JP2012226840A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid disadvantages due to heat treatment in a manufacturing process of a nonaqueous electrolyte secondary battery using a resin monoblock battery container.SOLUTION: The nonaqueous electrolyte secondary battery has a monoblock battery container 1. The monoblock battery container 1 includes: a resin body 1a with a plurality of battery containers 12 divided by partitions 11; and a resin lid to cover an open surface of the body 1a. Protrusions 11a shaped to protrude toward the lid are respectively formed on a side of the partitions 11 located close to the open surface. The lid and the partitions 11 are welded to each other at the protrusions 11a.

Description

  The present invention relates to a non-aqueous electrolyte secondary having a monoblock battery case including a resin main body portion provided with a plurality of battery cases partitioned by a partition and a resin lid portion covering an open surface of the main body portion. It relates to batteries.

  Such a non-aqueous electrolyte secondary battery has a resin-made monoblock battery case provided with a plurality of battery cases partitioned by partition walls, and the battery case of a plurality of cells is formed by forming the battery case with a resin. As a result, a plurality of cells can be mounted with high density, and there is an advantage that the number of parts can be greatly reduced and the weight can be reduced. Furthermore, as compared with the case where a metal battery case is used, even if a power generation element or the like housed in the battery case is displaced and contacts the wall surface of the battery case, a short circuit failure does not occur.

Japanese Utility Model Publication No. 6-70152

However, in a non-aqueous electrolyte secondary battery using a conventional resin monoblock battery case, the heat treatment in the manufacturing process may adversely affect components such as power generation elements arranged in the battery case. was there.
That is, the non-aqueous electrolyte secondary battery using a resin monoblock battery case is adjacent to each other in order to reliably prevent the electrolyte solutions from being mixed between adjacent battery cases in the manufacturing process. The body part and the lid part of the monoblock battery case are heat-welded at the partition wall between the battery cases to ensure that the electrolyte solution is blocked.
As a thing which can be influenced by this heat processing, there exists a separator which is a component of an electric power generation element, for example.
If the separator is overheated by the heat treatment, the shutdown function of the separator may be hindered.
When the battery temperature rises excessively during actual use, the separator functions to stop the battery operation by narrowing the gap in the separator and preventing the flow of ions and the like. If heat is applied, the separator deformation operation as described above may not function well.
The present invention has been made in view of such circumstances, and its object is to avoid the adverse effects of heat treatment in the manufacturing process in a non-aqueous electrolyte secondary battery using a resin monoblock battery case. There is in point to do.

1st invention of this application has a monoblock battery case provided with the resin-made main-body part provided with the some battery case divided by the partition, and the resin-made cover part which covers the open surface of the main-body part. In the nonaqueous electrolyte secondary battery, a protruding portion having a shape protruding toward the lid portion is formed on the open surface side of the partition wall, and the lid portion and the partition wall are welded to each other at the protruding portion. .
In other words, the heating action is applied to the protruding part of the shape protruding to the lid part side, the lid part and the partition wall of the main body part are welded, and the electrolyte solution is blocked from coming and going between adjacent battery cases. The distance between the working position and the battery case is increased by that much, and the influence of the heat treatment on the battery case can be suppressed.

According to a second invention of the present application, in addition to the configuration of the first invention, the monoblock battery case is housed in a metal case.
That is, if the battery case of the non-aqueous electrolyte secondary battery is composed only of a resin material, moisture may permeate through the battery case over a long period of use, which may adversely affect the battery life. By housing the resin monoblock battery case in a metal case, the intrusion of moisture can be blocked.

  Moreover, in addition to the structure of said 2nd invention, the said case corresponds to the said main-body part and the said cover part of the said monoblock battery case, 3rd invention of this application is a metal main-body part. And the lid part of the monoblock battery case, the main body part of the monoblock battery case and the lid part of the monoblock battery case are heated at the edge of the lid part of the monoblock battery case. The main body portion of the case and the lid portion of the case are joined by welding at an end edge portion of the lid portion of the case.

In other words, the battery casing of the non-aqueous electrolyte secondary battery is composed of a resin inner shell composed of a resin monoblock battery case and a metal outer shell composed of a metal case. It has a heavy structure, and each of its inner shell and outer shell is hermetically sealed by thermal welding and welding.
When the battery case has a double structure as described above, it is thought that moisture can be prevented from entering just by sealing either the inner shell or the outer shell by bonding. It has been found that other deterioration factors have been overcome by this improvement, and that slight water intrusion has become a major factor in battery deterioration.
Therefore, both the inner shell and the outer shell of the double structure are joined so as to be in a hermetically sealed state, and moisture penetration is suppressed as much as possible.

According to the first aspect of the present invention, when the main body portion and the lid portion of the monoblock battery case are welded at the partition wall position, the distance between the heating position and the battery case is increased, and the influence of the heat treatment is increased. Since it can suppress reaching into a battery case, in the nonaqueous electrolyte secondary battery using a resin-made monoblock battery case, the bad effect by the heat processing in a manufacturing process can be avoided.
Furthermore, as an effect of using the monoblock battery case, in the case where an assembled battery is configured using a plurality of individually manufactured cells, a member for connecting the cells and applying tight pressure is required. Even if connected in this way, vibrations, impacts, temperature changes, and material creep over time may cause each cell to fall apart, but when using a monoblock battery case, The structure for a simple connection is not required, and each cell does not fall apart.
Furthermore, as an effect of making the monoblock battery case made of resin, in the case of using a general metal battery case, electrical insulation between the power generation element arranged in the battery case and the inner wall of the battery case is achieved. In order to secure the power generation element, it is necessary to cover the power generation element with an insulating bag, etc., but when the monoblock battery case is made of resin, such a power generation element and the battery case inner wall arranged in the battery case There is no need for a member for ensuring electrical insulation.

In addition, according to the second aspect of the invention, since the intrusion of moisture can be blocked by housing the resin monoblock battery case in the metal case, the battery life can be improved.
Further, according to the third aspect of the invention, since both the resin inner shell and the metal outer shell are joined so as to be in a sealed state, the intrusion of moisture can be suppressed as much as possible. The life characteristics can be further improved.

The perspective view which shows the main-body part of the monoblock battery case concerning embodiment of this invention The perspective view which shows the main-body part of the case concerning embodiment of this invention. The perspective view which shows the cover part of the monoblock battery case concerning embodiment of this invention, and the cover part of a case 1 is an external perspective view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. Sectional drawing of the electrode terminal vicinity concerning embodiment of this invention The perspective view which shows the internal structure of the nonaqueous electrolyte secondary battery concerning embodiment of this invention. The perspective view in the manufacture process of the nonaqueous electrolyte secondary battery concerning embodiment of this invention The perspective view which shows the structure of the battery housing | casing concerning another embodiment of this invention.

Hereinafter, embodiments of the nonaqueous electrolyte secondary battery of the present invention will be described with reference to the drawings.
In the present embodiment, a lithium ion battery will be described as an example of a nonaqueous electrolyte secondary battery.

[Configuration of non-aqueous electrolyte secondary battery RB]
The non-aqueous electrolyte secondary battery RB according to the present embodiment includes a battery case BC having a double structure including a resin monoblock battery case 1 and a metal case 2 that completely covers the monoblock battery case 1. And the inner monoblock battery case 1 is housed in the case 2.
As shown in the perspective view of FIG. 4, positive and negative electrode terminals 3 and 4 formed as terminal bolts are arranged on the upper surface of the case 2. As will be described in detail later, the secondary battery RB of the present embodiment illustrates a case where four single batteries (cells) are integrated in one battery casing BC. Four sets are provided corresponding to the batteries.

The monoblock battery case 1 includes a resin main body 1a shown in FIG. 1 and a resin lid 1b shown in FIG.
The main body 1a of the monoblock battery case 1 is integrally molded into the shape shown in FIG. 1 by resin molding, and a plurality of (four in this embodiment) battery cases 12 partitioned by the partition walls 11 are provided. Formed and configured. Each battery case 12 has a flat rectangular parallelepiped internal space, and has the same shape and the same volume. The four battery cases 12 are arranged in a direction along the shortest side of the internal space. The lid portion 1b covers the open surface side of each of the battery cases 12.
The upper end of each partition wall 11, that is, the end portion on the open surface side of the main body portion 1 a extends further upward than the upper end position of each battery case 12, and a protruding portion 11 a that protrudes toward the lid portion 1 b is formed. .

The lid portion 1b of the monoblock battery case 1 is integrally formed by resin molding in the same manner as the main body portion 1a, and has a rectangular plate shape as a whole at a position corresponding to the position where the protruding portion 11a of the main body portion 1a exists. A U-shaped bent portion 14 is formed.
The lid portion 1b is arranged so as to cover the open surface of the main body portion 1a, and the protruding portion 11a of the main body portion 1a is fitted into the inner surface side of the bent portion 14 in a state where the main body portion 1a is covered with the lid portion 1b.
In addition, an opening 13 through which the wiring member to the electrode terminals 3 and 4 passes is formed at a position corresponding to the open surface side of each battery case 12, and between the pair of openings 13 corresponding to one battery case 12. A safety valve 16 configured as a rupture valve and a liquid injection port 17 for injecting an electrolytic solution are provided.
In the monoblock battery case 1 configured as described above, each battery case 12 constitutes an independent battery, and in the case of the present embodiment, one independent battery cell (cell) shares one battery casing BC. Yes.

The metal case 2 includes a metal main body 2a shown in the perspective view of FIG. 2 and a metal lid 2b shown in FIG.
The main body 2a of the case 2 is formed as a substantially rectangular parallelepiped can whose one side surface is opened with a metal plate such as stainless steel.
The shape of the internal space of the main body 2a of the case 2 is a rectangular parallelepiped shape adapted to the outer shape of the main body 1a of the monoblock battery case 1, and the monoblock battery case 1 is placed in the internal space of the main body 2a of the case 2. The main body 1a is completely stored, and the gap between the two is made as small as possible.
The lid 2b of the case 2 is formed of a metal plate such as stainless steel, like the main body 1a, and is a rectangular plate as a whole, and is formed on the lid 1b of the monoblock battery case 1. A U-shaped bent portion 21 is formed at a position corresponding to the U-shaped bent portion 14. Furthermore, the opening 22 of the same dimension is formed in the position corresponding to the opening 13 of the cover part 1b of the monoblock battery case 1, and it is comprised as a rupture valve between a pair of openings 22 corresponding to one battery case 12. A safety valve 24 and an injection port 25 for injecting an electrolytic solution are provided.
The safety valve 24 and the liquid injection port 25 of the lid part 2b of the case 2 are arranged in the vertical direction with the safety valve 16 and the liquid injection port 17 of the lid part 1b of the monoblock battery case 1, respectively. The liquid injection port 25 of the lid portion 2 b is formed with a larger diameter than the liquid injection port 17 of the lid portion 1 b of the monoblock battery case 1.

In each battery case 12 of the monoblock battery case 1, a power generation element 5 indicated by a two-dot chain line in FIG. 6 showing a perspective view of the inside of the battery housing BC is arranged. Further, the power generation element 5 and the electrode terminal 3 are arranged. , 4 are arranged for current collectors 6 and 7 to be electrically connected to each other.
The current collector 6 and the current collector 7 are both conductors, and as shown in FIG. 6, the same shape is symmetrically arranged, but the materials are different between them. The positive current collector 6 is made of aluminum, and the negative current collector 7 is made of copper.
The shape of the current collectors 6 and 7 is such that, for connection with the electrode terminals 3 and 4, a portion extending along the lid portion 2 b of the case 2, which is an attachment surface of the electrode terminals 3 and 4, and the power generation element 5 In order to connect to the cable, a substantially L-shaped bent shape is formed in which the portion bent 90 degrees downward and extending in the normal direction of the lid 2b is continuous. Connection portions 6a and 7a for connecting to the power generation element 5 are formed at portions extending in the normal direction of the lid portion 2b.

Although detailed description is omitted, the power generation element 5 applies an active material to each of a pair of electrode plates composed of a positive electrode plate formed in a long foil shape and a negative electrode plate formed in a long foil shape, Similarly, it is configured as a so-called wound type power generation element wound in a stacked state with a long separator interposed therebetween. As this separator, a porous film containing a thermoplastic resin can be used. As said thermoplastic resin, since it has the outstanding shutdown function, polyolefin resin is preferable and especially polyethylene or a polypropylene is preferable.
In the state where the power generation element 5 is wound as described above, the uncoated portion 5a of the active material of the foil-like positive electrode plate extends laterally (in a direction perpendicular to the longitudinal direction of the foil-like positive electrode plate) to form a foil shape. The uncoated portion 5b of the active material of the negative electrode plate extends to the side opposite to the active material 5b (the direction perpendicular to the longitudinal direction of the foil-shaped negative electrode plate).
In the power generation element 5 of the present embodiment, a foil-like positive electrode plate and a foil-like negative electrode plate coated with an active material, and a separator are wound in a flat shape to be adapted to the flat battery case 12.
The arrangement posture of the power generation element 5 in the battery case 12 is such that the winding axis of the foil-like positive electrode plate is parallel to the line segment connecting the positive and negative electrode terminals 3, 4. The connection portions 6a and 7a of the current collectors 6 and 7 enter the uncoated portions 5a and 5b of the power generation element 5 wound in a spiral shape.
The uncoated portion 5a of the foil-like positive electrode plate is welded to the connecting portion 6a of the current collector 6 in a bundled state, and the uncoated portion 5b of the foil-like negative electrode plate is connected to the current collector 7 in a bundled state. It is welded to the part 7a.

The positive electrode terminal 3 attached to the lid 2b of the case 2 is electrically connected to the positive current collector 6, and the negative electrode terminal 4 is electrically connected to the negative current collector 7. It is connected.
Attachment structure of electrode terminal 3 to lid 2b and connection structure of electrode terminal 3 and current collector 6, attachment structure of electrode terminal 4 to lid 2b and connection structure of electrode terminal 4 and current collector 7 Is that the same configuration is arranged symmetrically with respect to the center of each unit cell, and between each unit cell, the arrangement of the positive electrode and the negative electrode is alternately reversed, The other configuration is the same.
In the following, description will be made by using the configuration on the positive electrode side of one unit cell as a representative.
As shown in the sectional view of FIG. 5, the electrode terminal 3 is integrally formed with a conductive rivet member 3 a for fixing the current collector 6 to the battery housing BC on the head side thereof. . The portion of the rivet member 3 a is arranged in a state of penetrating through the opening 22 formed in the lid portion 2 b of the case 2 and the opening 13 formed in the lid portion 1 b of the monoblock battery case 1. That is, the lid portion 1b of the monoblock battery case 1 and the lid portion 2b of the case 2 are overlapped in the direction shown in FIG. 3, and the electrode terminals 3 and 4 are fixed to the overlapped portions.
For fixing the electrode terminal 3 and the current collector 6 to the lid portions 1b and 2b, a gasket 8 for securing electrical insulation and airtightness is inserted into the openings 13 and 22 in a state of surrounding the rivet member 3a. The rivet member 3a and the current collector 6 are sandwiched between the heads of the electrode terminals 3 and the inner ends of the battery casing BC are caulked. 6 forms an energization path between the power generation element 5 and the electrode terminal 3, and electrically connects the power generation element 5 and the electrode terminal 3.
The vertical wall 15 is positioned on the lower surface side (inside of the battery casing BC) of the lid portion 1b of the monoblock battery case 1 and is located on the side of the horizontal posture portion of the upper ends of the current collectors 6 and 7. The current collectors 6, 7 or the electrode terminals 3, 4 are prevented from rotating around the vertical axis when, for example, electrical wiring is performed on the electrode terminals 3, 4.

[Manufacturing process of secondary battery RB]
Next, the manufacturing process of the secondary battery RB will be schematically described.
As described above, the power generation element 5 is applied to the long strip-like foil-like positive electrode plate and foil-like negative electrode plate by applying the positive electrode active material and the negative electrode active material, leaving the uncoated portions 5a and 5b, respectively. Later, it is wound into a flat shape with a separator in between. The uncoated portions 5a and 5b are wound so that the positive electrode and the negative electrode are located at the end edges on the opposite side in the width direction, and the uncoated portions 5a and 5b protrude laterally.

The battery casing BC is assembled by first aligning the edge portions of the lid portion 1b of the monoblock battery case 1 and the lid portion 2b of the case 2 formed in the shape shown in FIG. The bent portion 21 of the lid portion 2b is fitted into the bent portion 14 of the lid portion 1b in the direction shown to be integrated.
The gasket 8 is inserted into the openings 13 and 22 of the integrated lid portions 1b and 2b. Further, the rivet member 3a of the electrode terminal 3 is inserted into the gasket 8, and the tip of the rivet member 3a passes through the openings 13 and 22. , Projecting to the opposite side. Similarly, the gasket 8 and the electrode terminal 4 are fitted into the openings 13 and 22 on the negative electrode side.
The arrangement of the electrode terminal 3 on the positive electrode side and the electrode terminal 4 on the negative electrode side is such that they are arranged one by one in one unit cell, and between the adjacent unit cells, as shown in FIG. Arrangement is made so that the terminals 3 and 4 are arranged in opposite directions. This is because, in the present embodiment, four unit cells are connected in series to form an assembled battery.
With the electrode terminals 3 and 4 inserted into the lid portions 1b and 2b, the openings formed in the current collectors 6 and 7 are inserted into the protruding portions of the electrode terminals 3 and 4 on the rivet member side, and the rivet members are caulked. Thus, the electrode terminals 3 and 4 are fixed to the lid portions 1b and 2b.
At this time, the positive electrode current collector 6 is connected to the positive electrode terminal 3, and the negative electrode current collector 7 is connected to the negative electrode terminal 4.
The current collectors 6 and 7 are arranged along the vertical wall 15 formed in the lid portion 1b.
As shown in FIG. 6, the above-described power generation element 5 is assembled to the connecting portions 6a and 7a of the current collectors 6 and 7 in this state.
That is, the uncoated portion 5a of the positive electrode plate is welded to the connection portion 6a of the current collector 6 on the positive electrode side, and the uncoated portion 5b of the negative electrode plate is welded to the connection portion 7a of the current collector 7 on the negative electrode side.

With respect to the main body part 1a of the monoblock battery case 1 in which the assembly on the lid part 1b, 2b side assembled as described above is molded into a shape shown in FIG. Insert it so that it enters, and the state shown in the perspective view of FIG. At this time, the bent portion 14 of the lid portion 1b is fitted into the protruding portion 11a of the main body portion 1a.
In this state, the main body 1a and the lid 1b of the monoblock battery case 1 are heat-welded.
By this thermal welding, the battery cases 12 are sealed in an airtight state, the electrolyte solution is prevented from passing between adjacent battery cases 12, and the battery cases 12 are separated.
Specifically, the boundary position between the edge portion of the lid portion 1b and the main body portion 1a indicated by the arrow A in FIG. 7 is heated from the outside, and the two are joined by thermal welding. 7 is heated from the outside in the vicinity of the upper end of the bent portion 21 of the lid portion 2b of the case 2 indicated by the arrow B in FIG.
By heating the bent portion 21, the vicinity of the upper end of the protruding portion 11a in the main body portion 1a of the monoblock battery case 1 and the bent portion 14 in the lid portion 1b of the monoblock battery case 1 are welded, and in the protruding portion 11a, The lid portion 1b and the partition wall 11 are welded together.
Thus, by forming the protrusion 11a in the monoblock battery case 1, when the main body part 1a and the lid part 1b of the monoblock battery case 1 are thermally welded, the heating position is separated from the power generation element 5. It is possible to suppress the heat during welding from adversely affecting the separator of the power generation element 5.

Next, what welded the main-body part 1a and the cover part 1b of the monoblock battery case 1 as mentioned above is inserted in the main-body part 2a of the case 2 shown in FIG. 2, and it is set as the state shown in FIG. At this time, the rectangular protruding piece 23 formed at the upper end edge of the main body portion 1a of the case 2 is a junction between the protruding portion 11a on the main body portion 1a side of the monoblock battery case 1 and the bent portion 14 of the lid portion 1b. The direction of insertion is set so as to cover the end of the.
Thereafter, the boundary portion between the end edge portion of the lid portion 2b of the case 2 and the upper end of the main body portion 2a indicated by an arrow C in FIG. 4 is joined by welding.
In the present embodiment, the case where four unit cells housed in the battery casing BC are connected in series is illustrated, and therefore, as shown in FIG. 4, the electrode terminal 3 on the positive electrode side between adjacent unit cells. And the electrode terminal 4 on the negative electrode side are connected over the metal plate 31, and the nut 32 is screwed into the bolt portion of the electrode terminals 3 and 4 and fixed.
When the assembly of the battery casing BC is completed in this way, the electrolytic solution is injected into the battery casing BC from the liquid injection ports 17 and 25 of the monoblock battery case 1 and the case 2. The liquid injection port 17 is hermetically sealed by welding a liquid stopper made of metal, and the liquid injection port 25 is hermetically sealed by welding a metal liquid stopper 26 (see FIG. 4). As described above, since the liquid injection port 25 of the lid 2b of the case 2 has a larger diameter than the liquid injection port 17 of the lid 1b of the monoblock battery case 1, the liquid injection port 17 is smoothly sealed. It can be carried out.
Thereafter, initial charging (preliminary charging), aging, and the like are performed to complete the secondary battery RB.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
(1) In the above embodiment, as a configuration of the monoblock battery case 1, the battery case 12 having a flat rectangular internal space is arranged in the same direction along the direction of the shortest side of the internal space. For example, as illustrated in FIG. 8, the battery case 12 having a flat rectangular inner space may be arranged in the same direction along the long side direction of the open surface. In FIG. 8, the configuration of the battery casing BC is shown with the same reference numerals as the corresponding components in the above embodiment.
The configuration of the power generation element 5 and the like may be the same as in the above embodiment, and the connection of the electrode terminals 3 and 4 between cells may be a configuration in which the positive and negative electrodes of adjacent cells are connected by a metal plate 31. .
The secondary battery RB having the battery housing BC as shown in FIG. 8 has a shape in which a flat surface with a large area is exposed to the outside air as compared with the configuration shown in the above embodiment. Each cell, including the enclosed cells, has good heat dissipation and can be easily cooled.

(2) In the above-described embodiment, in the main body portion 1a of the monoblock battery case 1, the partition walls 11 that define each battery case 12 are directly extended to the lid portion 1b side, and are projected for joining to the lid portion 1b. Although the portion 11a is formed, the specific shape of the protrusion 11a can be variously changed, for example, the thickness of the protrusion 11a is made thinner than the thickness of the partition wall 11.
(3) In the said embodiment, although the monoblock battery case 1 illustrated the case where it comprises and comprises the four battery cases 12 divided by the partition 11, the number of the battery cases 12 is three pieces. The following may be sufficient and five or more may be sufficient.

1 Monoblock battery case 1a Body (monoblock battery case)
1b Lid (monoblock battery case)
2 Case 2a Body (Case)
2b Lid (case)
11 Bulkhead 11a Protruding part 12 Battery case

Claims (3)

A non-aqueous electrolyte secondary battery having a monoblock battery case including a resin main body portion including a plurality of battery cases partitioned by a partition and a resin lid portion covering an open surface of the main body portion. ,
A protruding portion having a shape protruding toward the lid portion is formed on the open surface side of the partition wall,
The nonaqueous electrolyte secondary battery in which the lid and the partition are welded to each other in the protruding portion.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the monoblock battery case is housed in a metal case. The case includes a metal main body and a metal lid corresponding to the main body and the lid of the monoblock battery case,
The body part of the monoblock battery case and the lid part of the monoblock battery case are joined by thermal welding at an edge of the lid part of the monoblock battery case,
The nonaqueous electrolyte secondary battery according to claim 2, wherein the main body portion of the case and the lid portion of the case are joined by welding at an end edge portion of the lid portion of the case.

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