal exposes a part of the PTC unit 26 and the battery case 2 to the outside. However, the terminal member may be welded to each of the external connection terminals to expose the surface to the outside, thereby forming the external connection terminal. . Also, as shown in FIG. 6, one end of the L-shaped positive electrode terminal member 38 and negative electrode terminal member 39 is welded to the PTC unit 26 and the battery case 2 respectively, and as shown in FIG. When the battery pack 25a is externally exposed from the positive terminal opening 31a and the negative terminal opening 32a formed on the side surface of the battery pack 25a, the battery pack 25a is provided with the positive external connection terminal and the negative external connection terminal on the short side surface.
[0025]
In the above configuration, since the PTC element 33 is connected in series to the positive electrode circuit, it is possible to prevent a rise in battery temperature due to a short circuit. The PTC element 33 is a resistance element having a negative temperature characteristic and shows a small resistance value in a normal temperature state, so that the PTC element 33 does not affect the performance as the battery packs 20 and 20a. When the terminal is short-circuited due to some trouble, self-heating is caused by a large short-circuit current to rapidly increase the resistance value, and excessive short-circuit current is suppressed to prevent the battery 1 from generating heat. Also, when the device in which the battery packs 20 and 20a are loaded is exposed to a high temperature environment, the PTC element 33 rapidly increases the resistance value, so that the operation of the battery packs 20 and 20a is stopped, The battery 1 can be prevented from exploding or firing.
[0026]
In the space formed on the step 6 of the battery 1, in addition to the PTC unit 26, a circuit board that configures a battery circuit that protects the battery 1 from overcharge, overdischarge, and overcurrent can be provided. . By forming the conductor pattern formed on the circuit board on the terminal land, and exposing it to the outside from the opening of the frame 25, it can be used as an external connection terminal.
[0027]
【The invention's effect】
As described above, according to the present invention, a battery pack using a battery thinned by accommodating a power generation element in a battery case formed in a half-shell and seam-welding a lid plate at a peripheral flange portion is provided. When configuring the battery, heat-sensitive elements, external connection terminals, etc. are accommodated in steps formed in the battery, and a frame is arranged under the flange to cover the steps, so that the volume of the battery is increased. It is possible to configure the battery pack while suppressing it. Therefore, it is possible to provide a thin battery pack corresponding to a device required to be thin.
[Brief description of the drawings]
FIG. 1 is an exemplary perspective view showing the external shape of a battery pack according to an embodiment.
FIG. 2 is a perspective view showing the appearance of a battery applied to the battery pack.
FIG. 3 is an exploded perspective view showing a configuration of the battery.
FIG. 4 is a sectional view showing a configuration of a PTC unit.
FIG. 5 is an exploded perspective view showing components of the battery pack.
FIG. 6 is a perspective view showing a structure in which an external connection terminal position is changed by a terminal member.
FIG. 7 is a perspective view showing the appearance of a battery pack using the above structure.
FIG. 8 is an exploded perspective view of a battery using another embodiment of the electrode plate group.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 battery 2 battery case 3 cover plate 4, 4 a electrode plate group 5 recess 6 stepped portion 8 welding allowance 20, 20 a battery pack 25 frame 27 insulating sheet 31 positive electrode terminal opening 32 negative electrode opening 33 PTC element (thermosensitive element) )

Claims (8)

A flange is provided around an opening of a concave portion formed by providing a step portion having a reduced depth at an end portion, and an electrode plate group is accommodated in the concave portion of the battery case formed in a half-shell body, and the step portion is provided. A positive electrode terminal and a negative electrode terminal are formed by being connected to the electrode plate group, and a battery formed by joining a lid plate and a flange, which are disposed with the peripheral portion overlapping the flange, is formed. A battery pack comprising a frame disposed over the short side surface and the step, and an external connection terminal being externally exposed from an opening formed in the frame. A battery case is formed of metal, and a positive or negative electrode external connection terminal is formed by connecting a positive electrode plate or a negative electrode plate of an electrode plate group to the battery case and exposing a part of the battery case to the outside through an opening. Item 7. The battery pack according to Item 1. 2. The battery pack according to claim 1, wherein a heat-sensitive element is arranged on an outer surface of the step portion and connected to the positive electrode terminal or the negative electrode terminal. 3. 4. The battery pack according to claim 3, wherein the external connection terminal is configured such that an electrode plate of the thermosensitive element is externally exposed from the opening. 5. The battery pack according to any one of claims 1 to 4, wherein the external connection terminal is configured such that a terminal member joined to a required portion is externally exposed from an opening. The battery pack according to any one of claims 1 to 5, wherein a circuit board is provided on an outer surface of the step portion so as to be connected to the positive electrode terminal and the negative electrode terminal. 7. The battery pack according to claim 6, wherein the external connection terminal is formed by exposing a land formed on the circuit board or a metal plate bonded to the land to the outside from the opening. The battery pack according to any one of claims 1 to 7, wherein the battery and the frame are wound and an insulating sheet is attached.

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