JP2005191507A - Coin-shaped storage element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim at providing a coin-shaped storage element whose leakage resistance at the time of reflow solder for carrying out treatment under a temperature higher than usual is improved. <P>SOLUTION: The coin-shaped storage element comprises an element in which a pair of electrodes 17 are arranged such that the electrodes are in face to face with each other via an insulating separator 19, and a top cover 13 (cathode side) by which the element is sealed via an insulating ring packing 15 in a state that the element is housed in a metal casing 11 (positive side). Since stress at the time of curling can be centralized on a projection 16 of the ring packing 15 by constituting the element such that the projection 16 is formed on a portion in contact with the bottom face of the metal casing 11 of the ring packing 15, thermal resistance to high temperature reflow can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coin-type energy storage device such as a capacitor or a battery used in various electronic devices.

  This type of coin-type energy storage device includes an electric double-layer capacitor, a button battery, and the like. FIG. 6 shows the configuration of an electric double-layer capacitor as an example of these coin-type energy storage devices. As shown in the figure, an anodic polarizable electrode 41 made of an activated carbon electrode and a cathode-side polarizable electrode 42 made of an activated carbon electrode are arranged to face each other with a separator 43 therebetween, and the anodic polarizable electrode 41 is arranged. Is provided with an anode current collector 44, and the cathode side polarizable electrode 42 is provided with a cathode current collector 45, and then the pair of polarizable electrodes 41, 42 and separator 43 are impregnated with an electrolyte 46. These are housed in a housing space composed of an upper case 47 serving as a cathode terminal and a lower case 48 serving as an anode terminal, and a bent portion 50 formed on the outer periphery of the upper case 47 and an outer periphery of the lower case 48 The packing 49 having electrical insulation is disposed between the two and the front end portion 51 of the outer peripheral portion of the lower case 48 is curled to wrap the bent portion 50 of the upper case 47 from the outside with the packing 49. And to perform the hermetic port of the housing space which houses the polarizable electrodes 41, 42 of the pair.

  Such electric double layer capacitors are widely used as a main power source and a memory backup power source for small portable devices such as mobile phones, and the demand is increasing year by year due to the trend toward miniaturization of electronic devices. There is a tendency. In light of these times, it is indispensable to ensure high reliability over a long period of time for electric double layer capacitors, which are important components of electronic devices.

  As a method for ensuring the reliability, in Patent Document 1, by providing a guide portion around the polarizable electrode at the bottom of the lower case, the polarizable electrode can be adhered to a predetermined position to prevent electrode displacement. It has been proposed that you can.

  In addition, improvement of the leakage resistance of the electric double layer capacitor is an important issue in terms of quality. The leakage of the electrolytic solution not only causes deterioration of the characteristics of the power storage element, but may cause failure of peripheral circuits and devices.

  In order to improve such leakage resistance, in Patent Document 2, the outer case bending portion of the upper case is made flat, and the width of the flat portion is in the range of 75 to 150% of the thickness of the upper case. Therefore, it has been proposed that leakage resistance can be improved.

On the other hand, in the button battery, the electrode having the separator interposed between the positive electrode and the negative electrode is accommodated in the two metal containers, and the appearance structure thereof is the same as that of the electric double layer capacitor. Yes.
JP 2003-22935 A JP 2000-48780 A

  In recent years, along with the high integration of electronic components due to the miniaturization of equipment, the integration of electronic components on a substrate has been advanced. As a soldering method suitable for this, surface mounting by reflow soldering has become the mainstream. The reflow soldering is a method of performing soldering by passing the power storage element placed on a printed circuit board coated with solder through a furnace in a high-temperature atmosphere of 200 ° C. or more. Furthermore, with the progress of lead-free solder considering environmental issues, reflow soldering with silver solder having a melting point of about 20 ° C. higher than that of lead solder has been performed, and the electrons mounted on the substrate Higher heat resistance is also required for parts.

  However, in the conventional electric double layer capacitor, the vapor pressure of the solvent of the organic electrolyte solution is increased at a high temperature when lead-free reflow soldering at which the soldering temperature reaches about 250 ° C., and the internal pressure of the electricity storage device is significantly increased. As a result, a gap is formed between the sealing surfaces of the lower case 48 and the bottom surface of the packing 49, and the electrolytic solution 46 leaks to the outside.

  An object of the present invention is to solve such a conventional problem and to provide a coin-type energy storage device having improved heat resistance against high-temperature reflow.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is characterized in that an element in which a pair of electrodes face each other through an insulating separator, and the element is placed in a metal case (anode side). A coin-type energy storage device comprising an upper lid (cathode side) that is housed in an insulating ring packing and sealed with an insulating ring packing, and has a configuration in which a protrusion is provided on a portion that contacts the bottom surface of the metal case of the ring packing. Thus, airtightness can be improved, and heat resistance against high temperature reflow can be improved.

  According to a second aspect of the present invention, there is provided an element in which a pair of electrodes are arranged so as to face each other with an insulating separator interposed therebetween, and the element is housed in a metal case (anode side). A coin-type energy storage device comprising an upper lid (cathode side) that is sealed via a ring packing, wherein a protrusion that presses the ring packing is provided on the outer periphery of the metal case, whereby the shrinkage rate of the ring packing Since the stress increases with the upper lid end bent portion, the airtightness can be improved, and the heat resistance against high temperature reflow can be improved.

  The invention according to claim 3 of the present invention has a configuration in which a convex annular bulge is provided on the inner side of the position where the ring packing is arranged on the bottom surface of the metal case, and increases the internal pressure during high-temperature reflow. The bulging of the metal case can be reduced by concentrating on the inner side of the convex annular bulge, that is, in the center of the product, and as a result, the airtightness and leakage resistance are not lowered even at high temperature reflow.

  The present invention has a structure in which a protrusion is provided on a portion of the ring packing disposed between the outer peripheral portion of the metal case and the outer peripheral portion of the upper lid so as to contact the bottom surface of the metal case. Since it can be concentrated on the ring packing protrusions, the compression ratio of the ring packing bottom surface can be partially increased, the airtightness can be improved without excessively lowering the bending compression position of the metal case, and high temperature The heat resistance against reflow can be improved.

  In addition, since the protrusions that press the ring packing are provided on the outer periphery of the metal case, the horizontal stress when the ring packing and the metal case come into contact can be concentrated on the upper lid end bent portion. The compression ratio of the side surface of the ring packing can be partially increased, and the airtightness and the heat resistance against high temperature reflow can be improved.

  In addition, by providing a convex annular bulging portion on the inner side of the bottom surface of the metal case relative to the position where the ring packing is disposed, it is possible to maintain a sealing property that can withstand an increase in internal pressure during high-temperature reflow. This is an effect.

  In addition, it is more preferable if the installation position of the protrusion provided on the portion of the ring packing that contacts the bottom surface of the metal case is close to the center of the surface that contacts the bottom surface of the metal case.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
FIG. 1 is a partial cross-sectional view showing a configuration of a coin-type electric double layer capacitor according to Embodiment 1 of the present invention. In the figure, current collectors 18 are respectively applied to the inner bottom surfaces of the metal case 11 and the upper lid 13, and inserted into the metal case 11 and the upper lid 13 so that the pair of polarizable electrodes 17 are in contact with the current collector 18 through the separator 19. Has been. The pair of polarizable electrodes 17 is impregnated with the electrolytic solution 20.

  Then, by placing a ring packing 15 having electrical insulation between the bent portion 14 formed on the outer peripheral portion of the upper lid 13 and the outer peripheral portion 12 of the metal case 11, the tip of the outer peripheral portion 12 of the metal case 11 is curled. The ring packing 15 is pressed to wrap around the bent portion 14 of the upper lid 13 to be hermetically sealed.

  The ring packing 15 has a shape as shown in FIG. 2, and by curling, the projecting portion 16 provided on the ring packing 15 is crushed and brought into close contact with the inner bottom surface of the metal case 11, thereby providing a highly airtight seal. be able to.

(Embodiment 2)
FIG. 3 is a partial cross-sectional view showing the configuration of a coin-type electric double layer capacitor according to Embodiment 2 of the present invention. In the figure, current collectors 28 are respectively applied to the inner bottom surfaces of the metal case 21 and the upper lid 23 and inserted into the metal case 21 and the upper lid 23 so that the pair of polarizable electrodes 27 are in contact with the current collector 28 via the separators 29. Has been. The pair of polarizable electrodes 27 is impregnated with the electrolytic solution 30.

  Then, by placing a ring packing 25 having electrical insulation between the bent portion 24 formed on the outer peripheral portion of the upper lid 23 and the outer peripheral portion 22 of the metal case 21, the tip of the outer peripheral portion 22 of the metal case 21 is curled. The ring packing 25 is pressed to wrap around the bent portion 24 of the upper lid 23 to be hermetically sealed.

  Since the protrusion 26 that presses the ring packing 25 is provided on the outer peripheral portion 22 of the metal case 21, the protrusion 26 provided on the outer peripheral portion 22 of the metal case 21 causes stress on the side surface of the ring packing 25 by curling. The stress is concentrated and the stress is transmitted to the bent portion 24 of the upper lid 23, whereby a highly airtight sealing can be performed.

(Embodiment 3)
FIG. 4 is a partial cross-sectional view showing the configuration of a coin-type electric double layer capacitor according to Embodiment 3 of the present invention. In FIG. 3, a pair of polarizable electrodes 27 are arranged so as to face each other via an insulating separator 29 as in FIG. 3, and the pair of polarizable electrodes 27 are housed in a metal case 21 to provide insulation. The ring cover 25 is hermetically sealed with an upper lid 23, and a protrusion 26 that presses the ring packing 25 is provided on the outer peripheral portion 22 of the metal case 21, and a ring is formed on the bottom surface of the metal case 21. In this configuration, a convex annular ridge 31 is provided on the inner side of the position where the packing 25 is disposed.

  Hereinafter, specific examples of the respective embodiments will be described.

(Example 1)
In the first embodiment, the polarizable electrode includes petroleum coke-based activated carbon powder having an average particle diameter of 5 μm and carbon black and polytetrafluoroethylene (hereinafter abbreviated as PTFE) having an average particle diameter of 0.05 μm as a conductivity-imparting agent. The obtained water-soluble binder solution (PTFE concentration: 60%) was mixed at a weight ratio of 10: 2: 1 and thoroughly kneaded with a kneader, and then a water dispersion solvent was added little by little to further knead to produce a paste. Then, this paste was molded with a molding machine and dried in the atmosphere at 100 ° C. for 1 hour to obtain a molded body.

  This molded body was cut into a disk shape having a dimension of 60 mm to obtain a pair of polarizable electrodes.

  Next, the two polarizable electrodes and a disc-shaped separator having a thickness of 50 μm and a thickness of 65 mm were impregnated with an electrolytic solution obtained by dissolving 4 ethylammonium tetrafluoride in a propylene carbonate solvent.

  Next, the pair of polarizable electrodes are arranged so as to face each other with a separator interposed therebetween, and then, the polarizable electrodes are arranged in contact with the inner surface of the stainless steel metal case and the upper lid via a conductive layer. The peripheral portion was sealed with an insulating ring packing to obtain a coin-type electric double layer capacitor having a diameter of 6.8 mm and a height of 1.4 mm.

(Example 2)
In Example 1, a coin-type electric double layer capacitor was produced in the same manner as in Example 1 except that sulfolane was used as the solvent for the electrolyte.

(Example 3)
In the second embodiment, a coin-type electric double layer capacitor was fabricated in the same manner as in the second embodiment except that the same polarizable electrode and electrolyte as in the first example were used.

Example 4
In Example 3, a coin-type electric double layer capacitor was produced in the same manner as in Example 3 except that sulfolane was used as the solvent for the electrolyte.

(Example 5)
In the third embodiment, a coin-type electric double layer capacitor was fabricated in the same manner as in the third embodiment except that the same polarizable electrode and electrolyte as in the first example were used.

(Example 6)
In Example 5, a coin-type electric double layer capacitor was produced in the same manner as in Example 5 except that sulfolane was used as a solvent for the electrolyte.

(Comparative Example 1)
A coin-type electric double layer capacitor was produced in the same manner as in Example 1 except that no protrusion was provided on the ring packing 15 in Example 1.

(Comparative Example 2)
A coin-type electric double layer capacitor was produced in the same manner as in Example 2 except that no protrusion was provided on the ring packing 15 in Example 2.

  The coin-type electric double layer capacitors of Examples 1 to 6 and Comparative Examples 1 and 2 were subjected to reflow soldering with the temperature profile shown in FIG. 5, and the capacitance change and leakage test results are shown in (Table 1). . The number of samples is 20, and the capacity change is the capacity change rate before and after reflow.

  As is clear from Table 1, the coin-type electric double layer capacitors of Examples 1 to 6 are extremely stable with no leakage from the ring packing 15 compared to the coin-type electric double layer capacitor of the comparative example. A coin-shaped electric double layer capacitor was obtained.

  As described above, the electric double layer capacitor of the present invention has a configuration in which a protrusion is provided on a portion of the ring packing that contacts the bottom surface of the metal case, or a protrusion that presses the ring packing is provided on the outer periphery of the metal case. Therefore, compared with the conventional electric double layer capacitor, the stress at the time of curling can be concentrated on a part, so that the air tightness of the electric double layer capacitor is improved and the heat resistance against high temperature reflow can be improved. Is.

  In addition, by providing a convex annular bulging portion on the inner side of the bottom surface of the metal case relative to the position where the ring packing is disposed, it is possible to maintain a sealing property that can withstand an increase in internal pressure during high-temperature reflow. This is an effect.

  Although the electric double layer capacitor has been described in the present embodiment, it can also be used for a coin-type power storage element such as a coin-type battery.

  The coin-type energy storage device of the present invention can be used for capacitors and batteries, has a sealing property that can withstand an increase in internal pressure during high-temperature reflow, and is a main power source for electronic equipment that requires surface mounting by reflow soldering of lead flow And it is useful as a memory backup power source.

The fragmentary sectional view which shows the structure of the coin-shaped electric double layer capacitor by Embodiment 1 of this invention Partial enlarged view of the ring packing according to the first embodiment The fragmentary sectional view which shows the structure of the coin-shaped electric double layer capacitor by Embodiment 2 Sectional drawing which shows the structure of the coin-shaped electric double layer capacitor by the same Embodiment 3 Temperature profile diagram for reflow soldering Cross section of conventional electric double layer capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Metal case 12 Outer peripheral part of metal case 13 Upper cover 14 Bending part of upper cover 15 Ring packing 16 Protrusion part 17 A pair of polarizable electrode 18 Current collector 19 Separator 20 Electrolyte

Claims (3)

An element in which a pair of electrodes are arranged to face each other via an insulating separator, and an upper lid (cathode side) that houses the element in a metal case (anode side) and seals it via an insulating ring packing A coin-shaped energy storage device comprising: a coin-shaped energy storage device comprising a protrusion on a portion of the ring packing that contacts a bottom surface of a metal case. An element in which a pair of electrodes are arranged to face each other via an insulating separator, and an upper lid (cathode side) that houses the element in a metal case (anode side) and seals it via an insulating ring packing A coin-type energy storage device comprising a protrusion for pressing a ring packing on an outer peripheral portion of the metal case. The coin-type electricity storage device according to claim 1 or 2, wherein a convex annular bulge is provided on an inner side of a position where the ring packing is disposed on a bottom surface of the metal case.

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