JP2019160825A - Sealing structure for electrochemical element - Google Patents

Abstract

To provide a sealing structure for an electrochemical element capable of preventing dielectric breakdown inside a capacitor.SOLUTION: A sealing structure for an electrochemical element comprises: a capacitor body 1 which is configured such that a plurality of positive polarizable electrodes and a plurality of negative polarizable electrodes are alternately laminated; a positive current collector terminal 18A connected to each of the positive polarizable electrodes; a negative current collector terminal 18B connected to each of the negative polarizable electrodes; and a laminate film 2 which internally houses the capacitor body 1, and whose opening end is heat-welded with the positive and negative current collector terminals 18A and 18B extending from the opening end. The sealing structure for the electrochemical element further comprises an inter-terminal film 3 which is made of an insulation member formed into a film shape. The inter-terminal film 3 is arranged so as to extend along the opening end of the laminate film 2, and is interposed at least between the laminate film 2 and a minor angle side of bending portions of the positive and negative current collector terminals 18A and 18B.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sealing structure for an electrochemical element.

  An electric double layer capacitor (hereinafter referred to as a capacitor) is mainly composed of a pair of opposed activated carbon electrodes and a separator that electrically separates the electrodes, and a cell made of an organic electrolyte that develops capacity, and electrical insulation between the cells. And packing for preventing liquid leakage, and a collecting electrode and a lead wire for taking out electricity.

  For example, in Patent Document 1 below, a positive electrode plate and a negative electrode plate are wound in a spiral shape through two separators, and are crushed to weld a negative electrode tab to a copper foil exposed portion of the negative electrode and to form positive electrode aluminum. The electrode body formed by welding the positive electrode tab to the exposed foil portion is housed in a so-called cup-molded laminate exterior in which a known laminate film of a predetermined size is folded in two, and is topped using a bar-shaped mold. It is disclosed that the electrode body is sealed by welding the part and the side part, and that the negative electrode tab and the positive electrode tab are provided with a sealing material made of polypropylene resin.

  Further, in Patent Document 2 below, a battery element formed by alternately laminating a plurality of positive plates and a plurality of negative plates each coated with an electrode material via a separator is provided with two laminate films. The battery element is sealed by enclosing the outer periphery of the laminate film from above and below, and the peripheral portions of these laminate films are thermally welded. At this time, the resin film is previously applied to the positive electrode lead terminal and the negative electrode lead terminal. It is disclosed that it is heat welded.

JP 2005-108486 A JP-A-2005-116228

  Here, when sealing a single electrochemical element (hereinafter referred to as a single cell) with a laminate film, since the rated voltage is as low as about 2 to 4 V, it does not become an insulation problem between film terminals, Since current collector terminals (tabs, lead terminals, etc.) and laminate films are integrated by heating the heat-bonding layer, a large number of single cells are stacked in series for high voltage applications (for example, multilayer bipolar) In an electric double layer capacitor, etc., the insulation voltage borne between the positive electrode side and the negative electrode side is high, and a current collecting terminal and a heat-welding insulating layer (such as the above-mentioned sealing material, resin film, etc.) welded thereto, and a laminate film When the heat-welded layer is heat-pressed with a heat press device, the heat-welding insulating layer of the current collector terminal melts and the insulating layer becomes thin, and insulation between the current collector terminal metal and the laminate film Away there is a risk leading to dielectric breakdown not be maintained. If this breakdown occurs, an electric arc due to insulation failure may occur, the laminate film may be damaged, the airtightness may deteriorate, the function of the capacitor may not be maintained, and the capacitor may emit smoke or ignite. It was.

  Note that the place where the breakdown is likely to occur is a bent part with a crank shape when the current collector terminal is viewed from the side, and the welded layer of the laminate film and the metal base of the current collector terminal are too close. Therefore, dielectric breakdown may occur at a relatively low voltage. Then, when the voltage which leads to a dielectric breakdown was measured, it turned out that there is very dispersion | variation with 670-2.5 kV in an alternating voltage, and reliability has fallen.

  In view of the above, an object of the present invention is to provide an electrochemical element sealing structure capable of suppressing dielectric breakdown inside a capacitor with a simple configuration.

The sealing structure of an electrochemical element according to the first invention for solving the above-described problem is
An electrochemical element configured by alternately laminating a plurality of positive electrode cells and a plurality of negative electrode cells;
A positive collector terminal connected to the positive cell;
A negative collector terminal connected to the negative cell;
In the sealing structure of the electrochemical device, the electrochemical device is housed therein, and the positive electrode and the negative electrode current collecting terminals extend from the open end, and the laminate film is thermally bonded to the open end.
An insulating member formed in the form of a film, which extends along the opening end of the laminate film, and is interposed between at least the angle-reduced side of the bent portion of the current collector terminal of the positive electrode and the negative electrode and the laminate film. It is provided with the film between terminals to be equipped.

The sealing structure of the electrochemical device according to the second invention for solving the above-described problems is the first invention,
The laminate film and the inter-terminal film are heat-welded at a position closer to the opening end side than the bent portion of the current collecting terminal and away from the bent portion of the current collecting terminal, and the current collecting of the inter-terminal film The portion facing the bent portion of the terminal is not welded.

In addition, the electrochemical device sealing structure according to the third invention for solving the above-mentioned problems is the first or second invention,
The inter-terminal film includes a heat-resistant core material.

Moreover, the electrochemical device sealing structure according to the fourth invention for solving the above-described problems is any one of the first to third inventions,
The current collecting terminal is provided with an insulating member in a portion welded to the laminate film or the inter-terminal film,
The end of the insulating member on the front end side of the current collecting terminal is provided to protrude from the opening end by a predetermined length or more.

  According to the electrochemical element sealing structure of the present invention, it is possible to suppress dielectric breakdown inside the capacitor with a simple configuration.

It is a top view which shows typically the sealing structure of the electrochemical element which concerns on the Example of this invention. It is a front view which shows typically the sealing structure of the electrochemical element which concerns on the Example of this invention. It is sectional drawing which shows typically the state which looked at the sealing structure of the electrochemical element which concerns on the Example of this invention from the side surface. It is a front view of the film between terminals shown in FIG. It is sectional drawing which shows the structure of a capacitor typically. It is explanatory drawing which shows the structure of a laminate film typically.

  Hereinafter, the sealing structure of the electrochemical device according to the present invention will be described with reference to the drawings.

Details of the sealing structure of the electrochemical device according to the embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the electrochemical element sealing structure according to the present invention is applied to the bipolar electric double layer capacitor shown in FIG.

  As shown in FIG. 1 to FIG. 3, the electrochemical element sealing structure according to the present embodiment has a capacitor main body (electrochemical element) 1, a laminate film 2, an inter-terminal film 3, and a non-thermal welding insulation. Layer 4.

  As shown in FIG. 5, the capacitor body 1 includes an electrode portion 11, end plates 13A and 13B sandwiching the electrode portion 11 via insulating sheets (resin sheets) 12A and 12B, and an insulating spacer between the end plates 13A and 13B. Screws 15A and 15B that are tightened via (resin spacer) 14 and an insulating film (PET film) 16 that covers them are configured.

  The electrode unit 11 includes a laminate in which a plurality of positive polarizable electrodes (cells) 111A and a plurality of negative polarizable electrodes (cells) 111B are alternately laminated via a separator 112, and one of the laminates. Positive electrode collector plate 113 disposed at the terminal end (one end surface side), negative electrode collector plate 114 disposed at the other terminal end (the other end surface side) of the laminate, and between adjacent separators 112, A packing 115 is provided between the separator 112 and the positive collector plate 113 and between the separator 112 and the negative collector plate 114 along the outer peripheral edge thereof.

  The positive polarizable electrode 111A and the negative polarizable electrode 111B are configured by applying activated carbon electrodes 111b to both surfaces of the collector electrode 111a. The collector electrode 111a of each of the positive polarizable electrode 111A and the negative polarizable electrode 111B includes a positive current collector terminal (lead wire) 18A and a negative current collector terminal (lead wire) 18B shown in FIGS. Is connected. The current collecting terminals 18 </ b> A and 18 </ b> B are spaced apart from each other along the longitudinal direction of the capacitor body 1.

  The insulating sheets 12A and 12B use, for example, polyethylene terephthalate (hereinafter referred to as PET) having a thickness of 0.5 mm, whereby the electrode portion 11 and the end plates 13A and 13B are electrically insulated.

  The end plates 13A and 13B are provided to maintain the shape of the capacitor, and the insulating film 16 is provided to further improve the insulating performance of the capacitor body 1. For the insulating film 16, for example, a PET film having a thickness of 50 μm is used.

  The bipolar capacitor configured as described above has an effect of increasing the rated voltage of the stacked capacitors by adsorbing electrolyte ions in electrolytic solutions having different polarities to the two activated carbon electrodes 111b sandwiching the collector electrode 111a.

  The laminate film 2 is an aluminum laminate film in which an aluminum foil is used as a base, a nylon layer is disposed on the outside, and polypropylene is disposed on the inside (welding side). As an example, the thickness of the substrate was 40 μm, the thickness of the weld layer was 45 μm, the thickness of the nylon layer was 25 μm, and the total thickness was 110 μm.

  As shown in FIGS. 6A to 6D, the laminate film 2 is formed into a cylindrical shape having a gusset fold 2b, and the capacitor main body 1 is formed by the heat welding portion 2a of the laminate film 2 being the capacitor main body. It arrange | positions so that it may be located in the approximate center of 1 longitudinal direction.

  The inter-terminal film 3 is a film in which an insulating member is formed, and has a core material formed of polyester. The length W in the width direction shown in FIG. 4 has dots in FIG. The width of the heat press mold (width of the portion to be pressed and heated by the heat press apparatus) w is larger (that is, W> w. In this embodiment, W = 14 mm, w = 10 mm).

  The inter-terminal film 3 is extended along the opening end of the laminate film 2, and one side in the longitudinal direction of the inter-terminal film 3 is positive so that one surface of the inter-terminal film 3 faces the positive current collecting terminal 18 </ b> A. Current collector terminal 18 </ b> A and laminate film 2, and the other side of the longitudinal direction of the negative electrode current collector terminal 18 </ b> B faces the other surface of the inter-terminal film 3. It is interposed between the current collecting terminal 18B and the laminate film 2.

  In this embodiment, the length of the interterminal film 3 in the longitudinal direction is substantially the same as the length of the valley of the gusset folding portion 2 b of the laminate film 2. The length W in the width direction is longer than the length between the opening end of the laminate film 2 and the bent portions of the current collecting terminals 18A and 18B. The inter-terminal film 3 has one side on the long side (one side opposite to the capacitor body 1) coincides with the opening end of the laminate film 2, and the portion on the capacitor body 1 side is bent of the current collecting terminals 18A and 18B. It is bent along the bent portion of the current collecting terminals 18A and 18B so as to cover the portion.

  The non-heat-weldable insulating layer 4 has an extra heat-welded portion formed by heat received from the mold when the current collecting terminals 18A and 18B and the laminate film 2 are heat-pressed and welded using the mold. This ensures the electrical insulation.

  The terminal film (heat-weldable insulating layer) 5 is welded in advance to the portions of the current collecting terminals 18A and 18B that are welded to the laminate film 2 or the inter-terminal film 3 in advance. The terminal film 5 is made of, for example, a polyester heat-resistant crosslinked resin as a base material, and a welding layer made of acid-modified polypropylene is disposed on both surfaces of the base material. As an example, the thickness of the polyester substrate was about 10 μm, the thickness of the welded layer was about 30 μm, and the total thickness was 70 μm. The terminal film 5 ensures the weldability between the current collecting terminals 18A and 18B and the laminate film 2.

  The edge of the terminal film 5 is disposed so as to protrude outside the laminate film 2 by a predetermined length or more (at least 1 mm) from the opening end of the laminate film 2. Thereby, an arc is prevented from being generated on the creeping surface between the current collecting terminals 18 </ b> A and 18 </ b> B and the end portion of the laminate film 2.

  Laminate film 2 is provided with dots in FIG. 2 such that the edges of laminate film 2 and interterminal film 3 arranged so as to be flush with the edges of the die of the heat press device are aligned. By pressurizing and heating the portion of the width w shown, the opening end is heat-welded with the current collecting terminals 18A and 18B extending from the opening end. At this time, the portion of the inter-terminal film 3 on the capacitor body 1 side (the portion on the side of the bent portion of the current collecting terminals 18A and 18B) is not thermally welded. And an unwelded portion of the inter-terminal film 3 are left between the laminated film 2 and the laminated film 2.

  According to the sealing structure of the electrochemical device according to this embodiment configured as described above, the laminate film 2 is heated and pressurized by a heat press device with the current collecting terminals 18A and 18B extending from the opening end. In this case, since the unwelded portion of the inter-terminal film 3 can be interposed between the inclined angle side of the bent portion of the current collecting terminals 18A and 18B and the laminate film 2, the laminate film 2 and the current collecting terminals 18A, It is possible to ensure an insulation distance from 18B.

  When a withstand voltage test was performed by applying an AC voltage to a capacitor to which the configuration of this example was applied, dielectric breakdown inside the capacitor did not occur up to a voltage of 3.0 kV.

  For this reason, only the pressure heating operation by the heat press apparatus is performed in applications where the sealing structure by the laminate film 2 requires high insulation performance, such as when the rated voltage is high and the laminate film 2 is grounded. Thus, it is easily understood that the sealing of the electrochemical element and the insulation of the current collecting terminals 18A and 18B can be realized simultaneously, and the reliability of the electrochemical element can be improved without adding a special man-hour.

  In addition, since the inter-terminal film 3 has a core material, the inter-terminal film 3 is not melted and flows at the time of heat melting, so that the inferior angle side of the bent portions of the current collecting terminals 18A and 18B and the laminate film 2 An unwelded portion of the inter-terminal film 3 can be interposed between the current collecting terminals 18A and 18B and the laminate film 2 can be secured.

  In addition, this invention is not limited to the Example mentioned above, A various change is possible in the range which does not deviate from the meaning of this invention.

  For example, the length in the longitudinal direction and the length in the width direction of the inter-terminal film 3 may be set as necessary within the scope of the present invention, and are not limited to the above-described embodiments.

  Moreover, the laminate film 2 does not need to have a gusseted fold structure and does not need to be formed into a cylindrical shape.

DESCRIPTION OF SYMBOLS 1 Capacitor body 2 Laminate film 2a Thermal welding part 2b Folding part 3 Film between terminals 4 Non-thermal welding insulating layer 5 Thermal welding insulating layer 11 Electrode part 12A, 12B Insulating sheet 13A, 13B End plate 14 Insulating spacer 15A, 15B Clamping screw 16 Insulating film 18A Positive current collector terminal 18B Negative current collector terminal 111A Positive polarizable electrode 111B Negative polarizable electrode 111a Current collector 111b Activated carbon electrode 112 Separator 113 Positive electrode collector plate 114 Negative electrode collector plate 115 Packing

Claims (4)

An electrochemical element configured by alternately laminating a plurality of positive electrode cells and a plurality of negative electrode cells;
A positive collector terminal connected to the positive cell;
A negative collector terminal connected to the negative cell;
In the sealing structure of the electrochemical device, the electrochemical device is housed therein, and the positive electrode and the negative electrode current collecting terminals extend from the open end, and the laminate film is thermally bonded to the open end.
An insulating member formed in the form of a film, which extends along the opening end of the laminate film, and is interposed between at least the angle-reduced side of the bent portion of the current collector terminal of the positive electrode and the negative electrode and the laminate film. An electrochemical element sealing structure comprising an inter-terminal film to be mounted. The laminate film and the inter-terminal film are heat-welded at a position closer to the opening end side than the bent portion of the current collecting terminal and away from the bent portion of the current collecting terminal, and the current collecting of the inter-terminal film 2. The sealing structure for an electrochemical element according to claim 1, wherein a portion facing the bent portion of the terminal is not welded. The sealing structure for an electrochemical element according to claim 1, wherein the inter-terminal film includes a heat-resistant core material. The current collecting terminal is provided with an insulating member in a portion welded to the laminate film or the inter-terminal film,
The end of the insulating member on the front end side of the current collecting terminal is provided so as to protrude from the opening end by a predetermined length or more. Electrochemical element sealing structure.

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