JPH01262617A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To improve withstand voltage by using an electrolyte which contains salt consisting of a specific acid and a specific alkali. CONSTITUTION:An electric double layer capacitor consists of polarizable electrodes, separators and current collectors. It is an electrolyte-impregnated capacitor element contained in a case. If an electrolyte which contains salt consisting of one or more kinds of acids out of boron tetrafluoride ion, thiocyanic acid ion, tantalum hexafluoride ion and boron nitrotrifluoride ion and one or more kinds of alkalis out of quaternary ammonium ion, sulfonium ion and pyrrolidinium ion is used in the electric double layer capacitor, stability can be gained against the electrolyte and there is no precipitation of metal. As a result, withstand voltage and reliability of the capacitor is increased.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electric double layer capacitor.

<Prior Art> Conventionally, as electrolytes used in electric double layer capacitors, acidic or alkaline aqueous solutions, non-aqueous solutions such as perchlorinated M salts of alkali metals or alkaline earth metals, borofluoride salts, fluorophosphates, etc. have been used as electrolytes. It is used.

(Problems to be Solved by the Invention) However, those using an aqueous electrolyte have a drawback of low withstand voltage. In addition, non-aqueous electrolytes have the disadvantage that metal precipitation occurs and the capacity decreases.

In particular, those using perchlorine M salt have the disadvantage that radicals are easily generated under high voltage and high temperature conditions, and the electrolyte is easily decomposed.

The object of the present invention is to provide an electric double layer capacitor which improves the above-mentioned drawbacks, improves the withstand voltage, and increases the capacity.

(Means for Solving: 11!ii) In order to achieve the above object, the present invention provides an electric secondary battery in which a capacitor element comprising a polarizable electrode, a separator and a current collector and impregnated with an electrolyte is housed in a case. In the multilayer capacitor, the electrolyte contains at least one acid selected from tetrafluoroboronium ion, thiocyanate ion, tantalum hexafluoride ion, or nitroboron trifluoride ion, and quaternary ammonium ion, sulfonium ion, or The present invention provides an electrical engineering mm capacitor characterized by containing a salt consisting of at least one type of alkali among pyrrolidinium ions.

Both the tantalum hexafluoride ion and the boron nitrotrifluoride ion are chemically stable with respect to the electrolytic solution at a temperature of 50° C. or higher and a voltage of 2 V or higher.

Further, tantalum hexafluoride ions, thiocyanate ions, and boron trifluoride ions do not cause metal precipitation unlike alkali metals and alkaline earth metals. Therefore, the withstand voltage of the capacitor is improved.

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

As the polarizable electrode, a sheet formed by pressing electrochemically inactive activated carbon, activated carbon fiber, carbon black, etc. into an electrolytic solution, forming a sheet, and punching it out into a circular shape is used.

As the solvent for the electrolytic solution, electrochemically stable non-aqueous solvents such as propylene carbonate, γ-butyl lactone, acetonitrile, dimethylformamide, 1,2-dimethoxyethane, sulborane, nitromethane, etc. are used. In particular, propylene carbonate, γ-Butyl lactone and acetonitrile are preferred and used in a substantially anhydrous state. In addition, solutes include trimethylethylammonium tetrafluoroborate, tetraisobutylammonium tetrafluoroborate, tetraethylammonium thiocyanate, tetrabutyl hexafluorotantalate, ammonium, tetraethylammonium nitrotrifluoroborate, and tetrafluoroborate. Triethylsulfonium fluoroborate, triinebutylsulfonium tetrafluoroborate, triethylbutylsulfonium tetrafluoroborate, triethylsulfonium hexafluorotantalate, tributylsulfonium hexafluorotantalate, triethylbutyl hexafluorotantalate Ammonium, triethylbutylammonium thiocyanate, methylbutylpyrrolidium tetrafluoroborate, methylethylpyrrolidium hexafluorotantalate, methylisobutylpyrrolidium thiocyanate, etc. are used. The separator has a thickness of 10
A non-woven fabric such as µm volip O pyrene is used.

A stainless steel button-shaped case is used as the current collector, which also serves as the case.

According to the above embodiment, since the electrolyte is a stable non-aqueous solvent such as propylene carbonate and a solute containing salts such as boron tetrafluoride ions and tantalum hexafluoride ions, It is chemically stable and improves the withstand voltage of capacitors.

(Effects of the Invention) As described above, according to the present invention, since the electrolyte contains a salt consisting of an acid such as boron tetrafluoride ion and an alkaline salt such as quaternary ammonium ion, the voltage resistance is high and the reliability is high. Electric double layer capacitors with high efficiencies are being sold.

Patent applicant: Hitachi Capacitor Co., Ltd.

Claims (1)

[Claims] (1) In an electric double layer capacitor in which a capacitor element consisting of a polarizable electrode, a separator, and a current collector is impregnated with an electrolytic solution and housed in a case, boron tetrafluoride ion, thiocyanate ion, tantalum hexafluoride ion is used as the electrolyte. or an electric double layer capacitor characterized by containing a salt consisting of at least one kind of acid among nitroboron trifluoride ions and at least one kind of alkali among quaternary ammonium ions, sulfonium ions, or pyrrolidinium ions. .