JP2012015189A - Electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric double layer capacitor in which electrical connection of a laminate of a capacitor body and an electrode terminal is made reliably and securely, and variation in electric characteristics can be inhibited sufficiently.SOLUTION: An electric double layer capacitor 10 comprises: a capacitor body 11 provided, respectively, with an electrode terminal 22 for the positive electrode on the positive electrode body side of a laminate 21 laminating a positive electrode body and a negative electrode body while sandwiching a separator, and an electrode terminal 22 for the negative electrode on the negative electrode body side; a spring member 12 which urges each electrode terminal 22 toward the laminate 21 side; and a mold resin 13 which covers and seals the capacitor body 11 and the spring member 12 integrally.

Description

  The present invention relates to an electric double layer capacitor.

  An electric double layer capacitor stores electric energy in an electric double layer formed at the interface between a polarizable electrode such as activated carbon and an electrolyte or electrolyte gel. Can be charged / discharged instantaneously, and the charge / discharge efficiency is also high.

  As a structure of this electric double layer capacitor, a positive electrode body and a cathode body in which a collector electrode is bonded to a polarizable electrode are laminated via a separator, and electrode terminals for anode and cathode are conductively bonded to both surfaces of this laminated body. A capacitor body bonded with an agent is temporarily fixed in a box-shaped case, and the inside of the case is sealed with an insulating resin.

  In this case, if the shape of the laminated body or electrode terminal constituting the capacitor body changes due to temperature change or energization, the connection reliability between the laminated body and the electrode terminal may be lowered, or the electrical characteristics may be changed. For this reason, the laminated body and the electrode terminal are tightened in the laminating direction by inserting a wedge-shaped part into the case, and the change in the shape is suppressed (for example, see Patent Document 1).

  However, the wedge-shaped part has a weak propagation of the pressing force and cannot sufficiently suppress the change in shape. For this reason, in the said electrical double layer capacitor, the connection of a laminated body and an electrode terminal could not be stabilized enough, and the fluctuation | variation of the electrical property could not fully be suppressed.

JP 2002-110480 A

  The present invention has been made to solve the above-described problems of the prior art, and the electrical connection between the multilayer body of the capacitor main body and the electrode terminal is reliably and stably performed, and fluctuations in electrical characteristics are sufficiently suppressed. An object of the present invention is to provide an electric double layer capacitor capable of satisfying the requirements.

  The electric double layer capacitor according to one aspect of the present invention includes a positive electrode terminal on the positive electrode body side, a negative electrode terminal on the negative electrode body side of the laminate in which the positive electrode body and the cathode body are stacked via a separator, A capacitor main body provided; a spring member that presses and urges each electrode terminal toward the laminate; and a mold resin portion that covers and seals the capacitor main body and the spring member together. It is characterized by.

  According to the electric double layer capacitor of one embodiment of the present invention, stable electrical connection between the multilayer body and the electrode terminal can be obtained, and fluctuations in electrical characteristics can be sufficiently suppressed.

It is sectional drawing which shows the electric double layer capacitor of one Embodiment of this invention. It is sectional drawing explaining the manufacturing method of the electrical double layer capacitor of one Embodiment of this invention.

  Hereinafter, modes for carrying out the present invention will be described. Although the description will be made based on the drawings, the drawings are provided for illustration only, and the present invention is not limited to the drawings.

  FIG. 1 is a cross-sectional view showing an electric double layer capacitor according to an embodiment of the present invention.

  As shown in FIG. 1, the electric double layer capacitor 10 of the present embodiment includes a capacitor main body 11 having two electrode terminals for a positive electrode and a cathode, a spring member 12, and the capacitor main body 11 and the spring member 12. And a mold resin portion 13 that covers and seals together.

  The capacitor main body 11 has a laminated body 21 in which a positive electrode body and a cathode body are laminated via a separator, and two electrode terminals 22 and 22 for positive electrode and cathode are arranged on both surfaces of the laminated body 22. ing. The positive electrode body and the cathode body have a structure in which a polarizable electrode mainly composed of activated carbon is laminated on a collector electrode made of, for example, an aluminum foil, and each polarizable electrode is impregnated with an electrolytic solution. The two electrode terminals 22 and 22 are made of, for example, an aluminum plate, and are disposed so as to be in contact with the collector electrodes of the positive electrode body and the cathode body, respectively.

  The electrolyte solution impregnated in the polarizable electrode includes an aqueous electrolyte solution such as sulfuric acid and potassium hydroxide, an electrolyte such as triethylmethylammonium tetrafluoroborate and tetraethylammonium tetrafluoroborate, an aprotic organic solvent such as A non-aqueous electrolyte solution dissolved in propylene carbonate or the like is used. In place of such an electrolytic solution, an electrolyte gel obtained by adding a polymer and an organic plasticizer to the electrolyte to form a gel can also be used. For the separator, paper, a glass fiber nonwoven fabric, a film made of an insulating resin such as polytetrafluoroethylene (PTFE), or the like is used.

  The spring member 12 presses and urges the two electrode terminals 22 and 22 toward the laminated body 21, whereby each electrode terminal 22 is electrically and electrically connected to the positive electrode body and the cathode body constituting the laminated body 21. Mechanically connected. In the present embodiment, a metal clip-like leaf spring is attached as the spring member 12 so as to sandwich the laminated body 21 from above the electrode terminals 22 and 22. The spring member 12 is not particularly limited to such a shape as long as the two electrode terminals 22 and 22 can be pressed and urged toward the laminated body 21. The material is not limited to metal but may be made of plastic or the like. Specifically, examples of the metal material include stainless steel, aluminum, copper, nickel, chromium, and brass. Examples of the plastic material include polypropylene, vinyl chloride resin, and polyethylene terephthalate. Further, the spring member 12 is not limited to one place, and may be attached to a plurality of places.

  In addition, it is preferable that the contact pressure with the electrode terminal 22 of the spring member 12 is 0.01-4.0 MPa, and it is more preferable that it is 0.1-1.0 MPa. If the contact pressure is less than 0.1 MPa, the electrical connectivity between the laminate 21 and the electrode terminal 22 may not be improved, or the temporal characteristics of the electrical characteristics such as equivalent series resistance (ESR) may not be sufficiently suppressed. There is. On the other hand, if the contact pressure exceeds 4.0 MPa, the laminate 21 may be destroyed and the electrolyte may leak out.

  For example, the mold resin portion 13 is formed by setting the capacitor body 11 with the spring member 12 in a split mold 33 having an upper mold 31 and a lower mold 32 as shown in FIG. It is formed by injecting a material into the mold 33 and curing it. The mold 33 is preferably made of a metal having heat resistance and corrosion resistance such as stainless steel.

  The mold resin portion 13 preferably has a flexural modulus at 70 ° C. of 1 GPa or less. By setting the flexural modulus to 1 GPa or less, the internal pressure in the capacitor body 11 can be relaxed.

  The resin forming the mold resin portion 13 preferably has a glass transition point of 20 to 60 ° C. If the glass transition point is less than 20 ° C., the electrolytic solution impregnated in the capacitor body 11 may be leached to the outside and the capacitor performance may be reduced. In addition, when the glass transition point exceeds 60 ° C., the pressing force of the spring member 12 to the capacitor body 11 is not sufficiently transmitted, so that the electrical connection between the multilayer body 21 and the electrode terminal 22 is stabilized and the fluctuation of electrical characteristics is suppressed. There is a risk that it cannot be fully achieved.

  The resin material for forming the mold resin portion 13 is not particularly limited as long as it has an insulating property and can be used as a molding material. Generally, an epoxy resin, a phenol resin, an unsaturated polyester resin, A thermosetting resin such as melamine resin is used. Among these, an epoxy resin is preferable.

  In the present invention, as a resin material for forming the mold resin portion 13, in particular, (a) an epoxy resin having at least two epoxy groups in one molecule, and (b) a curing agent, An epoxy resin composition containing c) a filler and (d) a curing accelerator is preferably used.

  Examples of the epoxy resin having at least two epoxy groups in one molecule of the component (a) include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, novolac type epoxy resin, and glycidyl ester type. An epoxy resin, an alicyclic epoxy resin, etc. are mentioned. In order to ensure reliability, these epoxy resins preferably have a low content of chloro ions and sodium ions. Moreover, these epoxy resins may be used individually by 1 type, and 2 or more types may be mixed and used for them. In addition to the above epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, heterocyclic epoxy resins, hydrogenated bisphenol A epoxy resins, aliphatic epoxy resins, aromatic, aliphatic or alicyclic Epoxy resins obtained by reaction of carboxylic acids with epichlorohydrin, spiro ring-containing epoxy resins, and the like can also be used. These are preferably used in combination with the above epoxy resin.

  As the curing agent of the component (b), any generally known curing agent can be used without particular limitation as long as it can be cured by reacting with the epoxy resin of the component (a). Specific examples include aliphatic amines, methylhexahydrophthalic anhydride, novolac phenolic resin, cresol novolac phenolic resin, phthalic anhydride derivatives, dicyanamide, imidazole and the like. One of these curing agents may be used alone, or two or more thereof may be mixed and used.

  Examples of the filler of component (c) include silica, alumina, silicon nitride, boron nitride, calcium carbonate, aluminum hydroxide, talc powder, and beads formed by spheroidizing these. These fillers may be used individually by 1 type, and 2 or more types may be mixed and used for them. In general, silica powder is used, and spherical silica powder is particularly preferably used.

  This epoxy resin composition has a coupling agent (for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane), a release agent and the like within a range not inhibiting the effects of the present invention. Molding agent (for example, synthetic wax, natural wax, linear aliphatic metal salt, acid amide, ester, etc.), coloring agent (for example, carbon black, cobalt blue, etc.), low stress imparting agent (for example, silicone oil, Silicone rubber etc.), an antifoaming agent, etc. may be further blended.

  Such an epoxy resin composition is poured into the mold 33 and, for example, the mold resin portion 13 can be formed by heating and curing at 70 to 100 ° C. for 10 minutes. The resin is preferably post-cured after the mold 33 is released.

  In the electric double layer capacitor 10 of the present embodiment, the electrode terminals 22 disposed on both surfaces of the multilayer body 21 are pressed toward the multilayer body 21 by the spring member 12, and these are integrated by the mold resin portion 13. Is covered. For this reason, although the electrode terminal 22 is not adhered to the laminated body 22 with an adhesive but is simply disposed, a stable electrical connection can be obtained over a long period of time. In addition, since deformation of members such as the collecting electrode constituting the multilayer body 22 due to temperature change and energization is suppressed, variation with time in electrical characteristics such as equivalent series resistance (ESR) is also suppressed. Therefore, good capacitor performance can be maintained for a long time.

  In the above embodiment, the electrode terminal 22 and the laminated body 22 are not bonded with an adhesive, that is, not bonded. However, the electrode terminal 22 and the laminated body 22 can be bonded with an adhesive, further improving connection reliability. be able to. As the adhesive, a conductive adhesive is used.

  Moreover, in the said embodiment, although the laminated body 21 is made into the structure where the polarizable electrode was impregnated with electrolyte solution or electrolyte gel, the structure which laminated | stacked electrolyte solution or electrolyte on the polarizable electrode may be sufficient. Further, a structure in which an external electrode is further stacked on the collector electrode, and the external electrode is connected to the electrode terminal 22 may be employed. Also in the electric double layer capacitor configured as described above, a stable electrical connection between the multilayer body 21 and the electrode terminal 22 can be obtained as well as the above-described embodiment, and a change in electrical characteristics due to a temperature change or energization is also suppressed. . Therefore, good capacitor performance can be maintained for a long time.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. In the following description, “parts” means “parts by mass” unless otherwise specified. Moreover, the contact pressure of the clip-shaped leaf | plate spring in an Example is measured by the method shown below.
[Contact pressure]
Using the measuring jig connected to the load cell, measure the load when the opening of the clip-shaped leaf spring opens to the thickness of the capacitor body (laminated body and electrode terminal), and calculate the value per unit area of the electrode terminal did.

Example 1
100 parts of bisphenol A type epoxy resin (trade name Epicoat 828, manufactured by Japan Epoxy Resin Co., Ltd.) as the epoxy resin, and 60 parts of aliphatic polyamine (trade name, EH4357S, manufactured by ADEKA Corporation) as the curing agent Then, 20 parts of nonylphenol as a curing accelerator and 0.1 part of an antifoaming agent (product name TSA720, manufactured by Momentive Performance Materials Japan) were uniformly stirred and mixed to prepare an epoxy resin composition. Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. After this, the above composition is poured into the molding die 33, heated and cured at 70 ° C. for 60 minutes, and after opening the mold, further heated at 70 ° C. for 180 minutes and then cured to produce an electric double layer capacitor. Manufactured.

(Example 2)
An electric double layer capacitor was manufactured in the same manner as in Example 1 except that the clip-shaped leaf spring was changed to one made of carbon steel (S60C) and capable of obtaining a contact pressure of 294 Pa.

(Example 3)
An electric double layer capacitor was manufactured in the same manner as in Example 1 except that the clip-shaped leaf spring was changed to a carbon steel (S60C) product that could obtain a contact pressure of 20 Pa.

Example 4
100 parts of chain epoxy resin (trade name EP4000 manufactured by ADEKA Corporation) as an epoxy resin, 40 parts of aliphatic polyamine (trade name EH4357S manufactured by ADEKA Corporation) as a curing agent, and an antifoaming agent (trade name TSA720) 0. An epoxy resin composition was prepared by uniformly stirring and mixing 1 part. Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. Thereafter, the composition was poured into the molding die 33, heated and cured at 70 ° C. for 60 minutes, and after the mold was opened, further heated at 70 ° C. for 180 minutes and then cured to produce an electric double layer capacitor. .

(Example 5)
100 parts bisphenol A type epoxy resin (trade name Epicoat 828) as an epoxy resin, 40 parts aliphatic polyamine (trade name HD-5000 manufactured by Daito Sangyo Co., Ltd .; written as a hardener (2)) as a curing agent, and antifoaming An epoxy resin composition was prepared by uniformly stirring and mixing 0.1 part of an agent (trade name: TSA720). Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. Thereafter, the composition was poured into the molding die 33, heated and cured at 70 ° C. for 60 minutes, and after the mold was opened, further heated at 70 ° C. for 180 minutes and then cured to produce an electric double layer capacitor. .

(Example 6)
100 parts of bisphenol A type epoxy resin (trade name Epicoat 828) as epoxy resin, 20 parts of aliphatic polyamine (trade name HD-5000 manufactured by Daito Sangyo Co., Ltd.) as curing agent, spherical fused silica powder (electrochemical industry) as filler Product name FB959; average particle size 18 μm) 300 parts, 3-glycidoxypropyltrimethoxysilane (Nihon Unicar Co., Ltd. product name A-187) 1 part as a silane coupling agent, and antifoaming agent (Product name TSA720) 0.1 part was uniformly stirred and mixed to prepare an epoxy resin composition. Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. Thereafter, the composition was poured into the molding die 33, heated and cured at 70 ° C. for 60 minutes, and after the mold was opened, further heated at 70 ° C. for 180 minutes and then cured to produce an electric double layer capacitor. .

(Example 7)
100 parts of a chain epoxy resin (trade name EP4000) as an epoxy resin, 35 parts of an aliphatic polyamine (trade name D-400 manufactured by Huntsman Japan Co., Ltd .; written as a hardener (3)) as a curing agent, and an antifoaming agent (Product name TSA720) 0.1 part was uniformly stirred and mixed to prepare an epoxy resin composition. Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. Thereafter, the composition was poured into the mold 33, heated and cured at 70 ° C. for 180 minutes, and after opening the mold, further heated at 70 ° C. for 360 minutes and then cured to produce an electric double layer capacitor. .

(Example 8)
100 parts of polyfunctional epoxy resin (trade name jER630, manufactured by Japan Epoxy Resin Co., Ltd.) as an epoxy resin, aliphatic polyamine (trade name: HD-110TP manufactured by Daito Sangyo Co., Ltd .; indicated as curing agent (4)) 20 And 0.1 part of an antifoaming agent (trade name TSA720) were uniformly mixed with stirring to prepare an epoxy resin composition. Further, as shown in FIG. 1, the capacitor body 11 and the electrode terminal 22 are fixed by a clip-shaped leaf spring (made of carbon steel (S60C), contact pressure 147 Pa) and set in a mold 33 made of stainless steel. did. Thereafter, the composition was poured into the molding die 33, heated and cured at 70 ° C. for 60 minutes, and after the mold was opened, further heated at 70 ° C. for 180 minutes and then cured to produce an electric double layer capacitor. .

Example 9
An electric double layer capacitor was manufactured in the same manner as in Example 1 except that the clip-shaped leaf spring was changed to a carbon steel (S60C) product that could obtain a contact pressure of 490 Pa.

(Example 10)
An electric double layer capacitor was manufactured in the same manner as in Example 1 except that the clip-shaped leaf spring was changed to a carbon steel (S60C) product that could obtain a contact pressure of 9.8 Pa.

(Comparative example)
An electric double layer capacitor was manufactured in the same manner as in Example 1 except that the capacitor body 11 and the electrode terminal 22 were set in the molding die 33 via the positioning pins.

  For the electric double layer capacitors obtained in each of the above Examples and Comparative Examples, and further for a commercially available electric double layer capacitor (reference example), using an LCR meter (HP4284A manufactured by Hewlett-Packard) at 1 kHz, 4.5 V, The equivalent series resistance (ESR) after 1000 hours at initial (25 ° C.) and 70 ° C. was measured. The results are shown in Table 1 together with the composition and physical properties (flexural modulus, glass transition point) of the resin composition used as the molding material. The measuring method of the physical properties of the resin composition is as follows.

[Bending elastic modulus]
A sample prepared by curing the resin composition at 70 ° C. for 5 hours was measured using a solid thermoelasticity measuring device (DMS thermal analyzer) manufactured by Seiko Instruments.
[Glass transition point]
For a sample prepared by curing the resin composition at 70 ° C. for 5 hours, a thermal expansion curve was measured by a thermomechanical analyzer manufactured by Seiko Instruments, and obtained from the midpoint of the displacement point.

  As is apparent from Table 1, the electric double layer capacitor formed in the example has suppressed fluctuations in electric characteristics, the contact pressure of the clip-shaped leaf spring is 0.01 to 4.0 MPa, and 70 Particularly good results were obtained in Examples 1 to 6 using resins having a flexural modulus of 1 GPa or less at ° C and a glass transition point of 20 to 60 ° C.

  DESCRIPTION OF SYMBOLS 10 ... Electric double layer capacitor, 11 ... Capacitor main body, 12 ... Spring member, 13 ... Mold resin part, 21 ... Laminated body, 22 ... Electrode terminal, 33 ... Mold.

Claims (6)

  A capacitor body provided with a positive electrode terminal on the positive electrode body side, a negative electrode terminal on the negative electrode body side, and a capacitor body provided with the positive electrode body and the cathode body, respectively, with a separator interposed therebetween, and the respective electrode terminals. An electric double layer capacitor comprising: a spring member that presses and urges toward the laminated body side; and a mold resin portion that covers and seals the capacitor body and the spring member together.   2. The electric double layer capacitor according to claim 1, wherein a contact pressure of the spring member with respect to the electrode terminal is 0.01 to 4.0 MPa.   The electric double layer capacitor according to claim 1, wherein the spring member is a clip-shaped plate spring.   4. The electric double layer capacitor according to claim 1, wherein the mold resin portion is made of a resin having a flexural modulus at 70 ° C. of 1 GPa or less. 5.   5. The electric double layer capacitor according to claim 1, wherein the mold resin portion has a glass transition point of 20 to 60 ° C. 6.   6. The electric double layer capacitor according to claim 1, wherein the mold resin portion is made of a thermosetting resin.

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