JPS63184314A - 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] (Industrial application field) The present invention relates to an electric double layer capacitor.

(Prior Art) Electric double layer capacitors are used as backup power sources for computers during power outages, and as power sources for solar clock batteries and motor drives.

Electric double layer capacitors used for these various applications have conventionally placed an ion-permeable and electrically insulating porous separator impregnated with an electrolyte between polarizable electrodes such as activated carbon electrodes. A current collecting electrode is brought into contact with the electrode,
The structure is such that a voltage can be applied to the polarizable electrodes.

(Problem to be solved by the invention) By the way, an alkali metal compound such as lithium perchlorate can be used as an electrolyte, but in this substance, the ionic radius of the alkali metal, which is a cation, is smaller than that of an anion. However, if the pore radius of the polarizable electrode on the cathode side is large, it is difficult to retain alkali metal ions, making it difficult to obtain a large capacity.

Further, when a substance with a large ionic radius is used, there is a drawback that the resistance during ion movement is large and the voltage drop when drawing a constant current is large.

An object of the present invention is to provide an electric double layer capacitor that can improve the above-mentioned drawbacks, easily obtain a large capacity, and reduce the voltage drop when drawing a constant current.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a polar electric double layer capacitor having polarizable electrodes impregnated with an electrolyte, an electrolyte made of an alkali metal compound, The present invention provides an electric double layer capacitor characterized by having a polarizable electrode with a cathode having a pore radius of 15A or less.

(Function) Since the pore radius on the cathode side of the polarizable electrode is 15 Å or less, alkali metal ions can be well retained and a large capacity can be easily obtained.

(Example) Hereinafter, the present invention will be explained based on illustrated embodiments.

1 and 2 are polarizable electrodes on the anode side and the cathode side, respectively,
Activated carbon, activated carbon fibers, or S-electrocarbon black mixed with a binder and press-molded are used. In particular, the polarizable electrode 2 on the cathode side is formed to have a pore radius of 15 Å or less. 3 is a separator capable of separating the polarizable electrode 1 on the anode side and the polarizable electrode 2 on the cathode side, and is made of a plastic nonwoven fabric or a porous plastic film.

4 and 5 are current collecting electrodes on the anode side and the cathode side, respectively;
Valve metals such as 80, Ti, and Ta, and Au.

It is formed by pasting a metal plate made of a noble metal such as PT or stainless steel on the polarizable electrodes 1 and 2, or by plating it. Further, the polarizable electrodes 1 and 2 and the separator 3 are impregnated with an electrolyte. As an electrolyte, organic solvents such as propylene carbonate, Y-butyrolactone, 3-methyl 1,3-oxalidin-2-one, and dimethyl sulfoxide are combined with lithium perchlorate, lithium selenate, and hexafluoroarsenic acid. Lithium compounds such as lithium, aluminum lithium chloride, and lithium tetrafluoroborate, and compounds containing alkali metal ions such as potassium perchlorate are used as electrolytes.

According to the above example, for example, an electrolyte made of lithium perchlorate exhibits the following reaction: i C104 = l i '' + Cρ04-, but the ionic radius of li'' is 2.4 A of CIog- with o and e included. Less than or equal to the value. Then, li+ is attracted to the polarizable electrode 2 on the cathode side, which has a small pore radius, and a large capacity can be obtained. In particular, when the pore radius of the polarizable electrode 1 on the anode side is larger than that on the cathode side, each ion is attracted to and retained by the polarizable electrode having an appropriate pore radius, resulting in a larger capacity. It will be done. This applies not only to Li+ ions but also to other alkali metal ions.

Furthermore, since the ionic radius of at least the positive ions can be made small and the movement speed and storage speed can be increased, it is possible to suppress a voltage drop when drawing a constant current.

The table shows the change in capacity when changing the configuration.

Note that the polarizable electrode has a specific surface area of 2000'rIt/
9 activated carbon s & lig and its pore radius is a-10 ~
There are two types: 15A and b=20-70A. Moreover, propylene carbonate is used as the organic solvent of the electrolytic solution, and two types of solutes are used: α=lithium perchlorate and β-tetramethylammonium perchlorate.

As is clear from the margin table below, according to the present invention, the capacity is increased by more than 2.5 times compared to the comparative example.

Further, FIG. 2 shows voltage changes during constant current draw.

The extraction current is 500 CmA).

The figure shows that the voltage drop is suppressed when the pore radius of the polarizable electrode on the cathode side is smaller than that of the polarizable electrode on the anode side, or when lithium perchlorate is used as the electrolyte. Recognize.

(Effects of the Invention) As described above, according to the present invention, since the pore radius of the polarizable electrode on the cathode side is set to 15A or less, the capacity can be increased and the voltage drop during constant current extraction can be suppressed. Electric double layer capacitor h (obtained)

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a graph of voltage changes when drawing a constant current. 1... Polarizable electrode on the anode side, 2... Polarizable electrode on the cathode side, 3... Separator, 4... Current collector electrode on the anode side, 5... Current collector electrode on the cathode side.

Claims (1)

[Claims] (1) A polar electric double layer capacitor having a polarizable electrode impregnated with an electrolyte, which has an electrolyte made of an alkali metal compound and a polarizable electrode with a pore radius of 15 Å or less on the cathode side. double layer capacitor.