JP2005243530A - Battery and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which the swelling of an outer package case on adhesion side can be suppressed and the separation of a both-side tape from a battery case or the outer package case can be prevented, and also provide a battery pack. <P>SOLUTION: The battery pack consists of a battery 10 which houses a battery element including a positive electrode and a negative electrode in a battery case 14 which has two sets of opposed side walls and bottoms and in which the thickness of one side wall of any set is thicker than the other, and of outer package cases 2, 4 housing the battery 10. The one side wall of the battery 10 is adhered inside the outer package case 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery in which a power generation element including a positive electrode and a negative electrode is housed in a battery case, and a battery pack including the battery and an outer case housing the battery, and the battery is fixed in the outer case.

  As a driving power source for small electronic devices or portable electronic devices, a battery in which a power generation element including a positive electrode and a negative electrode is housed in a battery case and a circuit board including a protective circuit or PTC (Positive Temperature Coefficient) are made of synthetic resin. A battery pack housed in an outer case is used. The exterior case is divided into two case halves before completion, and after storing the battery and circuit board in the two case halves, the case halves are integrated by ultrasonic welding or the like to complete the battery pack. I am letting.

  The battery is usually fixed to one side of the case half with a double-sided tape or the like. Therefore, the battery and one of the case halves are fixed to each other with a double-sided tape portion, and there is a gap (for example, 0.1 mm) corresponding to the thickness of the double-sided tape other than the double-sided tape portion. On the other hand, a gap (for example, 0.5 mm) larger than the thickness of the double-sided tape is provided between the battery and the other half of the case in consideration of swelling due to the charge / discharge cycle of the battery or swelling due to high temperature storage. .

  However, the swelling of the battery is not different between the fixing side and the facing side, and the same deformation occurs on both sides. For this reason, the case half is more likely to be deformed on the side having the smaller gap than the side having the larger gap, and the battery bulge causes a large deformation on the one side of the case half to adversely affect external devices. Or the double-sided tape may peel from the battery or the case half and the battery may move in the outer case. In particular, in recent years, as the thickness of the resin case becomes thinner, the battery pack becomes more easily deformed, and there is also a problem that the swelling of the battery deforms the battery pack.

As a method for suppressing the swelling of the battery, for example, it has been proposed that the thickness of the pair of wide surfaces of the battery case is made thicker than the pair of narrow surfaces of the battery case (see, for example, Patent Document 1).
JP-A-6-52842

  However, when the thickness of the battery case is increased, it is possible to suppress the battery swelling, but in order to keep the outer dimensions of the battery the same as before the thickness increase, the inner volume of the battery case is reduced. There is a problem that the battery capacity is reduced because it is necessary to reduce the increase.

  The present invention has been made in view of such circumstances, and by making one of the opposing side walls of the battery case thicker than the other, swelling of the one side wall can be suppressed more than the other. An object is to provide a battery.

  In addition, the present invention provides a battery that can suppress swelling of the one side wall, which has a large area and is easily deformed, more than the other by making one of the opposing side walls having a larger area thicker than the other. The purpose is to provide.

  In addition, the present invention suppresses swelling on the fixing side of the outer case by making the thickness of the side wall fixed to the outer case of the battery case thicker than that of the facing side wall, and both sides from the battery case or the outer case. Another object is to provide a battery pack capable of preventing the tape from peeling off.

  A battery according to the present invention is a battery in which a power generation element including a positive electrode and a negative electrode is accommodated in a battery case having a bottom and two sets of opposing side walls, and one side wall of any set is thicker than the other. It is characterized by that.

  In the present invention, one of the opposing side walls of the battery case is made thicker than the other. For example, it is possible to make one of the opposing side walls provided on the long side of the rectangular bottom thicker than the other. If the battery case bulges due to the charge / discharge cycle of the power generation element inside the battery case or the bulge due to being left at high temperature, the battery case swells, but the thicker the strength becomes higher. It is suppressed. For example, when the battery is accommodated in the outer case, the one side wall that is prevented from being swollen can be fixed to the inner surface of the outer case.

  The battery according to the present invention is characterized in that the two opposing side walls have different areas for each set, and the one side wall is a side wall of a set having a larger area.

  In the present invention, of the two sets of opposing side walls of the battery case, the thickness of one of the sets with the larger area is made thicker than the other. Of the two sets of opposing side walls, the side wall with a larger area is more likely to be deformed, but by increasing the thickness of one of the side walls with a larger area than the other, the strength is increased, and the swelling of the one side wall is increased. Is suppressed compared to the other. For example, when the battery is accommodated in the outer case, the one side wall that is prevented from being swollen can be fixed to the inner surface of the outer case.

  The battery pack according to the present invention includes the battery according to the present invention and an outer case that houses the battery, and the one side wall of the battery is fixed in the outer case.

  In the present invention, the thickness of the side wall (hereinafter referred to as a fixed side wall) fixed to the outer case of the battery case is made thicker than the opposite side wall. If the battery case bulges due to the charge / discharge cycle of the power generation element inside the battery case or bulges due to high temperature exposure, the battery case swells, but the thicker the strength becomes higher, so the bulge of the fixed side wall is larger than the side wall It is suppressed. The fixed side wall of the battery case is fixed to the inner surface of the outer case with a double-sided tape, and the gap between the outer surface of the battery (the outer surface of the fixed side wall) and the inner surface of the outer case is small. Although it tends to occur, by increasing the thickness of the fixing side wall to increase the strength, it is possible to suppress the swelling of the outer case on the fixing side and to prevent the double-sided tape from peeling off from the battery or the outer case.

  According to the present invention, by making one of the opposite side walls of the battery case thicker than the other, the strength of the one side wall is higher than the other, and the swelling of the one side wall is suppressed more than the other. can do.

  According to the present invention, by increasing the thickness of one of the opposing side walls having a larger area than the other, the strength of the one side wall is higher than the other, and the one of the side walls is easily deformed. The swelling of the side wall can be suppressed more than the other.

  According to the present invention, the thickness of the fixing side wall fixed to the outer case of the battery case is made thicker than the facing side wall, thereby increasing the strength of the fixing side of the battery case and suppressing the swelling of the fixing side of the outer case. In addition, it is possible to prevent peeling of the double-sided tape from the battery case or the outer case. Further, although the thickness of the fixed side wall of the battery case is increased, the thickness of the facing side wall is not increased, so that the decrease in battery capacity can be minimized.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
FIG. 1 is an exploded perspective view showing an example of a battery pack before welding according to the present invention, and FIG. 2 is a schematic sectional view showing an example of a battery pack after welding. The battery pack includes a first case half 2 and a second case half 4 having a rectangular bottom and a side wall formed on the outer periphery of the bottom, and a rectangular parallelepiped lithium ion battery (hereinafter referred to as a battery) 10. And the battery 10 is housed in an outer case in which the end portions of the side walls of the first case half 2 and the second case half 4 are welded together.

  The battery 10 has a negative electrode plate obtained by applying a negative electrode mixture containing graphite (graphite) to a copper current collector, and a positive electrode mixture containing lithium cobalt composite oxide applied to an aluminum current collector. The positive electrode plate accommodates a flat wound power generation element 20 wound through a separator such as a polyethylene microporous membrane and a non-aqueous electrolyte in an aluminum rectangular battery case 14.

  3A to 3C are diagrams illustrating an example of the battery case 14. The battery case 14 has a rectangular bottom 14d, opposed wide side walls 14a, 14b provided on the long side of the bottom 14d, and opposed narrow side walls 14c, 14c provided on the short side of the bottom 14d. A case lid 16 having a negative electrode terminal 18 and a safety valve (not shown) is attached to the opening by laser welding. The negative electrode terminal 18 is connected to the negative electrode plate through a negative electrode lead, and the positive electrode plate is in contact with and electrically connected to the case lid 16 through the positive electrode lead.

  The battery case 14 has a width a = 34 mm, a width b = 50 mm, and a thickness c = 5.2 mm. Of the four side walls 14a, 14b, 14c, and 14c of the battery case 14, the thickness of one side wall (the side wall 14a in the example of FIG. 3) is thicker than the opposite side wall 14b, and more than the other side walls 14c. thick. The thicker side wall 14a and 14b of the wide side walls 14a and 14b (hereinafter referred to as a fixed side wall) 14a has a thickness e of 0.3 mm, the other side wall 14b has a thickness d of 0.2 mm, and the narrow side wall 14c. , 14c has a thickness f of 0.25 mm. In addition, the distinction between the fixed side wall 14a and the facing side wall 14b can be made by the case lid 16 portion, but a mark for distinguishing the fixed side wall 14a and the facing side wall 14b on the outer surface of the battery case 14. Is preferably provided. For example, a mark can be printed on the narrow side wall 14c, or a position of an electrolyte injection port (not shown) provided on one side of the side wall 14c can be used as the mark.

  The battery 10 is provided with a circuit board 12 having an external connection terminal connected to the electrode and a protection circuit for preventing overcharge and overdischarge. The first case half 2 and the second case half 4 are made of synthetic resin, and for example, polycarbonate and / or ABS (Acrylonitrile Butadiene Styrene) are used. In the example of FIG. 1, when the battery 10 is stored in the second case half 4 with the bottom facing down, both end portions of the fixing side wall 14 a of the battery 10 are attached to the inner surface of the second case half 4 by the double-sided tape 6, 6. The first case half 2 and the second case half 4 are integrated by ultrasonic welding.

  The double-sided tape is obtained by adding an acrylic adhesive to a base material such as PET (Polyethylene Terephthalate) or a nonwoven fabric, and has a thickness of about 0.1 mm. Therefore, a gap g of about 0.1 mm is generated between the central portion of the fixed side wall 14 a of the battery case 14 and the inner surface of the second case half 4. In addition, the battery 10 has a large swelling at the center, and the double-sided tape 6 has, for example, a ring shape in addition to fixing both ends of the fixing side wall 14a of the battery 10 using two rectangular pieces as shown in FIG. Alternatively, a single rectangular frame can be used. In addition, a gap h of about 0.5 mm is provided between the side wall 14 b facing the fixed side wall 14 a of the battery case 14 and the inner surface of the first half case 2.

  When the battery 10 is swollen due to a charge / discharge cycle or is swollen due to being left at a high temperature, the fixed side wall 14a and the side wall 14b facing the same have conventionally been swollen. However, in the present invention, the fixed side wall 14a is Since it is thicker and stronger than the side wall 14b, the swell of the fixed side wall 14a is suppressed to be smaller than that of the facing side wall 14b. By suppressing the swelling of the fixed side wall 14a to be small, it is possible to prevent the conventional separation between the double-sided tape 6 and the battery case 14 or the separation between the double-sided tape 6 and the second case half 4. The swelling of the facing side wall 14b is absorbed in the gap h between the battery 10 and the first case half 2 as in the conventional case. Further, although the thickness e of the fixed side wall 14a is increased, the thickness d of the facing side wall 14b is the same as the conventional one. Therefore, when the outer dimensions of the battery case are kept the same, the thickness of one set of side walls is increased. Compared with the conventional method of increasing, the internal volume (battery capacity) of the battery case 14 can be increased.

  In the present invention, the thickness of the fixing side wall 14a of the battery case 14 is made thicker than that of the facing side wall 14b. However, when the difference in thickness (increase) is small, the fixing side wall 14a is likely to be deformed. If the increase is large, the battery size is increased in order to maintain the battery capacity, or the battery capacity is decreased in order to maintain the outer dimensions. Therefore, the thickness of the fixed side wall 14a is set to the opposite side wall 14b. Is preferably 1.4 to 1.9 times, more preferably about 1.5 times. In the embodiment described above, since the thickness d of the facing side wall 14b is 0.2 mm, the thickness e of the fixed side wall 14a is preferably 0.28 mm to 0.38 mm, and more preferably 0.3 mm. In addition, as a method for manufacturing the battery case, for example, in deep drawing, a mold may be set so that one of the side walls is thick.

It is a disassembled perspective view which shows the example of the battery pack before welding which concerns on this invention. It is a schematic sectional drawing which shows the example of the battery pack after welding. It is a figure which shows the example of a battery case.

Explanation of symbols

2 First case half (exterior case)
4 Second case half (exterior case)
6 Double-sided tape 10 Battery 12 Circuit board 14 Battery case 14a Fixed side wall 16 Case lid 18 Negative electrode terminal 20 Power generation element

Claims (3)

In a battery case containing a power generation element including a positive electrode and a negative electrode in a battery case having a bottom and two opposing side walls,
A battery characterized in that the thickness of one side wall of either set is thicker than the other.   2. The battery according to claim 1, wherein the two opposing side walls have different areas for each set, and the one side wall is a side wall of a set having a larger area. The battery according to claim 1 or 2,
And an outer case for housing the battery, wherein the one side wall of the battery is fixed in the outer case.

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