JP4068403B2 - Battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack configured by making use of the characteristics of a thinly formed battery.
[0002]
[Prior art]
Portable electronic devices such as mobile phones and PDAs are becoming increasingly smaller and thinner with higher functionality, and the batteries applied to them are required to be smaller and thinner and have a higher energy density. As a result, demand for flat rectangular lithium-ion secondary batteries is increasing. The recent trend of portable electronic devices is toward thinning rather than downsizing, and since it is easy to put in a pocket or bag and does not impair usability, there are also products that compete for thinning.
[0003]
In order to reduce the thickness of the device, it is required to reduce the thickness of the battery as the power source. However, there is a limit to the reduction in thickness in the battery case manufacturing methods currently in practical use. Since the battery case is thus formed on the diaphragm machining, the opening area with respect to the depth of the processing direction becomes higher in the process becomes difficult small, it becomes difficult to insert the electrode plate group into the battery case. In order to further reduce the thickness of the current flat rectangular battery, it is necessary to fundamentally change the structure of the battery case. After the battery case is formed into a half shell and the electrode plate group is accommodated, a flat plate or A battery structure has been developed in which a battery case is closed by a half-shell lid.
[0004]
[Problems to be solved by the invention]
When a battery pack is configured using such a thinned battery, the thinned battery cannot be used unless the thinness of the battery is not impaired. The inventors of the present application have developed a thin battery by accommodating a power generation element in a half-shell battery case, and have created a structure considering the construction of a battery pack.
[0005]
An object of the present invention is to provide a battery pack constructed by making use of the characteristics of a thinned battery structure and suppressing a volume increase slightly.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a battery pack according to the present invention has a battery case formed in a half-shell by providing a flange around the opening of a recess formed by providing a stepped portion having a reduced depth at the end. A lid plate and a flange disposed in the concave portion, wherein a positive electrode terminal and a negative electrode terminal are formed by connecting to the electrode plate group at the stepped portion, and a peripheral portion is superimposed on the flange. For the battery formed by joining the two, a frame body is disposed so as to cover the short side surface and the stepped portion of the battery, and the external connection terminal is exposed to the outside from the opening formed in the frame body. It is characterized by.
[0007]
According to the above configuration, since the frame body is disposed to cover the short side surface and the step portion of the battery, the frame body is accommodated under the flange portion for joining the lid body to the battery case, and the step portion and the frame The battery pack is configured by accommodating the constituent members of the battery pack in a space between the body and the volume increase from the battery is small.
[0008]
In the above configuration, the external connection terminal of the battery pack is configured such that the battery case is formed of metal, the positive electrode plate or the negative electrode plate of the 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]
In addition, when a heat sensitive element is provided on the outer surface of the stepped portion and connected to the positive electrode terminal or the negative electrode terminal, a function of protecting the battery from a short circuit or a high temperature state can be provided. The electrode plate of the element can be externally exposed from the opening and used for external connection.
[0010]
In addition, if a circuit board is disposed on the outer surface of the stepped portion so as to be connected to the positive electrode terminal and the negative electrode terminal, and a battery circuit such as a protection circuit for protecting the battery from overcharge or overdischarge is formed on the circuit board, battery protection is achieved. At this time, the external connection terminal can be used for external connection by exposing the land formed on the circuit board or the metal plate joined to the land from the opening. .
[0011]
Further, the external connection terminal can be provided at an arbitrary position if the terminal member joined to the required part is exposed from the opening.
[0012]
Further, by winding the battery and the frame and sticking the insulating sheet, the appearance can be improved by suppressing the increase in volume, and the product number, precautions, and the like can be printed on the insulating sheet.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0014]
FIG. 1 shows an external appearance of a battery pack 20 according to the present embodiment, in which a secondary battery 1 of a flat rectangular battery described later is covered with a frame body 25 and an insulating sheet 27, and a positive electrode terminal formed on the frame body 25. The positive electrode external connection terminal is exposed to the outside from the opening 31, and the negative electrode external connection terminal is exposed to the outside from the negative electrode terminal opening 32.
[0015]
FIG. 2 shows a configuration of the battery 1 applied to the battery pack 20 and is formed as a lithium ion secondary battery. As shown in FIG. 3 in which each battery 2 is disassembled, the battery 2 accommodates an electrode plate group 4 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 comprised so that it may seal.
[0016]
As shown in FIG. 3 , the battery case 2 is formed by pressing a metal plate to form a recess 5 having a stepped portion 6 at the end and providing a welding allowance 8 in the form of a flange around the recess 5. Is done. Further, as shown in FIG. 3, a rivet 10 which is insulated from the battery case 2 by an upper gasket 40 and a lower gasket 12 and is airtight and is used as a positive terminal in a terminal hole 7 formed in the step portion 6 is fastened and fixed. Is done. Further, an electrolyte inlet 14 is formed in the stepped portion 6.
[0017]
In the recess 5 of the battery case 2, an electrode plate group 4 in which a positive electrode plate and a negative electrode plate are wound via a separator is accommodated. The positive electrode lead 15 drawn out from the positive electrode plate of the electrode plate group 4 is joined to the rivet 10, and the negative electrode lead 16 drawn out from the negative electrode plate is joined onto the step portion 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 via a separator, pulls out the positive electrode lead 15 from the terminal end (winding end) of the positive electrode plate, The electrode plate group 4a can be configured by being drawn out from the terminal end (winding end) of the negative electrode plate, and can easily be joined to the rivet 10 of the positive electrode lead 15 and the stepped portion 6 of the negative electrode lead 16 to ensure the connection. Can be improved. A cover plate 3 is placed on the open portion of the battery case 2 that accommodates these electrode plate groups 4 and 4a, and the periphery of the cover plate 3 and the welding allowance 8 are subjected to seam welding, whereby the battery The recess 5 of the case is sealed by the lid plate 3. A predetermined amount of electrolyte is injected into the sealed recess 5 from the inlet 14, and after the completion of injection, a plug 13 is inserted into the electrolyte inlet 14, and the plug 13 is welded to the stepped portion. Thus, the inside of the recess 5 is sealed.
[0018]
As shown in FIG. 1, the battery 1 manufactured by the above manufacturing procedure is used for external connection with the rivet 10 formed on the step portion 6 as a positive external connection terminal and the outer surface of the step portion 6 as a negative external connection terminal. Can be provided. Since the positive and negative external connection terminals are formed on the step portion 6, the lead connected to the external connection terminal can be processed within the thickness of the battery 1. Further, the contact structure can be formed within the thickness of the battery 1 even when contact-connected to the external connection terminal. 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, the PTC element (heat sensitive element) 33 is mounted on the outer surface of the step portion 6 when the rivet 10 of the battery 1 is fastened. FIG. 4 shows a mounting example of the PTC element 33, which is mounted on the step portion 6 as the PTC unit 26. The PTC holder 34 and the PTC element 33 are fixed on the outer surface of the step portion 6 by insulating the step portion 6 by the lower gasket 11 and the upper gasket 35 and fastening the rivet 10, and the opening portion 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 lead 15 drawn out 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 those of the cover plate 3. Covered and covered. That is, by matching the outer peripheral edge of the cover plate 3 with the outer peripheral edge of the frame body 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 can be externally exposed from the positive terminal opening 31 formed in the frame 25 as a positive external connection terminal and used for positive external connection. 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 stepped portion 6 is not formed from the negative electrode terminal opening 32.
[0022]
Examples of the material of the frame 25 include polyolefin resins such as polyethylene resin and polypropylene resin, polyethylene terephthalate resin, polyether ether ketone resin, polyphenylene sulfide resin, polyarylate resin, polyamide resin, and polyimide resin. These resins can be used singly or as a blend, or modified resins, and can be used by adding fillers such as glass fiber, talc and silica.
[0023]
In the state where 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 for insulation, and there is a gap between the constituent members, which is not preferable for appearance. 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. A product number, a cautionary note, and the like can be printed on the surface of the insulating sheet 27 and can be used for convenience of use of the battery pack 20. The material of the insulating sheet 27 is not particularly limited, but polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkoxyethylene copolymer. Polymers (PFAs) and other fluororesins, polyethylene terephthalate resins, polyimide resins and other heat-resistant substrates and natural rubber, isobutyl rubber, styrene butadiene rubber, acrylic pastes, 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, a terminal member can be welded to the external connection terminal to expose the surface to the external connection terminal. . Further, as shown in FIG. 6, one end of a positive terminal member 38 and a negative terminal member 39 formed in an L shape are welded to the PTC unit 26 and the battery case 2, respectively, and as shown in FIG. When exposed to the outside from the positive electrode terminal opening 31a and the negative electrode terminal opening 32a formed on the side surfaces of the battery pack 25a, a battery pack 25a having a positive external connection terminal and a negative external connection terminal on the short side surface can be formed.
[0025]
In the above configuration, since the PTC element 33 is connected in series to the positive electrode circuit, an increase in battery temperature due to a short circuit can be prevented. The PTC element 33 is a resistance element having a negative temperature characteristic, and shows a slight resistance value in a normal temperature state, so that the performance as the battery packs 20 and 20a is not affected, but the positive external connection terminal and the negative external connection When the terminal is short-circuited due to some trouble, the resistance value is rapidly increased by self-heating due to a large short-circuit current, and the battery 1 is prevented from generating heat by suppressing an excessive short-circuit current. In addition, when the equipment loaded with the battery packs 20 and 20a 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 and used in a high temperature state. It is possible to prevent the battery 1 from being ruptured or ignited.
[0026]
In the space formed on the stepped portion 6 of the battery 1, in addition to the PTC unit 26, a circuit board constituting a battery circuit that protects the battery 1 from overcharge, overdischarge, and overcurrent can be disposed. . When the conductor pattern formed on the circuit board is formed on the terminal land and is exposed to the outside from the opening of the frame body 25, it can be used for the external connection terminal.
[0027]
【The invention's effect】
As described above, according to the present invention, a battery pack using a battery thinned by housing a power generation element in a battery case formed in a half shell and seam welding a cover plate at a peripheral flange portion. The heat sensitive element and the external connection terminal are accommodated in the step portion formed in the battery, and the frame is disposed under the flange portion so as to cover the step portion. It can suppress and can comprise in a battery pack. Therefore, it is possible to provide a thin battery pack corresponding to a device that is required to be thin.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external shape of a battery pack according to an embodiment.
FIG. 2 is a perspective view showing an external appearance of a battery applied to the battery pack.
FIG. 3 is an exploded perspective view showing the configuration of the battery.
FIG. 4 is a cross-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 the position of an external connection terminal is changed by a terminal member.
FIG. 7 is a perspective view showing an external appearance of a battery pack using the same structure.
FIG. 8 is an exploded perspective view of a battery using another embodiment of the electrode plate group.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery 2 Battery case 3 Cover plate 4, 4a Electrode plate group 5 Recess 6 Step part 8 Welding allowances 20 and 20a Battery pack 25 Frame 27 Insulation sheet 31 Positive electrode terminal opening 32 Negative electrode terminal opening 33 PTC element (heat sensitive element) )

Claims (1)

An electrode plate group is accommodated in the recess of the battery case formed in a half shell by providing a flange around the opening of the recess formed by providing a stepped portion having a reduced depth at the end, and the stepped portion The positive electrode terminal and the negative electrode terminal are formed by connecting to the electrode plate group, and the battery formed by joining between the cover plate and the flange disposed so as to overlap the flange on the periphery, A frame body is disposed to cover the short side surface and the stepped portion, and the external connection terminals are exposed to the outside from the opening formed in the frame body , the battery case is formed of metal, and the electrode case group is formed on the battery case. A battery pack, wherein a positive electrode plate or a negative electrode plate is connected, and a part of the battery case is externally exposed from the opening to form a positive electrode or negative electrode external connection terminal .

Images