JP2005347611A - Electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric double layer capacitor with which the number of production processes can be reduced and high performance can be obtained by a simple structure. <P>SOLUTION: The capacitor is provided with slurry-like polarizable electrode active materials 12 and 14 including activated carbon, conductive materials and electrolyte, a collector 15 disposed in the polarizable electrode active materials, a bag-like separator 13 where the polarizable electrode active material 14 and the collector 15 are stored, an armour case 11 where the bag-like separator 13 is stored, the polarizable active material 12 arranged between the bag-like separator 13 and the armor case 11 and a sealing member 16 sealing the armor case 11 through a sealing material disposed in an opening part of the armor case 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric double layer capacitor, and more particularly to an electric double layer capacitor used in an electric vehicle and various electric devices.

  In a conventional electric double layer capacitor, a strip-like positive electrode and a strip-like negative electrode are overlapped with a first separator interposed therebetween, and one of the strip-like positive and negative electrodes is overlapped with a second separator impregnated with an electrolyte. The electrode winding body wound in a spiral shape is configured to be housed in a bottomed cylindrical case (see, for example, Patent Document 1).

However, in the step of forming the belt-like electrode of the electric double layer capacitor as in Patent Document 1 above, activated carbon, a conductive material, and a binder are kneaded, the kneaded material is rolled, and dried to form an electrode sheet. Since it is formed by bonding to aluminum foil, which is an electric body, the number of operations has increased. Moreover, the number of processes, such as the process of winding an electrode and the process of impregnating a separator with an electrolyte, has increased. In addition, the belt-like electrode has a problem that a binder is required to bond the electrode sheet to the aluminum foil current collector, and the number of parts increases. In addition, the internal resistance may be increased.
JP 2002-134370 A

  The object of the present invention is to eliminate the problem that the number of operations in the process of forming the strip electrode of the conventional electric double layer capacitor is increased, and the process of winding the electrode, impregnating the separator with the electrolytic solution It is to solve the problem that the number of processes increases, such as a process to be performed, and further, the problem that the number of parts increases and the problem that the internal resistance may increase.

  In view of the above-described problems, an object of the present invention is to provide an electric double layer capacitor capable of reducing the number of production steps and obtaining high performance with a simple structure.

  In order to achieve the above object, an electric double layer capacitor according to the present invention is configured as follows.

  A first electric double layer capacitor (corresponding to claim 1) includes a slurry-like polarizable electrode active material containing activated carbon, a conductive material and an electrolyte, and a current collector disposed in the polarizable electrode active material, A bag-shaped separator in which the polarizable electrode active material and the current collector are housed, an outer case in which the bag-shaped separator is housed, a polarizable active material disposed between the bag-shaped separator and the outer case, It is characterized by having a sealing member that seals the exterior case via a sealing material disposed in the opening of the exterior case.

  In the above configuration, the second electric double layer capacitor (corresponding to claim 2) is preferably characterized in that the current collector is configured to form a rectangular parallelepiped side.

  In the above configuration, the third electric double layer capacitor (corresponding to claim 3) is preferably characterized in that the current collector is a punching plate made of an aluminum material.

  A fourth electric double layer capacitor (corresponding to claim 4) is preferably characterized in that, in the above-described configuration, the conductive material includes carbon nanotubes or vapor-grown carbon fibers.

  A fifth electric double layer capacitor (corresponding to claim 5) is characterized in that, in the above-mentioned configuration, the electrolyte preferably contains dimethylethylammonium borofluoride or ethylmethylimidazolium borofluoride.

  According to the present invention, since no solid electrode is used, the number of operations can be reduced and the electrode can be easily formed. Moreover, since the process of winding an electrode and the process of impregnating the separator with an electrolytic solution are unnecessary, the number of processes can be reduced. In addition, since a slurry-like electrode is used, there is no need for an aluminum foil current collector, and there is no need for bonding, so a binder is not required, resistance can be reduced, and a simple structure and high-performance electric A multilayer capacitor is obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments (examples) of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view of the structure of the electric double layer capacitor according to the first embodiment of the present invention. The electric double layer capacitor 10 includes an outer case 11 that includes a negative electrode active material 12, a separator 13, a positive electrode active material 14, a current collector plate 15, and a sealing member 16.

  The positive electrode active material 14 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution. The current collector 15 is disposed in a positive electrode active material 14 that is a polarizable electrode active material. The separator 13 has a bag shape and accommodates the positive electrode active material 14 and the current collector 15. The negative electrode active material 12 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution similar to the positive electrode active material 14, and includes an outer case 11 in which a bag-shaped separator 13 is accommodated, and a bag-shaped separator 13. And the outer case 11. The sealing member 16 seals the outer case 11 via a sealing material disposed in the opening of the outer case 11.

  The electrode slurry of the positive electrode active material 14 and the negative electrode active material 12 is configured by kneading activated carbon and a conductive material in an electrolytic solution. In the structure of the conventional electric double layer capacitor, the electrode material is applied to the aluminum foil or the like, so that the conductivity is good. However, in the structure of the present invention, the aluminum foil is not used, so the conductivity is inferior. . For this reason, it is conceivable to increase the blending ratio of the conductive material. However, increasing the conductivity reduces the blending ratio of the activated carbon, which degrades the performance of the electric double layer capacitor. Therefore, by using carbon nanotubes having a high current collecting effect as the conductive material, high conductivity can be obtained without increasing the blending ratio of the conductive material. As the carbon nanotube, a multi-walled carbon nanotube or a single-walled carbon nanotube can be used. Alternatively, VGCF (vapor-grown carbon fiber; a carbon nanotube having a surface on which graphite is laminated) can be used.

  An ionic liquid is used as the electrolytic solution of the positive electrode active material 14 and the negative electrode active material 12. Generally used electrolytic solution is used by dissolving a solid salt in a solvent such as water or an organic solvent, but the salt concentration cannot be increased. An electrolytic solution in which TEMA.BF4 (triethylmethylammonium borofluoride) used in the prior art is dissolved in PC (polycarbonate) as a solvent can dissolve only 1.8 mol. However, since the ionic liquid is a salt that melts at room temperature, it does not need to be dissolved in a solvent and can be used at a high concentration. In this example, DEME.BF4 (diethylmethylammonium borofluoride), EMI.BF4 (ethylmethylimidazolium), or the like is used at a high concentration of about 5 mol. (Also, since an ionic liquid, which is an organic solvent, is used for the electrolyte, the activated carbon and the conductive material can be uniformly dispersed, and no precipitation occurs even if the polarizable electrode is in a slurry state.)

  Thus, the electrode is made into a slurry with the positive electrode active material 14 and the negative electrode active material 12, and an aluminum foil is unnecessary, so that no binder is required. Therefore, the resistance can be reduced and the compounding ratio of activated carbon can be increased, so that the performance of the electric double layer capacitor can be improved.

  Next, the separator 13 will be described. The separator used for the conventional electric double layer capacitor has used a fibrous separator. Since it is necessary to provide electrolyte solution retention, a separator having a high porosity and a high liquid retention rate was required. Therefore, it was a thick separator. However, in the electric double layer capacitor of the present invention, since the electrolytic solution is contained in the electrode slurry, it is not necessary to provide the separator with liquid retention, so the separator can be made thin and the internal resistance can be lowered. it can. However, since a generally used fibrous separator is thin, self-discharge increases, so it is better to use a porous separator such as a polyimide-based porous film.

  Thus, since the electric double layer capacitor according to the first embodiment of the present invention uses the slurry-like electrode and the bag-like separator, the shape of the electric double layer capacitor is not limited. As described above, a high performance electric double layer capacitor can be obtained by arranging the negative electrode slurry and the positive electrode slurry through a bag-shaped separator.

  FIG. 2 is a cross-sectional view of the structure of the electric double layer capacitor according to the second embodiment of the present invention. The electric double layer capacitor 20 includes an outer case 21, a negative electrode active material 22, a plurality of separators 23, a positive electrode active material 24, a current collector plate 25, an electrode terminal 26, and a sealing member 27.

  The positive electrode active material 24 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution. The current collector 25 is disposed in a positive electrode active material 24 that is a polarizable electrode active material. The separator 23 has a bag shape and accommodates the positive electrode active material 24 and the current collector 25. The negative electrode active material 22 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution similar to the positive electrode active material 24, and includes an outer case 21 in which a bag-like separator 23 is accommodated, and a bag-like separator 23. And the outer case 21. The sealing member 27 seals the outer case 21 via a sealing material disposed in the opening of the outer case 21.

  Since the positive electrode active material 24, the negative electrode active material 22, and the separator 23 use the same materials as those in the first embodiment, description thereof is omitted.

  In the electric double layer capacitor according to the second embodiment of the present invention, since the slurry-like electrode and the bag-like separator are used, the above-described negative electrode slurry and the positive electrode slurry are disposed through the bag-like separator. A performance electric double layer capacitor can be obtained.

  In addition, in this embodiment, there is no negative electrode side partition and it is a parallel structure, However, It can be made in series by providing a partition between each separator.

  FIG. 3 is a sectional view of the structure of an electric double layer capacitor according to the third embodiment of the present invention. The electric double layer capacitor 30 includes an outer case 31 including a negative electrode active material 32, a separator 33, a positive electrode active material 34, a current collector plate 35, a sealing member 36, a gasket 37, and an explosion-proof valve 38.

  The positive electrode active material 34 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution. The current collector 35 is disposed in a positive electrode active material 34 that is a polarizable electrode active material. The separator 33 has a bag shape and accommodates the positive electrode active material 34 and the current collector 35. The negative electrode active material 32 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution similar to the positive electrode active material 34, and includes an outer case 31 in which a bag-shaped separator 33 is accommodated, and a bag-shaped separator 33. And the outer case 31. The sealing member 36 seals the exterior case 31 via a sealing material disposed in the opening of the exterior case 31.

  Since the positive electrode active material 34, the negative electrode active material 32, and the separator 33 use the same materials as those in the first embodiment, the description thereof is omitted.

  The electric double layer capacitor 30 is manufactured as follows. A bag-like separator 33 having pores such as a polyimide-based porous film is placed on an aluminum current collecting plate 35, and a positive electrode slurry 34 in which activated carbon and a conductive material are kneaded is injected into the electrolytic solution. The aluminum current collecting plate 35 has a shape that forms a side portion of a rectangular parallelepiped, and supports the bag-like separator 33. They are inserted into the outer case 31, and a negative electrode slurry 32 in which activated carbon and a conductive material are kneaded into the electrolytic solution is injected between the outer case 31 and the separator 33 in the same manner as the positive electrode slurry. After injection, the opening of the outer case is sealed with a sealing plate and an explosion-proof valve through a sealing member. At this time, if the current collector plate comes into contact with the negative electrode slurry, a short circuit is caused. Therefore, the separator is securely sandwiched between the sealing plate and the current collector plate. In the electric double layer capacitor of the present invention, it is necessary to make the positive electrode thinner than the negative electrode because of the voltage sharing between the positive electrode and the negative electrode.

  Since the slurry-like negative electrode and positive electrode are directly injected through the bag-like separator, the steps for producing the electrode are reduced. Further, a support such as an aluminum foil that supports the electrode is not required. In addition, since the activated carbon and the conductive material are kneaded in the electrolytic solution, the separator can be made thin because the separator does not require electrolyte solution retention.

  FIG. 4 is a cross-sectional view of the structure of the electric double layer capacitor according to the fourth embodiment of the present invention. The electric double layer capacitor 40 includes a negative electrode active material 42, a plurality of separators 43, a positive electrode active material 44, a current collector plate 45, a sealing member 46, a gasket 47, and an explosion-proof valve 48 on an outer case 41. An aluminum plate having a hole like a plate is arranged near the center of the bag-like separator. At this time, it arrange | positions so that the distance from a separator to a current collecting plate may become as uniform as possible.

  The positive electrode active material 44 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material, and an electrolytic solution. The current collector 45 is disposed in a positive electrode active material 44 that is a polarizable electrode active material. The separator 43 has a bag shape and accommodates the positive electrode active material 44 and the current collector 45. The negative electrode active material 42 is a slurry-like polarizable electrode active material containing activated carbon, a conductive material and an electrolytic solution similar to the positive electrode active material 44, and includes an outer case 41 in which a bag-like separator 43 is accommodated, and a bag-like separator 43. And the outer case 41. The sealing member 46 seals the outer case 41 via a sealing material disposed in the opening of the outer case 41.

  Since the positive electrode active material 44, the negative electrode active material 42, and the separator 43 use the same materials as those in the first embodiment, the description thereof is omitted.

  A bag-like separator 43 having pores such as a polyimide-based porous film is placed on an aluminum current collector plate 45, and a positive electrode slurry in which activated carbon and a conductive material are kneaded is injected into the electrolytic solution. The aluminum current collecting plate 45 is an aluminum plate having holes like a punching plate, and is disposed near the center of the bag-like separator 43. At this time, it arrange | positions so that the distance from the separator 43 to the current collecting plate 45 may become as uniform as possible. They are inserted into the outer case 41 and a negative electrode slurry in which activated carbon and a conductive material are kneaded is injected between the outer case 41 and the separator 43 in the same manner as the positive electrode slurry. After the injection, the opening of the outer case is sealed with a sealing plate 46 and an explosion-proof valve 48 through a sealing member. At this time, if the current collector plate 45 comes into contact with the negative electrode slurry, a short circuit is caused. Therefore, the separator 43 is securely sandwiched between the sealing plate 46 and the current collector plate 45. In the electric double layer capacitor of the present invention, it is necessary to make the positive electrode thinner than the negative electrode because of the voltage sharing between the positive electrode and the negative electrode.

  Since the slurry-like negative electrode and positive electrode are directly injected through the bag-like separator, the steps for producing the electrode are reduced. Further, a support such as an aluminum foil that supports the electrode is not required. In addition, since the activated carbon and the conductive material are kneaded in the electrolytic solution, the separator can be made thin because the separator does not require electrolyte solution retention.

  The present invention can be used as a high performance electric double layer capacitor.

1 is a cross-sectional view of an electric double layer capacitor according to a first embodiment of the present invention. It is a perspective view of the electric double layer capacitor concerning a 2nd embodiment of the present invention. It is sectional drawing of the electric double layer capacitor which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the electric double layer capacitor which concerns on the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric double layer capacitor 11 Exterior case 12 Negative electrode active material 13 Separator 14 Positive electrode active material 15 Current collector 16 Sealing member 20 Electric double layer capacitor 21 Exterior case 22 Negative electrode active material 23 Separator 24 Positive electrode active material 25 Current collector plate 26 Electrode terminal 27 Sealing material

Claims (5)

A slurry-like polarizable electrode active material containing activated carbon, a conductive material and an electrolyte;
A current collector disposed in the polarizable electrode active material;
A bag-like separator in which the polarizable electrode active material and the current collector are accommodated;
An outer case in which the bag-shaped separator is accommodated;
The polarizable active material disposed between the bag-shaped separator and the outer case;
An electric double layer capacitor comprising: a sealing member that seals the outer case through a sealing material disposed in an opening of the outer case.   2. The electric double layer capacitor according to claim 1, wherein the current collector is configured to form a rectangular parallelepiped side.   2. The electric double layer capacitor according to claim 1, wherein the current collector is a punching plate made of an aluminum material.   2. The electric double layer capacitor according to claim 1, wherein the conductive material includes carbon nanotubes or vapor grown carbon fibers.   2. The electric double layer capacitor according to claim 1, wherein the electrolytic solution contains dimethylethylammonium borofluoride or ethylmethyl imidazolium borofluoride.

Images