JP2011129378A - Laminated sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated sealed battery which has a structure with no appearance defects by impregnating an electrolyte in the whole battery element and in which the whole battery element can contribute to charge and discharge. <P>SOLUTION: The laminated sealed battery houses a battery element 2 in which a positive electrode and a negative electrode are laminated through a separator, in a sheath material 1. A negative electrode side through hole 11 which penetrates the front and rear is installed in the negative electrode, and a positive electrode side through hole which has an area same as or larger than the negative electrode side through hole is installed in one set or more at a position corresponding to the negative electrode side through hole in the positive electrode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a stacked sealed battery in which a battery element is housed in an exterior material.

  In recent years, with the widespread use of electric vehicles and hybrid vehicles, technical demands for higher energy and higher capacity of non-aqueous electrolyte secondary batteries that serve as drive power sources for long-time operation have further increased.

  In order to meet these technical requirements, development of non-aqueous electrolyte secondary batteries using a substance capable of inserting and extracting lithium has been actively promoted. Among these non-aqueous electrolyte secondary batteries, reducing the volume occupied by elements other than battery elements has been conventionally used as a battery exterior material from the technical viewpoint that it is advantageous for increasing the energy and size of the battery. Instead of the metal cans made of iron or aluminum, attention has been paid to a laminated sealed battery using a film-like exterior material that can be made thinner and whose structure can be determined freely.

  The film-shaped exterior material is formed by laminating and laminating a metal film such as an aluminum foil capable of preventing permeation of electrolyte solution, moisture and gas, and a plastic film such as nylon, polyethylene, and polypropylene. . When this metal laminate resin film is used as a battery outer packaging material, a structure is generally employed in which the outer periphery of the film-shaped outer packaging material is sealed by thermal fusion in a state where the battery element is accommodated.

  When adopting the above sealing structure, the form of the film-like exterior material is roughly divided into two types, one is forming the film-like exterior material as it is in a bag shape and storing the battery element inside The form to do is adopted.

  The other is a form in which an embossing process is performed on the film-shaped exterior material and the battery element is accommodated in the embossed part. In the latter form, since the drawn portion that matches the shape of the battery element to be housed is formed, the proportion of the battery element in the entire battery volume is increased compared to the former bag-shaped exterior material. There is an advantage that the battery capacity can be increased.

  For example, in Patent Document 1, an insulating resin film is also heat-sealed to a portion inside a battery of an external terminal extending from a power generation element that is a battery element, and the insulating resin film is heat-sealed. It is described that the external terminal portion is bent along the power generation element in the internal space of the drawn portion to increase the battery capacity.

Japanese Patent Laying-Open No. 2005-222901 (FIG. 1)

  7 to 9 are views showing a conventional stacked sealed battery, FIG. 7 is a perspective view of the conventional stacked sealed battery, FIG. 8 is an exploded perspective view of the conventional stacked sealed battery, and FIG. It is a side view at the time of liquid injection of a laminated sealed battery.

  As shown in FIG. 8, a battery element in which the negative electrode current collector exposed portion 3 is connected to the negative electrode tab 5, the positive electrode current collector exposed portion 4 is connected to the positive electrode tab 6, and the positive electrode and the negative electrode are stacked via a separator. 2 is accommodated in the film-shaped exterior material 1. The battery element 2 including the current collector is housed inside the film-shaped exterior material 1, and as shown in FIG. 9, the negative electrode tab 5 and the positive electrode tab 6 are pulled out to the outside, and the outer periphery of the film-shaped exterior material 1 Three sides are heat-sealed to form the sealing portion 18.

  As shown in FIG. 9, the electrolyte solution 7 is injected from a side that is not thermally fused using a metering pump or the like. The battery element is impregnated with the electrolytic solution 7 by being left for a certain period of time under vacuum conditions, and a sealed portion is formed by thermal fusion at the side not thermally fused in the vacuum state.

  In order to meet the technical demands for higher energy and higher capacity of the laminated sealed battery, the battery element 2 tends to increase in volume. However, if the laminated sealed battery is made thick, heat may be accumulated inside the battery by repeatedly charging and discharging the battery. Therefore, in order to prevent heat accumulation in the battery and to cope with a higher capacity, the electrode area of the laminated sealed battery tends to be increased.

  As the electrode area increases, the electrolytic solution 7 is less likely to be impregnated to the center of the battery element 2, and there is a problem that gas such as air tends to accumulate inside the battery element 2.

  The reason for this is that when the electrolyte solution is injected between the negative electrode and the positive electrode of the battery element 2 and the separator, the electrolyte solution 7 is impregnated from the periphery of the battery element 2 so that the negative electrode, the separator and the positive electrode are in close contact with each other. This is because the gas accumulated in the battery element 2 cannot be discharged.

  A portion where the electrolyte element 7 is not impregnated in the battery element 2 creates a space between the separator and the electrode and does not adhere to the separator 10, and the separator 10 is liable to be wrinkled. As shown in FIG. There is a problem that it is recognized as a wrinkle 17 and becomes a defect in appearance and deteriorates the yield.

  Moreover, when charging / discharging the battery element 2 in a state where the electrolytic solution 7 is not impregnated, the electrode portion corresponding to the space not impregnated with the electrolytic solution 7 cannot contribute to charging / discharging, and the battery capacity decreases. There are also challenges.

  Accordingly, an object of the present invention is to provide a laminated sealed battery that has a structure having no appearance defect by impregnating the entire battery element 2 with the electrolytic solution 7 and can contribute to charge and discharge.

In order to solve the above-described problems, a laminated sealed battery according to the present invention is a laminated sealed battery in which a battery element in which a negative electrode and a positive electrode are stacked via a separator is housed in an exterior material, and the negative electrode has a front and back sides. A negative electrode side through hole penetrating therethrough is provided, and at least one set of positive electrode side through holes having the same or larger plane area than the negative electrode side through hole is provided at a position corresponding to the negative electrode side through hole in the positive electrode. It is characterized by that. Further, a plane area of the negative electrode is characterized in that a one of the negative electrode side through hole for each 0.02 m ² at 0.02 m ² or more. Furthermore, the planar area of the negative electrode side through hole is 0.5-2.0 mm ² .

  That is, according to the present invention, when the battery element is impregnated with the electrolytic solution, the negative electrode side through hole and the positive electrode side penetration can be obtained even when the battery element cannot be impregnated with the electrolytic solution and an air pocket is generated. A stacked hermetic battery that can escape to the outside of the battery element through the hole is obtained.

  The present invention impregnates the entire battery element with an electrolyte, prevents air from accumulating inside, the electrode and the separator are in close contact, there is no defect in the appearance of the battery, and the entire battery element can contribute to charge and discharge. There is an effect that a battery is obtained.

1 is a schematic perspective view of a part of a battery element according to Embodiment 1 of the present invention. The top view which shows the positive electrode, negative electrode, and separator which are used for the battery element concerning Embodiment 1 of this invention. 1 is a schematic cross-sectional view of a part of a battery element according to Embodiment 1 of the present invention. The perspective view of the lamination type sealed battery of the present invention. The top view which shows the positive electrode, negative electrode, and separator which are used for the battery element concerning Embodiment 2 of this invention. The typical perspective view of a part of battery element concerning Embodiment 2 of this invention. The perspective view of the conventional laminated sealed battery. The disassembled perspective view of the conventional laminated sealed battery. The side view at the time of liquid injection of the conventional multilayer sealed battery.

  Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, a laminated sealed battery according to Embodiment 1 of the present invention includes a film-shaped exterior material 1, a battery element 2 housed in the exterior material 1, and a negative electrode drawn from the battery element 2. It is mainly composed of a negative electrode tab 5 and a positive electrode tab 6 connected to the current collector exposed portion 3 and the positive electrode current collector exposed portion 4, respectively, and an electrolyte solution 7 impregnated in the battery element 2.

  As shown in FIG. 2, the battery element 2 is configured by interposing a separator 10 between a negative electrode 8 and a positive electrode 9 and laminating a plurality of each.

  As shown in FIG. 3, the negative electrode 8 is obtained by forming a negative electrode active material 13 on a negative electrode current collector 14. A negative electrode active material 13 made of graphite powder and a preparation prepared in a slurry state together with an adhesive made of PVDF were applied to both sides of a negative electrode current collector 14 made of metal such as copper, dried, and rolled by a roll press. It is formed by doing. A negative electrode side through hole 11 is formed in the negative electrode 8. In the first embodiment, a negative electrode side through hole 11 is formed in the central portion of the negative electrode 8. Formation of the negative electrode side through hole can be performed by processing with a press machine or the like after rolling.

  As shown in FIG. 3, the positive electrode 9 is obtained by forming a positive electrode active material 15 on a positive electrode current collector 16. A formulation prepared by adding an adhesive made of PVDF and a conductive agent made of acetylene black to a positive electrode active material made of lithium cobalt oxide and adjusted to form a slurry is formed on both surfaces of the positive electrode current collector 16 made of a metal such as aluminum. The positive electrode 9 is formed by coating, drying, and rolling with a roll press. Formation of the positive electrode side through hole can be performed by pressing or the like after rolling.

  The positive electrode 9 corresponding to the negative electrode side through hole 11 is formed with a positive electrode side through hole 12 that is equal to or larger than the area of the negative electrode side through hole 11.

  A separator 10 is interposed between the negative electrode 8 and the positive electrode 9 and a predetermined number of layers are stacked to produce a battery element. The positive electrode side through hole 12 has a size relationship as contained in the negative electrode side through hole 11. And by setting such a magnitude relationship, precipitation of lithium metal during charging / discharging is avoided.

  The separator 10 is made of polyethylene or polypropylene. The separator 10 has a large number of small holes throughout.

  As shown in FIG. 4, the negative electrode tab 5 is welded to the negative electrode current collector exposed portion of the battery element. Further, the positive electrode tab 6 is welded to the exposed portion of the positive electrode current collector of the battery element.

  The film-shaped exterior material 1 has a three-layer structure of nylon / aluminum / polypropylene. In order to accommodate the battery element, the exterior material 1 is provided with a storage portion by drawing so that the polypropylene side is concave.

  The tab-welded battery element is stored in the battery element storage portion of the outer packaging material 1, the battery element is covered with the other outer packaging material 1, the joints are overlapped, and the outer periphery 3 of the outer packaging material 1 is sealed by thermal fusion. A stop 18 is formed (see FIG. 9). The electrolyte solution 7 is poured into the battery element housing part from one side that is not heat-sealed, and after the liquid is poured, sealing is performed by heat-sealing in a vacuum, and a laminated hermetic seal having a sealing part on the outer periphery of the exterior material 1 A type battery is produced.

  As shown in FIG. 3, the air accumulated in the battery element during the injection is discharged out of the battery element through the negative electrode side through hole 11, the positive electrode side through hole 12, and the small holes of the separator. Thus, no air remains inside the battery.

When the area of the negative electrode is 0.02 m ² or more, as shown in FIG. 2, the negative electrode side through hole 11 having a diameter of about 1 mm is formed at the center of the negative electrode 8, and the positive electrode corresponding to the negative electrode side through hole 11 is φ1.5 mm. Providing the positive electrode side through hole 12 to the extent can prevent the air in the battery element 2 from remaining. The size of the negative electrode side through hole is preferably 0.5 to 2.0 mm ² (diameter 0.8 to 1.6 mm) as a flat area. Even if wrinkles do not occur when it exceeds 2.0 mm ² , it is easily recognized as the shape of the hole and appearance defects are likely to occur, which is not preferable. Moreover, when less than 0.5 mm < ² >, it is unpreferable from workability | operativity at the time of the impregnation of electrolyte solution, discharge | emission of gas, and a process.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, a case where two negative through holes and two positive through holes are provided will be described. As shown in FIG. 5, two negative side through holes 11 having a diameter of about 1 mm are provided in the vicinity of the center in the width direction of 1/3 from the end when the negative electrode 8 is divided into three equal parts in the length direction. The positive electrode 9 corresponding to 11 is provided with two positive-side through holes 12 having a diameter of about 1.5 mm. A battery element is formed by stacking a plurality of separators with a separator interposed between the negative electrode and the positive electrode, and a film-shaped exterior member 1 and a battery element 2 accommodated in the exterior member 1 as shown in FIG. And a negative electrode tab 5 and a positive electrode tab 6 respectively connected to the negative electrode current collector exposed portion 3 and the positive electrode current collector exposed portion 4 drawn from the battery element 2, and the electrolyte 7 is placed inside the battery element 2. Inject and impregnate. After pouring, sealing is performed by heat sealing in vacuum, and a laminated sealed battery having a sealing portion on the outer periphery of the outer packaging material 1 is manufactured. When the negative electrode area is 0.04 m ² or more, there may be cases where the negative electrode side through hole and the positive electrode side through hole are not sufficient in one place, and the negative electrode side through hole and the positive electrode side through hole are provided every 0.02 m ^2. Providing at least one location for each can sufficiently prevent air in the battery element from remaining. That 0.02 m ² or more 0.04m least one location is less than ^2, may 0.04m ² or 0.06m is less than ² providing through holes in at least two places.

  Hereinafter, examples and comparative examples according to the present invention will be described.

Example 1
Example 1 will be described with reference to FIGS. 1 to 3 used in the first embodiment. As shown in FIG. 3, the negative electrode active material 13 is formed on a negative electrode current collector 14 made of a copper foil having a thickness of 10 μm. A negative electrode 8 is formed by applying a negative electrode active material made of graphite powder on both sides of the negative electrode current collector 14 with a slurry prepared together with an adhesive made of PVDF, drying it, and rolling it with a roll press. It was. The area where the negative electrode active material 13 was applied was 200 mm long and 100 mm wide, and a negative electrode side through hole 11 having a diameter of 0.8 mm was formed in the center of the negative electrode 9.

  The positive electrode active material 15 is formed on a positive electrode current collector 16 made of an aluminum foil having a thickness of 20 μm. The positive electrode active material made of lithium cobaltate was coated on both sides of the positive electrode current collector 16 with a preparation adjusted to form a slurry by adding an adhesive made of PVDF and a conductive agent made of acetylene black, and dried. The positive electrode 9 was formed by rolling with a roll press. The area where the positive electrode active material 13 was applied was 198 mm long and 98 mm wide. Further, a positive electrode side through hole 12 having a diameter of 1.5 mm was formed in the central portion of the positive electrode 9 corresponding to the negative electrode side through hole 11.

  Between the negative electrode 8 and the positive electrode 9, 9 negative electrodes and 8 positive electrodes were laminated via a polyethylene nonwoven fabric separator 10 to produce a battery element. As shown in FIG. 1, the negative electrode tab 5 was welded at the tip of the negative electrode current collector exposed portion 3. The positive electrode tab 6 was welded at the tip of the positive electrode current collector exposed portion 4. The film-shaped exterior material has a three-layer structure of nylon / aluminum / polypropylene, and a storage portion by drawing is provided so that the polypropylene side is concave to store the battery element 2.

  The battery element 2 to which the tab is welded is stored in the battery element housing portion of the film-shaped outer packaging material 1 that has been subjected to drawing processing, and the battery element is similarly covered with the outer packaging material 1 that has been subjected to drawing processing. Thus, the outer periphery 3 sides of the exterior material 1 were fused. The electrolyte solution 7 was injected into the battery element storage portion from one side that was not heat-sealed. After the liquid injection, sealing was performed in a vacuum with a heat-sealing machine, and a laminated sealed battery covered with a film-like exterior material 1 was produced.

  The length of the wrinkles on the surface of the film-shaped outer packaging material 1 of the three laminated sealed batteries produced was measured. Further, the stacked sealed battery was charged, and the actual charge capacity / theoretical charge capacity was calculated.

(Example 2)
A laminated sealed battery was prepared in the same manner as in Example 1 except that the negative electrode side through hole was φ1.6 mm and the positive electrode side through hole was φ1.8 mm, the wrinkle length was measured, and the charge capacity was calculated.

(Comparative Example 1)
A laminated sealed battery was produced in the same manner as in Example 1 except that no through hole was provided in the negative electrode and the positive electrode. The length of the wrinkle on the surface of the film-like exterior material of the produced laminated sealed battery was measured. Further, charging was performed in the same manner as in Example 1, and the actual charge capacity / theoretical charge capacity was calculated.

  The relationship between the wrinkle length of the film-like exterior material surface and the actual charge capacity / theoretical charge capacity was investigated. The results are shown in Table 1.

  In Comparative Example 1, a total wrinkle length of 90 mm occurs on the surface of the film-shaped exterior material, but in Examples 1 and 2, the presence of electrode through holes can prevent the occurrence of air accumulation in the battery element, and the appearance A laminated sealed battery free from defects was obtained. For the same reason, in Comparative Example 1, the actual charge capacity / theoretical charge capacity was as low as 0.97, but in Example 1, it was 1.00, and a theoretical charge capacity could be obtained.

(Example 3)
Next, Example 2 of the present invention will be described with reference to FIGS. 5 and 6 used in the description of Embodiment 2 according to the present invention. The basic manufacturing method of the laminated sealed battery is the same as that in Example 1. However, the negative electrode and the positive electrode were increased in size to a width of 200 mm, a length of 210 mm, a width of 198 mm, and a length of 208 mm, respectively. The difference is that there are two through holes. The negative electrode side through hole 11 was formed with a diameter of 1.0 mm at the central portion in the width direction at 1/3 from the end when the negative electrode 8 was divided into three equal parts, that is, 70 mm from the end. Corresponding positive electrode side through-holes 12 were formed with a diameter of 1.5 mm.

  The length of the wrinkles on the surface of the film-like exterior material of the three laminated sealed batteries produced was measured. Further, the stacked sealed battery was charged, and the actual charge capacity / theoretical charge capacity was calculated.

(Comparative Example 2)
A laminated sealed battery was produced in the same manner as in Example 2 except that no through hole was provided in the negative electrode and the positive electrode. The wrinkle length of the film-like exterior surface of the produced laminated sealed battery was measured. Moreover, it charged similarly to Example 2, and calculated actual charge capacity / theoretical charge capacity.

  The relationship between the wrinkle length of the film-like exterior material surface and the actual charge capacity / theoretical charge capacity was investigated. The results are shown in Table 2.

  In Comparative Example 2, wrinkles are generated on the surface of the film-like exterior material in total of 150 mm. However, in Example 3, since there are two through holes in the electrode, it is possible to prevent the occurrence of air accumulation in the battery element, Thus, a laminated sealed battery was obtained. For the same reason, in Comparative Example 2, the actual charge capacity / theoretical charge capacity was as low as 0.94, but in Example 3, the charge capacity was 1.00, and a theoretical charge capacity could be obtained.

DESCRIPTION OF SYMBOLS 1 Exterior material 2 Battery element 3 Negative electrode collector exposed part 4 Positive electrode collector exposed part 5 Negative electrode tab 6 Positive electrode tab 7 Electrolytic solution 8 Negative electrode 9 Positive electrode 10 Separator 11 Negative electrode side through-hole 12 Positive electrode side through hole 13 Negative electrode active material 14 Negative electrode current collector 15 Positive electrode active material 16 Positive electrode current collector 17 Wrinkle 18 Sealing portion

Claims (3)

  A stacked-type sealed battery in which a battery element in which a negative electrode and a positive electrode are stacked via a separator is housed in an exterior material, wherein the negative electrode is provided with a negative-side through hole penetrating the front and back, and the negative electrode side of the positive electrode A laminated sealed battery characterized in that at least one set of positive electrode side through holes having the same or larger plane area than the negative electrode side through hole is provided at a position corresponding to the through hole. ^2. The stacked sealed battery according to claim 1, wherein one negative electrode side through hole is provided for every 0.02 m ² when a plane area of the negative electrode is 0.02 m ² or more. 3. The laminated sealed battery according to claim 1, wherein a planar area of the negative electrode side through hole is 0.5 to 2.0 mm ^{2. 4} .

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