JPS6136920A - Electric double layer capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a small, thin, large capacity wet type electric double layer capacitor.

(Conventional Structure and Problems thereof) FIG. 1 shows an example of the structure of a conventional canopy shed of this type. Activated carbon fiber cloth is used as the polarizable electrode 1 and the current collector 2
As, metal layers such as aluminum, titanium, nickel, etc.
Alternatively, after forming a conductive resin layer and facing each other via a separator 3, an electrolytic solution is injected, and then a sealed casing is formed using a case 4, a sealing plate 5, and a gasket 6.

The activated carbon fibers used in the polarizable electrodes are obtained by directly carbonizing and activating phenolic (cured) lac fibers, rayon, acrylic, and pitch fibers, or by further activating them after carbonization. Considering the electrical resistance, strength, activation yield, etc. of the activated carbon fibers obtained, phenolic fibers are the best among the above fibers. In addition, metal current collectors can be made by plasma spraying, arc spraying, or gas spraying, and conductive electrodes made of conductive materials such as conductive resin can be made by screen printing, streaking, or Izzo methods. Polarizable electrodes having such a shape can be punched into a circle with a desired diameter, making it possible to realize a coin-shaped flat plate small-sized large-capacity capacitor as shown in FIG. Since the polarizable electrode does not use a binder, it not only can reduce internal resistance, but also the activated carbon surface is not covered with a binder, which reduces the loss of effective area for double layer formation and allows for smaller size and larger capacity.

In particular, when the current collector is formed by a thermal spraying method, the adhesive strength between the thermal sprayed metal layer and the activated carbon fiber layer is strong, the contact resistance is small, and good capacitor characteristics can be obtained.

However, today, there has been a remarkable improvement in the characteristics of electronic devices, especially semiconductor memories, and there is a strong demand for capacitors with excellent charging and discharging characteristics (rapid charging) even if they have a smaller capacity than before. Furthermore, as devices become lighter, thinner, and shorter, double-layer capacitors are required to be even smaller and thinner.
It is extremely difficult to keep it below m.

Further, FIG. 2 shows a polarizable electrode body in which a metal current collector layer 8 of aluminum or the like is formed on an activated carbon fiber cloth 7.

A polarizable electrode body with such a configuration has a
- The conductivity in the a' direction is good, but b - b'
The directional conductivity is considered to be very poor.

Therefore, the impedance also increases, resulting in a capacitance that is not suitable for rapid charging. Furthermore, when constructing a larger capacitor, the activated carbon fiber cloth, which does not require a binder, has good volumetric efficiency. However, how much phenolic? Activated carbon fiber cloth obtained from lac resin fibers can have a specific surface area of up to 2,500 m2/9, but when the specific surface area exceeds 2,300 m2/g, the strength decreases significantly, and activated carbon fiber cloth alone has poor workability and is not practical. It cannot withstand use.

(Objective of the Invention) An object of the present invention is to improve the charging and discharging characteristics of a conventional electric double layer capacitor, and to make it thinner, smaller, and larger in capacity.

(Structure of the Invention) The present invention achieves the above object, and the polarizable electrode body is paper-like or felt-like made of activated carbon fibers, short metal fibers, and a binding medium. It has a structure in which a current collector is provided on at least one side of the body, and furthermore, these are opposed to each other via a seven-layer plate, and an electrolyte is injected.

(Example 1) As a polarizable electrode body■ Phenol-based hardening material? Activated carbon fiber whose specific surface area obtained by carbonization activation of lac resin fiber is 2300 m 1g by BET method and whose pore diameter is 50% or more in the range of 20 to 40A.

■ A round metal bar is compressed into chips with a diameter of 1 to 20 μΦ and a length of 1 to 10 m by a method usually called the "chattering vibration method."

■ A binder consisting of Se'loose #M yjP polyethylene terephthalate, ]:1.

Thoroughly mix the above ■, ■, ■ in a weight ratio of 75:5:2Of.
The wet papermaking method is used to prevent uneven dispersion due to differences in specific gravity of each material as much as possible.
A 4'-shaped polarizable electrode body is formed. A schematic diagram of the polarizable electrode body thus formed is shown in FIG. In the figure, 9 indicates activated carbon fibers, 1o indicates short metal fibers, and 11 indicates a binder consisting of cellulose fibers and polyethylene terephthalate. Furthermore, a nickel current collector layer of about 100 to 200 μm is formed on the surface of this polarizable electrode using a plasma spraying method.

After forming the current collector layer in this manner, the current collector layer is spot-welded to the sealing plate 5 and the sealing case 4 as shown in FIG. After injecting 20wt% potassium hydroxide as an electrolyte through a separator 3 made of repropylene, the positive and negative electrodes are insulated with a gasket 6 and sealed with a casing.The polarizable electrode in this embodiment has a surface resistance. It has a diameter of 110026, a diameter of 14 cm, and a thickness of 800 μm.

FIG. 4 shows a charging curve when the capacitor of the present invention is charged at a constant voltage of 1. The solid line is for this example, and the dotted line is for activated carbon fibers and binder containing no short metal fibers.
: Charging curve of a capacitor consisting of 25.

It is clear from the figure that rapid charging is possible when short metal fibers with good conductivity are included.

Table 1 shows the characteristics of this capacitor. It can be seen that this is a small and large-capacity cano four-seater with extremely excellent charge and discharge characteristics and an electrode length of 1 m+ or less.

First Example (Example 2) Similarly to Example 1, the coin-shaped capacitor shown in FIG. 1 was manufactured. In this example, an organic electrolytic solution consisting of 1 mol zolopyrene carbonate of tetraethylammonium/-f'-florest was used as the electrolytic solution.

In addition, the current collector is made of aluminum 100% by plasma spraying method.
A layer ˜300 μm thick was formed.

In this example, the mixing ratio of activated carbon fibers and short metal fibers was
I created a capacitor by changing it as shown in the table. Is each Kiya A in the second garment? The characteristics of the shita are also added. From the table,
The more short metal fibers are added, the faster charging becomes possible, but the capacity becomes smaller when comparing electrodes from the same date. Therefore, it is considered that the respective compounding ratios may be changed depending on the intended use. Also, from Table 2, the capacity of the phenol-based activated carbon fiber is larger than that of the phenol-based activated carbon fiber. This is due to the fact that

Furthermore, rather than using only pulp as a binder, using a mixture of pulp and polyethylene terephthalate a provides a more durable polarizable electrode.

(Example 3) For the current collector, conductive 4 indium containing carbine as conductive particles was applied and formed on the polarizable electrode of I62 of Example 2, and for the electrolyte, 1 mol glopyrene carbonate of potassium borofluoride was used. A coin-shaped canopy seat similar to that in Example 1.2 was produced as a trial using the nate solution. Table 3 shows the characteristics of this capacitor. Since the conductive auxiliary current collector is used, the specific vane impedance is larger than that of Examples 1 and 2, but in terms of other characteristics, a capacitor of #1 that is on the same level as Examples 1 and 2 can be obtained.

Third fitting (Example 4) It has the composition shown in Table 1 44 of Example 2, and has a basis weight of 300 V.
m2 of hard, flattened activated carbon fibers were used as polarizable electrodes, and about 100 μm of nickel was formed on the current collector.

Then, double layer capacitors as shown in FIGS. 5(A) and 5(B)K were fabricated. FIG. 5(B) shows a cross section of FIG. 5(A) taken along line AA'. In FIG. 5, 12 is a peno9-shaped polarizable electrode body about 1 thick, and 13 is about 100 mm thick.
A current collector made of nickel with a thickness of μm, 14 a non-woven separator made of polypropylene with a thickness of about 1 cm, and 15 a heat-sealable 100 μm thick film sheet made of polyethylene terephthalate coated with an ionomer adhesive. be. Further, 16 is a lead wire. 17 is a current collecting plate made of nickel, and the polarizable electrode body 12 is spot welded to it. 9 In the capacitor of this embodiment, the polarizable electrode body has strong strength and has sufficient workability even when the size K is about 1100 x 200. Can be assembled. Table 4 shows various characteristics of the canopy four-seater of this example. The activated carbon fiber used in the present invention has a specific surface area of 2300 m22/g, and when the specific surface area is this large, the activated carbon fiber cloth form is too brittle and difficult to use for capacitors. However, the polarizable electrode of the present invention is very stiff and has a firm I2. In addition, the electrolyte contains 20wt 96 KO
) I was used.

Table 4 (Example 5) F-type activated carbon fibers having the composition shown in Table 1 42 of Example 2 and having a basis weight of 200 gAn2 were used as polarizable electrode bodies 18.19 as shown in FIG. In the current collector 20, aluminum was formed to a thickness of about 100 μm on both sides of the polarizable electrode body. A 1 mol solution of tetraethylammonium perchlorate in zolobylene carmenate was then used as an electrolytic solution via a polypropylene separator 21. Then, the polarizable electrode and separator were completely wound to create a cylindrical case and armpit. Polarizable electrodes of the present invention: 18 on the positive electrode side, 19 on the negative electrode side,
Since the thickness is as thin as approximately 400 μm, the resistance in the thickness direction is small and the charge/discharge characteristics are excellent. Lead wire 22
was attached to the polarizable electrode by caulking.

In Figure 6, 23 is the case, 24 is the sealing box, 2
5 is a gasket.

Table 5 shows various characteristics of the capacitor of the present invention.

As can be seen from Table 5, the capacitor of this example is also small and large in capacity with good charging and discharging characteristics. Note that the dimensions of the polarizable electrode body are 30×200+a+.

Table 5 (Effects of the Invention) As described above, according to the present invention, a small, large-capacity electric double layer capacitor with excellent charge/discharge characteristics and good workability can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of a conventional electric double layer capacitor, Figures 2 and 3 are diagrams showing the configuration of the polarizable electrode body, Figure 4 is a diagram showing charging characteristics, Figure 5 (A), ( B) is a diagram showing one example of the configuration of the xeno9 capacitor of the invention, and FIG. 6 is a diagram showing one example of the configuration of the capacitor of the invention. l... Polarizable electrode body, 2... Current collector, 3... Separator, 4... Case, 5... Sealing plate, 6... Gasket, 7... Activated carbon fiber cloth, 8... Metal current collector layer, 9... Activated carbon fiber, 10... Metal short fiber, 11
... cellulose fiber and polyethylene terephthalate binder, 12 ... vapor-like polarizable electrode, 13 ... current collector, 14 ..., 1e IJ propylene separator,
15... Film sheet, 16... Lead wire, 17
...Current plate, 18...Positive side polarizable electrode, 19...
・Negative polarizable electrode, 20... Current collector, 21... Senorator, 22... IJ-)" wire, 23... Case, 24... Sealing packing, 25... Gasket. Figure 1 Figure 3 Figure 4 Time (sec) Figure 5 (△) △ +3 17 15 Figure 6

Claims (8)

[Claims] (1) In an electric double layer capacitor that utilizes an electric double layer formed between a polarizable electrode body and an electrolyte interface, the polarizable electrode body is paper-like or felt-like made of activated carbon fibers, short metal fibers, and a binding medium. An electric double layer capacitor having a structure in which the polarizable electrode body has a current collector on at least one side thereof, and further, these polarizable electrode bodies face each other with a separator interposed therebetween and an electrolytic solution is injected. (2) The electric double layer capacitor according to claim (1), wherein the binding medium accounts for 5% or more by weight of the polarizable electrode body having no current collector. (3) The activated carbon fibers and carbon fibers constituting the polarizable electrode body are obtained by carbonization activation or carbonization of a phenolic resin, and the activated carbon fibers have a specific surface area of 1500 m^2/g or more by the BET method. An electric double layer capacitor according to claim (1) or (2). (4) The activated carbon fibers and carbon fibers constituting the polarizable electrode body are obtained by carbonizing or carbonizing polyacrylonitrile resin or rayon fibers, and the specific surface area of the activated carbon fibers is B.
The electric double layer capacitor according to claim (1) or (2), characterized in that it has a density of 300 m^2/g or more by ET method. (5) The electric double layer capacitor according to claim (1) or (2), wherein the activated carbon fibers and carbon fibers constituting the polarizable electrode body are of pitch type. (6) Claim No. 1, characterized in that the binding medium constituting the polarizable electrode body is a natural fiber such as pulp or a synthetic resin such as polyethylene terephthalate.
) to (4). (7) Any one of claims (1) to (5), characterized in that the current collector formed on at least one side of the polarizable electrode body is in contact with the conductive case. The electric double layer capacitor described. (8) The electric double layer capacitor according to any one of claims (1) to (7), wherein the metal fibers are made of nickel, aluminum, stainless steel, or the like.