JP4566049B2 - Electric double layer capacitor - Google Patents

Description

  The present invention relates to an electric double layer capacitor, and more particularly to an electrode structure of an electric double layer capacitor suitable for increasing the capacity and reducing the thickness of the electric double layer capacitor.

  An electric double layer capacitor is a capacitor that uses an electric double layer generated at the interface between a polarizable electrode and an electrolyte to accumulate charges. The electric double layer has a very small thickness of several nanometers. Moreover, large capacity is realized by using activated carbon having a large specific surface area for the polarizable electrode. Electric double layer capacitors are characterized by excellent charge / discharge cycle life because they do not use hazardous materials such as heavy metals in their constituent materials, so there is very little risk of environmental pollution and they do not involve chemical reactions like secondary batteries. is there. Because of this excellent feature, electric double layer capacitors have come to be widely used as backup power sources for microcomputers and memories as an alternative to secondary batteries.

  In recent years, taking advantage of the characteristics of electric double layer capacitors, new applications have been investigated and partially put into practical use as energy sources for driving motors such as electric vehicles or auxiliary power sources for small electronic devices such as energy regeneration systems and mobile phones. . In such applications, it is desired to reduce the thickness of the electric double layer capacitor in response to an increase in the capacity and an electronic device.

  Auxiliary power sources for small electronic devices such as mobile phones are required to reduce the thickness of electric double layer capacitors, and until now, the reduction in thickness has been improved by using an electric double layer capacitor having a laminate outer structure.

  Next, an electric double layer capacitor having a general laminate outer structure will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of a basic cell of a general electric double layer capacitor. FIG. 2 is a schematic diagram showing a multilayer cell of an electric double layer capacitor. 3A and 3B are external views of an electric double layer capacitor having a laminate outer structure according to a conventional example. FIG. 3A is a plan view, FIG. 3B is a side view, FIG. 3C is a cross-sectional view, and FIG. (D) is explanatory drawing which shows the state which combined the terminal board after the primary bending process with the exterior film which gave the shaping | molding process of the prior art example, FIG.3 (e) shows the state of the exterior film which gave the shaping | molding process of the prior art example. It is explanatory drawing.

  As shown in FIG. 1, a unit cell 5 of an electric double layer capacitor has a polarizable electrode 1 to which an electrolyte is added arranged on both sides of a porous and insulating separator 2, and the surroundings are covered with an insulating gasket 3. The upper and lower sides are sandwiched between current collectors 4. As shown in FIG. 2, the unit cell 5 of the electric double layer capacitor is laminated in a plurality of layers to form a laminated cell 6. As the electric double layer capacitor, a unit cell 5 or a stacked cell 6 in which a required number of unit cells 5 are stacked in accordance with the withstand voltage is used.

  The polarizable electrode 1 is composed of activated carbon typified by a coconut shell system, carbon and a binder for ensuring conductivity, and further added with an electrolyte. As the electrolyte, an aqueous electrolytic solution such as dilute sulfuric acid or potassium hydroxide, or an organic electrolytic solution in which an electrolyte salt such as a quaternary ammonium salt is dissolved in an electrolytic solution of propylene carbonate or γ-butyrolactone is used. The separator 2 is composed of a porous polytetrafluoroethylene film or polyolefin film. For the gasket 3 for ensuring insulation in the cell, butyl rubber or thermoplastic resin is used. The current collector 4 is made of conductive rubber or elastomer.

  As shown in FIG. 3, an electric double layer capacitor is manufactured by using a laminated cell 6 in which a plurality of unit cells 5 are stacked in accordance with a predetermined voltage, providing an electrode terminal to be taken out, and applying an exterior. In order to easily attach the electric double layer capacitor to the substrate, a tape 11 for bending the electrode terminal 10 and fixing the electric double layer capacitor shown in FIG. As shown in FIGS. 3 (c) and 3 (d), an electric double layer capacitor having a conventional laminated exterior structure has a terminal plate 8 stacked on the upper and lower surfaces of the laminated cell 6 via a conductive paste 9, An exterior film 7 is arranged on the outside, and an electrode terminal 10 in which a part of the terminal plate 8 is taken out is formed. When manufacturing the electric double layer capacitor, as shown in FIG. 3, the exterior film on the top surface and the bottom surface is preliminarily molded, and the exterior film (laminate film) 7 that has been subjected to the concave shape molding process is subjected to primary bending. Combined terminal boards 8 are combined. Next, the laminated cell 6 is sandwiched between the two terminal plates 8 to which the conductive paste 9 is applied, and the periphery of the exterior film 7 is crimped and sealed to produce an electric double layer capacitor.

  In the conventional structure, the thickness of the primary bending process corresponding to about half of the thickness of the laminated cell 6 inside the terminal plates 8 is necessary for manufacturing. Moreover, in order to produce an exterior film that accommodates the internal laminated cell 6 and stabilizes the sealing, an exterior film in which a recess is formed on the top and bottom surfaces of the outer shape of the electric double layer capacitor is required. . An electric double layer capacitor having such a conventional laminated exterior structure is disclosed in Patent Document 1.

JP 2002-170552 A

  In the above-mentioned Patent Document 1, the lead terminal is required to be bent from one side, and the lead terminal needs to be bent, and the electrode terminal plate has two electrode terminals from one side on one side. When the electric double layer capacitor is placed on a flat surface, the stability is poor, and it is necessary to apply a fixing tape for ensuring the stability, and there is a problem that the height of the electric double layer capacitor is increased.

  The present invention has been made to solve the above-described problems, and a technical problem thereof is to provide a thin electric double layer capacitor excellent in stability when placed on a flat surface.

Invention for achieving the above object, a laminate of unit cells or unit cells consisting of a gasket arranged around the pair of polarizable electrodes and the current collector and the polarizable electrode opposing each other via a separator and the separator In the electric double layer capacitor in which the electrode terminal plate and the exterior film are disposed outside the laminated cell, the electric double layer capacitor in which three or more electrode terminals are taken out from the side surface portion of the main surface to the at least two sides of the bottom surface, including positive and negative electrodes. It is a multilayer capacitor.

  The present invention provides a unit cell comprising a separator and a pair of polarizable electrodes facing each other through the separator, a current collector, and a gasket disposed around the polarizable electrode, or an electrode terminal plate on the outside of a laminated cell in which unit cells are laminated, and In an electric double layer capacitor in which an outer film is disposed, an outer film having a recess shape formed on the upper surface side of the main surface of the electric double layer capacitor and a flat plate shape not subjected to molding processing on the bottom surface side of the main surface Electric double layer capacitor with three or more electrode terminals from which a part of the terminal plate is taken out from the side part of the bottom surface of the main surface, and taken out from at least two sides of the bottom surface. This is an electrode structure.

  According to the present invention, three or more electrode terminals from which a part of the terminal plate is taken out to the outside are taken out from the side portion of the bottom surface of the main outer shape of the electric double layer capacitor, and the taking-out points are taken out from at least two sides of the bottom surface. By adopting the structure, stability when the electric double layer capacitor is placed on a flat surface can be secured. In addition, by using a combination of an exterior film that has been molded into a concave shape on the upper surface side of the outer main surface of the electric double layer capacitor and a flat outer film that is not molded on the bottom surface side of the main surface, It is possible to make an electric double layer capacitor that does not need to be fixed with a fixing tape to ensure stability, and the thickness corresponding to the fixing tape can be reduced, so the height when mounting the electric double layer capacitor is increased. Can solve the problem.

  An electric double layer capacitor according to the best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a unit cell of an electric double layer capacitor. FIG. 2 is a schematic diagram showing a multilayer cell of an electric double layer capacitor. 4A and 4B are diagrams showing an electric double layer capacitor (Example 1) having a laminate outer structure according to the best mode for carrying out the present invention. FIG. 4A is a plan view, and FIG. 4B is a side view. 4 (c) is a cross-sectional view, FIG. 4 (d) is an explanatory view showing a state in which a terminal plate is combined with an exterior film, and FIG. 4 (e) is a diagram showing a primary bending process for a molded exterior film. It is explanatory drawing which shows the combined state of the terminal plate which carried out.

  5A and 5B are diagrams showing an electric double layer capacitor (Example 2) having a laminate outer structure according to the best mode for carrying out the present invention, FIG. 5A is a plan view, and FIG. 5B is a side view. FIG. 5 (c) is a cross-sectional view, FIG. 5 (d) is an explanatory view showing a state in which the terminal board is combined with the exterior film, and FIG. 5 (e) is a primary bending process performed on the molded exterior film. It is explanatory drawing which shows the state which combined the terminal board.

  As the unit cell structure of the electric double layer capacitor according to the best mode for carrying out the present invention, the same structure as the conventional one is used. As shown in FIG. A polarizable electrode 1 to which an electrolyte is added is disposed on both sides of a porous and insulating separator 2, the periphery is covered with an insulating gasket 3, and the upper and lower sides are sandwiched between current collectors 4. As shown in FIG. 2, a plurality of unit cells 5 of the electric double layer capacitor are stacked to form a stacked cell 6. For the electric double layer capacitor, a stacked cell 6 in which a required number of unit cells 5 are stacked in accordance with the withstand voltage is used. Depending on the withstand voltage, the unit cell 5 may be used in only one layer.

  The polarizable electrode 1 is composed of activated carbon typified by a coconut shell system, carbon and a binder for ensuring conductivity, and an electrolyte is added thereto. The electrolyte is preferably an aqueous electrolyte such as dilute sulfuric acid or potassium hydroxide, or an organic electrolyte obtained by dissolving an electrolyte salt such as a quaternary ammonium salt in an electrolyte of propylene carbonate or γ-butyrolactone. . Here, an electrolytic solution of dilute sulfuric acid is used. For the separator 2, a porous polytetrafluoroethylene film is used. The current collector 4 is preferably a conductive rubber or elastomer, and here, a conductive olefin copolymer is used. The gasket 3 for ensuring insulation in the cell is preferably butyl rubber or a thermoplastic resin, and here, an ethylene methacrylic acid copolymer resin is used. The size of the produced unit cell 5 is 18 × 30 × 0.225 mm, and the size of the produced unit cell 5 is 18 × 30 × 0.225 mm. The current collector 4 is preferably a conductive rubber or elastomer, and here, a conductive olefin copolymer is used. Six unit cells 5 are stacked to produce a stacked cell 6. The dimension of the laminated cell 6 is 18 × 30 × 1.35 mm.

  The terminal plate 14 coated with the conductive paste 16 with a thickness of 0.01 mm and the terminal plate 17 coated with the conductive paste 19 with a thickness of 0.01 mm are tin-plated copper plates with a thickness of 0.1 mm. Such a terminal plate is bonded by thermocompression bonding to the exterior film 15 and the exterior film 18 that has been previously molded according to the thickness of the laminated cell. As the exterior film 15 and the exterior film 18 subjected to the molding process, a four-layer laminate film composed of an ethylene methacrylic acid copolymer resin, polyester, aluminum foil, and nylon resin having a thickness of 0.1 mm is used.

  More specifically, first, two sheets of the current collector 4 bonded with the gasket 3 by thermocompression bonding are prepared. The composition ratio of powdery coconut shell activated carbon with an average particle diameter of 15 μm, non-spherical carbon with an average particle diameter of 15 μm, fibrous carbon with a fiber diameter of 0.1 to 0.2 μm and binder is 75: 10: 10: 5 Blend in to make mud. This mud is applied to the upper surface of the current collector inside the gasket 3 and dried to form the polarizable electrode 1. Two current collectors 4 to which the polarizable electrode 1 is applied in this way are produced.

  Next, a 40 wt% sulfuric acid aqueous solution is added onto the polarizable electrode 1. The separator 2 is placed on one of the sheets to which sulfuric acid is added, the two sheets are bonded together so that the current collector 4 is on the outside, the gasket 3 is melted, and bonded by thermocompression bonding. With this method, six unit cells 5 are produced and stacked to form a stacked cell 6.

  As shown in FIG. 4C and FIG. 4D, a conductive paste is applied in advance by printing and dried. The terminal plate 14 coated with the conductive pastes 16 and 19 and the terminal plate 17 subjected to primary bending so that the electrode terminals can be taken out from the bottom surface of the outer main surface of the electric double layer capacitor are attached to the inner surface (ethylene methacrylic acid) of the outer film. The outer film bodies 29 and 30 are produced by thermocompression bonding to the copolymer resin). The laminated cell 6 is arranged on the upper surface of 16 parts of the conductive paste of the exterior film body 29, and is superposed in a direction in contact with the laminated cell 6 so that 19 parts of the conductive paste of the exterior film body 30 faces the 16 parts of the conductive paste. Next, the overlapping part of the exterior film 15 that is the upper and lower exterior film bodies and the exterior film 18 that has been molded into the shape of the recesses is thermocompression bonded under reduced pressure conditions and sealed to form an electric double layer capacitor.

  Also, as shown in FIG. 4 and FIG. 5, take out three or more electrode terminals from which a part of the terminal plate is taken out from the side of the bottom surface of the main outer surface of the electric double layer capacitor, and at least two sides of the bottom surface The terminal board taken out from was installed in three places. Here, three terminal boards are installed. However, as the number of terminal boards increases, the electric double layer capacitor can be stably fixed on a flat surface.

  An embodiment of the present invention will be described in detail with reference to the drawings in comparison with a conventional example.

(Example 1 and Example 2)
A multilayer cell 6 (see FIG. 5) was produced in the same manner using the same electric double layer capacitor as the above-described best mode for carrying out the present invention. Next, tin-plated copper terminal boards 22 and 25 having a thickness of 0.1 mm and conductive pastes 23 and 26 having a thickness of 0.01 mm applied to both sides of the laminated cell 6 were superposed. Further, with the terminal plates 22 and 25 superimposed on the laminated cell 6, a laminate film 24 having a thickness of 0.1 mm and a laminate film 27 molded into a concave shape are arranged on both sides, and an exterior film is formed under reduced pressure. The electric double layer capacitor was formed by thermocompressing the part which 24 and the exterior film 27 overlapped, and sealing. In Example 1, as shown in FIG. 4, in Example 2, as shown in FIG. 5, there are 3 electrode terminals from which a part of the terminal plate is taken out from the side surface of the bottom surface of the main surface of the electric double layer capacitor. The terminal board which took out more than a part and was taken out from at least 2 sides or more of the bottom face was installed in three places.

(Conventional example)
As shown in FIG. 3, a conventional electric double layer capacitor was fabricated as follows. The material used for the conventional example was the same as that of the electric double layer capacitor according to the best mode for carrying out the present invention described above, and the laminated cell 6 was produced by the same method. Next, a tin-plated copper terminal board 8 having a thickness of 0.1 mm and a conductive paste 9 having a thickness of 0.01 mm applied to both sides of the laminated cell 6 were superposed. Furthermore, in the state where the terminal plate 8 subjected to the primary bending process is superimposed on the laminated cell 6, the laminate film 7 molded into the shape of the recess 33 having a thickness of 0.1 mm is disposed on both sides, and both sides are subjected to a reduced pressure condition. The overlapping portion of the outer packaging film 7 was thermocompression bonded and sealed to form an electric double layer capacitor. Thereafter, the electrode terminal 10 was subjected to a secondary bending process along the bottom surface of the electric double layer capacitor. Further, a double-sided adhesive tape 11 having a thickness of 0.05 mm was bonded to the bottom surface of the electric double layer capacitor.

  Ten electric double layer capacitors of Example 1, Example 2 and the conventional example were produced by the above-described method, respectively, and equivalent series resistance (ESR), capacitance, thickness, and distance between the substrate and the electrode terminal. Measurements were made. ESR was obtained by applying an alternating voltage of 1 kHz, 10 mVrms, and measuring the current and phase difference. The capacitance was determined by applying an alternating voltage of 1 Hz and 10 mVrms and measuring the current and phase difference. The thickness was measured with calipers. The distance between the substrate and the electrode terminal was measured with a projector.

  Table 1 shows the measurement results of the electric double layer capacitors of Example 1, Example 2, and the conventional example. The measured values of ESR, capacitance, thickness, and distance between the substrate and the electrode terminal are measured average values of 10 samples.

  When the ESR, capacitance, thickness, and distance between the electrode terminals of the substrate of Example 1 and Example 2 and the conventional example are compared, the thickness of Example 1 shows the best value, and between the substrate and the electrode terminal The distance of Example 2 was the best value. As for the thickness and the distance between the substrate and the electrode terminal, there was almost no difference between Example 1 and Example 2, and a better result than the conventional example was obtained. Further, the ESR and capacitance of Example 1 and Example 2 were the same values as in the conventional example.

  It can be seen from comparison of FIGS. 3, 4, and 5 that the thicknesses of Example 1 and Example 2 can be reduced by the amount of the fixing tape for stably fixing the electric double layer capacitor to the plane. The distance between the substrate and the electrode terminal can be determined by using the outer packaging film on the top surface molded into the concave shape and the outer packaging film on the flat bottom surface not molded into the concave shape. It became possible to take out. Moreover, by taking out three electrode terminals, the electric double layer capacitor can be stably installed on the substrate without a fixing tape for stably fixing to the flat surface.

  As described above, the electric double layer capacitor according to the embodiment of the present invention can be thinned, and the electric double layer capacitor can be thinned and the electric double layer capacitor can be stably fixed to a flat surface without secondary bending of the electrode terminal plate. It can be seen that there is an effect that the multilayer capacitor can be stably installed on the substrate. In addition, in the conventional example, the fixing tape for stably fixing to the flat surface, the secondary bending process of the electrode terminal board, and the man-hours for the pretreatment processing of the exterior film and the terminal board on both sides required in the conventional structure, In the embodiment of the present invention, only the number of man-hours for the pretreatment of the upper surface exterior film and the terminal board is required, so that the processing cost can be reduced.

  Here, although an example was shown about an electric double layer capacitor, it is applicable not only to an electric double layer capacitor but to thickness reduction of an electronic component which shape | molds an electrochemical element with an exterior film.

Sectional drawing of the unit cell of an electric double layer capacitor. The schematic diagram which shows the lamination cell of an electric double layer capacitor. The figure which shows the electric double layer capacitor of the laminated exterior structure in a prior art example. FIG. 3A is a plan view. FIG. 3B is a side view. FIG. 3C is a cross-sectional view. FIG.3 (d) is explanatory drawing which shows the state which combined the terminal board after the primary bending process with the exterior film which gave the shaping | molding process. FIG.3 (e) is explanatory drawing which shows the state of the exterior film which gave the shaping | molding process. The figure which shows the electric double layer capacitor (Example 1) of the laminate exterior structure which concerns on the best form for implementing this invention. FIG. 4A is a plan view. FIG. 4B is a side view. FIG. 4C is a cross-sectional view. FIG.4 (d) is explanatory drawing which shows the state which combined the terminal board with the exterior film of the electrical double layer capacitor (Example 1) of the laminate exterior structure which concerns on the best form for implementing this invention. FIG.4 (e) is explanatory drawing which shows the combined state of the terminal board which gave the primary bending process to the exterior film which gave the shaping | molding process. The figure which shows the electric double layer capacitor (Example 2) of the laminate exterior structure which concerns on the best form for implementing this invention. FIG. 5A is a plan view. FIG. 5B is a side view. FIG.5 (c) is sectional drawing. FIG.5 (d) is explanatory drawing which shows the state which combined the terminal board with the exterior film. FIG.5 (e) is explanatory drawing which shows the state which combined the terminal board which gave the primary bending process to the exterior film which gave the shaping | molding process.

Explanation of symbols

1 Polarized electrode 2 Separator 3 Gasket 4 Current collector 5 Unit cell 6 Laminated cell 7, 18, 27 (molded) exterior film (laminate film)
8, 17, 22 (primary bending process completed) terminal plate 9, 16, 19, 23, 26 conductive paste 10 electrode terminal (secondary bending process)
11 (For product fixing) Tape 12, 13, 20, 21 Electrode terminal 14, 22, 25 Terminal plate 15, 24 Exterior film (laminate film)
28, 29, 30, 31, 32 Exterior film body 33, 34, 35 Molding recess

Claims (1)

  A unit cell composed of a separator and a pair of polarizable electrodes facing each other through the separator, a current collector, and a gasket disposed around the polarizable electrode, or an electrode terminal plate and an exterior outside the laminated cell in which the unit cells are laminated An electric double layer capacitor in which a film is disposed, wherein at least two electrode terminals including positive and negative electrodes are taken out from at least two sides of the bottom surface of the main surface to at least two sides of the bottom surface.

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