JP4237557B2 - Battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack in which a battery body is housed together with a protection circuit or the like.
[0002]
[Prior art]
As a battery pack in which a battery body and a built-in component such as a protection circuit are housed in a case, those described in Patent Documents 1 and 2 below are known. In Patent Document 1, a heat shrinkable tube into which a battery main body and a built-in component such as a protective substrate are inserted is heat-treated to bring the heat shrinkable tube into close contact with the surface of the battery main body. A battery pack that covers parts is disclosed. Patent Document 2 discloses a battery pack that is covered with a heat-shrinkable tube in the same manner as the battery pack described in Patent Document 1 with a buffer member disposed on a built-in component such as a protection circuit. Yes.
[0003]
[Patent Document 1]
JP 2003-17020 A [Patent Document 2]
Japanese Patent Laid-Open No. 2003-123714 [0004]
[Problems to be solved by the invention]
However, in the conventional battery pack including the battery pack described in Patent Document 1 and Patent Document 2, when a large impact is locally applied to the case, such as when falling from the side edge or corner of the case, In some cases, cracks may occur not only in the case but also in the battery body housed therein. When a crack occurs in the battery body, there is a risk of leakage of an electrolyte such as a harmful nonaqueous electrolyte solution. That is, in the above conventional battery pack, sufficient reliability against external impact has not been obtained.
[0005]
An object of this invention is to provide the battery pack which has sufficient reliability with respect to the impact from the outside.
[0006]
The battery pack of the present invention includes an anode, a cathode, a separator, an electrolytic solution, and a battery main body having a battery outer body that houses the anode, cathode, separator, and electrolytic solution in a sealed state, and a case that covers the battery main body in a sealed state The battery outer body has a polymer layer and an aluminum layer in this order from the side in contact with the electrolytic solution, and the case is formed by heat shrinking a polymer film having heat shrinkability , The case has a protective part that protects the edge of the battery body, and the protective part is formed by heat-sealing the overlapping part of the film. In this case, it is preferable that the protection part is provided at a corner part or a side edge part of the case.
[0007]
According to the present invention, since the polymer protective portion for protecting the edge of the surface of the battery body is provided, for example, even when the battery pack falls from the side edge or corner, the protection is provided. The part absorbs the impact of dropping and the impact applied to the case and the battery body is reduced. Accordingly, it is possible to sufficiently prevent the case and the battery body from being damaged due to external impact, and thus it is possible to provide a battery pack having sufficient reliability against external impact. In addition, since the case is formed by heat shrinking a film having heat shrinkability, the battery body can be covered only by heating and shrinking the case after covering the battery body. The battery pack can be easily manufactured.
[0008]
The case is preferably made of a polymer alloy of PET and polyolefin or poly-4-methylpentene.
[0009]
In this case, the case is preferably formed by heat-sealing the opening of the polymer tubular film, and the protective part is preferably a seal portion formed in the opening by heat-sealing. Thereby, after inserting a battery main body in a tube-shaped film, the battery pack covered with the case can be easily produced only by heating and heat-sealing the opening part of a tube-shaped film. Moreover, since the protective part can be formed simultaneously with sealing the opening of the tubular film to cover the battery body, the protective part can be provided easily and with a small number of parts. Therefore, a battery pack suitable for mass production can be realized.
[0010]
In the above battery pack, it is preferable that an elastically deformable buffer member is disposed between the protection portion and the battery body. Thereby, since the absorption rate of the impact applied to the battery pack from the outside can be improved, damage to the battery main body and the case can be made less likely to occur.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.
[0012]
FIG. 1 is a perspective view showing a battery pack according to an embodiment of the present invention, and FIG. 2 is a perspective view of the battery pack shown in FIG. 1 viewed from the bottom side. The battery pack 1 includes a columnar battery body 2, a protection circuit unit 3 disposed in the vicinity of the battery body 2, and a case 12 that covers the battery body 2 and the protection circuit unit 3 in a sealed state. ing. In addition, the case 12 that covers the battery body 2 and the protection circuit unit 3 has a protection unit 13 that protrudes outward from the edge of the battery pack 1. The “columnar battery body” includes those having a trapezoidal cross section and those having different sizes and shapes of opposing surfaces.
[0013]
Here, the battery body 2 built in the battery pack 1 according to the present embodiment will be described.
[0014]
3 is a side view of the battery main body 2 shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along line IV-IV of the battery main body 2 shown in FIG. The battery body 2 according to the present embodiment is a thin lithium ion secondary battery having a columnar hexahedral structure. The battery body 2 mainly includes a plate-like anode 4 and a plate-like cathode 5 facing each other, a plate-like separator 6 disposed adjacent to the anode 4 and the cathode 5, a non-aqueous electrolyte solution, And a battery exterior body (power generation element storage case) 8 that stores them in a sealed state. The anode 4, the cathode 5, and the separator 6 are each made of a porous material, and the power generation element is made up of these three. Most of the non-aqueous electrolyte solution is impregnated in the power generation element. FIG. 3 shows a case where the anode 4 is located on the front side (the front side in the drawing) and the cathode 5 is located on the far side (the back side in the drawing). Furthermore, the anode 4 and the cathode 5 in this embodiment are determined based on the polarity when the battery body 2 is discharged. Therefore, at the time of charging, the anode 4 becomes a cathode and the cathode 5 becomes an anode.
[0015]
The cathode 5 is formed by, for example, pasting a composition composed of polyvinylidene fluoride (PVDF), LiNi _1/3 Mn _1/3 Co _1/3 O ₂ and graphite with N-methyl-2-pyrrolidone, It is produced by applying to an aluminum foil current collector. On the other hand, the anode 4 is formed by pasting a composition composed of, for example, polyvinylidene fluoride (PVDF) and mesocarbon microbeads (MCMB) with N-methyl-2-pyrrolidone and applying the paste to a copper foil current collector. It is produced by doing.
[0016]
Moreover, the separator 6 will not be specifically limited if it is formed from the insulating porous body, The separator used for the well-known lithium ion secondary battery can be used. For example, the insulating porous body includes at least one structure selected from the group consisting of a laminate of films made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above polymers, or cellulose, polyester and polypropylene. Nonwoven fabric made of a material can be mentioned.
[0017]
The battery outer package 8 is, for example, a composite having at least a polymer layer located on the inside and in contact with the power generation element, and a metal layer disposed on the opposite side of the polymer layer from the side in contact with the power generation element A packaging film is used. As an example, a laminate material in which polypropylene (PP), aluminum (Al), and polyethylene terephthalate (PET) are laminated in this order from the inside can be cited.
[0018]
The battery body 2 has one end side electrically connected to the anode 4, the other end side protruding to the outside of the battery outer body 8, and one end side electrically connected to the cathode 5. The cathode lead 10 is provided so that the end side protrudes outside the battery exterior body 8. The contact portions of the anode lead 9 and the cathode lead 10 with the battery outer body 8 may be covered with insulators 21 and 22 for preventing contact with the metal layer of the battery outer body 8, respectively. .
[0019]
Next, referring to FIGS. The protection circuit unit 3 has a circuit for preventing overcharge, overdischarge, overcurrent, and the like with respect to the battery body 2, and is electrically connected to the anode 4 and the cathode 5 of the battery body 2.
[0020]
The case 12 is formed of, for example, a heat-shrinkable film, and entirely covers the battery body 2 and the protection circuit unit 3 while being in close contact with the side surface of the battery body. At this time, part of the anode lead 9 and the cathode lead 10 protrudes outward from the case 12. By forming the case 12 with a heat-shrinkable film, the battery body 2 and the protection circuit portion 3 can be covered only by heating after covering the battery body 2 and the protection circuit portion 3. Therefore, the battery pack 1 can be easily manufactured. Moreover, compared with the case where the battery main body 2 and the protection circuit part 3 are accommodated in a plastic or metal case to produce a battery pack, it is possible to achieve a reduction in size, weight, and cost.
[0021]
FIG. 5 is an exploded perspective view of the battery pack 1 according to the present embodiment. As shown in FIG. 5, the case 12 has a tubular shape, and is formed of, for example, a film having heat shrinkability made of a polymer alloy of PET and polyolefin. The length L of the case 12 is long enough to cover at least the battery main body 2.
[0022]
When the battery pack 1 according to this embodiment is manufactured using such a case 12, the battery body 2 to which the protection circuit unit 3 is connected is inserted into the case 12, and the case 12 is heated in that state. . The case 12 made of a heat-shrinkable film shrinks when heated and adheres closely to the side surface of the battery body 2. Thereafter, the opening located at the end of the case 12 is heat-sealed using an impulse heat sealer or the like. At this time, the heat-sealed portion (sealed portion) of the case 12 protrudes outward from the edge of the battery pack 1 as shown in FIGS. Thus, the battery pack 1 in which the battery body 2 and the protection circuit unit 3 are integrally covered with the case 12 is manufactured.
[0023]
Since the battery pack 1 according to the above-described embodiment includes the protection unit 13 that protrudes outward from the edge of the battery pack 1, for example, when the battery pack 1 falls to the ground, The protection part 13 contacts the ground before the side edge part and the corner part. Therefore, the impact applied to the side edges and corners of the battery body 2 is reduced, and the risk of cracking in the battery body 2 can be reduced. For this reason, the battery pack which has sufficient reliability with respect to the impact from the outside can be provided.
[0024]
Further, in the battery pack 1 according to the present embodiment, a part of the case 12 when the battery body 2 and the protection circuit unit 3 are covered serves as the protection unit 13. For this reason, another member for the protection part 13 is unnecessary, and the protection part 13 can be provided easily and with a small number of parts.
[0025]
FIG. 6 is a perspective view showing a modification of the battery pack 1 according to the present embodiment. The battery pack 14 shown in the figure is provided with a buffer member 15 in the gap between the protection portion 13 of the battery pack 1 shown in FIGS. 1 and 2 and the side surface of the battery body 2. The buffer member 15 is disposed so as to cover the surface of the battery body 2 that faces the protection part 13. Such a buffer member 15 is a member formed of an elastically deformable material, and for example, a polyurethane sponge or the like is used.
[0026]
In the battery pack 14 provided with such a buffer member 15, when an impact from the outside is applied to the side edge portion or the corner portion, the shock is also absorbed by the buffer member 15 in addition to the protection portion 13. Therefore, damage to the battery body 2 and the case 12 can be prevented with a higher probability. In addition, you may make it provide the buffer member 15 disperse | distributing to each corner vicinity of the battery main body 2.
[0027]
As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the tubular case 12 is used, but the battery body or the like may be wrapped using the sheet-like case 12.
[0028]
In the present embodiment, the battery body 2 is a lithium ion secondary battery. However, the battery pack according to the present invention includes a lead-based secondary battery, a nickel hydride secondary battery, and a nickel cadmium secondary battery. It is also possible to apply an electrochemical capacitor such as a secondary battery or an electric double layer capacitor. Of course, not only the secondary battery but also a primary battery is applicable. Furthermore, the battery body 2 may have a shape such as a columnar shape or a truncated circle (square) pyramid shape.
[0029]
EXAMPLES Hereinafter, although an Example is given and the battery pack of this invention is demonstrated in more detail, this invention is not limited to these Examples at all.
[0030]
[Example 1]
In this example, a battery body having a width of 87 mm, a length of 115 mm, a thickness of 3.0 mm, and a nominal capacity of 2500 mAh was produced, and a battery pack was produced using this battery body.
[0031]
The cathode of the battery body has a composition composed of 6% by mass of polyvinylidene fluoride (PVDF), 90% by mass of LiNi _1/3 Mn _1/3 Co _1/3 O ₂ and 4% by mass of graphite. It was made by pasting with N-methyl-2-pyrrolidone and applying to an aluminum foil current collector.
[0032]
On the other hand, the anode was formed by pasting a composition composed of 10% by mass of polyvinylidene fluoride (PVDF) and 90% by mass of mesocarbon microbeads (MCMB) with N-methyl-2-pyrrolidone to obtain a copper foil. It was produced by applying to a current collector.
[0033]
A laminate was obtained by laminating a polyolefin separator between the anode and the cathode. The thickness of the separator was 25 μm. Further, an aluminum terminal was welded to the cathode current collector, and a nickel terminal was welded to the anode current collector.
[0034]
Next, the above laminate was inserted into the battery casing made of a laminate material, and a predetermined amount of electrolyte was injected into the battery casing. And the opening part of the battery exterior body was heat-sealed, and the battery main body was obtained. At this time, an electrolytic solution in which LiPF ₆ as an electrolyte was dissolved to a concentration of 1M in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 was used. Moreover, the battery exterior body used the laminated material comprised by laminating | stacking in order of polypropylene (PP) with a thickness of 50 micrometers, aluminum (Al) with a thickness of 40 micrometers, and polyethylene terephthalate (PET) with a thickness of 12 micrometers from the inside.
[0035]
Next, a protection circuit part was attached to the obtained battery body, and the battery body in a state where the protection circuit part was attached was inserted into a tube (case) having heat shrinkability made of a polymer alloy of PET and polyolefin. . In this example, as the tube having heat shrinkability, a trade name “COPALON DP TUBE” manufactured by Gunze Polymer Industries Co., Ltd. is used, and the mass ratio of PET to polyolefin is (PET) :( polyolefin) = 70. : 30, the width (length L shown in FIG. 5) is 134 mm, and the thickness is 0.1 mm.
[0036]
Next, the battery main body and the protection circuit portion inserted in the tube were put in a thermostat at 90 ° C. and heated to heat-shrink the tube having heat shrinkability. And finally, the opening part located in the edge part of a tube was heat-sealed using the impulse sealer, and the protection part was formed. As described above, a battery pack in which the battery main body and the protection circuit unit are integrated with the heat-shrinkable tube was obtained.
[0037]
[Example 2]
In this example, a battery pack was produced under the same conditions as in Example 1 except that poly-4-methylpentene was used as the material of the heat-shrinkable tube. As a tube having heat shrinkage, a trade name “COPALON OP Tube” manufactured by Gunze Polymer Industries Co., Ltd. was used. And the battery pack which integrated the battery main body and the protection circuit part with the tube which has heat shrinkability by passing through the process similar to the said Example 1 was obtained.
[0038]
【The invention's effect】
According to the present invention, since the polymer protective portion that protects the edge portion of the surface of the battery main body is provided, a battery pack having sufficient reliability against external impact can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a battery pack according to an embodiment of the present invention.
FIG. 2 is a perspective view of the battery pack shown in FIG. 1 as viewed from the bottom side.
3 is a side view of the battery body shown in FIG. 1. FIG.
4 is a cross-sectional view taken along the line IV-IV of the battery body shown in FIG. 3;
FIG. 5 is a perspective exploded view of the battery pack according to the present embodiment. FIG. 6 is a perspective view showing a modification of the battery pack according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Battery pack, 2 ... Battery main body, 3 ... Protection circuit part, 4 ... Anode, 5 ... Cathode, 6 ... Separator, 8 ... Battery exterior body, 9 ... Lead for anode, 10 ... Lead for cathode, 12 ... Case, 13 ... protection part, 14 ... battery pack, 15 ... buffer member.

Claims (6)

A battery body having an anode, a cathode, a separator, an electrolytic solution, and a battery exterior body that contains the anode, the cathode, the separator, and the electrolytic solution in a sealed state;
A case that covers the battery body in a sealed state;
The battery outer body has a polymer layer and an aluminum layer in this order from the side in contact with the electrolytic solution,
The case is formed by heat shrinking a polymer film having heat shrinkability , and the case has a protective part for protecting the edge of the battery body,
The protection part is formed by heat-sealing the overlapping part of the film.   The battery pack according to claim 1, wherein the protection portion is provided at a corner portion of the case.   The battery pack according to claim 1, wherein the protection portion is provided on a side edge portion of the case. The battery case according to any one of claims 1 to 3, wherein the case is made of a polymer alloy of PET and polyolefin or poly-4-methylpentene .   The said case is formed with a polymer tubular film, and the said protection part is formed by heat-sealing the opening part of the said tubular film, The any one of Claims 1-4 characterized by the above-mentioned. The battery pack described.   6. The battery pack according to claim 1, wherein an elastically deformable buffer member is disposed between the protection part and the battery main body.

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