JP5673314B2 - Secondary battery and case assembly and assembled battery using the same - Google Patents

Description

The present invention relates to an assembly of a secondary battery and a case, and an assembled battery using the same .

In recent years, electric vehicles and hybrid vehicles have attracted attention, and the development of high-power batteries with high energy density and high power density mounted on them has an industrially important position. As such a high-power battery, for example, there is a lithium ion secondary battery, and a laminated electrode body in which a flat positive electrode and a negative electrode, and a separator for preventing a short circuit between both electrodes are laminated together with an electrolyte is sealed in a battery container. And stored. The battery container accommodates the laminated electrode body by welding the outer peripheral part of the exterior member, and there is a surplus portion of the electrolyte between the welded part of the outer peripheral part and the battery body part covering the laminated electrode body. For example, an aluminum laminate sheet is used as the exterior member.

In this type of secondary battery, in order to maintain battery performance, it is important that the laminated electrode body contains a predetermined amount of electrolyte. For this reason, when it comes to the situation where the quantity of the electrolyte solution in a laminated electrode body runs short for some reason, such as a battery reaction, it is preferable that an electrolyte solution is replenished with respect to a laminated electrode body.

Therefore, in order to provide excellent electrolyte retention without causing the separator to swell and sufficient oxidation resistance, those described in Patent Document 1 below are known. The secondary battery described in Patent Document 1 includes a non-swellable fiber having a cross-sectional shape in which a capillary phenomenon occurs in a separator formed using a nonwoven fabric.

JP2007-141672A

By the way, in an electric vehicle or a hybrid vehicle, as a battery pack, a plurality of secondary batteries are stacked in a state of being electrically connected in a case, and a battery main body that covers the stacked electrode body by the case is stacked. Used in a fixed state with a high pressure in the direction.

In the secondary battery described in Patent Document 1, the electrolyte in the surplus portion of the electrolyte penetrates into the laminated electrode body with a force due to capillary action, but in a state where the battery main body portion is suppressed with high pressure, the laminated electrode body There is a possibility that the electrolyte does not sufficiently permeate into the pores lacking.

The present invention is welded to the outer periphery of the outer member that retract and the electrolyte and co-laminated electrode body obtained by laminating a positive electrode, a negative electrode and a separator, and the outer peripheral portion becomes I covering the laminated electrode body by the exterior member An assembly of a secondary battery and a case , in which a laminate-type secondary battery having a battery main body and an excess electrolyte portion in which an electrolyte is accumulated between the outer peripheral portion and the battery main body is accommodated in the case It is. The case includes a pressurizing unit that applies a pressing pressure to the surplus electrolyte part. Here, the pressing pressure applied to the surplus electrolyte part by the pressurizing means is larger than the pressing pressure applied to the battery main body part by the case, and is less than the opening pressure for peeling off the welding of the outer peripheral part.

According to the present invention, it is possible to reliably replenish the laminated electrode body with the electrolyte in the excess portion of the electrolyte.

A perspective view showing an assembled battery Perspective view showing the inside of the battery pack Perspective view showing secondary battery 10 3A-A sectional view showing the inside of the secondary battery 3B-B sectional view showing a side pressurizing means having a spacer according to the first embodiment. 3A-A sectional view showing a pressurizing means of a side having no spacer according to the second embodiment 3B-B sectional view showing the pressurizing means according to the third embodiment The figure which looked at the secondary battery which concerns on this 4th Embodiment from the Z direction

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The X-axis and Y-axis attached to the drawings indicate the short side direction and the long side direction of the flat secondary battery 10, respectively. The Z axis indicates the stacking direction.

FIG. 1 is a perspective view showing an assembled battery. The assembled battery 1 houses a plurality of secondary batteries 10 and an insulating cover 14 having electrical insulation inside a case 4. The assembled battery 1 can be used alone. For example, an assembled battery corresponding to a desired current, voltage, and capacity can be formed by serializing and paralleling a plurality of assembled batteries 1. it can.

The case 4 has a lower case 2 having a box shape and an upper case 3 forming a lid. The edge of the upper case 3 is wound around the edge of the peripheral wall of the lower case 2 by caulking. The lower case 2 and the upper case 3 are formed from a relatively thin steel plate or aluminum plate. The lower case 2 and the upper case 3 have a through hole 7. The through holes 7 are arranged at four corners, and are used to insert through bolts (not shown) for stacking a plurality of assembled batteries 1 and holding them as assembled batteries. Reference numerals 5 and 6 denote output terminals arranged so as to protrude from the opening on the front surface of the lower case 2.

  FIG. 2 is a perspective view showing the inside of the assembled battery. There are a stacked body 11 in which a plurality of flat secondary batteries 10 are electrically connected and stacked, and a plurality of spacers 12 and 13 for supporting the battery. The spacers 12 and 13 are electrically insulative. Have. The spacer 12 is disposed on the front side of the stacked body 11, and the spacer 13 (corresponding to a support member) is disposed on the back side of the stacked body 11. For example, the spacer 13 disposed on the back side of the stacked body 11 is positioned so as to sandwich an outer peripheral portion 32 of an exterior member 30 described later. The spacer 13 has through holes 15 at both ends in the longitudinal direction. The through hole 15 is aligned with the through hole 7 on the back side of the lower case 2 and the upper case 3.

FIG. 3 is a perspective view showing the secondary battery 10. In the secondary battery 10, the laminated electrode body 17 is accommodated in a pair of exterior members 30, and is sealed with an outer peripheral portion 32 of the pair of exterior members 30. The battery main body 21 is a portion that houses the laminated electrode body 17. The surplus electrolyte part 33 is between the battery main body part 21 and the outer peripheral part 32, and the laminated electrode body 17 is a part of only the electrolyte solution that is not accommodated. The elastic resin portion 16 provided to include the outer peripheral portion 32 of the exterior member 30 will be described later.

Each of the pair of exterior members 30 is formed into a rectangular flat shallow bowl so that the laminated electrode body 17 can be accommodated. After the laminated electrode body 17 and the electrolytic solution are put inside, the respective outer peripheral portions 32 are overlapped, A part or all of the outer peripheral portion 32 is joined by heat fusion or an adhesive.

The exterior member 30 is a sheet such as a polymer-metal composite laminate film in which a metal (including an alloy) such as aluminum, stainless steel, nickel, or copper is covered with an insulator such as a polypropylene film from the viewpoint of weight reduction and thermal conductivity. Made of material.

A positive electrode terminal 41 and a negative electrode terminal 42 are led out of the exterior member 30 from each of the positive electrode plate and the negative electrode plate of the laminated electrode body 17. The positive electrode terminal 41 and the negative electrode terminal 42 are also referred to as a positive electrode tab 41 and a negative electrode tab 42.

4 is a cross-sectional view of FIG. 3A-A (the elastic resin portion 16 is not shown). The laminated electrode body 17 is formed by sequentially laminating a positive electrode, a negative electrode, and a separator. The positive electrode has, for example, a positive electrode active material layer made of a lithium-transition metal composite oxide such as LiMn ₂ O ₄ . The negative electrode has, for example, a negative electrode active material layer made of carbon and a lithium-transition metal composite oxide. The separator is made of, for example, porous PE (polyethylene) having air permeability that can penetrate the electrolyte.

When the electrolytic solution on the electrode is decomposed and consumed by the battery reaction of the laminated electrode body 17 to form an unimpregnated portion, the electrolytic solution in the surplus electrolytic solution portion 33 is supplied to the laminated electrode body 17 by capillary action.

The pressure applied to the exterior member 30 will be described. The laminate-type secondary battery 10 is sealed under a reduced pressure environment of 5 kPa or less after injecting an electrolytic solution. On the other hand, since the secondary battery is actually used in an atmospheric pressure environment of 101 kPa, a differential pressure is applied to the exterior member 30, and the electrode in the laminated electrode body 17 and the separator always come into close contact with each other. .

By tightening the lower case 2 and the upper case 3, a high pressure is applied in the Z direction to the battery body 21 of the secondary battery 10 inside the assembled battery, so that the electrode and the separator in the laminated electrode body 17 are always in close contact with each other. As a result, deterioration of battery characteristics and misalignment of the laminated electrode body 17 are prevented.

The present invention includes pressurizing means 34 that presses the surplus electrolyte portion 33 from the outside, and presses the surplus electrolyte portion 33. As a result, when the electrolytic solution on the electrode is decomposed and consumed by the battery reaction of the laminated electrode body 17 and an unimpregnated portion is formed, the electrolytic solution in the surplus electrolytic solution portion 33 is supplied to the laminated electrode body 17. Moreover, it is preferable that the pressure which presses the excess electrolyte part 33 with the pressurization means 34 is larger than the pressure concerning the battery main body part 21. FIG. As a result, the electrolyte solution of the excess electrolyte solution part 33 is reliably supplied to the laminated electrode body 17 due to the pressure difference.
On the other hand, before the unimpregnated portion is formed on the electrode, pressing the surplus electrolyte portion 33 strongly may cause the outer peripheral portion 32 to peel off and open the exterior member. The pressure that presses the surplus electrolyte part 33 when the exterior member opens is called the release pressure. If the pressure for pressing the excess electrolyte part 33 is less than the release pressure, the exterior member can be further prevented from being opened. The opening pressure is obtained in advance by an experiment or the like.

Returning to FIG. 3, the embodiment of the pressurizing means will be described. In the secondary battery 10 of this example, the elastic resin portion 16 is formed by insert molding of a solid elastic resin over the entire outer peripheral portion 32 of the battery main body portion 21 including the end faces of the pair of exterior members 30. . Thereby, the external force input into the battery main body part 21 can be relieved, and the stability of the fixed state of the battery main body part 21 is improved. In particular, the elastic resin portion 16 is excellent in an external force relaxation action by an elastic force against a relatively high frequency vibration such as a vehicle vibration. Moreover, the electrolyte solution leakage from the laminated electrode body 17 which is going to leak from the joint surface of the outer peripheral part 32 can be prevented.

The elastic resin portion 16 is made of an elastic resin such as vulcanized rubber, thermosetting resin elastomer, thermoplastic resin elastomer, or polyamide resin, and is formed in the above range by insert molding described later.

FIG. 5 is a cross-sectional view of FIG. 3B-B showing the pressurizing means of the side having the spacer according to the first embodiment. The stacked body 11 has a plurality of spacers 12 and 13 for supporting the plurality of secondary batteries 10. By installing the elastic member 17 in a contracted state between the spacers 12 and 13 and the surplus electrolyte part 33, the surplus electrolyte part 33 is large from the outside in the Y direction and the Z direction due to the elastic force of the elastic member 17. Pressing pressure can be applied. Further, since the pressing force is applied to the outer peripheral portion 32 in the Z direction by the elastic member 17, the opening pressure of the outer peripheral portion 32 is increased, and the peeling of the welding can be prevented.

FIG. 6 is a cross-sectional view of FIG. 3A-A showing the pressurizing means on the side not having the spacer according to the second embodiment. The plurality of secondary batteries 10 are stacked, and the elastic member 18 is installed in contact with the elastic member 18 of the adjacent secondary battery in the Z direction. Further, the elastic member 18 is installed so as to include the surplus electrolytic solution portion 33.
By doing so, when the lower case 2 and the upper case 3 are tightened, a large pressing pressure can be applied to the surplus electrolyte part 33 from the outside in the Z direction by the elastic force of the elastic member 18. Further, since the pressing force is applied to the outer peripheral portion 32 in the Z direction by the elastic member 18, the opening pressure of the outer peripheral portion 32 is increased, and the peeling of the welding can be prevented.

If the elastic parts 17 and 18 are a stretchable material such as rubber made of EPDM, BR, or NBR, or a spring, for example, an effect can be obtained. Further, the elastic members 17 and 18 can use the elastic resin portion 16 without installing a new member, and at the same time, it is possible to obtain the effects of preventing vibration absorption and electrolyte leakage.

FIG. 7 is a cross-sectional view of FIG. 3B-B showing the pressurizing means according to the third embodiment. The stacked body 11 has a plurality of spacers 12 and 13 for supporting the plurality of secondary batteries 10. Two members 43 and 44 and one elastic member 19 are installed between the spacers 12 and 13 and the surplus electrolyte part 33. The members 43 and 44 have slopes 45 and 46, respectively, and are in contact with each other in the Y direction. One member 43 is in contact with the surplus electrolyte portion 33 at a portion that is not the slope 45. The elastic member 19 is between the spacers 12 and 13 and the other member 44 and is in contact with a surface 47 opposite to the inclined surface 46 of the other member 44 in the Y direction.
As a result, when the amount of the electrolyte in the surplus electrolyte part 33 decreases, the other member 44 is pressed against one member 43 by the elastic member 19, and the one member 43 presses the surplus electrolyte part 33. When the amount of the electrolyte in the surplus electrolyte portion 33 decreases, the one member 43 moves in the Z direction along the inclined surface 45, so that a large pressing pressure can always be applied.

FIG. 8 is a view of the secondary battery 10 according to the fourth embodiment viewed from the Z direction. One side or a part of the four sides of the secondary battery 10 has a portion 39 where no pressurizing means is provided. As a result, the gas generated by the battery reaction in the laminated electrode body 17 can easily move to the portion 39 where no pressurizing means is provided. Penetration is more reliable.

The present invention is not limited to the above-described embodiment, and can be modified as appropriate. For example, although an elastic member is installed between the spacers 12 and 13 and the surplus electrolyte part 33, the wall surface of the case 4 may be used instead of the spacers 12 and 13, or a positive or negative tab may be provided on one side of the exterior member 30. Although the secondary battery 10 in which both 41 and 42 are arranged is shown, it goes without saying that the present invention can also be applied to a secondary battery in which positive and negative tabs are arranged on different sides.

10 ... Secondary battery
12 ... Spacer
16 ... Elastic resin part
17 ... Elastic member
21 ... Battery body
32… Outer periphery
33 ... Excess electrolyte part
34 ... Pressure means

Claims (9)

The outer peripheral portion of the exterior member and retract and the electrolyte and co-laminated electrode body obtained by laminating a positive electrode, a negative electrode and a separator by welding, and the outer peripheral portion, the battery comprising I covering the laminated electrode body by said outer member A combination of a secondary battery and a case , in which a laminate-type secondary battery having a main body part and an excess electrolytic solution part in which an electrolytic solution is accumulated between the outer peripheral part and the battery main body part is accommodated in the case. Three-dimensional
The case includes a pressurizing unit that applies a pressing pressure to the surplus electrolyte part ,
The pressing pressure applied to the surplus electrolyte part by the pressurizing means is greater than the pressing pressure applied to the battery body by the case, and is less than the opening pressure to peel off the outer peripheral part. A secondary battery and case assembly . The assembly of the secondary battery and the case according to claim 1,
The assembly of a secondary battery and a case , wherein the pressing means also presses the outer peripheral portion. The assembly of the secondary battery and the case according to claim 2 ,
The assembly of a secondary battery and a case, wherein the pressing means is installed along the surface of the outer peripheral portion. In the assembled battery formed by stacking a plurality of the secondary batteries in the assembly of the secondary battery and the case according to claim 1 and housing the same in the case ,
The battery pack is characterized in that the pressurizing means is between the plurality of secondary batteries, and the plurality of secondary batteries are constrained in the stacking direction by the case . In the assembled battery according to claim 4,
The pressurizing means, the battery pack, which is a resilient member. In the assembled battery of claim 5,
A spacer that is disposed between the outer peripheral portions of the plurality of secondary batteries and has a fixing portion for fixing the secondary battery to a predetermined installation position. ,
The battery pack is characterized in that the elastic member is disposed between the spacer and the excess electrolyte part. In the assembled battery of claim 6,
Wherein the range encompassing the superimposing portion of the outer peripheral portion and the spacer, the battery pack, characterized in that said elastic member is formed by insert molding. The assembly of the secondary battery and the case according to claim 1,
The pressurizing means includes two members having slopes, an elastic member having elastic force, and a spacer that supports the elastic member ,
The two members are in contact along a direction parallel to the flat surface before Symbol laminated electrode body in slope between,
One of the two members is in contact with the excess electrolyte part,
The other member of the two members is in contact with one end of the elastic member on the side opposite to the surplus electrolyte part along the parallel direction of the flat surface of the laminated electrode body,
An assembly of a secondary battery and a case, wherein the other end of the elastic member is supported by the spacer . The assembly of the secondary battery and the case according to claim 1,
Before SL excess over - electrolyte unit, assembly of the secondary battery case and having a portion in which the not provided with pressure means.

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