JP2010245070A - Electric double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric double-layer capacitor which is used at ≥85°C and whose life is prolonged. <P>SOLUTION: Zeolite is added to an electrolyte, the moisture content of the electrolyte is ≤40 ppm, and the moisture content of a polarizable electrode is ≤150 ppm for the weight of the polarizable electrode, so that the zeolite adsorbs water in the electrolyte and deterioration in the electrolyte is suppressed by suppressing reaction between water in the electrolyte and a current collector to provide the electric double-layer capacitor which is used at ≥85°C and has long-life characteristics. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an electric double layer capacitor using a non-aqueous electrolyte.
About.

    An electric double layer capacitor is formed by winding or laminating a separator between a polarizable electrode in which a polarizable electrode layer (for example, a carbon layer) is provided on the surface of a metal foil made of, for example, aluminum. It is impregnated with an electrolytic solution, the capacitor cell is housed in a metal case, and the opening end is sealed.

  The electric double layer capacitor described above is required to have a high capacity and excellent long-term reliability, and a carbonate-based solvent such as propylene carbonate is used as an electrolytic solution of a conventional electric double layer capacitor. According to this, an electric double layer capacitor having a high capacity and excellent in high temperature load can be obtained.

  However, in an electrolytic solution using a carbonate-based solvent, carbon monoxide (CO) gas is generated due to decomposition of the solvent at a high temperature, so that the internal pressure of the container containing the polarizable electrode, the electrolytic solution, etc. increases. Problems arise. For this reason, 60 degreeC is a limit and there existed a problem that it cannot respond to the further high temperature use of 70-85 degreeC. On the other hand, there is an attempt to enable use at 70 ° C. using γ-butyrolactone. (Patent Document 1).

JP 2001-217150 A

  However, if further use at 85 ° C. is attempted, deterioration of characteristics cannot be suppressed. In addition, an improvement in life characteristics has been demanded for an electrolytic solution using a carbonate-based solvent. Accordingly, an object of the present invention is to solve this problem and to provide an electric double layer capacitor that can be used at a temperature of 85 ° C. or higher and can have a longer life.

  In order to solve the above-mentioned problems, the present invention is characterized in that a zeolite is added to a non-aqueous electrolyte in an electric double layer capacitor using a non-aqueous electrolyte and an electrode composed of a current collector and a polarizable electrode at both electrodes. And

  Further, the solvent of the electrolytic solution is mainly γ-butyrolactone, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. It is characterized by.

  Further, the solvent of the electrolytic solution is mainly sulfolane or a derivative thereof, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. It is characterized by that.

  Further, the solvent of the electrolytic solution is mainly composed of propylene carbonate, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. Features.

  In the present invention, since zeolite is added to the electrolyte, the zeolite adsorbs moisture in the electrolyte and suppresses the reaction between the moisture in the electrolyte and the current collector, thereby suppressing the deterioration of the electrolyte. In addition, it can be used at 85 ° C. or higher, and has an effect of realizing long life characteristics.

It is a figure which shows the lifetime characteristic of the capacity | capacitance which concerns on Examples 1-4 of this invention, and the comparative example 1. FIG. It is a figure which shows the lifetime characteristic of the internal resistance which concerns on Examples 1-4 of this invention, and the comparative example 1. FIG. It is a figure which shows the lifetime characteristic of the capacity | capacitance which concerns on Examples 5-8 and Comparative Example 2 of this invention. It is a figure which shows the lifetime characteristic of the internal resistance which concerns on Examples 5-8 of this invention, and the comparative example 2. FIG. It is a figure which shows the lifetime characteristic of the capacity | capacitance which concerns on Examples 9-12 and Comparative Example 3 of this invention. It is a figure which shows the lifetime characteristic of the internal resistance which concerns on Examples 9-12 of this invention, and the comparative example 3. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, an electric double layer capacitor is produced by making a capacitor cell by facing a metal current collector foil made of aluminum with a polarizable electrode layer facing through a separator, and impregnating the capacitor cell with an electrolyte. An electric double layer capacitor is obtained.

  Zeolite is added to the electrolytic solution of the present invention.

  The zeolite used in the present invention is a substance having a three-dimensional network structure formed by aluminum, silicon and oxygen tetrahedrons sharing a vertex, and adsorbs water in the network structure. The pore diameter in the network structure is preferably 4.1 mm, and the particle diameter is preferably 2.5 μm or less. Moreover, the addition amount in electrolyte solution has preferable 1-5 wt%.

  As the metal current collector foil used for the electrode, an aluminum foil or an aluminum etching foil is used. As the aluminum foil, high-purity aluminum having a purity of 99.9% or more is used. As the thickness, an aluminum foil having a thickness of about 10 to 50 μm is usually used.

  For example, a paste obtained by mixing activated carbon powder, a conductive additive, a binder, and a solvent such as an organic solvent or water is applied to the metal current collector foil. Alternatively, the paste is formed into a sheet shape, and this sheet is pressed against a current collector to form a polarizable electrode.

The raw material of the activated carbon is plant-based wood, sawdust, coconut husk, pulp waste liquid, fossil fuel-based coal, heavy petroleum oil, or coal and petroleum-based pitch, petroleum coke obtained by pyrolyzing them. Activated carbon is obtained by carbonizing these raw materials and then activating them.
As the conductive assistant, carbon black and graphite, which are carbon materials having conductivity, can be used. Examples of the carbon black include acetylene black, ketjen black, channel black, furnace black, and thermal black. Among these, ketjen black is preferable. Examples of graphite include natural graphite and artificial graphite.
Any binder may be used as long as it is usually used, for example, rubbers such as fluorine rubber, diene rubber and styrene rubber, fluorine-containing polymers such as polytetrafluoroethylene and polyvinylidene fluoride, and the like. , Polyolefin resin, acrylic resin, nitrile resin, polyester resin, phenol resin, polyvinyl acetate resin, polyvinyl alcohol resin, epoxy resin and the like.
A capacitor cell is produced by making the electrodes face each other with a separator interposed therebetween, and the capacitor cell is impregnated with an electrolytic solution to obtain an electric double layer capacitor.

      In the present invention, the moisture content contained in this polarizable electrode is 150 ppm or less, preferably 120 ppm or less.

  In the present invention, γ-butyrolactone, sulfolane or a derivative thereof, and propylene carbonate are used as the main solvent as the electrolytic solution. In addition, as a co-solvent, carbonates such as ethylene carbonate, butylene carbonate, dimethyl carbonate and diethyl carbonate; ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran Sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; nitrogen-containing compounds such as acetonitrile and nitromethane; methyl formate, methyl acetate, ethyl acetate, butyl acetate, Organic acid esters such as methyl propionate and ethyl propionate; inorganic acid esters such as phosphoric acid triester and diester carbonate such as dimethyl carbonate, diethyl carbonate and dipropyl carbonate; diglyme ; Triglyme like; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propane sultone, 1,4-butane sultone can be used sultone like such Nafutasuruton.

Examples of the electrolyte dissolved in the organic solvent include metal cations, quaternary ammonium cations, carbonium cations, and the like, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , and AlCl _4. ^-, or ^{_{RfSO 3 -, (RfSO 2)}} 2 N -, RfCO 2 - (Rf is a fluoroalkyl group having 1 to 8 carbon atoms) can be exemplified salts of anions selected from.

      In the present invention, the water content contained in the electrolytic solution mainly composed of γ-butyrolactone is 40 ppm or less, preferably 30 ppm or less.

The electric double layer capacitor of the present invention may have any shape such as a coin type, a wound type, and a laminated type. Such an electric double layer capacitor is obtained by, for example, cutting an electrode sheet into a desired size and shape, stacking or winding the separator sheet between both electrodes, inserting the electrolyte into the container, It can be produced by caulking the seal using a sealing plate or gasket.

The invention according to the embodiments of the present invention will be specifically described.
Example 1
A mixture of activated carbon powder, ketjen black as a conductive aid, and polyterafluorofluoroethylene (PTFE) as a binder was formed into a sheet using a rolling roller, and this was used as a polarizable electrode. The sheet-like polarizable electrode was attached to an aluminum current collector provided with a lead wire by using a conductive adhesive to obtain an electrode. The produced two electrodes face each other through a cellulose separator to produce an electric double layer capacitor element (electrode area 12 cm 2).
This electric double layer capacitor element was dried under reduced pressure at 150 ° C. for 12 hours or more, and then 2.3 μm of 3A zeolite in 100 mL of 1M tetraethylammonium tetrafluoroborate (TEABF4) / propylene carbonate (PC) in a dry box under an argon atmosphere. An electrolytic solution in which 1 g was dispersed was impregnated under reduced pressure and sealed in a laminate film to produce an electric double layer capacitor cell. This electric double layer capacitor cell was subjected to a 2.5 V constant voltage load test in an atmosphere of 60 ° C., and the capacity (F) and direct current resistance (DCIR) were measured at an arbitrary time.
(Example 2)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 2 g of 2.3 A 3A zeolite was dispersed in 100 mL of 1M TEABF4 / PC was impregnated under reduced pressure, and sealed in a laminate film. A cell was produced. The same test as in Example 1 was performed on the electric double layer capacitor cell.
Example 3
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 5 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEABF4 / PC was impregnated under reduced pressure, and sealed in a laminate film. Was made. The same test as in Example 1 was performed on the electric double layer capacitor cell.
Example 4
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 10 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEABF4 / PC was impregnated under reduced pressure, and sealed in a laminate film. A cell was produced. The same test as in Example 1 was performed on the electric double layer capacitor cell.
(Example 5)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolyte solution in which 1 g of 2.3 A 3A zeolite was dispersed in 100 mL of 1M TEABF4 / γ-butyrolactone (GBL) was impregnated under reduced pressure and sealed with a laminate film. An electric double layer capacitor cell was produced. This electric double layer capacitor cell was subjected to a 2.5 V constant voltage load test in an atmosphere of 85 ° C., and the capacity (F) and direct current resistance (DCIR) were measured at an arbitrary time.
(Example 6)
An electric double layer capacitor element was produced in the same manner as in Example 1, and an electrolytic solution in which 2 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEABF4 / GBL was impregnated under reduced pressure and sealed with a laminate film. A cell was produced. The same test as in Example 5 was performed on this electric double layer capacitor cell.
(Example 7)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 5 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEABF4 / GBL was impregnated under reduced pressure, and sealed in a laminate film. A cell was produced. The same test as in Example 5 was performed on this electric double layer capacitor cell.
(Example 8)
An electric double layer capacitor element was produced in the same manner as in Example 1, and an electrolytic solution in which 10 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEABF4 / GBL was impregnated under reduced pressure, and sealed in a laminate film. A cell was produced. The same test as in Example 5 was performed on this electric double layer capacitor cell.
Example 9
An electric double layer capacitor element was prepared in the same manner as in Example 1, and impregnated under reduced pressure with an electrolytic solution in which 1 g of 2.3 A 3A zeolite was dispersed in 100 mL of 1M triethylmethylammonium (TEMA) BF4 / sulfolane (SLF). An electric double layer capacitor cell was prepared by enclosing in a laminate film. This electric double layer capacitor cell was subjected to a 2.5 V constant voltage load test in an atmosphere of 105 ° C., and the capacity (F) and direct current resistance (DCIR) were measured at an arbitrary time.
(Example 10)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 2 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEMABF4 / SLF was impregnated under reduced pressure, and sealed with a laminate film. A cell was produced. The same test as in Example 9 was performed on this electric double layer capacitor cell.
(Example 11)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 5 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEMABF4 / SLF was impregnated under reduced pressure, and enclosed in a laminate film. A cell was produced. The same test as in Example 9 was performed on this electric double layer capacitor cell.
(Example 12)
An electric double layer capacitor element was prepared in the same manner as in Example 1, and an electrolytic solution in which 10 g of 2.3 micron 3A zeolite was dispersed in 100 mL of 1M TEMABF4 / SLF was impregnated under reduced pressure, and sealed in a laminate film. A cell was produced. The same test as in Example 9 was performed on this electric double layer capacitor cell.
(Comparative Example 1)
An electric double layer capacitor element was produced in the same manner as in Example 1, impregnated with 1M TEABF4 / PC electrolyte under reduced pressure, and enclosed in a laminate film to produce an electric double layer capacitor cell. The same test as in Example 1 was performed on the electric double layer capacitor cell.
(Comparative Example 2)
An electric double layer capacitor element was produced in the same manner as in Example 1, impregnated with 1M TEABF4 / GBL electrolyte under reduced pressure, and enclosed in a laminate film to produce an electric double layer capacitor cell. The same test as in Example 5 was performed on this electric double layer capacitor cell.
(Comparative Example 3)
An electric double layer capacitor element was produced in the same manner as in Example 1, impregnated with 1M TEMABF4 / SLF electrolyte under reduced pressure, and enclosed in a laminate film to produce an electric double layer capacitor cell. The same test as in Example 9 was performed on this electric double layer capacitor cell.

(result)
As is apparent from FIGS. 1 to 6, the examples of the present application are better in capacity change and internal resistance change than Comparative Examples 1 to 3 in which no zeolite is added. In particular, the characteristics of Examples 1 to 3, Examples 5 to 7, and Examples 9 to 11 to which 1 to 5% of zeolite is added are even better.

Claims (4)

An electric double layer capacitor in which zeolite is added to a nonaqueous electrolytic solution in an electric double layer capacitor using a nonaqueous electrolytic solution and electrodes composed of a current collector and a polarizable electrode on both electrodes. The solvent of the electrolytic solution is mainly γ-butyrolactone, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. The electric double layer capacitor as described. The solvent of the electrolytic solution is mainly composed of sulfolane or a derivative thereof, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. 2. The electric double layer capacitor according to 1. The solvent of the electrolytic solution is mainly composed of propylene carbonate, the water content in the electrolytic solution is 40 ppm or less, and the water content of the polarizable electrode is 150 ppm or less with respect to the weight of the polarizable electrode. Electric double layer capacitor.