JP2006164784A - Film-armored electric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability film-armored electric device where air tightness of a sealed space in armoring films is hardly impaired. <P>SOLUTION: A film-armored battery 50 has a sheet-like electrode tab 15a extracted from an internal battery element, and the electrode tab 15a is sandwiched between two armoring films 21a and 21b. A thin part 18 is formed in the vicinity of an end of at least one side in the width direction of the electrode tab 15a. In the thin part 18, the plate thickness of the electrode tab 15a is gradually reduced toward the outside in the width direction of the electrode tab 15a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film-clad electrical device in which electrical device elements that store and output electrical energy, such as chemical battery elements and capacitor elements, represented by batteries and capacitors, are sealed with a packaging material made of a film. .

  Conventionally, development of a lightweight and thin battery as a power source for driving a motor of an electric vehicle or a hybrid electric vehicle (hereinafter simply referred to as an “electric vehicle or the like”) has been underway. As an example of this type of battery, an assembled battery is known in which a plurality of film-clad batteries are stacked to obtain a predetermined voltage.

  FIG. 8 is a diagram illustrating an example of a conventional film-clad battery disclosed in Patent Document 1. In FIG. As shown in FIG. 8, the film-clad battery 150 includes a battery element 120 disposed in a sealed space formed by the two exterior films 130 a and 130 b, and is electrically connected to the battery element 120. It has the electrode tab 125a for positive electrodes and the electrode tab 125b for negative electrodes pulled out from the sealing part of 130a, 130b. The battery element 120 is obtained by alternately laminating positive and negative plates through separators, and outputs a predetermined voltage by being housed in a sealed space in an exterior film together with a predetermined electrolyte. .

FIG. 9 is a plan view showing the electrode tab 125a and its peripheral structure of the film-clad battery 150 of FIG. 8 as viewed from the direction of arrow B in FIG. As shown in FIG. 9, the plate thickness of the electrode tab 125a is constant over the entire width direction. Therefore, the two exterior films 130a and 130b are bent at a relatively steep angle along the outer peripheral surface of the electrode tab 125a at the end portion (right end portion in the drawing) of the electrode tab 125a.
JP 2004-95471 A

  However, since the plate thickness of the electrode tab is constant in the conventional configuration as described above, as shown in FIG. 9, the gap between the end portion of the electrode tab 125a and each inner side surface of the exterior films 130a and 130b. There is a possibility that the air gap 135 may be generated. Such a gap 135 causes a decrease in the airtightness of the sealed space in the exterior film. If the gap 135 communicates with the sealed space inside, the electrolyte enclosed in the sealed space passes through the gap 135. There is also a risk of leaking outside. On the contrary, if moisture enters the gap 135, it may cause corrosion of the electrode tab.

  In any case, the presence of such a gap 135 is not preferable because it causes the electrical performance of the film-clad battery to deteriorate or the life of the battery to be shortened. In addition, the battery has been described above as an example, but such a problem may occur in a film-covered electric device in which an electric device element including a capacitor or the like is housed in an outer film instead of the battery element 120. is there.

  In FIG. 9, when the thickness of the electrode tab 125a is thin, the gap 135 is relatively less likely to be generated, but the gap 135 is more likely to be generated as the thickness of the electrode tab is increased. On the other hand, in recent technological development, the performance of the battery element 120 has been improved, and the battery element 120 can output a higher current. In order to cope with the high performance of the battery element 120, it is necessary to increase the cross-sectional area of the electrode tabs 130a and 130b. For this purpose, the thickness of the electrode tab may need to be increased. From such a technical background, it is preferable that the gap 135 is not easily generated even when a relatively thick electrode tab is used.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a highly reliable film-covered electrical device in which the airtightness of the sealed space in the exterior film is not impaired. .

  In order to achieve the above object, according to the film-covered electrical device of the present invention, an electrical device element that stores and outputs electrical energy is enclosed in a sealed space formed by the exterior film and is electrically connected to the electrical device element. In the film-covered electrical device in which a sheet-like electrode tab connected to the exterior film is drawn out from the sealing portion between the exterior films, the electrode tab is at least one end in the width direction of the electrode tab in the sealing portion. In the vicinity, the electrode tab has a thin portion where the plate thickness gradually decreases toward the outside.

  In the film-clad electrical device of the present invention, in the thin portion, one surface of the electrode tab may be flat and the other surface may be an inclined surface. Moreover, in the sealing part, the sealing material may be inserted | pinched between the inner surface of each said exterior film, and the said electrode tab outer peripheral surface. As the exterior film, a laminate film including at least a heat-sealing resin layer and a non-air-permeable layer for hermetically sealing the sealed space can be used. In this case, the heat-sealing resin layer and the sealing material include It is preferable that they are heat-sealed to each other.

  According to the film-covered electrical device of the present invention as described above, since the thin portion is formed in the vicinity of the end portion of the electrode tab in the sealing portion of the exterior film, the exterior is provided when the electrode tab is sandwiched between the exterior films. Since air gaps are less likely to occur between the film and the electrode tab, even when using a relatively thick electrode tab, the hermeticity of the sealed space in the exterior film is unlikely to be impaired, High reliability of the film-clad electrical device can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a film-clad battery will be described as an example of the film-clad electrical device of the present invention. FIG. 1 is an external perspective view of the film-clad battery of this embodiment. FIG. 2 is an exploded perspective view showing the configuration of the film-clad battery of FIG.

  As shown in FIGS. 1 and 2, the film-covered electrical device 50 has a battery element 10 that is enclosed in a sealed space formed by two exterior films 21 a and 21 b and stores and outputs electrical energy. ing.

  The battery element 10 is, for example, a lithium ion secondary battery generally used for this type of film-clad battery, and outputs a predetermined voltage by being sealed together with an electric field liquid in a sealed space in the exterior film. Although not shown in detail, the battery element 10 is made by alternately laminating metal foils for positive electrodes and negative electrodes via separators, and the total thickness thereof is, for example, about several mm to several tens of mm. . Moreover, in this embodiment, the battery element 10 has a rectangular outline shape, and electrode tabs 15a and 15b are drawn out from the respective short sides.

  As shown in FIG. 2, the exterior films 21a and 21b sandwich and surround the battery element 10 from both sides in the thickness direction. The exterior films 21a and 21b are, for example, laminate films, and specifically, a resin layer having heat-fusibility, a non-venting layer made of a metal thin film, and a protective layer made of polyamide synthetic fiber or the like in this order. Is laminated. The exterior films 21a and 21b are arranged so that the surfaces facing each other become the resin layer. Thereby, by heating in a state where the resin layers of the exterior films 21a and 21b are in close contact with each other, the close contact portions are thermally melted together. Eventually, the part joined by this thermal melting becomes a sealing part 23 as shown in FIG. The sealing portion 23 is formed over the entire outer periphery of the exterior film so as to surround the battery element 10.

  Each of the electrode tabs 15a and 15b is formed of a sheet-like metal thin plate having a thickness of about 300 μm, for example. In the present embodiment, the electrode tab 15a is a positive electrode terminal, and the material thereof is, for example, aluminum or a ruminium alloy. The electrode tab 15b is a terminal for a negative electrode, and the material thereof is, for example, copper or an alloy.

  In the film-clad battery 50 configured as described above, as described above, the battery element 10 is enclosed with the electrolytic solution in the sealed space of the exterior film, and a predetermined voltage is extracted from the electrode tabs 15a and 15b. . Therefore, it is preferable that the sealed space formed by the exterior film is surely airtight. If this airtightness is impaired, the entire film exterior battery 50 may fail.

  Therefore, in the present embodiment, the thin portion 18 (see FIG. 2) is provided on the electrode tab so that the airtightness is not easily lost. Hereinafter, the thin portion 18 and its peripheral structure will be described in detail with reference to FIGS. 3 and 4 in addition to FIG. FIG. 3 is a perspective view showing the electrode tab and the peripheral structure of the film-clad battery of this embodiment, and shows a state viewed from the direction of arrow A in FIG. FIG. 4 is a perspective view showing a thin portion formed on the electrode tab. In addition, although the thin part 18 is formed in both the electrode tabs 15a and 15b, it demonstrates below taking the one electrode tab 15a as an example.

  As shown in FIG. 2, the electrode tab 15a is a region sandwiched between the sealing portions 23 of the exterior film, and the thin portions 18 are formed on both sides in the width direction (depth direction of FIG. 2) of the electrode tab 15a. Yes. As shown in FIG. 3, the thin-walled portion 18 is a structural portion formed such that the plate thickness of the electrode tab 15a gradually decreases toward the outside (right side in the drawing). As shown in FIG. 4, the thin portion 18 can be formed by, for example, pressing the vicinity of the end of the electrode tab 15a from both side surfaces. In this case, inclined surfaces 16a and 16b are formed on the upper and lower surfaces of the electrode tab 15a.

  Further, when the thin portion 18 is formed by pressing, as shown in FIG. 4, the thin portion 18 may slightly extend from the side edge of the electrode tab 15a. There is no particular problem. However, if inconvenience arises due to the extension of the thin portion 18, the extension portion may be partially cut afterwards. In addition, as such an inconvenience, the case where the width | variety of the electrode tab 15a is as wide as the length of the short side of exterior film 21a, 21b is mentioned, for example. In addition, for example, when a jig is used in the process of sandwiching the electrode tab 15a between films, the width of the electrode tab 15a needs to be set within a predetermined size range in advance due to the structure of the jig. Such as when.

  Next, an example of a step of sandwiching the electrode tab 15a having the thin portion 15 formed in this manner between the two exterior films 21a and 21b will be described.

  In this step, two sheet-like seal members 30a and 30b (see FIG. 2) are used. For example, the sealing members 30a and 30b are melted to each other by being heated, and become an integral member (see the sealing material 30, see FIG. 3) after being melted. Specifically, an adhesive or a caulking material is used. For example, it may be made of any one of polypropylene, modified polypropylene, polyethylene, modified polyethylene, and the like. As will be described later, since the sealing material 30 is a member for maintaining the airtightness of the sealed space in the exterior film, it is preferable to select a material excellent in chemical resistance and water resistance.

  First, the sealing members 30a and 30b are respectively disposed on the inner side surfaces (resin layers) of the exterior films 21a and 21b. Here, you may arrange | position so that a sealing member may protrude slightly from the side edge of an exterior film. Next, the battery element 10 prepared in advance is placed on the exterior film 21b. Next, the two exterior films 21a and 21b are overlapped so that the outer peripheral portions overlap each other. Next, by heating the outer peripheral portions of the two exterior films 21a and 21b, the exterior films are joined together to form the sealing portion 23. In this heating process, the two sealing members 30a and 30b are also heated at the same time, and are melted together to finally become an integral sealing material 30 as shown in FIG.

  The sealing material 30 is formed so as to fill a gap between the inner side surfaces of the exterior films 21a and 21b and the outer peripheral surface of the electrode tab 15a. Thereby, the airtightness of the sealed space in the exterior film is further improved. Thus, from the viewpoint of improving the airtightness, it is preferable that the sealing members 30a and 30b are melted together with the resin layer of the exterior film (laminate film) when heated. Thereby, since the sealing material 30 finally formed and the resin layer of the laminate film are integrally joined, the sealing material 30 and the resin layer are difficult to peel off, and the airtightness of the sealed space in the exterior film is reduced. More improved.

  According to the film-clad battery 50 of the present embodiment as described above, as shown in FIG. 3, the thin part 18 is formed in the vicinity of the end of the electrode tab 15a, and each of the external films 21a and 21b is a thin part. Bend along 18 inclined surfaces 16a and 16b. Therefore, as compared with the conventional configuration in which the corners remain on the electrode tab 125a as shown in FIG. 9, the angle of bending of each of the exterior films 21a and 21b becomes relatively gentle. A gap 135 (see FIG. 9) hardly occurs between the inner side surface and the outer peripheral surface of the electrode tab. Further, such an effect can be obtained in the same manner even when the electrode tab 15a having a relatively thick plate thickness is used. Therefore, the present invention particularly provides a battery element that outputs a high current. This is advantageous when 10 is used. This is because, as described above, when the battery element 10 that outputs a high current is used, the electrode tab 15a may have to be thicker.

  Moreover, the formation of the thin portion 18 on the electrode tab as described above has an advantage that the sealing material 30 can be effectively used. That is, as shown in FIG. 5, when using the electrode tab 125 a having a conventional shape and forming the sealing material 30 between the electrode tab 125 a and the exterior films 21 a and 21 b, the thickness of the electrode tab 125 a or the sealing material 30 Depending on the characteristics, the bubbles 31 may be generated in the sealing material 30. On the other hand, if the thin portion 18 is formed as in this embodiment, when the two sheet members 30a and 30b (see FIG. 2) are heated, the sheet members 30a and 30b melt relatively easily. As a result, the bubbles 31 are less likely to be generated as compared with the configuration of FIG.

  However, in this embodiment, the sealing material 30 is used to further improve the airtight reliability of the sealed space in the exterior film, but the sealing material 30 is not necessarily required. Even if the sealing material 30 is not provided, the bend angle of the exterior films 21a and 21b becomes gentle due to the formation of the thin portion 18, and as a result, the advantage of the present invention that the gap 135 is hardly generated can be obtained. it can.

  In addition, this invention is not limited to what was mentioned above, The shape or material of each component of the film-clad electrical device of this invention can be variously changed.

  In the embodiment described above, the two thin portions 18 are formed on both sides of the electrode tab 15a in the width direction. However, the thin portions 18 may be formed on at least one side of the electrode tab. Moreover, although the step shape of the electrode tab 15a described above is a shape as shown in FIG. 6A, the thin portion 19 having a shape as shown in FIG. 6B may be used. That is, in the thin portion 19 of FIG. 6B, an inclined surface is formed only on the upper surface of the electrode tab 15a, and the lower surface of the electrode tab 15a remains flat. Even if the thin-walled portion 19 has such a shape, the same effect as the thin-walled portion 18 described above can be obtained because the thickness of the tab in the thin-walled portion 19 gradually decreases toward the outside. Moreover, since one surface (lower surface) of the thin part 19 remains flat, it is not necessary to bend the exterior film 21b arranged on the lower surface side.

  Next, the formation of the thin portion can also be performed by a method as shown in FIG. The electrode tab 17 shown in FIG. 7A shows a state before the thin portion is formed. In the vicinity of the end of the electrode tab 17, for example, a semicircular cutout 17 a is formed in advance. Next, when the portion around the notch 17a is pressed, as shown in FIG. 17B, the pressed portion is deformed while being thinned, and the thin portion 20 is formed. Thus, by providing the notch part 17a previously, the side edge of the thin part 20 finally formed can be made to correspond substantially to the side edge of the electrode tab 17. FIG. In other words, the shape of the notch portion 17a may be set as appropriate in consideration of the thickness or material of the tab so that the thin portion 20 as shown in FIG. 17B can be formed. For forming the thin portion, grinding, peening, or the like can be used in addition to pressing. However, as shown in FIG. 7C, the thin-walled portion 20 'may be formed with the notch remaining.

  Although not described in detail in the above description, the battery element 10 that is a lithium ion secondary battery, specifically, a positive electrode active material such as lithium-manganese composite oxide or lithium cobaltate is used as an aluminum foil or the like. A positive electrode plate coated on both sides of the electrode and a negative electrode plate coated with a lithium-doped / de-doped carbon material on both sides of a copper foil or the like are opposed to each other through a separator and impregnated with an electrolyte containing a lithium salt. It may be a thing. In addition to the lithium ion secondary battery, the battery element 10 may be a battery element of other types of chemical batteries such as a nickel metal hydride battery, a nickel cadmium battery, a lithium metal primary battery or secondary battery, and a lithium polymer battery. . Further, the battery element 10 is not limited to the stacked type as in the present embodiment, and a belt-like positive electrode side active electrode and a negative electrode side active electrode are stacked with a separator interposed between them, and then compressed into a flat shape. The winding type of the structure where the positive electrode side active electrode and the negative electrode side active electrode were laminated | stacked alternately by this may be sufficient. The present invention also relates to a film-clad battery device in which an electrical device element that stores or outputs electrical energy, such as a capacitor element exemplified by a capacitor such as an electric double layer capacitor or an electrolytic capacitor, is enclosed in an exterior film. Applicable.

It is an external appearance perspective view of the film-clad battery of this embodiment. It is a disassembled perspective view which shows the structure of the film-clad battery of FIG. It is a perspective view which shows the electrode tab of the film-clad battery of this embodiment, and its periphery structure, and has shown the state seen from the arrow A direction of FIG. It is a perspective view which shows the thin part formed in the electrode tab. It is a figure for demonstrating the problem at the time of utilizing the conventional electrode tab. It is sectional drawing which shows the other example of the thin part formed in an electrode tab. It is a perspective view which shows the other example of the method of forming a thin part, and the other example of a thin part. It is a figure which shows an example of the conventional film-clad battery. It is a top view which shows the electrode tab of the film-clad battery of FIG. 8, and its surrounding structure seeing from the arrow B direction of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Battery element 15a, 15b, 17 Electrode tab 16a, 16b Inclined surface 18, 19, 20, 20 'Thin part 21a, 21b Exterior film 23 Sealing part 30a, 30b Seal member 30 Sealing material 31 Bubble 50 Film exterior battery

Claims (4)

An electrical device element for storing and outputting electrical energy is enclosed in a sealed space formed by the exterior film, and a sheet-like electrode tab electrically connected to the electrical device element is formed between the exterior films. In the film-covered electrical device pulled out from the sealing part,
The electrode tab has a thin-walled portion in which the plate thickness of the electrode tab gradually decreases toward the outside in at least one end portion in the width direction of the electrode tab in the sealing portion. Film exterior electrical device.   The film-covered electrical device according to claim 1, wherein in the thin portion, one surface of the electrode tab is flat and the other surface is an inclined surface.   3. The film-covered electrical device according to claim 1, wherein a sealing material is sandwiched between an inner surface of each of the exterior films and an outer peripheral surface of the electrode tab in the sealing portion.   The exterior film is a laminate film including at least a heat-sealing resin layer and a non-air-permeable layer for hermetically sealing the sealed space, and the heat-sealing resin layer and the sealing material are heat-sealed to each other. The film-clad electrical device according to claim 3.

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