JP2014022529A - Manufacturing method for electrochemical capacitor and electrochemical capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for electrochemical capacitor which allows for production of such an electrochemical capacitor that can minimize damage and performance degradation by reducing the amount of gas generated, while ensuring excellent coulomb efficiency, and to provide an electrochemical capacitor.SOLUTION: In the manufacture of a hybrid capacitor 1, an electrolyte 5 is injected into a cell bath 6 so that a positive electrode 2 and a negative electrode 3 are immersed therewith, and an additive is added to the electrolyte 5. A mixture solvent consisting of a first solvent composed of ethylene carbonate and at least one kind of second solvent, selected from a group consisting of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, but not containing propylene carbonate is contained in the electrolyte 5, and a lithium salt containing an oxalate complex as anion, and (meth)acrylic acid ester of polyatomic alcohol are contained in the additive.

Description

  The present invention relates to a method for manufacturing an electrochemical capacitor and an electrochemical capacitor, and more particularly, to a method for manufacturing a hybrid capacitor and an electrochemical capacitor having both power storage by an electric double layer and power storage by an oxidation-reduction reaction.

  Conventionally, secondary batteries such as lithium-ion batteries, electric double layer capacitors, and hybrid capacitors (in addition to electric double layers, energy is obtained by oxidation-reduction reactions in the positive electrode or negative electrode as power storage devices mounted in hybrid vehicles and fuel cell vehicles. Research and development of electrochemical capacitors such as storage capacitors) are underway.

  An electrochemical capacitor generally has a positive electrode, a negative electrode, a separator interposed between the electrodes, and a cell tank that contains the electrodes and the separator and is filled with an electrolyte so as to immerse them. doing.

  Moreover, in an electrochemical capacitor, normally, after assembly, a voltage is applied to the positive electrode and the negative electrode, and an electrochemical activation process is performed, thereby improving electrical characteristics. And after an electrochemical activation process, in each electrode, the electrical energy stored by an electrical double layer and / or oxidation-reduction reaction is discharged, and charging / discharging is performed.

In such an electrochemical capacitor, in order to further improve the electrical characteristics, it has been studied to add an additive to the electrolytic solution, specifically, from ethylene carbonate, diethyl carbonate, and propylene carbonate. After dissolving LiPF _{6 in the} mixed solvent, a lithium salt having an oxalato complex as an anion and an acrylic acid or methacrylic acid ester of a polyhydric alcohol are added to prepare a non-aqueous electrolyte for a lithium ion capacitor However, it has been proposed to manufacture a lithium ion capacitor using the non-aqueous electrolyte for the lithium ion capacitor (see, for example, Patent Document 1).

JP 2011-204828 A

  However, the electrochemical capacitor manufactured using the non-aqueous electrolyte described in Patent Document 1 cannot obtain sufficient electrical characteristics. For example, a side reaction is caused by a charge / discharge reaction, and Coulomb There is a problem that efficiency decreases.

  In the side reaction, the electrolytic solution may be decomposed to generate a gas such as carbon dioxide. When the gas is generated in the electrochemical capacitor, the electrochemical capacitor may be damaged or the performance may be reduced.

  An object of the present invention is to provide an electrochemical capacitor manufacturing method and electrochemical that can obtain an electrochemical capacitor that can ensure excellent coulomb efficiency, reduce the amount of gas generation, and suppress breakage and performance degradation. It is to provide a capacitor.

  In order to achieve the above object, an electrochemical capacitor manufacturing method of the present invention includes a positive electrode, a negative electrode disposed opposite to the positive electrode, a cell tank containing the positive electrode and the negative electrode, and a cell tank. A method of manufacturing an electrochemical capacitor comprising an electrolytic solution stored and in which the positive electrode and the negative electrode are immersed, and injecting the electrolytic solution into the cell tank so that the positive electrode and the negative electrode are immersed An injection step, and an addition step of adding an additive to the electrolytic solution, wherein the electrolytic solution does not contain propylene carbonate, and includes a first solvent made of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl. A mixed solvent comprising at least one second solvent selected from the group consisting of carbonates, wherein the additive comprises an oxalato complex The lithium salt as an anion, and is characterized by containing a (meth) acrylic acid esters of polyhydric alcohols.

  The electrochemical capacitor according to the present invention includes a positive electrode, a negative electrode disposed opposite to the positive electrode, a cell tank containing the positive electrode and the negative electrode, and stored in the cell tank, wherein the positive electrode and the negative electrode are An electrolytic solution to be immersed, and the electrolytic solution does not contain propylene carbonate, and includes at least one selected from the group consisting of a first solvent made of ethylene carbonate, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. A mixed solvent consisting of a second solvent of a seed and a lithium salt having an oxalato complex as an anion and an additive containing a (meth) acrylic acid ester of a polyhydric alcohol are added. It is said.

  In the method for producing an electrochemical capacitor and the electrochemical capacitor of the present invention, the electrolytic solution does not contain propylene carbonate, and is selected from the group consisting of a first solvent made of ethylene carbonate, and ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate. A mixed solvent composed of at least one second solvent and a lithium salt having an oxalato complex as an anion and a (meth) acrylic acid ester of a polyhydric alcohol. Additives to contain are added.

  According to such a method for manufacturing an electrochemical capacitor and an electrochemical capacitor, it is possible to suppress the occurrence of a side reaction and to ensure excellent Coulomb efficiency.

  Also, in the electrochemical capacitor manufacturing method and the electrochemical capacitor, the decomposition of the electrolyte solution due to side reactions can be suppressed, so that the amount of gas generated can be reduced. The decrease can be suppressed.

It is a schematic block diagram of the hybrid capacitor which shows one Embodiment of the electrochemical capacitor of this invention. It is a graph which shows the relationship between the generation amount of gas in the hybrid capacitor of each Example and each comparative example, and the number of charge / discharge cycles.

  FIG. 1 is a schematic configuration diagram of a hybrid capacitor showing an embodiment of an electrochemical capacitor manufactured by the method for manufacturing an electrochemical capacitor of the present invention.

  In FIG. 1, a hybrid capacitor 1 includes a positive electrode 2, a negative electrode 3 disposed opposite to the positive electrode 2 with a gap, a separator 4 interposed between the positive electrode 2 and the negative electrode 3, a positive electrode 2, a negative electrode 3, a cell tank 6 containing a separator 4 and a capture member 7 (described later) provided if necessary, and a positive electrode 2, a negative electrode 3, a separator 4 (and a capture member 7 (optional) provided if necessary) stored in the cell tank 6. ) Is immersed in the electrolyte solution 5. The hybrid capacitor 1 is a battery cell employed on a lab scale, and industrially a hybrid capacitor 1 that is appropriately scaled up by a known technique is employed.

  Below, the manufacturing method of a hybrid capacitor as one Embodiment of the manufacturing method of the electrochemical capacitor of this invention is explained in full detail.

  In this method, first, a positive electrode 2, a negative electrode 3, a separator 4, an electrolytic solution 5, and a cell tank 6 are prepared, and an electrolytic solution is placed in the cell tank 6 so that the positive electrode 2, the negative electrode 3, and the separator 4 are immersed therein. 5 is injected (injection step).

  The positive electrode 2 is formed by, for example, forming a mixture obtained by blending a positive electrode material (polarizable carbon material) and a binder, and further, for example, a conductive agent, if necessary, into an electrode shape, and then drying, Is formed.

  The positive electrode material is obtained by, for example, activating a carbon material.

  Examples of the carbon material include soft carbon and hard carbon.

With soft carbon, for example, by heat treatment in an inert atmosphere, the hexagonal network surface composed of carbon atoms tends to form a relatively regular laminated structure (graphite structure) than the hexagonal network surface of hard carbon. A general term for carbon. Specifically, when heat-treated in an inert atmosphere at 2000 to 3000 ° C., preferably 2500 ° C., the (002) plane average plane distance d ₀₀₂ is 3.40 mm or less, preferably 3.35 to It is a general term for carbon that forms a crystal structure of 3.40%.

  Specific soft carbons include, for example, pitches such as petroleum pitches, coal pitches, and mesophase pitches, and graphites such as petroleum needle cokes, coal needle cokes, anthracene, polyvinyl chloride, polyacrylonitrile, etc. Thermally decomposed products such as chemical coke. These can be used alone or in combination of two or more.

Also, hard carbon, for example, in an inert atmosphere, when it is heat treated at 2500 ° C., is a general term for carbon to form a crystal structure of greater than 3.40Å average spacing _{d 002} of (002) plane.

  Specific hard carbons include, for example, phenol resins, melamine resins, urea resins, furan resins, epoxy resins, alkyd resins, unsaturated polyester resins, diallyl phthalate resins, furfural resins, resorcinol resins, silicone resins, xylene resins, urethanes. Thermosetting resin such as resin, for example, carbon black such as thermal black, furnace black, lamp black, channel black, acetylene black, for example, non-graphitizable coke such as flue coke and gilsonite coke Examples include coke, for example, plant raw materials such as palm, wood flour, and the like, for example, pyrolysates such as glassy carbon.

  These can be used alone or in combination. Of these, soft carbon is preferable.

As the activation treatment, for example, alkaline activation treatment using potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH), cesium hydroxide (CsOH), rubidium hydroxide (RbOH) or the like as an activator. For example, chemical activation treatment using zinc chloride (ZnCl ₂ ), phosphoric acid (H ₃ PO ₄ ) or the like as an activator, for example, gas activation treatment using carbon dioxide (CO ₂ ), air or the like as an activator, for example, Examples include steam activation treatment using steam (H ₂ O) as an activator. Among these, Preferably, an alkali activation process is mentioned, More preferably, the alkali activation process (KOH activation process) which uses potassium hydroxide (KOH) as an activator is mentioned.

  In the activation treatment, for example, in the case of KOH activation treatment, the carbon material is pre-fired at 500 to 800 ° C., for example, and then fired together with KOH at 700 to 1000 ° C. in a nitrogen atmosphere. The quantity of KOH used is 0.5-5 mass parts with respect to 1 mass part of carbon materials, for example.

In the hybrid capacitor using the positive electrode material obtained by the activation process as the positive electrode 2, for example, the potential of the positive electrode 2 is 4.23 V vs. A relatively large irreversible capacity can be developed in the positive electrode 2 in a charge / discharge cycle of Li / Li ⁺ or more. Therefore, in the discharge process, the positive electrode can be discharged to a lower potential. As a result, the electric capacity of the positive electrode 2 can be increased.

  A positive electrode material is mix | blended so that the mass ratio of solid content may be a ratio of 70-99 mass% with respect to the mixture whole quantity, for example.

  The binder is not particularly limited. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluoroolefin copolymer crosslinked polymer, fluoroolefin vinyl ether copolymer crosslinked polymer, carboxymethylcellulose, polyvinylpyrrolidone, Examples thereof include polyvinyl alcohol and polyacrylic acid.

  These binders may be used alone or in combination.

  Of these binders, PTFE is preferable.

  The blending ratio of the binder is, for example, 1 to 20% by mass, preferably 5 to 15% by mass with respect to the total amount of the mixture.

  The conductive agent is not particularly limited, and examples thereof include carbon black, ketjen black, and acetylene black.

  Such conductive agents may be used alone or in combination.

  Among these conductive agents, carbon black is preferable.

  The blending ratio of the conductive agent is, for example, 0 to 20% by mass, preferably 5 to 10% by mass with respect to the total amount of the mixture. That is, the conductive agent may or may not be blended.

  In order to form the positive electrode 2, for example, a mixture containing the above-described positive electrode material, a binder, and, if necessary, a conductive agent is pressure-stretched using, for example, a roll press to form an electrode sheet. obtain. Next, the electrode sheet is punched into a predetermined shape, and then dried, and if necessary, pressed onto a metal foil (current collector).

  For example, similarly to the production of the negative electrode 3 described later, a mixture containing the positive electrode material, the conductive agent and the polymer binder is stirred in a solvent described later, and the resulting slurry (solid content: 10 to 60% by weight) is obtained. The positive electrode 2 can also be formed by coating on the surface of a metal foil (current collector), press-stretching using a roll press, punching into a predetermined shape, and drying.

  Examples of the metal foil include aluminum foil, copper foil, stainless steel foil, and nickel foil.

  Among these metal foils, aluminum foil is preferable.

  The thickness of the positive electrode 2 obtained by such a method varies depending on the scale of the hybrid capacitor 1. For example, in the lab scale, the thickness is 30 to 150 μm, and the thickness excluding the metal foil serving as a current collector is excluded. Is 10 to 140 μm.

  Moreover, although the magnitude | size of the positive electrode 2 changes with scales of the hybrid capacitor 1, for example, in a lab scale, for example, in the case of a rectangular shape, the length in the longitudinal direction is, for example, 10 to 200 mm, preferably 10 to 10 mm. 100 mm, the length orthogonal to the longitudinal direction (width direction) is, for example, 10 to 200 mm, preferably 10 to 100 mm, and in the case of a circular shape, the diameter is, for example, 5 to 15 mm. .

  The negative electrode 3 is formed, for example, by molding a mixture obtained by blending a negative electrode material and a binder into an electrode shape and then drying it.

  The negative electrode material is made of a material capable of reversibly occluding and releasing lithium ions, and is not particularly limited, and examples thereof include the hard carbon described above, the soft carbon described above, and graphite.

  The graphite is not particularly limited. For example, natural graphite, artificial graphite, graphitized mesophase carbon microspheres, graphitized mesophase carbon fiber, graphite whisker, graphitized carbon fiber, pitch, coke, etc. Examples thereof include graphite-based carbon materials such as pyrolysates. Further, graphite is preferably used in the form of powder (for example, having an average particle size of 25 μm or less).

  These negative electrode materials may be used alone or in combination.

  Of these negative electrode materials, hard carbon is preferable.

  The mixing ratio of the negative electrode material is, for example, 80 to 99% by mass, preferably 85 to 95% by mass, based on the total amount of the mixture.

  Although it does not restrict | limit especially as a binder, For example, above-mentioned binder is mentioned.

  These binders may be used alone or in combination.

  Of these binders, PVdF is preferable.

  The blending ratio of the binder is blended so that, for example, the mass ratio of the solid content is 1 to 20 mass%, preferably 5 to 15 mass% with respect to the total amount of the mixture.

  Moreover, in manufacture of the negative electrode 3, a electrically conductive agent can also be mix | blended as needed.

  Although it does not restrict | limit especially as a electrically conductive agent, For example, above-mentioned electrically conductive agent etc. are mentioned.

  These conductive agents may be used alone or in combination.

  The blending ratio of the conductive agent is blended so that, for example, the mass ratio of the solid content is 0 to 20 mass%, preferably 1 to 10 mass% with respect to the total amount of the mixture.

  In order to form the negative electrode 3, for example, a mixture containing a negative electrode material, a binder, and, if necessary, a conductive agent is stirred in a solvent to obtain a slurry (solid content: 10 to 60% by mass). obtain.

  Next, the slurry is applied (applied) onto a metal foil (current collector) and dried to obtain an electrode sheet. Next, the electrode sheet is punched into a predetermined shape and then dried. Thereby, the negative electrode 3 is obtained.

  The solvent is not particularly limited, but for example, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, ethyl acetate, dimethyl phthalate, ethanol , Methanol, butanol, water and the like.

  These solvents may be used alone or in combination.

  Of these solvents, aprotic polar solvents are preferable, and N-methyl-2-pyrrolidone (NMP) is more preferable.

  Although it does not restrict | limit especially as metal foil, For example, above-mentioned metal foil is mentioned.

  Among these metal foils, copper foil is preferable.

  The thickness of the negative electrode 3 obtained by the method as described above varies depending on the scale of the hybrid capacitor 1. For example, in the lab scale, the thickness is 5 to 70 μm, and the thickness excluding the metal foil serving as the current collector is 5. ~ 60 μm.

  Moreover, although the magnitude | size of the negative electrode 3 changes with scales of the hybrid capacitor 1, for example, in a lab scale, for example, in the case of a rectangular shape, the length in the longitudinal direction is, for example, 10 to 200 mm and orthogonal to the longitudinal direction. The direction (width direction) length is, for example, 10 to 200 mm, and in the case of a circular shape, the diameter is, for example, 5 to 15 mm.

  Although it does not restrict | limit especially as the separator 4, For example, the separator which consists of inorganic fibers, such as glass fiber, ceramic fiber, a whisker, For example, natural fibers, such as a cellulose, For example, organic fibers, such as polyolefin and polyester, is mentioned.

  Among these separators, a separator made of ceramic fibers is preferable.

  Specifically, the thickness of the separator 4 varies depending on the scale of the hybrid capacitor 1, but is 100 to 1000 μm, for example, in the laboratory scale.

  Moreover, although the magnitude | size of the separator 4 changes with scales of the hybrid capacitor 1, for example, in a lab scale, for example, in the case of a rectangular shape, the length in the longitudinal direction is, for example, 15 to 220 mm, and the length in the width direction. The length is, for example, 15 to 220 mm. In the case of a circular shape, the diameter is, for example, 10 to 30 mm.

  The electrolytic solution 5 is made of an organic solvent containing lithium ions, and is prepared by dissolving a lithium salt (excluding a lithium salt having an oxalato complex described below as an anion) in an organic solvent.

The lithium salt is not particularly limited, has an anionic component containing a halogen, for _{example, LiClO 4, LiCF 3 SO 3} , LiC (SO 2 CF 3) 3, LiC 4 F 9 SO 3, LiC 8 F 17 SO ₃ , LiB [C ₆ H ₃ (CF ₃ ) ₂ -3, ₅ ] ₄ , LiB (C ₆ F ₅ ) ₄ , LiB [C ₆ H ₄ (CF ₃ ) -4] ₄ , LiBF ₄ , LiPF ₆ , Examples include LiAsF ₆ , LiSbF ₆ , LiCF ₃ CO ₂ , LiN (CF ₃ SO ₂ ) _{2 and the} like. In the above formula, [C ₆ H ₃ (CF ₃ ) ₂ -3, 5] is the 3rd and 5th positions of the phenyl group, and [C ₆ H ₄ (CF ₃ ) -4] is the 4th position of the phenyl group. Each of which is substituted with —CF ₃ .

  These lithium salts may be used alone or in combination.

Of these lithium salts, LiPF ₆ is preferable.

  Examples of the organic solvent include organic solvents that do not contain propylene carbonate, and specifically, at least one selected from the group consisting of a first solvent composed of ethylene carbonate and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. A mixed solvent consisting of the second solvent is used.

  Preferably, the mixed solvent is a two-type mixed solvent of ethylene carbonate (first solvent) and dimethyl carbonate (second solvent), or a two-type mixed solvent of ethylene carbonate (first solvent) and diethyl carbonate (second solvent). , Two mixed solvents of ethylene carbonate (first solvent) and ethyl methyl carbonate (second solvent), more preferably two kinds of ethylene carbonate (first solvent) and dimethyl carbonate (second solvent) A mixed solvent is mentioned.

  Using a mixed solvent of ethylene carbonate (first solvent) and dimethyl carbonate (second solvent) ensures even better coulomb efficiency, reduces the amount of gas generated, and suppresses damage and performance degradation. An electrochemical capacitor can be obtained.

  In the mixed solvent, the content ratio of the first solvent and the second solvent is such that the first solvent is, for example, 20 parts by mass or more, preferably 30 parts by mass with respect to 100 parts by mass of the total amount of the first solvent and the second solvent. Part or more, for example, 70 parts by mass or less, preferably 50 parts by mass or less. Further, the second solvent is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, for example, 80 parts by mass or less, preferably 70 parts by mass or less.

  The density | concentration of the lithium salt in the electrolyte solution 5 is 0.5-5 mol / L, for example, Preferably, it is 0.5-2 mol / L.

  The cell tank 6 is not particularly limited and may be a known container or a bag for a metal laminate film.

  In the injection step, first, the positive electrode 2 is laminated on one side of the separator 4 and the negative electrode 3 is laminated on the other side so that the positive electrode 2 and the negative electrode 3 are opposed to each other with a gap therebetween. The body is placed in the cell tank 6, and the electrolytic solution 5 is injected into the cell tank 6. Thereby, the positive electrode 2 and the negative electrode 3, and the separator 4 are immersed in the electrolytic solution 5.

  Next, in this method, after the above-described injection step, a voltage is applied to the positive electrode 2 and the negative electrode 3 to perform an electrochemical activation treatment (first electrochemical activation treatment step).

Specifically, constant current charging is performed at a current density (current value) of, for example, 0.5 to ² mA / cm ² until the cell voltage rises to, for example, 4.7 to 4.9 V.

After charging, the cell voltage is maintained at 4.7 to 4.9 V, for example, until the current density drops to, for example, 0.1 to 0.3 mA / cm ² .

Thereafter, until the cell voltage drops to 2.0 to 3.0 V, for example, constant current discharge is performed at a current density of 0.5 to ² mA / cm ² , for example.

  This charge / discharge cycle is performed, for example, 1 to 10 times, preferably once.

Thereafter, until the cell voltage rises to 4.5 to 4.7 V, for example, constant current charging is performed at a current density of ^{3 to} 7 mA / cm ² , for example.

After charging, for example, constant current discharge is performed at a current density of ^{3 to} 7 mA / cm ² until the cell voltage drops to 2.0 to 3.0 V, for example.

  This charge / discharge cycle is performed, for example, 10 to 1000 times, preferably 50 times.

  By such a first electrochemical activation treatment, a hybrid capacitor 1 having a high energy density and good durability can be obtained.

  Next, in this method, after the first electrochemical activation treatment step, an additive having a composition different from that of the lithium salt is added to the electrolytic solution 5 (addition step).

  Specifically, the additive contains a lithium salt having an oxalato complex as an anion and a (meth) acrylic acid ester of a polyhydric alcohol.

A lithium salt having an oxalato complex as an anion is a lithium salt having an anion in which C ₂ O ₄ ²⁻ is coordinated to a central atom, and includes, for example, lithium bis (oxalato) borate (LiBOB), lithium difluorooxalatoborate, Examples thereof include lithium difluorobis (oxalato) phosphate and lithium tris (oxalato) phosphate.

  These lithium salts having an oxalato complex as an anion can be used alone or in combination of two or more.

  The lithium salt having an oxalato complex as an anion is preferably lithium bis (oxalato) borate.

  The addition amount of the lithium salt having an oxalato complex as an anion is, for example, 0.05 to 10% by mass, preferably 0.1 to 10% by mass with respect to the total amount of the electrolytic solution 5 after the addition of the additive, More preferably, it is 0.2-5 mass%.

  If the addition amount of the lithium salt having an oxalato complex as an anion is not less than the above lower limit, a decrease in capacity when charging and discharging are repeated can be suppressed.

  Moreover, if the addition amount of the lithium salt which uses an oxalato complex as an anion is below the said upper limit, the increase in resistance by the film produced | generated to an electrode can be suppressed.

  The (meth) acrylic acid ester of a polyhydric alcohol is an acrylic acid ester of a polyhydric alcohol and / or a methacrylic acid ester of a polyhydric alcohol, wherein the polyhydric alcohol and (meth) acrylic acid (acrylic acid and / or It can be obtained by an esterification reaction with (methacrylic acid).

  The polyhydric alcohol is a compound having two or more hydroxyl groups in the molecule. Specifically, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, pentyl glycol, Examples include dihydric alcohols such as neopentyl glycol and diethylene glycol, trihydric alcohols such as glycerol, and tetrahydric alcohols such as pentaerythritol.

  These polyhydric alcohols can be used alone or in combination of two or more.

  The polyhydric alcohol is preferably a dihydric alcohol.

  Specific examples of such polyhydric alcohol (meth) acrylic acid esters include, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, and 1,4-butanediol diacrylate. 1,4-butanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, pentyl glycol diacrylate, pentyl glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, (Meth) acrylic acid esters of dihydric alcohols such as diethylene glycol diacrylate and diethylene glycol dimethacrylate, such as glycero Triacrylate, trivalent (meth) acrylic acid esters of alcohols such as glycerol trimethacrylate, for example, pentaerythritol tetraacrylate, etc. (meth) acrylic acid ester of a tetravalent alcohols such as pentaerythritol tetra methacrylate.

  These (meth) acrylic acid esters of polyhydric alcohols can be used alone or in combination of two or more.

  As the (meth) acrylic acid ester of a polyhydric alcohol, a (meth) acrylic acid ester of a dihydric alcohol is preferably used.

  The addition amount of the (meth) acrylic acid ester of the polyhydric alcohol is, for example, 0.01 to 5% by mass, preferably 0.05 to 5% by mass with respect to the total amount of the electrolytic solution 5 after the addition of the additive. %, More preferably 0.1 to 1% by mass.

  If the addition amount of the (meth) acrylic acid ester of the polyhydric alcohol is not less than the above lower limit, an increase in resistance when charging / discharging is repeated can be suppressed.

  Moreover, if the addition amount of the (meth) acrylic acid ester of the polyhydric alcohol is not more than the above upper limit, an increase in resistance due to the coating film formed on the electrode can be suppressed.

  Further, the total concentration of the lithium salt having an oxalato complex as an anion and the concentration of the (meth) acrylic acid ester of the polyhydric alcohol is, for example, with respect to the total amount of the electrolytic solution 5 after the addition of the additive, It is 10 mass% or less, Preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 2 mass% or less, Usually, 0.05 mass% or more.

  Moreover, the addition ratio of the lithium salt which uses an oxalato complex as an anion and the (meth) acrylic acid ester of a polyhydric alcohol is the addition amount of the lithium salt which uses an oxalato complex as an anion with respect to 100 parts by mass of the total amount. For example, it is 25-95 mass parts, Preferably, it is 50-90 mass parts, and the addition amount of the (meth) acrylic acid ester of a polyhydric alcohol is 5-75 mass parts, for example, Preferably, 10-50 masses Part.

  As additives, in addition to the above, known additives can be added at an appropriate ratio if necessary.

  In addition, after adding an additive, in order to diffuse an additive to the whole electrolyte 5, as needed, it leaves still suitably.

  Next, in this method, a voltage is applied to the positive electrode 2 and the negative electrode 3 after the above-described injection step and further after the above-described addition step to perform an electrochemical activation treatment (second electrochemical activation treatment step).

Specifically, the cell voltage is, for example, until the rise 4.3～4.5V, for example, 0.1~7mA / cm ^2, preferably, constant current charge at a current density of 1~5mA / cm ² To do.

After the charging, until the cell voltage drops to 2.0 to 3 V, for example, constant current discharge is performed at a current density of 0.1 to 7 mA / cm ² , preferably 1 to 5 mA / cm ² .

  This charge / discharge cycle is performed, for example, 10 to 1000 times, preferably 50 times.

  By such a second electrochemical activation treatment, the hybrid capacitor 1 having a high energy density and good durability can be obtained.

  And by the manufacturing method of such a hybrid capacitor 1, the electrolyte solution 5 is selected from the group which does not contain propylene carbonate and consists of the 1st solvent which consists of ethylene carbonate, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. And an additive containing a lithium salt having an oxalato complex as an anion and a (meth) acrylic acid ester of a polyhydric alcohol. The hybrid capacitor 1 can be obtained.

  In such a manufacturing method of the hybrid capacitor 1 and the hybrid capacitor 1, the electrolytic solution 5 does not contain propylene carbonate, but includes a first solvent made of ethylene carbonate, and a group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate. A mixed solvent comprising at least one selected second solvent, and the electrolyte solution 5 includes a lithium salt having an oxalato complex as an anion, and a (meth) acrylic acid of a polyhydric alcohol Additives containing esters are added.

  According to the manufacturing method of the hybrid capacitor 1 and the hybrid capacitor 1, it is possible to suppress a side reaction from being caused, and it is possible to ensure excellent Coulomb efficiency.

  Moreover, in the manufacturing method of the hybrid capacitor 1 and the hybrid capacitor 1, the decomposition of the electrolytic solution due to the side reaction can be suppressed, so that the amount of gas generated can be reduced. The decrease can be suppressed.

  In the above description, the two electrochemical activation processes of the first electrochemical activation process and the second electrochemical activation process are performed, and during these electrochemical activation process steps (after the first electrochemical activation process). Yes, the additive is added before the second electrochemical activation treatment), for example, the additive may be added before the first electrochemical activation treatment, or the second electrochemical activation treatment An additive may be added later, and further, either or both of the first electrochemical activation treatment and the second electrochemical activation treatment may be omitted.

  In the above description, the electrolytic solution 5 is injected (injection step) into the cell tank 6 so that the positive electrode 2 and the negative electrode 3 and the separator 4 are immersed, and then the additive is added to the electrolytic solution 5. However, the order of these is not particularly limited. For example, an additive is previously added to the electrolytic solution 5 (addition step), and the electrolytic solution 5 is added to the positive electrode 2 and the negative electrode 3, Moreover, it can also inject | pour in the cell tank 6 so that the separator 4 may be immersed (injection process).

In the hybrid capacitor 1, the potential of the positive electrode 2 is preferably 4.23 V vs Li / Li ⁺ or more.

In order to set the potential of the positive electrode 2 to 4.23 V vs Li / Li ⁺ or higher, for example, when soft carbon and / or hard carbon is used for the negative electrode 3, the cell voltage is applied at 3 V or higher.

If the potential of the positive electrode 2 is 4.23 V vs Li / Li ⁺ or more, the energy density of the hybrid capacitor 1 can be improved.

On the other hand, in this hybrid capacitor 1, when the potential of the positive electrode 2 is set to a high potential of 4.23 V vs Li / Li ⁺ or more, the anion contained in the electrolyte solution 5 is caused by the irreversible capacity of the positive electrode 2. (e.g., PF ₆ contained in LiPF ₆ ^-, etc.) negative active inhibitor derived from in some cases be generated.

  The process in which the negative electrode activity inhibitor is generated, for example, the process in which HF is generated due to the development of the irreversible capacity of the positive electrode 2 is presumed as follows.

First, when the above-described predetermined voltage (that is, 4.23 V vs Li / Li ⁺ or more) is applied to the positive electrode 2 and the negative electrode 3, in the electrolytic solution 5, for example, from moisture and organic substances contained in the positive electrode 2 and the electrolytic solution 5. As shown in the following formulas (1) and (2), protons (H ⁺ ) are generated.
(1) 2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
(2) R−H → R + H ⁺ + e ⁻ (R is an alkyl group)
Then, the generated protons, anion contained in the electrolytic solution 5 (e.g., PF ₆ contained in LiPF ₆ ^-, etc.) and react, HF is generated (see the following formula (3)).
(3) PF ₆ ⁻ + H ⁺ → PF ₅ + HF
A negative electrode activity-inhibiting substance such as HF may reduce the electric capacity of the negative electrode 3 and reduce the energy density of the hybrid capacitor 1.

  Therefore, in this hybrid capacitor 1, it is preferable to capture a negative electrode activity inhibiting substance derived from an anion contained in the electrolytic solution 5 between the positive electrode 2 and the negative electrode 3 and at least one of the positive electrode 2 and the negative electrode 3. The scavenger to be contained is included.

  By including a capture agent in the hybrid capacitor 1, for example, even if a negative electrode activity inhibitor is generated due to the irreversible capacity of the positive electrode 2, the negative electrode activity inhibitor can be captured by the capture agent.

Examples of the scavenger include alkali metal carbonates such as lithium carbonate (Li ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), and potassium carbonate (K ₂ CO ₃ ). These can be used alone or in combination of two or more. Of these, lithium carbonate is preferable.

  More specifically, for example, when the capture agent is contained (arranged) between the positive electrode 2 and the negative electrode 3, the capture agent is preferably formed as the capture member 7.

  The capturing member 7 is, for example, a sheet obtained by press-stretching a capturing agent for capturing a negative electrode activity inhibitor and a polymer binder.

  Examples of the polymer binder include the above-described polymer binder, and preferably PTFE.

  And in order to form the capture member 7, for example, first, the capture agent and the polymer binder, for example, the blending ratio of the capture agent: polymer binder is 20:80 to 98: 2, as a mass ratio of solid content, Preferably, it mix | blends so that it may become 50: 50-90: 10, and prepares a mixture. Next, the mixture is pressurized and stretched using, for example, a roll press to obtain a capturing agent-containing sheet.

  Then, the scavenger-containing sheet is punched into a predetermined shape (for example, a rectangular shape) and then dried as necessary. Thereby, the capture member 7 is obtained.

  In this hybrid capacitor 1, for example, as shown in FIG. 1, as the separator 4, a separator 4a disposed on the positive electrode 2 side and a separator 4b disposed on the negative electrode 3 side are provided, and these separators 4a and 4b are provided. The capturing member 7 is provided between the two.

  By providing the capture member 7, for example, even if a negative electrode activity inhibitor is generated due to the irreversible capacity of the positive electrode 2, the negative electrode activity inhibitor can be captured by the capture member 7. Moreover, such a capture | acquisition member 7 can serve as a separator as a capture agent containing separator.

  In the hybrid capacitor 1, for example, the above carbonate can be disposed between the separator 4 a and the separator 4 b as a capturing agent without forming the capturing member 7.

  In order to arrange the carbonate between the separator 4a and the separator 4b, for example, powdery carbonate is added to one surface of the separator 4a or the separator 4b, and the surface and the surface of the other separator 4a (4b) are added. And sandwich the carbonate.

  In the hybrid capacitor 1, the carbonate may be coated on the surface of the positive electrode 2 and / or the negative electrode 3.

  In order to coat the carbonate on the surface of the positive electrode 2 and / or the negative electrode 3, for example, a mixture containing carbonate and a binder is stirred and mixed in a solvent, and then applied onto the positive electrode 2 and / or the negative electrode 3 After that, it is dried.

  Examples of the binder include the polymer binder described above.

  Examples of the solvent include the above-mentioned solvents, preferably NMP (N-methyl-2-pyrrolidone) and water.

  Furthermore, in this hybrid capacitor 1, lithium foil can also be used as a scavenger.

  As the lithium foil, a known lithium foil can be used. For example, the lithium foil is formed in a circular shape or a rectangular shape.

  The lithium foil is preferably formed so that the surface area thereof is substantially the same as or larger than the surface areas of the positive electrode 2 and the negative electrode 3. When the surface area of the lithium foil is such an area, the negative electrode activity inhibiting substance (for example, HF) can be efficiently captured.

  Furthermore, the thickness is 0.01-0.1 mm, for example, Preferably, it is 0.01-0.05 mm.

  The lithium foil has a plurality of holes in the thickness direction. By forming such a hole, the electrolytic solution 5 can pass between the separator 4a and the separator 4b, and can be charged and discharged.

  The lithium foil may be any lithium metal. For example, lithium powder or paste-like lithium may be provided as a scavenger.

  In addition to the lithium metal described above, the negative electrode activity inhibitor can also be captured by including in the cell tank 6 a compound having a Si—N bond (for example, perhydropolysilazane, methylpolysilazane, etc.). In this case, the negative electrode activity inhibiting substance is captured and stabilized by the compound having a Si—N bond.

  When the scavenger is contained in the positive electrode 2 and / or the negative electrode 3, the scavenger is used as a material component of the positive electrode 2 and / or the negative electrode 3, for example.

  That is, in such a case, a scavenger (for example, carbonate, lithium powder, etc.) is blended with the positive electrode material or the negative electrode material in the manufacturing process of the positive electrode 2 and / or the negative electrode 3. Thereby, the scavenger is contained in the positive electrode 2 and / or the negative electrode 3.

Then, such scavenger (catching member 7), to the irreversible capacity 1mAh expressed in the positive electrode 2, preferably in a ratio of ^{2 × 10 -5 mol~175 × 10 -5} mol.

  When the amount of the scavenger is within such a range, a further excellent energy density can be expressed.

For example, referring to the above formulas (1) to (3), 1 mol of HF is generated with the flow of 1 mol of electrons. In other words, the irreversible capacity expressed in positive electrode 2 and Q (mAh), a Faraday constant 96500 (C / mol) Then, the amount _{M HF} of HF generated in the hybrid capacitor _1, M HF = 3.6 × Q × F ⁻¹ (mol).

In the case of using the _Li 2 CO ₃ as a scavenger, as shown in the following formula (4), HF is (reacts with _Li 2 CO ₃₎ is trapped in _Li 2 CO _3, LiF and _H 2 CO ₃ is generated.
(4) Li ₂ CO ₃ + 2HF → 2LiF + H ₂ CO ₃
As shown in the above formula (4), 0.5 mol of Li ₂ CO ₃ is required to capture 1 mol of HF. More specifically, the required amount M _Li2CO3 of Li ₂ CO ₃ is M _Li2CO3 = 0.5M _HF = 1.8 × Q × F ⁻¹ (mol). When F = 96500 is substituted, M _Li2CO3 = 2 × 10 ⁻⁵ × Q (mol). That is, when Li ₂ CO ₃ is contained 2 × 10 ⁻⁵ × Qmol or more with respect to the irreversible capacity Q (mAh), HF can be sufficiently captured. As a result, since a decrease in energy density due to the negative electrode activity inhibitor (HF) can be suppressed, a further excellent energy density can be expressed.

  Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example.

Example 1
1. Production of positive electrode unit A mesophase pitch (AR resin manufactured by Mitsubishi Gas Chemical Company) was heated in the atmosphere at 350 ° C for 2 hours. Next, the heated pitch was pre-fired at 800 ° C. for 2 hours in a nitrogen atmosphere. Thereby, soft carbon was obtained. The obtained soft carbon was put in an alumina crucible, and 4 parts by mass of KOH was added to 1 part by mass of the soft carbon. Next, the soft carbon was calcined with KOH at 800 ° C. for 2 hours under a nitrogen atmosphere to activate KOH. Next, the KOH activated soft carbon was washed with ultrapure water. Washing was performed until the waste liquid became neutral. Thereby, KOH activated soft carbon (positive electrode material) was obtained. After washing, KOH activated soft carbon was pulverized in a mortar and classified with a sieve (32 μm). Then, the grinding operation in the mortar was repeated until almost all the KOH-activated soft carbon had a particle size that could pass through the sieve.

  After classification, a KOH-activated soft carbon powder, a conductive agent (carbon black, VXC-72R manufactured by Cabot Specialty Chemicals, Inc.), and a polymer binder (PVdF manufactured by Kureha Co., Ltd.) with a solid content of 75: 8.3: A slurry of the mixture (solid content: 30% by mass) was added to an NMP (N-methyl-2-pyrrolidone) solvent at a mass ratio of 16.7 and stirred at room temperature (25 ° C. to 30 ° C.) for 12 hours. Got.

  Next, the obtained slurry was applied to the surface of an aluminum foil (positive electrode current collector) having a thickness of 15 μm and dried at 80 ° C. for 12 hours to form a positive electrode. Next, the dried aluminum foil was subjected to pressure stretching with a roll press to obtain an electrode sheet having a coating layer (positive electrode) thickness excluding the aluminum foil of 72 μm.

Next, the electrode sheet was cut into a rectangular shape having a longitudinal length of 60 mm and a direction (width direction) perpendicular to the longitudinal direction of 41 mm, thereby producing a positive electrode unit.
2. Production of negative electrode unit NMP (N-methyl-2-pyrrolidone) solvent with artificial graphite, soft carbon, and polymer binder (PVdF manufactured by Kureha Co., Ltd.) in a solid content of 67.5: 22.5: 10 The mixture was stirred at room temperature (25 ° C. to 30 ° C.) for 12 hours to obtain a slurry of the mixture (solid content: 40% by mass).

  Next, the obtained slurry was applied to the surface of a 10 μm thick copper foil (negative electrode current collector) and dried at 80 ° C. for 12 hours. Subsequently, the dried copper foil was subjected to pressure stretching with a roll press, thereby obtaining an electrode sheet having a coating layer (negative electrode) excluding the copper foil having a thickness of 14 μm.

Subsequently, the negative electrode unit was manufactured by cutting into a rectangular shape having a length in the longitudinal direction of 60 mm and a length (direction in the width direction) orthogonal to the longitudinal direction of 45 mm.
3. Production of Capture Agent-Containing Separator Lithium carbonate (Li ₂ CO ₃ ) powder (Kishida Chemical Co., Ltd. average particle size 85.0 μm) and polymer binder (Daikin Industries, Ltd. PTFE dispersion) are in a mass of 80:20 solids. Mixtures of these were obtained by kneading in a mortar.

Next, the mixture was subjected to pressure stretching using a manual roll press to obtain a separator sheet having a thickness of 30 μm. Next, the separator sheet was cut into 49 mm × 54 mm, and then carried into a dryer and vacuum-dried at 120 ° C. for 12 hours. Then, after purging the inside of the dryer with nitrogen, the scavenger-containing separator was carried into a glove box in a dry Ar atmosphere so as not to be exposed to the air. By the above operation, a scavenger-containing separator was produced.
4). Production of Separator A separator made of cellulose having a thickness of 25 μm (TF40-25 manufactured by Nippon Kogyo Paper Co., Ltd.) was cut into 50 mm × 54 mm.
5. Preparation of electrolyte (preparation of electrolyte without additives)
LiPF ₆ (lithium salt) is added to a mixed solvent (mass ratio EC: EMC = 1: 1) of ethylene carbonate (first solvent (EC)) and ethyl methyl carbonate (second solvent (EMC)) with a concentration of An electrolytic solution was prepared by dissolving to 1.5 mol / L.
6). Manufacturing of hybrid capacitors <Assembly of hybrid capacitors>
One positive electrode unit, one negative electrode unit, one capture agent-containing separator and two auxiliary separators were laminated.

  Specifically, first, one capture agent-containing separator is sandwiched between two separators, and then placed on one side of the stacked separators so that the positive electrode 2 and the negative electrode 4 are opposed to each other with a gap therebetween. The positive electrode unit and the negative electrode unit on the other side were laminated.

  Next, the positive electrode current collector of the positive electrode unit and the aluminum plate (positive electrode current collection tab) on which the sealant was welded were ultrasonically bonded. Similarly, the negative electrode current collector of the negative electrode unit and the nickel plate (negative electrode current collection tab) on which the sealant was welded were ultrasonically bonded. The electrode body was obtained by the above operation.

  Next, the electrode body was wrapped with an aluminum laminate film, and the three sides were joined by thermal welding of the aluminum laminate film to form a cell tank.

Next, the electrode body wrapped with the aluminum laminate film was carried into a dryer and vacuum-dried at 120 ° C. for 12 hours. After the inside of the dryer was purged with nitrogen, it was carried into a glove box in a dry Ar atmosphere so as not to be exposed to the air. The hybrid capacitor was assembled by the above operation.
<Injection process>
The assembled hybrid capacitor was decompressed in the chamber, and an electrolytic solution containing LiPF ₆ was injected into the cell tank so that the positive electrode unit, the negative electrode unit, and the separator were immersed therein.

Subsequently, the hybrid capacitor was sealed by heat welding of an aluminum laminate film, and then returned to normal pressure.
<Precycle 1> (First cycle (first electrochemical activation treatment step))
The battery was charged at a constant current of 1 mA / cm ² until the cell voltage increased to 4.8V. After charging, the cell voltage was held at 4.8 V until the current value dropped to 0.3 mA / cm ² , and then constant current discharge was performed at 1 mA / cm ² until the cell voltage dropped to 2.3 V.
<Precycle 2> (2nd to 51st cycles (first electrochemical activation treatment step))
Next, constant current charging was performed at 5 mA / cm ² until the cell voltage increased to 4.6V. After charging, constant current discharge was performed at 5 mA / cm ² until the cell voltage dropped to 2.3V. This charging / discharging was repeated 50 times in total.
<Addition process>
The hybrid capacitor was carried into a glove box in an Ar atmosphere, a part of the aluminum laminate film was cut, and the hybrid capacitor was opened. Then, lithium bis (oxalato) borate and ethylene glycol dimethacrylate were added to 0.3% by mass and 0.1% by mass, respectively, with respect to the total amount of the electrolytic solution.
<Precycle 3> (52nd to 101st cycles (second electrochemical activation treatment step))
Subsequently, in order to diffuse the said additive to the whole cell, the cell was left still for 12 hours.

Thereafter, constant current charging was performed at 5 mA / cm ² until the cell voltage increased to 4.4V. After charging, constant current discharge was performed at 5 mA / cm ² until the cell voltage dropped to 2.3V. This charging / discharging was repeated 50 times.

Example 2
As a mixed solvent, instead of a mixed solvent of ethylene carbonate (first solvent (EC)) and ethyl methyl carbonate (second solvent (EMC)), ethylene carbonate (first solvent (EC)) and dimethyl carbonate (second A hybrid capacitor was produced in the same manner as in Example 1 except that a mixed solvent (mass ratio EC: DMC = 1: 1) with the solvent (DMC)) was used.

Example 3
As a mixed solvent, instead of a mixed solvent of ethylene carbonate (first solvent (EC)) and ethyl methyl carbonate (second solvent (EMC)), ethylene carbonate (first solvent (EC)) and diethyl carbonate (second A hybrid capacitor was produced in the same manner as in Example 1 except that a mixed solvent (mass ratio EC: DEC = 1: 1) with the solvent (DEC) was used.

Comparative Example 1
As a mixed solvent, instead of a mixed solvent of ethylene carbonate (first solvent (EC)) and ethyl methyl carbonate (second solvent (EMC)), propylene carbonate (PC), ethylene carbonate (EC) and dimethyl carbonate (DMC) ) And ethyl methyl carbonate (EMC) mixed solvent (mass ratio PC: EC: DMC: EMC = 1: 1: 1: 1) was used to produce a hybrid capacitor in the same manner as in Example 1.

Comparative Example 2
A hybrid capacitor was manufactured in the same manner as Comparative Example 1 except that the additive was not added and the first electrochemical activation treatment and the second electrochemical activation treatment were not performed.
<Performance evaluation>
The hybrid capacitor obtained in each example and each comparative example was subjected to a charge / discharge test, and gas generated by decomposition of the electrolytic solution was captured.

Specifically, each hybrid capacitor was charged at a constant current of 5 mA / cm ² until the cell voltage increased to 4.4V. After charging, constant current discharge was performed at 5 mA / cm ² until the cell voltage dropped to 2.3V. This charging / discharging was repeated 2000 cycles.

  In this charging / discharging, after completion of the 100th cycle, 500th cycle, 1000th cycle, and 2000th cycle, the hybrid capacitor was opened in a sealed bag, and the gas therein was collected in the bag.

  Then, the bag from which the gas was recovered was submerged in a water tank filled with water, and the volume of water increased thereby was measured to determine the volume of the gas. The results are shown in Table 1.

  FIG. 2 shows the relationship between the amount of gas generated and the number of charge / discharge cycles in the hybrid capacitors of the examples and the comparative examples.

The abbreviations in the table are as follows.
EC: ethylene carbonate EMC: ethyl methyl carbonate DMC: dimethyl carbonate DEC: diethyl carbonate PC: propylene carbonate (consideration)
As is apparent from Table 1 and FIG. 2, according to the hybrid capacitor of each example, when the electrolytic solution contains propylene carbonate (Comparative Example 1), or when no additive is added (Comparative Example) Compared to 2), it was confirmed that the amount of gas generated can be reduced.

  That is, according to the hybrid capacitor of each example, it was confirmed that the decomposition of the electrolytic solution due to the side reaction can be suppressed, and the electrochemical capacitor can be prevented from being damaged or the performance is lowered.

  From this, it was speculated that according to the hybrid capacitor of each example, it is possible to suppress the occurrence of a side reaction, so that excellent Coulomb efficiency can be ensured.

  It was speculated that such an effect can be achieved by using a mixed solvent having a specific composition in the electrolytic solution to improve the adhesive force between the film formed on the electrode surface by the additive and the electrode.

  That is, if an additive is added to the electrolytic solution, a film that suppresses side reactions can be formed on the electrode surface. In such a hybrid capacitor, when the electrolytic solution contains propylene carbonate or the like, it is presumed that the adhesive force between the film and the electrode is reduced, and the film is easily peeled off. On the other hand, it is speculated that the adhesive force between the film and the electrode can be improved by using a specific composition in the electrolytic solution, specifically, a mixed solvent containing no propylene carbonate. And if the peeling of a film | membrane is suppressed by this, it will be guessed that a side reaction can be suppressed more effectively.

DESCRIPTION OF SYMBOLS 1 Hybrid capacitor 2 Positive electrode 3 Negative electrode 5 Electrolyte 6 Cell tank

Claims (2)

Electrochemistry comprising a positive electrode, a negative electrode disposed opposite to the positive electrode, a cell tank containing the positive electrode and the negative electrode, and an electrolyte stored in the cell tank and immersed in the positive electrode and the negative electrode A method for manufacturing a capacitor, comprising:
An injection step of injecting the electrolytic solution into the cell tank so that the positive electrode and the negative electrode are immersed;
An addition step of adding an additive to the electrolytic solution,
The electrolytic solution does not contain propylene carbonate,
A first solvent comprising ethylene carbonate;
Containing a mixed solvent consisting of at least one second solvent selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate;
The said additive contains the lithium salt which uses an oxalato complex as an anion, and the (meth) acrylic acid ester of a polyhydric alcohol, The manufacturing method of the electrochemical capacitor characterized by the above-mentioned. A positive electrode;
A negative electrode disposed opposite to the positive electrode;
A cell tank containing the positive electrode and the negative electrode;
An electrolyte solution stored in the cell tank, in which the positive electrode and the negative electrode are immersed,
The electrolytic solution does not contain propylene carbonate,
A first solvent comprising ethylene carbonate;
Containing a mixed solvent consisting of at least one second solvent selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and
An electrochemical capacitor, wherein an additive containing a lithium salt having an oxalato complex as an anion and a (meth) acrylic acid ester of a polyhydric alcohol is added.

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