JP2000348773A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evenly press positive and negative electrodes and to securely fix them by covering a stack type power generation element composed by laminating plural positive electrodes and plural negative electrodes through separators by constricting a constrictive synthetic resin sheet. SOLUTION: A power generation element is composed by superposing multiple positive electrodes 2 and negative electrodes 3 through separators 4. The positive electrodes 2 each are composed by applying a positive electrode active material to the surface of rectangular Al foil and by forming a tapping part 2a to which the positive electrode active material is not applied at one lengthwise end in order to connect and fix a positive electrode collector. The negative electrodes 3 each are composed by applying a negative electrode active material to the surface of rectangular Cu foil and by forming a tapping part 3a to which the negative electrode active material is not applied at the other lengthwise end in order to connect and fix a negative electrode collector. When the power generation element 1 is inserted into a heat contraction tube 7 and heated, the superposed parts of the positive electrodes 2 and the negative electrodes 3 are tightly fitted. Thereby, the superposition of the positive electrodes 2 and the negative electrodes 3 is never displaced, the spaces among them are uniformed by the pressure of the contraction, and the leakage of an electrolyte never occurs, so that battery performance is never deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery such as a stacked lithium ion secondary battery in which a large number of positive and negative electrodes are stacked via a separator.

[0002]

2. Description of the Related Art A relatively small-capacity lithium ion secondary battery has a long cylindrical winding type in which positive and negative electrodes are wound into a long cylindrical shape via a separator so that a power generating element can be easily manufactured. Many were used. However, in the case of a large-sized lithium ion secondary battery, in order to make the positive and negative electrodes as thick as possible and to increase the capacity density, a stack type in which many positive and negative electrodes are stacked via a separator may be used. .

The structure of the above-mentioned conventional large-sized lithium ion secondary battery will be described. As shown in FIG. 3, the power generating element 1 of this lithium ion secondary battery is formed by laminating a large number of positive electrodes 2 and negative electrodes 3 with a separator 4 interposed therebetween. The positive electrode 2 is sandwiched between the folded separators 4 at the center in the longitudinal direction, and the negative electrode 3 is inserted between each of the separators 4 sandwiching the positive electrode 2.
In a lithium ion secondary battery, the positive electrode 2 must always face the negative electrode 3. Therefore, the negative electrode is placed on the uppermost and lowermost parts of the separator 4 sandwiching the positive electrode 2. 3 are disposed, and as a result, the negative electrode 3 is
One more sheet will be stacked.

[0004] Since the power generating element 1 is merely a stack of the positive electrode 2 and the negative electrode 3 sandwiched between the separators 4, there is a possibility that the overlapping may be displaced or disjointed, and it is difficult to perform later assembling work. Therefore, conventionally, an adhesive tape 11 was wound around the central portion of the power generating element 1 and fixed to prevent the positive electrode 2 and the negative electrode 3 from falling apart.

As shown in FIG. 4, the power generating element 1 fixed with the adhesive tape 11 has lead-out portions 2a, 3 of the positive electrode 2 and the negative electrode 3 protruding from both sides in the longitudinal direction, respectively.
The positive electrode current collector 5 and the negative electrode current collector 6 are connected and fixed to a. Each of the positive electrode current collector 5 and the negative electrode current collector 6 is formed of two conductive metal plates, and the lead portions 2a and 3a of the positive electrode 2 and the negative electrode 3 are sandwiched by being overlapped and securely connected and fixed by rivets or welding. It is. Further, a positive electrode terminal 9 and a negative electrode terminal 10 are connected and fixed to the positive electrode current collector 5 and the negative electrode current collector 6, respectively, by caulking or the like. As shown in FIG. 5, the power generating elements 1 are housed in a battery case 8 by stacking two of them as a set, and only the positive terminal 9 and the negative terminal 10 of each power generating element 1 are connected to the end of the battery case 8. Seal and project from the part. Then, when a non-aqueous electrolyte is injected into the battery case 8 and then sealed, a lithium ion secondary battery is obtained.

[0006]

However, in the case of a large-sized lithium ion secondary battery, since the weight of one power generating element 1 reaches several tens of kilograms, a conventional polypropylene (P) is used.
When the adhesive tape 11 made of P) or the like is wound, there is a problem that the stack may be displaced due to the weight of the positive electrode 2 or the negative electrode 3 at the time of work, or may be displaced at the time of transportation in a subsequent assembly process. there were. In addition, if the central portion of the power generating element 1 is wrapped with the adhesive tape 11 at only one position, the positive electrode 2 and the negative electrode 3 are tightened only at the central portion and are not evenly pressed, so that the gap between the electrodes has unevenness. There is also a problem that it occurs. In addition, if the adhesive tape 11 is wound at a plurality of locations along the longitudinal direction of the power generating element 1 in order to securely fix the positive electrode 2 and the negative electrode 3 and pressurize the same evenly, the work of fastening the adhesive tape 11 becomes troublesome. A new problem arises.

Further, large-sized stack type batteries are often used for a long period of time while the power generating element 1 is kept horizontal, so that the non-aqueous electrolyte filled in the power generating element 1 gradually leaks from the side or the like. In addition, there is also a problem in that the non-aqueous electrolyte between the positive electrode 2 and the negative electrode 3 stacked on the upper part is reduced, so that power cannot be generated and the battery performance may be reduced.

The present invention has been made in order to cope with such a situation. By covering the power generating element with a heat shrinkable tube or the like, the stacked positive and negative electrodes can be uniformly pressed and securely fixed. It is intended to provide a nonaqueous electrolyte battery that can be used.

[0009]

According to the first aspect of the present invention, there is provided a non-aqueous electrolyte battery provided with a stack-type power generating element in which a plurality of positive and negative electrodes are stacked with a separator interposed therebetween. The power generation element is covered with a contracted one.

According to the first aspect of the present invention, since the power generating element is covered with the synthetic resin sheet that shrinks due to heating or the synthetic resin sheet that shrinks due to other factors, the positive and negative electrodes stacked by the compression at the time of shrinkage. Can be uniformly pressed as a whole and fixed reliably. In addition, before the heating or the like is performed, the size of the synthetic resin sheet has a sufficient margin, so that the work of covering the power generation element becomes easy. In addition, when the power generating element is covered with such a synthetic resin sheet, the liquid retention of the nonaqueous electrolyte filled between the electrodes is improved, so that a decrease in battery performance can be prevented.

The invention of claim 2 is characterized in that the shrinkable synthetic resin sheet is a heat-shrinkable synthetic resin sheet that shrinks when heated.

According to the second aspect of the present invention, since the heat-shrinkable synthetic resin sheet which contracts by heating is used, the power generating element is covered and the positive and negative electrodes are covered by a simple operation of merely applying heat to the heat-shrinkable synthetic resin sheet. Can be uniformly pressed and securely fixed.

According to a third aspect of the present invention, there is provided a non-aqueous electrolyte battery including a stack-type power generating element in which a plurality of positive and negative electrodes are stacked via a separator, wherein the power generating element is covered with an elastic sheet. And

According to the third aspect of the present invention, since the power generating element is covered with the elastic sheet made of synthetic rubber or the like, the elasticity of the sheet presses the stacked positive and negative electrodes uniformly and reliably. It can be fixed to. Moreover, if the elastic sheet is spread with a jig or the like, the insertion of the power generating element becomes easy. In addition, when the power generation element is covered with such an elastic sheet, the liquid retention of the nonaqueous electrolyte filled between the electrodes is improved, so that a decrease in battery performance can be prevented.

According to a fourth aspect of the present invention, the shrinkable synthetic resin sheet or the elastic sheet has a bag-like shape in which only one end from which the lead portions of the positive and negative electrodes of the power generating element protrude is opened.

According to the fourth aspect of the present invention, when the lead portions of the positive and negative electrodes of the power generating element protrude from only one end for connection with the terminal, respectively, the bag-shaped shrinkable synthetic resin is provided. Since a sheet or an elastic sheet can be used, the work of inserting the power generating element is facilitated, and the workability is improved.

According to a fifth aspect of the present invention, the shrinkable synthetic resin sheet or the elastic sheet is formed in a tubular shape having open ends at which the leading portions of the positive and negative electrodes of the power generating element project.

According to the fifth aspect of the present invention, when the lead portions of the positive and negative electrodes of the power generating element protrude from both ends for connection with the terminal, a tubular shrinkable synthetic resin sheet is provided. Since an elastic sheet or an elastic sheet can be used, the work of inserting the power generating element is facilitated, and the workability is improved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. FIG. 1 is a perspective view showing a state in which a power generating element of a lithium ion secondary battery is covered with a heat-shrinkable tube, and FIG. FIG. 3 is a perspective view showing a power generation element of the ion secondary battery.
Components having the same functions as those of the conventional example shown in FIGS. 3 to 5 are denoted by the same reference numerals.

In this embodiment, a large lithium ion secondary battery similar to the conventional example will be described. As shown in FIG. 2, the power generating element 1 of this lithium ion secondary battery is a stack type in which a large number of positive electrodes 2 and negative electrodes 3 are stacked with a separator 4 interposed therebetween. The positive electrode 2 is obtained by applying a positive electrode active material such as a lithium-cobalt composite oxide on the surface of a rectangular aluminum foil. In order to connect and fix the positive electrode current collector 5 shown in FIG. The end portion is provided with a lead portion 2a to which the positive electrode active material is not applied.
The negative electrode 3 is formed by applying a negative electrode active material such as carbon to the surface of a square copper foil, and is connected to the negative electrode current collector 6 shown in FIG. Is provided with a lead portion 3a to which the negative electrode active material is not applied. The separator 4 is formed by laminating a polypropylene (PP) sheet having high heat resistance on a polyethylene (PE) sheet, and is formed into a microporous film by stretching. The separator 4 has a length approximately twice as long as the positive electrode 2 and is folded at a central portion in the longitudinal direction so that the positive electrode 2 is sandwiched between the folded portions. Then, the negative electrode 3 is disposed between the separators 4 sandwiching the positive electrode 2 and above and below it. Further, a lead portion 2a of the positive electrode 2 and a lead portion 3a of the negative electrode 3
Project from both sides of the power generating element 1. In addition, here, in order to simplify the drawing, the positive electrode 2
Although the number of laminations of the negative electrode 3 and the negative electrode 3 is reduced, more layers are actually stacked, for example, 60 positive electrodes 2 and 61 negative electrodes 3.

The power generating element 1 is inserted into a heat-shrinkable tube 7 shown by a dashed line in FIG. Heat shrink tube 7
Is a sheet obtained by forming a polyolefin-based synthetic resin sheet into a tube, crosslinking the sheet with an electron beam or the like, and then expanding the tube diameter. The heat-shrinkable tube 7 has a property of shrinking to a tube diameter at the time of crosslinking by heating to a predetermined temperature. When the heat-shrinkable tube 7 is heated with the power generating element 1 inserted therein, as shown in FIG. 1, the heat-shrinkable tube 7 shrinks and covers the overlapping portion of the positive electrode 2 and the negative electrode 3 of the power generating element 1 in close contact.

In the power generating element 1, the lead-out portions 2a, 3a of the positive electrode 2 and the negative electrode 3 protrude from the openings at both ends of the heat-shrinkable tube 7, respectively, so that the positive electrode current collector 5 and the negative electrode current collector shown in FIG. 6 is connected and fixed to these drawers 2a and 3a. Then, similarly to the conventional example shown in FIG. 5, the power generation elements 1 are set in a pair and stored in the battery case 8 in a vertically stacked manner, and after the non-aqueous electrolyte is injected into the battery case 8 and sealed. Thus, the lithium ion secondary battery of the present embodiment is completed.

In the lithium ion secondary battery having the above structure, since the power generating element 1 is entirely covered by the heat shrinkable tube 7, there is no possibility that the positive electrode 2 and the negative electrode 3 are displaced or disjointed. In addition, since the overlapping portion of the positive electrode 2 and the negative electrode 3 is pressed from the entire upper and lower surfaces by the heat-shrinkable tube 7, the pressure is evenly applied and the gap between the electrodes becomes uniform. In addition, when the non-aqueous electrolyte filled between the positive electrode 2 and the negative electrode 3 is not covered with the heat-shrinkable tube 7 in this manner, the non-aqueous electrolytic solution does not leak from the side surface or the like. It does not happen that the liquid performance is reduced and the battery performance is reduced. Further, the heat-shrinkable tube 7
Since the tube has a sufficiently large tube diameter before contraction, the operation of inserting the power generating element 1 into the inside thereof is extremely easy.

In the above embodiment, the polyolefin-based heat-shrinkable tube 7 is used. However, the present invention is not limited to this, and a polyvinyl chloride-based or polyvinylidene fluoride-based heat-shrinkable tube 7 can be used. In the above embodiment,
Although the heat-shrinkable tube 7 that shrinks by heating is used, a shrinkable synthetic resin tube that shrinks by other factors other than heating can also be used. In addition, it is not limited to the tube shape,
A shrinkable synthetic resin sheet of any shape can be used.

Further, in the above embodiment, the case where the lead-out portions 2a, 3a of the positive electrode 2 and the negative electrode 3 protrude from both ends of the power generating element 1 has been described. 3a can be protruded. In this case, the shrinkable synthetic resin sheet can be formed in a bag shape, and the power generation element 1 can be easily inserted.
When the lead portions 2a, 3a of the positive electrode 2 and the negative electrode 3 are made to protrude from the same end, for example, the lead portions 2a, 3a may be formed in the shape of a tag, and the positive electrode 2 and the negative electrode 3 may be divided into right and left parts and protruded. . In addition, since the connection between the power generating element 1 and the positive electrode terminal 9 or the negative electrode terminal 10 can be made by using a lead material or the like, almost the entire power generating element 1 can be covered with a shrinkable synthetic resin sheet. It is sufficient if there is a slight opening for passing lead materials and the like.

Further, an elastic sheet may be used instead of the shrinkable synthetic resin sheet which shrinks by heating or the like. As the elastic sheet, a sheet material such as natural rubber or synthetic rubber can be used. Even when such an elastic sheet is used, the entire periphery of the power generation element 1 is covered, so that there is no possibility that the overlap between the positive electrode 2 and the negative electrode 3 is displaced or scattered. In addition, since the overlapping portion of the positive electrode 2 and the negative electrode 3 is pressed from the entire upper and lower surfaces by the elasticity of the elastic sheet, the pressure is evenly applied, and the gap between the electrodes becomes uniform. In addition, when covered with the elastic sheet as described above, the nonaqueous electrolyte filled between the positive electrode 2 and the negative electrode 3 does not leak. Furthermore, since the elastic sheet can be expanded to a sufficient size with a jig or the like, the power generating element 1
Insertion work becomes easy.

Further, in the above embodiment, a large lithium ion secondary battery has been described. However, the present invention can be similarly applied to a non-aqueous electrolyte battery other than a small lithium ion secondary battery.

[0029]

As is apparent from the above description, according to the non-aqueous electrolyte battery of the present invention, since the power generating element is covered with the contracting sheet or the elastic sheet, the laminated positive and negative electrodes are entirely formed. And the pressure is evenly applied and is securely fixed. In addition, since the liquid retention property is improved by being covered with such a sheet, it is possible to prevent a decrease in battery performance due to leakage of the non-aqueous electrolyte.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a perspective view illustrating a state in which a power generating element of a lithium ion secondary battery is covered with a heat shrinkable tube.

FIG. 2, showing one embodiment of the present invention, is a perspective view illustrating a power generating element of a lithium ion secondary battery.

FIG. 3 is a perspective view showing a conventional example and showing a power generating element of a lithium ion secondary battery.

FIG. 4 is a perspective view showing a conventional example, in which a current collector is connected and fixed to positive and negative electrodes of a power generating element.

FIG. 5, which shows a conventional example, is an overall perspective view of a lithium ion secondary battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power generation element 2 Positive electrode 2a Leader 3 Negative electrode 3a Leader 4 Separator 7 Heat shrinkable tube

Claims (5)

[Claims] 1. A non-aqueous electrolyte battery provided with a stack type power generating element in which a plurality of positive and negative electrodes are stacked via a separator, wherein the power generating element is covered with a contracted synthetic resin sheet. Non-aqueous electrolyte battery characterized by the above-mentioned. 2. The non-aqueous electrolyte battery according to claim 1, wherein the shrinkable synthetic resin sheet is a heat-shrinkable synthetic resin sheet that shrinks when heated. 3. A non-aqueous electrolyte battery comprising a stack-type power generating element in which a plurality of positive and negative electrodes are stacked via a separator, wherein the power generating element is covered with an elastic sheet. battery. 4. The shrinkable synthetic resin sheet or the elastic sheet has a bag-like shape in which only one end from which a lead portion of a positive / negative electrode of a power generating element protrudes is opened.
The non-aqueous electrolyte battery according to claim 3. 5. The shrinkable synthetic resin sheet or the elastic sheet has a tubular shape with open ends at which both ends of the positive and negative electrodes of the power generating element protrude. 5. The non-aqueous electrolyte battery according to any one of 4.