U.S. patent application number 10/067253 was filed with the patent office on 2002-08-08 for cap member for electrical double layer capacitor container.
This patent application is currently assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. Invention is credited to Komatsuki, Masato, Matsuoka, Toshiyuki.
Application Number | 20020105776 10/067253 |
Document ID | / |
Family ID | 18896473 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020105776 |
Kind Code |
A1 |
Komatsuki, Masato ; et
al. |
August 8, 2002 |
CAP MEMBER FOR ELECTRICAL DOUBLE LAYER CAPACITOR CONTAINER
Abstract
A cap member 4 comprises electrode terminals 10, 11 which are
arranged in an opening 2a, and an insulating seal member 12
insert-molded between both the electrode terminals 10, 11. The
electrode terminals 10, 11 are provided with ribs 14, 17, and
chemically bond to the layer of an organic compound formed on the
surface of the terminals 10, 11. The bottom surface of the rib 17
is placed upwardly of the bottom surface of the rib 14. The
resin-molded article 12 contains therein the ribs 14 and 17 formed
on both the electrode terminals 10, 11 and chemically bonds to the
organic compound layers formed on the surfaces of both the
electrode terminals 10, 11.
Inventors: |
Komatsuki, Masato;
(Wako-shi, JP) ; Matsuoka, Toshiyuki; (Wako-shi,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
WASHINGTON
DC
20037
US
|
Assignee: |
HONDA GIKEN KOGYO KABUSHIKI
KAISHA
|
Family ID: |
18896473 |
Appl. No.: |
10/067253 |
Filed: |
February 7, 2002 |
Current U.S.
Class: |
361/518 |
Current CPC
Class: |
Y02T 10/70 20130101;
Y02T 10/7022 20130101; H01G 11/58 20130101; H01G 9/10 20130101;
Y02E 60/13 20130101; H01G 11/04 20130101 |
Class at
Publication: |
361/518 |
International
Class: |
H05K 005/06; H01G
009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2001 |
JP |
2001-32566 |
Claims
What is claimed is:
1. A cap member for an electrical double layer capacitor which
shields and caps an opening of a bottom-closed tubular container
housing electrode elements of a positive electrode and a negative
electrode impregnated with an electrolytic solution and oppositely
placed via a separator and which has a pair of electrode terminals
connected to each of the electrodes, said cap member comprising: a
first electrode terminal which is in the form of a hollow tube and
arranged in the outer peripheral side of the opening; a second
electrode terminal which is arranged with a predetermined space in
the inner peripheral side of the first electrode terminal; and an
insulating seal member consisting of a resin-molded article
including glass fibers of small pieces inserted and formed between
both the electrode terminals; wherein the first electrode terminal
has a rib projecting downward from its bottom surface and extending
in the axial direction of the container and chemically bonds to an
organic compound layer formed on the surface of the first terminal;
the second electrode terminal has a rib projecting upwardly from
its bottom surface and extending in the axial direction of the
container and chemically bonds to an organic compound layer formed
on the surface of the second terminal; the bottom surface of the
rib of the second electrode terminal is positioned above the bottom
surface of the rib of the first electrode terminal; and the
resin-molded article contains therein the ribs formed on both the
electrode terminals and chemically bonds to the organic compound
layers formed on the surfaces of both the electrode terminals.
2. A cap member for the electrical double layer capacitor according
to claim 1, wherein the organic compound layer comprises a silane
coupling agent.
3. A cap member for the electrical double layer capacitor according
to claim 1, wherein the organic compound layer comprises a
triazinethiol silane coupling agent.
4. A cap member for the electrical double layer capacitor according
to claim 1, wherein the resin-molded article is made of one resin
selected from the group consisting of a nylon, an
acrylonitrile-butadiene-styrene copolymer resin, polybutylene
terephthalate, polyphenylene sulfide, polyphenylene oxide, an epoxy
resin, and a phenol resin.
5. A cap member for the electrical double layer capacitor according
to claim 4, wherein the resin-molded article is made of one resin
selected from the group consisting of polyphenylene sulfide, an
epoxy resin, and a phenol resin.
6. A cap member for the electrical double layer capacitor according
to claim 1, wherein the resin-molded article is formed by insert
molding comprising the steps of placing a mold having an inner
surface shape coincident with the outside shape of the insulating
seal member and the second electrode terminal in the inner
peripheral side of the first electrode terminal, injecting a molten
resin from a gate provided on the-surface facing the second
electrode terminal in the inner peripheral side of the mold into
the mold, entering the injected resin along the surface of the
inner peripheral side of the mold into the side of the second
electrode terminal, guiding the resin hitting the bottom surface of
the second electrode terminal to the rib of the second electrode
terminal for the resin to backwardly flow in the direction of the
gate, guiding the resin hitting the bottom surface of the gate side
of the mold to the rib of the first electrode terminal for the
resin to flow between both the electrode terminals, and allowing a
part of the resin hitting the bottom surface of the gate side of
the mold to flow in the outer peripheral side of the rib of the
first electrode terminal.
7. A cap member for the electrical double layer capacitor according
to claim 2, wherein the resin-molded article includes the glass
fibers of small pieces which are oriented in the direction almost
parallel to the axial direction of the container.
8. A cap member for the electrical double layer capacitor according
to claim 1, wherein when the first electrode terminal is welded to
the opening of the bottom-closed tubular container, the
resin-molded article is formed so that a space is left between its
end portion facing the side wall of the bottom-closed tubular
container, and the welded portion of the electrode terminal and the
opening.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cap member for an
electrical double layer capacitor container.
[0003] 2. Description of the Related Art
[0004] In recent years, electrical double layer capacitors of high
capacity and high output have received attention as car-mounted
electric power sources for driving cars.
[0005] There is known electrical double layer capacitors in which
electrode elements are impregnated with an electrolytic solution
and housed into a bottom-closed tubular container. The electrode
elements have a positive electrode and a negative electrode
oppositely placed on opposite sides of separators, wherein the
positive electrode and the negative electrode are of solid
electrodes including activated carbon and the like as a main
ingredient and formed on the surfaces of current-collecting members
of metal foil and the like.
[0006] In the above electric double layer capacitor, a highly
wetting organic electrolytic solution is used in order to heighten
electrode density when the above active carbon is impregnated with
the above electrolytic solution. As such an organic electrolytic
solution, a solution wherein a quaternary ammonium salt is
dissolved in an organic solvent such as polycarbonate is used, for
example.
[0007] Furthermore, in the electrical double layer capacitors,
there is known a capacitor having such a configuration that the
opening of the container is sealed by a cap member having a pair of
electrode terminals connected to the respective electrodes. For
example, Japanese Patent Application Laid-open No. 2000-21684
discloses a cap member for an electrical double layer capacitor
comprising an insulating seal member formed by insert molding of a
synthetic resin in between a metallic member provided with a
through hole in the inner peripheral side and a pair of electrode
terminals passing into the through hole. The cap member described
in the application is ultra-sonic welded to the opening of a
bottom-closed tubular container, thereby shielding and capping the
opening.
[0008] However, the cap member is shrunk during solidification by
cooling of a synthetic resin insert-molded. Therefore, this method
has a disadvantage of a reduction in adhesion between the
insulating seal member formed and the metallic member or the
electrode terminal surface. The reduced adhesion results in a fear
that when the inside of the electrical double layer capacitor
becomes high pressured by the evolution of gas and the like, the
organic electrolytic solution having high wettability may leak
outside from a gap between the insulating seal member and the
metallic member or the electrode terminal.
SUMMARY OF THE INVENTION
[0009] The present invention has an object to resolve such
disadvantages and to provide a cap member for an electrical double
layer capacitor permitting securely preventing of electrolytic
solution therein from leaking to the outside even when the
electrolytic solution is of high wettability.
[0010] In order to achieve this object, an aspect of the present
invention is directed to a cap member for an electrical double
layer capacitor which shields and caps an opening of a
bottom-closed tubular container housing electrode elements of a
positive electrode and a negative electrode impregnated with an
electrolytic solution and oppositely placed via a separator and
which has a pair of electrode terminals connected to each of the
electrodes, said cap member comprising a first electrode terminal
which is in the form of a hollow tube and arranged in the outer
peripheral side of the opening, a second electrode terminal which
is arranged via a predetermined space in the inner peripheral side
of the first electrode terminal, and an insulating seal member
consisting of a resin-molded article including glass fibers of
small pieces inserted and formed between both the electrode
terminals, wherein the first electrode terminal has a rib
projecting downward from its bottom surface and extending in the
axial direction of the container and chemically bonds to an organic
compound layer formed on the surface of the first terminal, the
second electrode terminal has a rib projecting upwardly from its
bottom surface and extending in the axial direction of the
container and chemically bonds to an organic compound layer formed
on the surface of the second terminal, the bottom surface of the
rib of the second electrode terminal is positioned above the bottom
surface of the rib of the first electrode terminal, and the
resin-molded article contains therein the ribs formed on both the
electrode terminals and chemically bonds to the organic compound
layers formed on the surfaces of both the electrode terminals.
[0011] In the cap member according to the present invention, there
is a fear of a reduction in adhesion between the insulating seal
member and both the electrode terminals because a resin injected in
the molten state shrinks during solidification by cooling
thereof.
[0012] Here, the shrinking force of the resin-molded article
forming the insulating seal member largely acts in the radius
direction of the first electrode terminal in the form of a hollow
tube, that is, in the direction orthogonal to the axial direction
of the container. For this reason, in the cap member according to
the present invention, the electrode terminals each are provided
with the ribs projecting downward from the respective bottom
surfaces and extending in the axial direction of the container, and
the resin-molded article is formed to contain therein the ribs
formed on both the electrode terminals. As a result, according to
the cap member of the present invention, the rib works against the
shrinking force of the resin-molded article, thereby permitting the
prevention of a reduction in adhesion between the insulating seal
member and both the electrode terminals.
[0013] Furthermore, in the cap member according to the present
invention, both the electrode terminals chemically bond to the
organic compound layers formed on their respective surfaces, and
the resin-molded article chemically bonds to the organic compound
layer. As a result, in the cap member according to the present
invention, excellent adhesion can be provided between the
insulating seal member and both the electrode terminals through the
medium of the organic compound layers to which each of them
chemically bonds as described above.
[0014] As the above organic compound layer, the layer comprising a
silane coupling agent or a triazinethiol derivative may be
mentioned.
[0015] On the other hand, in order to be chemically bonded to the
above organic compound layer, the above resin-molded article is
preferably made of one resin selected from the group consisting of
a nylon, an acrylonitrile-butadienestyrene copolymer resin,
polybutylene terephthalate, polyphenylene sulfide, polyphenylene
oxide, an epoxy resin, and a phenol resin.
[0016] According to the cap member of the present invention, it is
possible to prevent a reduction in adhesion between the insulating
seal element and both the electrode terminals to hold excellent
adhesion between them. Therefore, in the case of using an organic
electrolytic solution of high wettability, it is possible to
securely prevent the organic electrolytic solution from
leaking.
[0017] Furthermore, in the cap member according to the present
invention, it is characterized that the resin-molded article is
formed by insert molding comprising the steps of placing a mold
having an inner surface shape coincident with the outside shape of
the insulating seal member and the second electrode terminal in the
inner peripheral side of the first electrode terminal, injecting a
molten resin from a gate provided on the surface facing the second
electrode terminal in the inner peripheral side of the mold into
the mold, entering the injected resin along the surface of the
inner peripheral side of the mold into the side of the second
electrode terminal, guiding the resin hitting the bottom surface of
the second electrode terminal to the rib of the second electrode
terminal for the resin to backwardly flow in the direction of the
gate, guiding the resin hitting the bottom surface of the gate side
of the mold to the rib of the first electrode terminal for the
resin to flow between both the electrode terminals, and allowing a
part of the resin hitting the bottom surface of the gate side of
the mold to flow in the outer peripheral side of the rib of the
first electrode terminal.
[0018] In the insert molding, the cap member according to the
present invention has the bottom surface of the rib of the second
electrode terminal positioned upwardly of the bottom surface of the
rib of the first electrode terminal. Therefore, the molten resin is
easy to flow into behind the rib of the second electrode terminal
when viewed from the flowing-in direction of the resin, that is, in
the side of the first electrode terminal, thereby permitting easy
molding of the insulating seal member.
[0019] Further, in the cap member according to the present
invention, during insert molding of the insulating seal member as
described above, the resin injected in the molten state is guided
by the rib to snake upward and downward in the axial direction of
the container as described above. As a result, in the resin-molded
article configuring the insulating seal member, the contained glass
fibers of small pieces is oriented in the direction almost parallel
to the axial direction of the container. Therefore, in the cap
member according to the present invention, the glass fibers of
small pieces oriented as described above cause a force acting
against the shrinking force of the resin-molded article, thereby
permitting prevention of a reduction in adhesion between the
insulating seal member and both the electrode terminals.
[0020] Although the cap member according to the present invention
is fixed to the outer peripheral side of the opening of the
bottom-closed tubular container via the first electrode terminal,
thus capping the opening, at this time, the electrode terminal is
welded to the opening by laser welding and the like. Therefore, the
cap member of the present invention is characterized in that when
the first electrode terminal is welded to the opening of the
bottom-closed tubular container, the resin-molded article is formed
so that a space is left between its end portion facing the side
wall of the bottom-closed tubular container, and the welded portion
of the electrode terminal and the opening.
[0021] As described above, the cap member according to the present
invention has a space between the end portion of the resin-molded
article and the side wall of the bottom-closed tubular container,
and therefore it is possible to prevent the heat generated by the
laser welding and the like from degrading the resin-molded article
configuring the insulating seal member. Therefore, in the cap
member according to the present invention, the insulating seal
member and both the electrode terminals can hold excellent adhesion
to each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an illustrative cross-sectional view of an
electrical double layer capacitor provided with a cap member of one
aspect of the present invention.
[0023] FIG. 2 is an enlarged view of the main portion of FIG.
1.
[0024] FIG. 3 is an illustrative cross-sectional view showing a
method of manufacturing the cap member shown in FIG. 1.
[0025] FIG. 4 is an illustrative cross-sectional view showing the
enlarged main portion of a cap member of another aspect of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] As shown in FIG. 1, an electrical double layer capacitor 1
is configured such that an electrode element 3 impregnated with an
organic electrolytic solution is housed in a bottom-closed tubular
container 2 of metal or alloy and the opening portion 2a of the
bottom-closed tubular container 2 is hermetically sealed with a cap
member 4.
[0027] The electrode element 3 comprises a positive electrode and a
negative electrode oppositely placing a pair of electrodes 5, 5 on
opposite sides of a separator 6, which electrodes 5, 5 are made by
forming a layer of activated carbon (not shown) on a
current-collecting element (not shown). The electrode element 3 is
formed by winding the electrodes 5, 5 and the separator 6 together
around a core 7.
[0028] The core 7 is hollow, and is mounted to the bottom portion
2b of the bottom-closed tubular container 2 by an insulating
mounting member 8 screwed into a hollow portion 7a. Although not
shown, the current-collecting element is connected to a positive
electrode connection member 9 in the positive electrode side and is
connected to the bottom portion 2b of the bottom-closed tubular
container 2 in the negative electrode side.
[0029] The activated carbon configuring the electrode 5 increases
the electrode density of the electrical double layer capacitor when
the organic electrolytic solution is used, and thus the organic
electrolytic solution preferably increases static capacity density
per unit volume. For this reason, the activated carbon has the mode
of a pore distribution by a TEM image analysis method in the range
from 7-25 .ANG..
[0030] For the activated carbon, as pores smaller than 7 .ANG. in
diameter increase, the adsorption amount of ions in the organic
electrolytic solution decreases and thus the static capacity of the
electrical double layer capacitor becomes smaller. Further, as
pores larger than 25 .ANG. in diameter increase, the static
capacity density per volume decreases.
[0031] Furthermore, the activated carbon used has the relative
surface area preferably in the range from 500 to 3000 m.sup.2/g,
and more preferably in the range 600 to 1500 m.sup.2/g. If the
relative surface area is out of the above range, sufficient static
capacity may be not obtained.
[0032] The activated carbon is mixed with a bonding agent and, if
desired, a conducting agent, kneaded with ethanol dropped and
rolled into a sheet-like electrode. The electrode 5 can be
manufactured by bonding and integrating the sheet-like electrode to
both the surfaces of the current-collecting element made of foil
and mesh of aluminum, stainless steel and the like with an
electroconductive adhesive.
[0033] The above electrode 5 may be produced by coating both the
sides of the above collector with a slurry obtainable by
dispersing, into a solvent, a mixture of the above active carbon, a
binder, and a conductive agent which is optionally mixed, followed
by drying.
[0034] As the above binder, for example, polyvinylidene fluoride,
polytetrafluoroethylene, a polyimide resin, a polyimideamide resin
can be used. Moreover, as the above conductive agent, for example a
material having a high electric conductivity such as carbon black
or carbon whisker can be used.
[0035] The above separator may be any of porous bodies which are
permeable by ions present in the above organic electrolytic
solution. Examples of such porous bodies include microporous
polyethylene film, microporous polypropylene film, polyethylene
nonwoven cloth, glass fiber-mixed nonwoven cloth, glass mat filter,
cellulose nonwoven cloth, rayon nonwoven cloth, and the like.
[0036] As the organic electrolytic solution, it is preferable to
use a highly wetting solution in order to attain a high electrode
density when the above active carbon is impregnated with the above
electrolytic solution and an electric double layer is formed by
penetration of the solution into pores of the active carbon. As
such a highly wetting organic electrolytic solution, a solution
wherein a quaternary onium salt is dissolved in an organic solvent
can be used.
[0037] As the above quaternary onium salt, any one of salts formed
from quaternary onium cations such as quaternary ammonium ions or
quaternary phosphonium ions and anions such as BF.sub.4.sup.-,
PF.sub.5.sup.-, SO.sub.3CF.sub.3.sup.-, AsF.sub.6.sup.-,
N(SO.sub.2CF.sub.3).sub.2.sup.-, or ClO.sub.4.sup.- or any mixture
of two or more of the salts can be used. As the above organic
solvent, there can be used a cyclic carbonate such as ethylene
carbonate, propylene carbonate, or butylene carbonate; a linear
carbonate such as dimethyl carbonate, ethyl methyl carbonate, or
diethyl carbonate; a lactone such as y-butyrolactone; sulfolane or
a sulfolane derivative; or the like.
[0038] As shown in FIG. 2, the cap member 4 is provided with a
negative electrode terminal 10 which is in the form of a hollow
tube and arranged on the outer peripheral side of the opening 2a,
and a positive electrode terminal 11 which is arranged via a
predetermined space in the inner peripheral side of the negative
electrode terminal 10. Further, the insulating seal member 12 is
formed between both the terminals 10, 11. The insulating seal
member 12 is made of synthetic resin-molded article including glass
fibers of small pieces.
[0039] The negative electrode terminal 10 is provided with a
ring-shaped recess portion 13 on the outer peripheral side of the
bottom surface 10a, and is fitted into the opening 2a of the
bottom-closed tubular container 2 by the recess portion 13, and is
then welded and joined to the bottom-closed tubular container 2 by
laser welding. At this time, the insulating seal member 12 is
positioned inwardly of the ring-shaped recess 13 through which the
negative electrode terminal 10 is welded to the opening 2a, and the
end portion 12a is formed via a space between it and the side-wall
of the bottom-closed tubular container 2. As a result, the
insulating seal member 12 does not directly undergo heat caused by
the laser welding due to the space, thereby permitting prevention
of degradation of the synthetic resin-molded article.
[0040] Furthermore, the negative electrode terminal 10 is provided
with a rib 14 projecting downward from its bottom surface 10a and
extending in the axial direction of the container 2, and has a
female thread portion 15 formed on the inner peripheral surface of
the top portion 10b thereof, wherein a bus bar (not shown) is
screwed into the female thread 15 as an external terminal. The bus
bar is provided with a negative electrode terminal in the shape of
a hollow tube on the external peripheral side thereof, and a
positive electrode terminal in the shape of a solid cylinder and
provided via an insulating member in the inner peripheral side of
the negative electrode terminal. Further, the bus bar is screwed
into the female thread 15 formed on the negative electrode terminal
10 of the cap member 4 by the male thread portion formed on the
outer peripheral surface of the negative electrode terminal,
thereby connecting to the negative electrode terminal 10. Moreover,
when the bus bar is screwed into the female thread 15, the end face
of the positive electrode terminal in the shape of a solid cylinder
makes contact with the positive electrode terminal 11 of the cap
member 4, thereby connecting the bus bar to the positive electrode
terminal 11.
[0041] Therefore, the upper end portion of the positive electrode
terminal 11 of the cap member 4 is placed to project upwardly of
the lower end portion of the female thread portion 15 formed on the
negative electrode terminal 10. The positive electrode terminal 11
is provided with a through hole 16, and a positive electrode
connection member 9 is fitted on the inner peripheral side of the
through hole. Moreover, the positive electrode terminal 11 has a
rib 17 projecting downward from the bottom surface 11a thereof and
extending in the axial direction of the container 2. Further, the
rib 17 has its bottom surface placed upward of the bottom surface
of the rib 14 formed in the negative electrode terminal 10.
[0042] The insulating seal member 12 is formed by insert molding of
a synthetic resin including glass fibers of small pieces, and is
provided within the inner peripheral side, a through hole 12b
linking the through hole 16 of the positive electrode terminal 11.
As shown in FIG. 3, the insert molding is performed such that a
metal mold 18 provided with an inner surface shape coincident with
the outside shape of the insulating seal member 12 and the positive
electrode terminal 11 are placed in the inner peripheral side of
the negative electrode terminal 10, and a molten resin is injected
into the metal mold 18 from a gate (not shown) provided on the
surface facing the positive electrode terminal 11 of the inner
peripheral side of the metal mold 18. At this time, a portion
including the rib 14 of the negative electrode terminal 10 and a
portion including the rib 17 of the positive electrode terminal 11
are exposed in the interior of the metal mold 18. Therefore, the
insulating seal member 12 formed by solidification by cooling of
the resin injected into the metal mold 18 includes the ribs 14, 17
therein, and joints them to the negative electrode terminal 10 and
the positive electrode terminal 11.
[0043] When the insert molding is performed as described
hereinbefore, the resin injected from the gate, as shown by arrows
in FIG. 3, runs into the side of the positive electrode terminal 11
along the surface of the inner peripheral side of the metal mold 18
(the surface forming the through hole 12b in the insulating seal
member 12), and hits the bottom surface 11a of the positive
electrode terminal 11, and then is guided by the rib 17 to backward
flow in the direction of the gate. Then, the resin hits the surface
of the gate side of the metal mold 18 and is then guided by the rib
14 to flow in between the negative electrode terminal 10 and the
positive electrode terminal 11. In addition, a part of the resin
flows into the outer peripheral side of the rib 14.
[0044] At this time, since the bottom surface of the rib 17 is
positioned upwardly of the bottom surface of the rib 14, the resin
guided by the rib 17 and backward flowing in the direction of the
gate 17 can easily flow in between the negative electrode terminal
10 and the positive electrode terminal 11. As a result, the
insulating seal member 12 having the above-described shape can be
formed ideally.
[0045] Furthermore, the resin injected in the metal mold 18 is
guided by the ribs 14, 17 to snake upward and downward as shown by
arrows in FIG. 3, so that the glass fibers of small pieces included
in the resin is easily orientated in the axial direction of the
container 2 along the flow of the resin snaking as mentioned
above.
[0046] After injected in the metal mold 18, the resin is subjected
to the large action of shrinking force toward the inner peripheral
direction during solidification by cooling thereof. However, in the
cap member 4, the ribs 14, 17 extending in the axial direction of
the container 2 as described above and the small pieces of glass
fibers orientated in the axial direction of the container 2 as
described above act against the shrinking force of the resin.
Therefore, in the cap member 4, the insulating seal member 12 can
hold excellent adhesion between the negative electrode terminal 10
and the positive electrode terminal 11.
[0047] Further, layers of an organic compound (not shown) forming
chemical bonds with the negative electrode terminal 10 and the
positive electrode terminal 11 are formed on the portions of the
negative electrode terminal 10 and the positive electrode terminal
11 exposed in the metal mold 18. The organic compound layers are
also able to form chemical bonds with the resin injected in the
metal mold 18. As a result, the insulating seal member 12 is
chemically coupled to the negative electrode terminal 10 and the
positive electrode terminal 11 through the layer of the organic
compound, whereby excellent adhesion can be obtained between the
insulating seal member 12 and the negative electrode terminal 10,
and between the insulating seal member 12 and the positive
electrode terminal 11.
[0048] As an organic compound forming the above organic compound
layer, a silane coupling agent or a triazinethiol derivative may be
mentioned. The above silane coupling agent and triazinethiol
derivative are convenient because the compounds do not react even
when they come into contact with the above organic electrolytic
solution with which the electrode element 3 is impregnated.
[0049] The above-mentioned silane coupling agent includes
vinyltriethoxysilane, vinyltris(2-methoxyethoxysilane),
3-methacryloxypropyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane,
2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
N-2-(aminoethyl)-3-aminopro- pyltrimethoxysilane,
N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane,
3aminopropyltrimethoxysilane,
N-phenyl-3aminopropyltrimethoxysilane,
3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane,
N-imidazolemethyltrimethoxysilane,
N-imidazolemethyltriethoxysilane,
2-(N-imidazole)ethyltrimethoxysilane,
2-(N-imidazole)ethyltriethoxysilane- ,
3-(N-imidazole)propyltrimethoxysilane,
3-(N-imidazole)propyltriethoxysil- ane,
N-2methylimidazolemethyltrimethoxysilane,
N-2-isopropylimidazolemethy- ltrimethoxysilane,
N-2-ethyl-4-methylimidazolemethyltrimethoxysilane, and the like. In
addition, as available agents of silane coupling agent aqueous
solutions, Parcoat 3751 (a trade name) and Parcoat 3841 (a trade
name) manufactured by Nihon Parkerizing Co., Ltd. and the like can
be used.
[0050] The above-mentioned midazole silane compounds have high heat
resistance. Therefore, even after high temperature drying performed
to remove moisture in the container 2 after construction of the
electrical double layer capacitor shown in FIG. 1, excellent
adhesion can be held between the insulating seal member 12 and the
negative electrode terminal 10 and between the insulating seal
member 12 and the positive electrode terminal 11.
[0051] In order to form a layer of a silane coupling agent on the
surfaces of the negative electrode terminal 10 and the positive
electrode terminal, after cleaning and drying of the surfaces of
the negative electrode terminal 10 and the positive electrode
terminal 11, then the negative electrode terminal 10 and the
positive electrode terminal 11 are dipped in an aqueous solution of
a silane coupling agent at room temperature for several seconds to
several minutes. Then, the negative electrode terminal 10 and the
positive electrode terminal 11 are pulled out from the aqueous
solution of the silane coupling agent and dried without
rinsing.
[0052] Shiran coupling agents form a layer of an amorphous organic
metal compound between the insulating seal member 12 and the
negative electrode terminal 10 and between the insulating seal
member 12 and the positive electrode terminal 11. The layer of the
amorphous organic metal compound is formed primarily by siloxane
bonding, and bonds to the metal surface of the negative electrode
terminal 10 and the positive electrode terminal 11, based on
chemical bonds. Further, the amorphous organic metal compound layer
is considered to bond to the resin forming the insulating seal
member 12 by the reaction of alkoxy groups.
[0053] The above-mentioned triazinethiol derivative includes the
compounds such as 1,3,5-triazine-2,4,6-trithiol,
1,3,5-triazine-2,4,6-trithiol monosodium,
1,3,5-triazine-2,4,6-trithiol triethanolamine,
1,3,5-triazine-2,4,6-trithiol di(tetrabutylammonium salt),
6-anilino-1,3,5-triazine-2,4-dithiol,
6-anilino-1,3,5-triazine-2,4-dithio- l monosodium,
6dibutylamino-1,3,5-triazine-2,4-dithiol,
6-dibutylamino-1,3,5-triazine-2,4-dithiol monosodium,
6-dibutylamino-1,3,5-triazine-2,4-dithiol di(tetrabutylammonium
salt), 6-diallylamino-1,3,5-triazine-2,4-dithiol,
6-diallylamino-1,3,5-triazine-- 2,4-dithiol monosodium,
6-dioctylamino-1,3,5-triazine-2,4-dithiol,
6-dioctylamino-1,3,5-triazine-2,4-dithiol monosodium,
6-dilaurylamino-1,3,5-triazine-2,4dithiol,
6-dilaurylamino-1,3,5-triazine- -2,4-dithiol monosodium,
6-stearylamino-1,3,5-triazine-2,4-dithiol,
6-stearylamino-1,3,5-triazine-2,4-dithiol monopotassium,
6-oleylamino-1,3,5-triazine-2,4-dithiol, and
6-oleylamino-1,3,5-triazine-- 2,4-dithiol monopotassium. For
forming the above triazinethiol derivative layer on the surfaces of
the negative electrode terminal 10 and positive electrode terminal
11, using an aqueous solution of a triazinethiol derivative as an
electrodeposition solution, the negative electrode terminal 10 or
positive electrode terminal 11 as a positive electrode, and a
platinum plate, a titanium plate or a carbon plate as a negative
electrode, a high-speed treatment at a low temperature is carried
out by passing an electric current between both the electrodes.
[0054] Aluminum, aluminum alloy, copper, stainless steel, iron,
nickel, titanium, tantalum, and the like can be used for the
negative electrode terminal 10 and the positive electrode terminal
11 because these materials make chemical bonds with silane coupling
agents or triazine thiol derivatives. Aluminum or aluminum alloy
can be suitably used for the negative electrode terminal 10 and the
positive electrode terminal 11 because of the excellent affinity of
aluminum and aluminum alloy to triazine thiol derivatives or silane
coupling agents.
[0055] Furthermore, for the insulating seal member 12, there can be
used a nylon, an acrylonitrile-butadiene-styrene copolymer resin
(ABS), polybutylene terephthalate (PBT), polyphenylene sulfide
(PPS), polyphenylene oxide (PPO), an epoxy resin, a phenol resin or
the like, because each of these materials makes a chemical bond
with a silane coupling agent or a triazine thiol derivative. For
the insulating seal member 12, the PPS, the epoxy resin or the
phenol resin can be suitably used, because of its excellent heat
resistance.
[0056] Next, the cap member 4 (working example) was produced by
using the negative electrode terminal 10 and the positive electrode
terminal 11 of which surfaces have an organic compound layer formed
by using available silane coupling agents, and by forming the
insulating seal member 12 in between the negative electrode
terminal 10 and the positive electrode terminal 11 by insert
molding of polyphenylene sulfide including glass fibers. Next, the
negative electrode terminal 10 was welded to the opening 2a of the
container 2 by laser welding to fix the cap member 4 to the
container 2, thereby configuring the electrical double layer
capacitor 1 shown in FIG. 1. Then, by applying hydraulic pressure
to the base portion and measuring the pressure at which the cap
member 4 was broken, the strength of withstand pressure was
determined.
[0057] Next, the cap member 4 (comparative example 1) was formed by
using the negative electrode terminal 10 and the positive electrode
terminal 11 not provided with the ribs 14, 17 and by forming the
insulating seal member 12 in between the negative electrode
terminal 10 and the positive electrode terminal 11 by insert
molding of polyphenylene sulfide not including glass fibers. Then,
the strength of withstand pressure was measured on the cap member 4
of comparative example 1 in the same manner as in the working
example. When the strength of withstand pressure of the cap member
4 of the comparative example 1 was assumed to be 100, the strength
of withstand pressure of the cap member 4 of the present working
example was 130.
[0058] Next, the cap member 4 (comparative example 2) was formed by
using the negative electrode terminal 10 and the positive electrode
terminal 11 not provided with the ribs 14 and 17 and by forming the
insulating seal member 12 in between the negative electrode
terminal 10 and the positive electrode terminal 11 by insert
molding of polyphenylene sulfide including glass fibers. Then, the
strength of withstand pressure was measured on the cap member 4 of
comparative example 2 in the same manner as in the working example.
The strength of withstand pressure of the cap member 4 of the
comparative example 2 was 110 when that of the comparative example
1 was assumed to be 100.
[0059] Next, the cap member 4 (comparative example 3) is formed by
using the negative electrode terminal 10 and the positive electrode
terminal 11 provided with the ribs 14, 17 and by forming the
insulating seal member 12 in between the negative electrode
terminal 10 and the positive electrode terminal 11 by insert
molding of polyphenylene sulfide not including glass fibers. Then,
the strength of withstand pressure was measured on the cap member 4
of comparative example 3 in the same manner as in the working
example. The strength of withstand pressure of the cap member 4 of
the comparative example 3 was 120 when that of the comparative
example 1 was assumed to be 100.
[0060] From the working example and the comparative examples, it is
clear that the excellent strength of withstand pressure can be
provided by the cap member 4 of the working example.
[0061] By the way, although the cap-member 4 according to the
present embodiment is configured to be provided with the ribs 14,
17 on the negative electrode terminal 10 and the positive electrode
terminal 11, it is possible to provide a tapered portion 19
gradually increasing in diameter from the inner peripheral side
toward the outer peripheral side, instead of the rib 14, as shown
in FIG. 4. The tapered portion 19 can act against shrinking force
during solidification by cooling of the resin to provide the effect
of holding the excellent adhesion between the insulating seal
member 12 and the negative electrode terminal 10 and between the
insulating seal member 12 and the positive electrode terminal 11.
Further, although FIG. 4 shows the rib 14 of FIG. 2 is replaced
with the tapered portion 19, the rib 17 may be replaced with a
tapered portion gradually increasing in diameter from the inner
peripheral side toward the outer peripheral side.
* * * * *