JP5278683B2 - Secondary battery - Google Patents

Description

  The present invention relates to a sealing performance of a peripheral structure of an electrode terminal of a secondary battery.

In this type of secondary battery, for example, a lithium ion battery is modularized for in-vehicle use. In one module, an electrode bundle in which thin film-like positive electrodes, negative electrodes, and separators are alternately stacked is placed in a cell case. The battery is sealed together with an electrolytic solution to form one battery cell, and a plurality of battery cells are bundled.
For example, an electrode terminal extending from an electrode bundle protrudes from the upper surface of the battery cell, and the electrode terminal of the adjacent battery cell is connected by a bus bar by attaching the electrode terminal to form a lithium ion battery as a module The structure which performs is known (patent document 1).

By the way, this lithium ion battery is vulnerable to water, and if water enters the battery cell, it will cause deterioration of the electrolyte and decrease the battery performance. Therefore, the battery cell has a high seal to prevent moisture from entering the battery cell. Performance is required.
For example, the periphery of the electrode terminal is sealed with a resin insulating seal member, and small holes that fit the protrusions on the upper surface of the battery cell are provided at the four corners so that the insulating seal member also functions as a detent for the electrode terminal. A lithium ion battery having the above configuration is known.

JP 2006-294551A

  However, as disclosed in Patent Document 1, the electrode terminals are connected to each other with a bus bar, and the periphery of the electrode terminals is sealed with an insulating seal member having a small hole portion at the four corners together with the anti-rotation function as described above. In this case, if excessive input is applied to the electrode terminal part during fastening by screwing the bus bar, stress concentrates on the small holes provided at the four corners of the insulating seal member, and extends from the small hole part to the electrode terminal or its peripheral part. There is a risk of cracking.

When cracks grow to the electrode terminal or its peripheral part and further reach the seal part in this way, the sealing performance on the upper surface of the battery cell is lost, moisture enters the battery cell, and the electrolyte changes in quality. However, there is a problem that the battery performance is significantly lowered.
For example, a battery pack used in an electric vehicle or the like is configured by arranging a plurality of modules configured by a plurality of battery cells and connecting them in series, so that even if one defective battery cell is connected, the battery pack is used. The power required for the entire pack cannot be sufficiently supplied, which is not preferable.

  The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a secondary battery in which the sealing performance around the electrode terminal is improved.

In order to achieve the above object, the secondary battery according to claim 1 reacts with the electrode bundle in a secondary battery in which an electrode bundle and an electrolytic solution are put in a cell case and sealed with a lid member to form a battery cell . a current collector for transmitting electricity, and the rivet from the current collector Ru extends through a through hole formed in said lid member, and the cell terminal of a fixed conductive to the battery cell by the rivet, the cell terminal insulation between the electrode terminal protrudes outside is threaded on the outer circumference of the battery cell, the peripheral and the rivet and the electrode terminals of the through hole is fitted around the rivet and the electrode terminals in contact with And an insulating seal member for preventing rotation of the electrode terminal by providing an engagement portion that engages with a rotation stop portion formed on the lid member, and the electrode end of the insulation seal member Characterized in that a weakened portion in the region between the engagement portion and.

A secondary battery according to claim 2 is characterized in that, in claim 1, the weakened portion is a hole.
The secondary battery according to claim 3 is characterized in that, in claim 1, the fragile portion is formed by thinly forming the insulating seal member.
A secondary battery according to a fourth aspect of the present invention is the rechargeable battery according to any one of the first to third aspects, wherein the fragile portion extends in a region extending between the electrode terminal and the plurality of engaging portions. It is characterized by.

According to the secondary battery of the first aspect, since the insulating seal member is provided with the fragile portion between the engaging portion and the electrode terminal, the fastening member is screwed into the screwed electrode terminal. Even if an excessive tightening torque is input at the time, the crack does not extend to the periphery of the electrode terminal only by the generation of a crack between the engaging portion and the fragile portion, and the sealing performance around the electrode terminal is maintained.
Thereby, the sealing performance of a battery cell can be hold | maintained favorably and reduction of battery performance can be prevented.

According to the secondary battery described in claims 2 and 3, since the fragile portion is formed with a thin hole or insulating sealing member, a crack generated from the engaging portion reaches the sealing portion of the electrode terminal by simple processing. It can be absorbed and blocked without fail.
According to the secondary battery of the present invention, since the weakened portion extends in a region extending between the electrode terminal and the plurality of engaging portions, cracks generated from the plurality of engaging portions are various. Even if it is inserted smoothly, the crack can be more reliably absorbed and prevented by the long fragile portion before the crack reaches the seal portion of the electrode terminal.

  In addition, by providing such a long fragile portion, the number of fragile portions can be reduced compared to the case where a fragile portion is provided for each engaging portion, and the fragile portion can be easily processed.

It is a top view of a lithium ion battery. It is a side view of a lithium ion battery. It is the schematic of the components which comprise a lithium ion battery. It is an enlarged view of the electrode terminal peripheral part which concerns on a 1st Example. It is an enlarged view of the electrode terminal peripheral part which concerns on a 2nd Example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the following embodiments, the side where the positive electrode terminal 3a and the negative electrode terminal 3b in FIG. 1 are provided will be described for the sake of convenience. However, it is arbitrary how the module is mounted in the implementation of the present invention. .
First, the first embodiment will be described.

FIG. 1 is a plan view of a lithium ion battery according to the present invention, and FIG. 2 is a side view of the lithium ion battery.
The lithium ion battery 1 includes a thin electrode-like positive electrode, a negative electrode, and an electrode bundle wound so that the separators are alternately stacked in a metal battery case (cell case) made of an insulating heat-resistant resin together with an electrolytic solution, and sealed with a lid member 14. Although not shown, a plurality of the battery cells 2 are arranged and bundled in series so that adjacent battery cells 2 are arranged at a predetermined interval. Connected and modularized.

As shown in FIG. 2, a positive electrode terminal 3a extending from the positive electrode and a negative electrode terminal 3b extending from the negative electrode are respectively provided at both upper ends of the battery cell 2, and the positive electrode terminal 3a is connected to the negative electrode terminal 3b of the adjacent battery cell 2. The negative terminal 3b is further provided with a bus bar (not shown) so as to be connected to the positive terminal 3a of the adjacent battery cell 2.
On the upper surface of the battery cell 2, a cell terminal 4 extending from the electrode terminal 3 and for joining a substrate, for example, is provided. The cell terminal 4 is fixed to the upper surface of the battery cell 2 by a rivet 10.

Between the conductive electrode terminals 3a and 3b, the rivet 10 and the cell terminal 4 and the lid member 14, a resin insulating seal member 6 is disposed. Small holes (engaging portions) 8 are provided at the four corners of the insulating seal member 6, while the lid member 14 is provided with corresponding protrusions (rotation preventing portions). The part 8 is fixed to the battery cell 2 by engaging the protrusion.
FIG. 3 is a schematic configuration diagram of a seal portion on the upper surface of the battery cell.

As shown in the figure, the electrode terminal 3 protruding from the upper surface of the battery cell 2 is in contact with the cell terminal 4. As described above, the cell terminal 4 is formed by the rivet 10 that penetrates the through hole 15 of the lid member 14. It is fixed to the upper surface of the battery cell 2. An insulating seal member 6 is provided between the electrode terminal 3, the rivet 10, the cell terminal 4, and the lid member 14.
The insulating seal member 6 includes an outer packing 12 and an inner packing 16, and the outer packing 12 and the inner packing 16 seal the periphery of the through-hole 15 and the rivet 10 and thus the upper surface of the battery cell 2. Further, a current collector 18 is provided below the inner packing 16, and electricity that has reacted with the electrode bundle is transmitted to the electrode terminal 3.

That is, the electrode terminal 3 is provided on the upper side of the outer packing 12, and the cell terminal 4 extending from the electrode terminal 3 and the current collector 18 are fixed to the lid member 14 by the rivet 10 with the insulating seal member 6 interposed therebetween.
FIG. 4 shows an enlarged view of the periphery of the electrode terminal according to the first embodiment.
As described above, the cell terminal 4 extending from the electrode terminal 3 is fixed to the lid member 14 by the rivet 10 with the insulating seal member 6 made of resin interposed therebetween.

As shown in the figure, the electrode terminal 3 and the rivet 10 are formed with hexagonal flanges in plan view for preventing rotation, and the flanges of the electrode terminal 3 and the rivet 10 are fitted to the insulating seal member 6 respectively. Are combined. Small holes 8 are provided at the four corners of the insulating seal member 6 corresponding to the protrusions of the lid member 14.
A circular fragile portion 20 is provided in a region located between the small hole portion 8 of the insulating seal member 6 and the electrode terminal 3. That is, a circular fragile portion 20 is provided inside the insulating seal member 6 and in an intermediate region between the small hole portion 8 and the electrode terminal 3 on a line connecting each small hole portion 8 and the electrode terminal 3. It has been. Note that the fragile portion 20 may be, for example, a hole formed in the insulating seal member 6 or the insulating seal member 6 formed thin.

  Thereby, when the nut is screwed into the electrode terminal 3 to connect the electrode terminals 3 of the adjacent battery cells 2 with the bus bar, excessive stress is applied to the small hole portion 8 adjacent to the electrode terminal 3 when an excessive force is applied. In some cases, cracks may occur from the small hole portion 8 toward the electrode terminal 3 inside the insulating seal member 6, but the cracks generated here are reliably absorbed by the fragile portion 20, and the crack grows at once. Thus, reaching the vicinity of the electrode terminal 3 and the rivet 10 is prevented.

Thus, even if a crack occurs due to an excessive tightening force in the insulating seal member 6 provided on the outer surface of the battery cell 2, the crack does not reach the seal portion by providing the fragile portion 20, and the battery The sealing performance of the upper surface of the cell 2 is maintained, and the battery performance can be prevented from deteriorating.
In addition, as shown in the figure, the fragile portion 20 may be similarly provided on the rivet 10 side of the electrode terminals 3a and 3b, thereby further preventing the crack from reaching the seal portion. it can.

Next, a second embodiment will be described.
FIG. 5 shows an enlarged view around the electrode terminal portion according to the second embodiment.
Similar to the first embodiment, a weak portion 20 ′ having an oblong shape (long) in plan view is formed in a region located between the small hole portion 8 provided at the four corners of the insulating seal member 6 and the electrode terminal 3. Is provided. That is, in the second embodiment, most of the region of the insulating seal member 6 located in the middle of the small hole portion 8 around the electrode terminal 3 is occupied by the fragile portion 20 ′.

Thereby, even if excessive stress is concentrated in the small hole portion 8 and a crack is generated in the insulating seal member 6 on the outer surface of the battery cell 2, the crack is absorbed by the fragile portion 20 ′ having an oblong shape in plan view. Again, cracks are prevented from growing at once and reaching the vicinity of the electrode terminal 3 and the rivet 10.
Further, the fragile portion 20 ′ formed in an oval shape in plan view according to the second embodiment is intermediate between the small hole portion 8 and the electrode terminal 3 as compared with the plurality of circular fragile portions 20 according to the first embodiment. Since the portion that occupies the region is large, even if the cracks generated from the plurality of small hole portions 8 are varied, the fragile portion 20 ′ can absorb the cracks, and the cracks can be absorbed all at once. Can be more reliably avoided.

Thus, even if a crack occurs in the insulating seal member 6 provided on the outer surface of the battery cell 2, the crack does not reach the seal portion at a stretch by providing the fragile portion 20 ′. Thus, it is possible to prevent the battery performance from being lowered.
In addition, as shown in the figure, a fragile portion 20 'may be provided on the rivet 10 side of the electrode terminals 3a and 3b as well, thereby further preventing cracks from reaching the seal portion. Can do.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the embodiment of the present invention.
For example, in the above-described embodiment, the battery type in which the battery elements are wound in layers has been described as an example. Is possible.

The small holes 8 are provided at the four corners of the insulating seal member 6, but are not limited to the four corners of the insulating seal member 6, and may function as a rotation stop.
Here, the small hole portion 8 is formed in the insulating seal member 6 and the projection of the lid member 14 is engaged with the small hole portion 8, but conversely, the small hole is formed in the lid member 14. It is also possible to form a protrusion (engagement portion) on the insulating seal member 6 while forming the portion (rotation stop portion).

Moreover, in the said 1st Example, although the weak part 20 provided in the peripheral part of the electrode terminal 3 by the side of the small hole 8 was two, the number of the weak parts 20 may be three or more, The fragile portions 20, 20 ′ may be provided in a region located between the portion where the stress of the insulating seal member 6 is concentrated and the electrode terminal 3 and the rivet 10.
Moreover, in the said embodiment, although the shape of the weak part 20 and 20 'was circular or an ellipse in planar view, it is not necessarily limited to these shapes, The stress of the insulating seal member 6 concentrates in a weak part. Any shape may be used as long as it occupies a region located in the middle of the portion and the electrode terminal 3 and the rivet 10.

DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 Battery cell 3a, 3b Electrode terminal 4 Cell terminal 6 Insulation seal member 8 Small hole part (engagement part)
10 Rivet 14 Lid member 20, 20 'Weak part

Claims (4)

In a secondary battery in which a battery cell is formed by putting an electrode bundle and an electrolyte in a cell case and sealing with a lid member,
A current collector that transmits electricity reacted by the electrode bundle ;
A rivet Ru extends through a through hole formed in said lid member from said current collector,
A conductive cell terminal fixed to the battery cell by the rivet;
An electrode terminal that is in contact with the cell terminal and protrudes to the outside of the battery cell and is screwed on the outer periphery;
To engage the insulation and performs seal, detent portion formed on the lid member between the periphery and the rivet and the electrode terminals of the through hole is fitted around the rivet and the electrode terminal An insulating seal member for preventing rotation of the electrode terminal by providing an engaging portion;
A secondary battery comprising a weakened portion in a region between the electrode terminal and the engaging portion of the insulating seal member.   The secondary battery according to claim 1, wherein the fragile portion is a hole.   The secondary battery according to claim 1, wherein the fragile portion is formed by thinly forming the insulating seal member.   The secondary battery according to claim 1, wherein the fragile portion extends in a region extending between the electrode terminal and the plurality of engaging portions.

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