JP2012212693A - Lithium ion secondary battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery pack which has relatively small weight and volume, which has high vibration resistance, and which can be cooled by air.SOLUTION: A foam filling material 24 to fix a battery pack 3 is used between corner parts and a lower case 2 of the battery pack 3, and a passage of air is secured in a lithium ion secondary battery pack.

Description

  The present invention relates to a lithium ion secondary battery pack using a lithium ion battery or a lithium ion polymer battery, and more particularly to a lithium ion secondary battery pack having an earthquake-resistant structure and a heat dissipation structure suitable for increasing the capacity.

With the development and popularization of portable information devices such as mobile phones, notebook personal computers, and video cameras in recent years, the demand for secondary batteries that are small, lightweight, and have high energy density has greatly increased. Considering higher performance. As such a secondary battery, a lithium ion secondary battery is particularly attracting attention.

  The general structure of a lithium ion secondary battery is that a positive electrode active material layer made of a positive electrode active material powder such as lithium-cobalt composite oxide, a conductive powder, and a binder is formed on the surface of a positive electrode current collector made of aluminum foil. A negative electrode formed by forming a negative electrode active material layer made of a copper foil and a negative electrode active material layer made of a copper foil on a surface of a negative electrode current collector made of a porous film. The power generation element is impregnated with an electrolytic solution.

  In order to reduce size and weight, lithium ion polymer batteries whose electrolytes are replaced with polymer electrolytes are used, and laminate films made of metal foil such as aluminum and polymer films are used as exterior materials to enclose power generation elements. It has been.

  FIG. 5 is a perspective view showing an example of a secondary battery using a conventional laminate film as an exterior. In FIG. 5, a power generation element is enclosed with a laminate film 13 to constitute a lithium ion battery, and a positive electrode tab 14 connected to the positive electrode of the power generation element and a negative electrode tab 15 connected to the negative electrode are provided so as to protrude from the laminate film. (See, for example, Patent Document 1).

  FIG. 8 is an exploded perspective view of the inside of a conventional laminated lithium ion secondary battery pack. Conventionally, as for the mounting of a laminated type lithium ion secondary battery to a case of an assembled battery, a structure in which the periphery of the assembled battery 3 is covered with elastic bodies 10, 11, and 12 as shown in FIG. For example, see Patent Document 2 and FIG.

  However, due to the diversification of devices equipped with laminate-type lithium ion secondary batteries in recent years, high mechanical strength (about 10G is added for several tens of hours) is required at the same time as, for example, commercial electric equipment. Applications that are required to suppress the heat generation of the battery due to the large current that flows sometimes have come out and have the following problems.

  FIG. 6 is a partial cross-sectional view of an assembled battery of a laminated lithium ion secondary battery, and FIG. 7 is a plan view of the assembled battery of a laminated lithium ion secondary battery. Normally, when a laminate type lithium ion secondary battery in which adjacent batteries are fixed with an adhesive or the like is vibrated, the electrode laminate 16 floats in the electrolyte inside the battery as shown in FIG. As a result, the edge portions of the electrode laminate 16 and the corner portions 17 of the embossed laminate exterior material rub against each other. When the vibration is weak, there is no problem when the shaking time is short, but when the acceleration is large or when exposed to vibration for a long time, due to the corrosion and mechanical destruction resulting from the deterioration of the insulation of the laminate exterior material, In some cases, leakage occurred from the vicinity of the center of the ridge 18 in the side surface and bottom surface of the exterior body shown in FIG.

  In addition, in order to solve the problem of the weakness of the laminate outer packaging material, it is conventionally necessary to apply pressure above a certain level in the stacking direction and pressurize so that the batteries or stacked electrodes in the battery do not move. was there. FIG. 9 is a perspective view of a conventional battery pack. As shown in FIG. 9, an assembled battery (single cell laminate) 3 in which laminated lithium ion cells are stacked is sandwiched between rigid metal plates 32 and tightened with bolts or nuts 33 (for example, patents). Reference 3, see FIG. 1). Further, when using an elastic body as shown in FIG. 8, the elastic body is thickened (about 5.0 to 7.0 mm) and compressed to about half of the original thickness and inserted into the case to load in the stacking direction. There was a way to get. In addition to the method of applying a load, there is also a method of sealing the entire assembled battery in the battery pack case with a resin (see, for example, Patent Document 4).

  However, in the structure in which the periphery of the assembled battery shown in FIG. 8 is covered with an elastic body, or in the structure in which the assembled battery shown in FIG. It requires a large space and is unsuitable for miniaturization. Also, when the entire assembled battery is sealed with a resin, or when the assembled battery is sandwiched between metal plates, the overall weight increases, resulting in a laminated lithium ion secondary battery. I could not take advantage of the light weight of the secondary battery. In consideration of cooling of the assembled battery by air, a structure in which the entire periphery of the assembled battery is covered with an elastic body and a method of sealing the entire assembled battery with a resin are unsuitable. Furthermore, in the structure in which the periphery of the assembled battery is covered with an elastic body and greatly compressed, there is a possibility that the battery pack case surface is deformed due to the repulsive force of the elastic body serving as a buffer material.

JP 2005-129234 A JP 2004-139924 A JP-A-2005-116427 JP 2003-162989 A

  Under such circumstances, it is an object of the present invention to provide a lithium ion secondary battery pack having good vibration resistance and air cooling performance with a relatively small volume and weight.

  In order to solve the above-mentioned problems, a lithium ion secondary battery pack according to the present invention is a lithium ion secondary battery pack in which an assembled battery composed of at least one single cell composed of a laminated lithium ion secondary battery is housed in a case. The case is box-shaped, filled with foamable filler between the case and the corners of the four corners of the assembled battery, ribs are provided on the inner surface of the case, and an air inlet is provided at one end of the case The battery pack is separated from the case by a rib, and a notch is provided in a part of the rib so that the gap between the battery pack and the inner surface of the case is provided. In addition, an air flow path for air cooling is formed.

  An elastic body may be provided between the assembled battery and the rib, and an air flow path for air cooling may be formed between the elastic body and the inner surface of the case.

  The assembled battery may be a battery in which a plurality of unit cells are fixed with an adhesive or a pressure-sensitive adhesive and stacked.

  As described above, in the present invention, a part of the space between the case and the assembled battery is fixed by the elastic body and the foaming filler, thereby improving the earthquake resistance and not completely covering the assembled battery for air cooling. A lithium ion secondary battery pack that secures a passage and is excellent in earthquake resistance and cooling performance with a relatively small volume and weight can be supplied.

FIG. 3 is a perspective plan view showing a process in the middle of manufacturing the lithium ion secondary battery pack according to the embodiment of the present invention. Sectional drawing in the AA of FIG. The disassembled perspective view which shows the lithium ion secondary battery pack of embodiment of this invention. The perspective view of the lower case used for the lithium ion secondary battery pack of embodiment of this invention. The perspective view of the secondary battery which used the conventional laminate film for the exterior. The fragmentary sectional view of the assembled battery of a laminate type lithium ion secondary battery. The top view of the assembled battery of a laminate type lithium ion secondary battery. The exploded perspective view inside the conventional lamination type lithium ion secondary battery pack. The perspective view of the conventional battery pack.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is an exploded perspective view showing a process in the middle of manufacturing the lithium ion secondary battery pack according to the embodiment of the present invention. An assembled battery 3 formed by laminating a plurality of laminate-type lithium ion secondary batteries in which a power generation element having a positive electrode, a negative electrode, and an electrolyte is sealed with a laminate film made of a metal foil and a resin is formed on the entire upper and lower surfaces and side surfaces. It is configured to be housed in a case made up of a lid-like upper case 1 and a box-like lower case 2 via elastic bodies 4, 5 and 6 that are partially covered. Here, an air inlet 7 for air cooling is provided at one end of the upper case 1, and an air outlet 8 is provided at the opposite end.

  An assembled battery fixes a plurality of single cells with a double-sided adhesive tape, an adhesive, or the like. This is suitable for constructing the assembled battery without impairing the thinness characteristic of the laminate battery.

  FIG. 4 is a perspective view of a lower case used in the lithium ion secondary battery pack according to the embodiment of the present invention. As shown in FIG. 4, the lower case 2 for housing the assembled battery is provided with ribs 29 for positioning the assembled battery at a distance from the inner wall of the case. In order to ensure the flow path 21, a part is notched in the center part. At this time, the elastic bodies 4 and 5 serving as cushioning materials are sandwiched between the ribs 29 of the lower case 2 and the surface of the laminate outer packaging material of the assembled battery. (Refer to FIG. 3) However, the elastic body serving as the buffer material does not need to have a thickness as shown in the conventional example of FIG. 8, and approximately 1.0 to 2.0 mm is sufficient according to the vibration test. It became clear by the comparative experiment. For this reason, the amount of use of the cushioning material can be reduced, and the possibility of deformation of the case is reduced.

  FIG. 1 is a plan perspective view showing a process in the middle of manufacturing a lithium ion secondary battery pack according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 1, after the assembled battery 3 is assembled into the lower case 2, the foamable filler 24 is injected into the corners of the four corners of the assembled battery 3. It is clear from a comparative experiment by a vibration test that the discharge amount at this time needs to be controlled to an amount that reaches a range 19 of ¼ to ３ of each side of the battery at the corner shown in FIG. 7 after foaming. However, since it is isolated from the air flow path by the ribs 29, it does not require so strict management. As shown in FIG. 2, since the filler is foamable, the foamable filler 24 fills the space between the assembled battery 3 and the lower case 2 following a complicated shape. The foamable filler to be injected is preferably a one-component urethane-based foam filler because it is easy to work and does not generate heat during curing.

  In general, a battery of less than 1 Ah is small in both volume and weight, and in many cases, a battery pack is configured in a single battery state as an assembled battery, and many of this class of single batteries are relatively strong Al. Because there are many cases that have a can case, there is no need to consider earthquake resistance too much. Moreover, the maximum capacity of the cell currently assumed is 18 Ah.

  As described above, according to the present invention, it is possible to obtain a battery pack that has a relatively low weight and volume, has high vibration resistance, and can be cooled by air.

DESCRIPTION OF SYMBOLS 1 Upper case 2 Lower case 3 Battery assembly 4, 5, 6 Elastic body 7 Intake port 8 Exhaust port 10, 11, 12 Elastic body 13 Laminated film 14 Positive electrode tab 15 Negative electrode tab 16 Electrode laminated body 17 Embossed corner 18 Edge 19 Range of 1/4 to 1/3 of each side 21 Air flow path 24 Foamable filler 29 Rib 30 Battery pack protection plate 32 Metal plate 33 Bolt or nut

Claims (3)

In a lithium ion secondary battery pack in which an assembled battery composed of at least one unit cell made of a laminate type lithium ion secondary battery is housed in a case, the case is box-shaped, and the case and the assembled battery have four corners. The foaming filler is filled between the side corners,
Ribs are provided on the inner surface of the case,
An intake port is provided at one end of the case, and an exhaust port is provided at the other end;
The assembled battery is separated from the case by the rib,
A lithium ion secondary battery pack, wherein an air flow path for air cooling is formed between the assembled battery and the inner surface of the case by providing a notch in a part of the rib. .   The elastic body is provided between the assembled battery and the rib, and an air flow path for air cooling is formed between the elastic body and the inner surface of the case. The lithium ion secondary battery pack described.   3. The lithium ion secondary battery pack according to claim 1, wherein the assembled battery includes a plurality of unit cells fixed and laminated with an adhesive or an adhesive. 4.

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