JP2014195017A - Electric power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power storage device which enables the increase in an electrostatic capacitance of a negative electrode.SOLUTION: An electric power storage device comprises: a nonaqueous electrolytic solution containing ions and amine; a negative electrode capable of absorbing and desorbing ions included in the nonaqueous electrolytic solution; and a positive electrode opposed to the negative electrode through the nonaqueous electrolytic solution. As the amine, tertiary amine having an acid dissociation constant pKa of 0.1-13 or the like may be used preferably. As the ions, at least one kind of ions selected from a group consisting of alkali-metal ions, alkali-earth metal ions and onium ions may be used preferably.

Description

  The present invention relates to an electricity storage device.

  Conventionally, an electric double layer capacitor is known as an electricity storage device having a high output density. This electric double layer capacitor usually has a structure in which a pair of activated carbon electrodes are immersed in an electrolytic solution. However, this electric double layer capacitor is not suitable for applications where the energy density is small and long-time discharge is required, such as a large installation space, and higher energy density (higher capacity) will be considered. Became. As a typical method for increasing the capacity, it is conceivable to increase the specific surface area of the activated carbon electrode. For example, the capacity is increased by treating the activated carbon by various methods.

Various studies have also been made on electrolytic solutions. For example, when an electrolyte containing a non-aqueous solvent, a lithium salt and a quaternary ammonium salt and having a salt concentration of 3.0 mol / dm ³ or less with respect to the entire electrolyte, the capacitance of the positive electrode can be increased. It is supposed to be possible (see Patent Document 1). Further, for example, when 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF ₄ ) containing LiBF ₄ is used as an electrolyte, the energy density can be increased, and in particular, the capacitance of the positive electrode can be increased. (See Non-Patent Document 1).

JP 2008-283161 A

Electrochemistry, Vol. 73.No.08 2005, 600-602

  However, although the thing of the patent document 1 mentioned above and the nonpatent literature 1 can raise the electrostatic capacitance of a positive electrode, it was not examined about raising the electrostatic capacitance of a negative electrode. For this reason, it has been desired to increase the capacitance of the negative electrode.

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide an electricity storage device capable of increasing the capacitance of the negative electrode.

In order to achieve the above-described object, the present inventors manufactured an electricity storage device using a non-aqueous electrolyte containing an amine in addition to an electrolyte such as LiBF _4. I found what I could do and came up with the present invention

That is, the electricity storage device of the present invention is
A non-aqueous electrolyte containing ions and amines;
A negative electrode capable of adsorbing and desorbing ions contained in the non-aqueous electrolyte;
A positive electrode facing the negative electrode through the non-aqueous electrolyte,
It is equipped with.

  In this electricity storage device, the capacitance of the negative electrode can be increased. The reason why such an effect can be obtained is presumed that, for example, the amount of ions adsorbed on the negative electrode surface increases due to some interaction between ions contained in the non-aqueous electrolyte and the amine.

FIG. 3 is an explanatory diagram showing an outline of the electricity storage device 10. The cyclic voltammogram of the 10th cycle of Example 1 and Comparative Examples 1 and 2. FIG. The graph showing the relationship between the electrostatic capacitance and voltage of the negative electrode of the 10th cycle of Example 1 and Comparative Examples 1 and 2. The cyclic voltammogram of the 16th-20th cycle of Example 1. FIG.

  An electricity storage device of the present invention comprises a non-aqueous electrolyte containing ions and amines, a negative electrode capable of adsorbing and desorbing ions contained in the non-aqueous electrolyte, and a positive electrode facing the negative electrode through the non-aqueous electrolyte. I have. In the electricity storage device of the present invention, the non-aqueous electrolyte contains ions such as anions and cations, the negative electrode stores electricity by adsorption of ions contained in the non-aqueous electrolyte, and the positive electrode is contained in the non-aqueous electrolyte. The battery may be charged by one or more of ion adsorption, intercalation, or electrochemical reaction. That is, the electricity storage device of the present invention may be configured as an electrochemical capacitor such as an electric double layer capacitor, an ion capacitor, or a hybrid capacitor. Hereinafter, the power storage device of the present invention will mainly be described as being configured as an electric double layer capacitor.

In the electricity storage device of the present invention, the nonaqueous electrolytic solution contains ions and amines. The nonaqueous electrolytic solution may be obtained by adding an amine to an organic solvent containing a supporting salt, for example. Such a nonaqueous electrolytic solution contains anions and cations constituting the supporting salt as ions. Examples of the anion constituting the supporting salt include inorganic anions such as PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ , Br ⁻ , Cl ⁻ and F ⁻ , bis (trifluoromethanesulfonyl) imide (TFSI), Examples thereof include imide anions such as bis (pentafluoroethanesulfonyl) imide (BETI). The cation constituting the supporting salt is not particularly limited, but is preferably at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and onium ions. As the alkali metal ion, lithium ion, sodium ion, potassium ion and the like are preferable, and lithium ion is more preferable. As alkaline earth metal ions, calcium ions, strontium ions, barium ions and the like are preferable. As the onium ions, ammonium ions (quaternary ammonium ions), phosphonium ions, oxonium ions, sulfonium ions, fluoronium ions, chloronium ions, iodonium ions, and the like are preferable, and ammonium ions are more preferable. Examples of ammonium ions include cyclic ammonium ions such as imidazolium ions, pyridinium ions, pyrrolidinium ions, piperidinium ions, and chain ammonium ions. Examples of imidazolium include 1-ethyl-3-methyl-imidazolium (EMI), 1-ethyl-3-butylimidazolium, 1-methyl-3-propylimidazolium, 1-methyl-3-octylimidazolium, 1 -(Hydroxyethyl) -3-methylimidazolium etc. are mentioned. Examples of pyridinium include 1-butyl-3-methylpyridinium and 1-butylpyridinium. Examples of pyrrolidinium include N, N-dimethylpropylpyrrolidinium, N-methyl-N-ethylpyrrolidinium, N-methyl-N-propylpyrrolidinium (P13), N-methyl-N-butylpyrrolidinium ( P14). As piperidinium, N, N-dimethylpropylpiperidinium, N-methyl-N-ethylpiperidinium, N-methyl-N-propylpiperidinium (PP13), N-methyl-N-butylpiperidinium ( PP14) and the like. Examples of chain ammonium include N, N, N-triethyl-N-methylammonium (TEMA), N, N, N-trimethyl-N-propylammonium (TMPA), and N, N-diethyl-N-methyl-N. -(2-methoxyethyl) ammonium, N, N-dimethylammonium, tetrabutylammonium and the like can be mentioned. The combination of an anion and a cation is not particularly limited, and for example, LiBF ₄ and TEMA · BF ₄ are preferable. The concentration of the supporting salt is preferably 0.1 to 2.0M, and more preferably 0.8 to 1.8M. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, and methyl-t-. Chain carbonates such as butyl carbonate, di-i-propyl carbonate, t-butyl-i-propyl carbonate, cyclic esters such as γ-butyllactone and γ-valerolactone, methyl formate, methyl acetate, ethyl acetate, butyric acid Chain esters such as methyl, ethers such as dimethoxyethane, ethoxymethoxyethane and diethoxyethane, nitriles such as acetonitrile and benzonitrile, tetrahydrofuran, Examples include furans such as methyltetrahydrofuran, sulfolanes such as sulfolane and tetramethylsulfolane, and dioxolanes such as 1,3-dioxolane and methyldioxolane. These may be used alone or in combination.

  The amine is not particularly limited, and may be a primary amine such as methylamine, ethylamine, phenylamine, benzylamine, ethylenediamine, pentane-1,2,5-triyltriamine, dimethylamine, diethylamine, and ethyl. Secondary amines such as methylamine, pyrrolidine, piperidine, morpholine, pyrrole and pyridine may be used, trimethylamine, triethylamine, N-ethyl-N methylbutan-1-amine, N-butyldimethylamine, N, N-diisopropylethylamine, Tertiary amines such as 1-ethylpyrrolidine, 1- (3-cyanopropyl) pyrrolidine and 4-methylmorpholine may be used. For example, tertiary amines can be preferably used. The amine may be an aliphatic amine, an alicyclic amine, or an aromatic amine, but an aliphatic amine and an alicyclic amine are preferable. This is because the capacitance of the negative electrode can be further increased. The chain hydrocarbon group bonded to nitrogen may be a straight chain or a branched chain. The chain hydrocarbon group may have 1 to 10 carbon atoms or 1 to 5 carbon atoms. When the number of carbon atoms is relatively small, the solubility in a highly polar solvent such as propylene carbonate can be increased. Further, the chain hydrocarbon group may have a substituent such as a cyano group.

  The amine preferably has an acid dissociation constant pKa of 0.1 or more and 13 or less. Among these, it is more preferable that it is 7 or more, and it is further more preferable that it is 9 or more. Also, it may be 12 or less, or 11 or less. In such a thing, the electrostatic capacity of a negative electrode can be raised more according to the Lewis basicity. As an example of pKa, pKa of 1,5-diazabicyclo [4.3.0] non-5-ene (DBN) is 12.7, and 1,8-diazabicyclo [5.4.0]. The pKa of undec-7-ene (DBU) is 12.5, the pKa of N, N-diisopropylethylamine is 11, the pKa of diethylamine is 10.9, and the pKa of triethylamine is 10.7, The pKa of ethylamine is 10.6, the pKa of N-butyldimethylamine is 9.84, the pKa of trimethylamine is 9.8, the pKa of ammonia is 9.3, and the pKa of 4-methylmorpholine Is 7.4, and the pKa of pyrrole is 0.4. DBN and DBU are known to exhibit particularly strong basicity among reagents that can be easily obtained with organic compound bases (non-metallic bases).

  The amine concentration is preferably from 0.1 M to 5 M, and more preferably from 0.8 M to 1.8 M. The amine dissolution amount is preferably 0.1 molar equivalent or more and 5 molar equivalent or less, and more preferably 0.5 molar equivalent or more and 2 molar equivalent or less with respect to the dissolution amount of ions adsorbed and desorbed at the negative electrode. If it is 0.1 molar equivalent or more, sufficient interaction is considered to work between the ion and the amine, and if it is 5 molar equivalent or less, the amount of amine is not excessive. The concentration of ions adsorbed and desorbed on the negative electrode is the same as the concentration of the supporting salt when the ratio of the anion and cation constituting the supporting salt is 1: 1.

In the electricity storage device of the present invention, the negative electrode is prepared by, for example, mixing a negative electrode active material, a conductive material, and a binder, and adding a suitable solvent to form a paste-like negative electrode material on the surface of the current collector. And it is good also as what was compressed and formed so that the electrode density might be raised as needed. The negative electrode active material is preferably capable of adsorbing and desorbing ions contained in the nonaqueous electrolytic solution, and preferably capable of adsorbing and desorbing cations. As such a negative electrode active material, for example, a carbon material having a large specific surface area may be used. Examples of the carbon material include activated carbon, activated carbon fiber, and ketjen black. Among these, activated carbon is preferable. The specific surface area of the carbon material is, for example, preferably 100 m ² / g or more, and more preferably 500 m ² / g or more. If the specific surface area is 100 m ² / g or more, more ions can be adsorbed and desorbed, and the discharge capacity can be further increased.

  The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the electrode performance. For example, graphite such as natural graphite (scale-like graphite, scale-like graphite) or artificial graphite, acetylene black, carbon black, ketjen A mixture of one or more of black, carbon whisker, carbon nanotube, needle coke, carbon fiber, metal (such as copper, nickel, aluminum, silver, and gold) can be used. The binder serves to bind the active material particles and the conductive material particles. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), a fluorine-containing resin such as fluororubber, polypropylene, Thermoplastic resins such as polyethylene, ethylene propylene diene monomer (EPDM), sulfonated EPDM rubber, natural butyl rubber (NBR) and the like can be used alone or as a mixture of two or more. Examples of the solvent for dispersing the active material, conductive material and binder include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N, N-dimethylamino. Organic solvents such as propylamine, ethylene oxide, and tetrahydrofuran can be used. Moreover, a dispersing agent, a thickener, etc. may be added to water, and an active material may be slurried with latex, such as SBR. As the thickener, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used alone or as a mixture of two or more. Examples of the application method include roller coating such as applicator roll, screen coating, doctor blade method, spin coating, bar coater, and the like, and any of these can be used to obtain an arbitrary thickness and shape. Current collectors include aluminum, copper, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, etc., as well as aluminum and copper for the purpose of improving adhesion, conductivity and oxidation resistance. What processed the surface of copper etc. with carbon, nickel, titanium, silver, etc. can be used. For these, the surface can be oxidized. Examples of the shape of the current collector include foil, film, sheet, net, punched or expanded, lath, porous, foam, and formed fiber group. The thickness of the current collector is, for example, 1 to 500 μm.

  In the electricity storage device of the present invention, the positive electrode is prepared by, for example, mixing a positive electrode active material, a conductive material, and a binder, and adding a suitable solvent to form a paste-like positive electrode material on the surface of the current collector. And it is good also as what was compressed and formed so that the electrode density might be raised as needed. The positive electrode active material is preferably a material capable of occluding and releasing anions, and examples thereof include carbon materials and metal oxides. Examples of the carbon material include graphite, carbon black, activated carbon, and the like. Examples of the metal oxide include lithium transition metal composite oxides containing transition metals such as nickel, cobalt, and manganese. As the conductive material, binder, solvent, and the like used for the positive electrode, those exemplified for the negative electrode can be used. Current collectors of the positive electrode include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, etc., as well as aluminum and titanium for the purpose of improving adhesion, conductivity and oxidation resistance. What processed the surface of copper etc. with carbon, nickel, titanium, silver, etc. can be used. For these, the surface can be oxidized. The shape of the current collector can be the same as that of the negative electrode.

  The electricity storage device of the present invention may include a separator between the negative electrode and the positive electrode. The separator is not particularly limited as long as it is a composition that can withstand the use range of the electricity storage device. For example, glass fiber glass filters, polypropylene nonwoven fabrics, polymer nonwoven fabrics such as polyphenylene sulfide nonwoven fabrics, polyethylene and polypropylene, etc. A thin microporous film of an olefin resin can be mentioned. These may be used alone or in combination.

  The shape of the electricity storage device of the present invention is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Moreover, you may apply to the large sized thing etc. which are used for an electric vehicle etc.

  In such an electricity storage device, the capacitance of the negative electrode can be increased. The reason why such an effect can be obtained is presumed that, for example, the amount of ions adsorbed on the negative electrode surface increases due to some interaction between ions contained in the non-aqueous electrolyte and the amine.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  Below, the example which produced the electrical storage device concretely is demonstrated as an Example.

[Example 1]
1. Production of electricity storage device (cell) The non-aqueous electrolyte was adjusted as follows. First, a 1M lithium tetrafluoroborate (LiBF ₄ ) solution in propylene carbonate (PC) (Toyama Chemical Co., Ltd.) was prepared. To this solution, tertiary amine N-butyldimethylamine (Tokyo Kasei Kogyo Co., Ltd.) was mixed so as to be 1 molar equivalent with respect to the supporting salt (LiBF ₄ ) in the non-aqueous electrolyte, and non-aqueous electrolysis. The liquid was adjusted.

The electrode was produced as follows. First, activated carbon (MSP-20, Kansai Thermochemical Co., Ltd., BET: 2000 m ² / g) as an active material, acetylene black as a conductive material, and PVDF powder as a binder, 85: 5: 10 The mixture was kneaded in a mortar and formed into a sheet using a molding apparatus. From the obtained sheet, a circular sheet having a diameter of 1.2 cm was punched to produce a negative electrode. In addition, a circular sheet having a diameter of 1.6 cm was punched out from the obtained sheet to produce a positive electrode.

Using the obtained non-aqueous electrolyte, negative electrode, and positive electrode, an electricity storage device was produced as follows. FIG. 1 is an explanatory diagram illustrating a configuration of an electricity storage device 10 configured as a three-electrode cell. First, the current collecting member 32 was connected to the aluminum cylindrical base 12. And the negative electrode 16, the separator 18, and the positive electrode 20 were laminated | stacked in this order in the cavity 14 provided in the upper surface center of the cylindrical base | substrate 12. FIG. Next, the insulating ring 22 is disposed so as to be in close contact with the inner periphery of the cavity 14, 1 mL of the nonaqueous electrolytic solution 36 is injected into the cavity 14, and the conductive pressing member 33 is inserted into the inner periphery of the insulating ring 22. . The insulating ring 22 is provided with through holes (not shown) in the vertical direction so that the non-aqueous electrolyte 36 can flow. Subsequently, a conductive pressing spring 34 was inserted through a support provided at the upper center of the pressing member 33. Next, the packing 28 and the insulating ring 29 were disposed on the upper surface of the cylindrical substrate 12, and the conductive lid 26 was disposed thereon. The lid 26 is obtained by connecting a current collecting member 37 and inserting a reference electrode 42 whose side surface is coated with an insulator in advance. Then, the lower surface of the cylindrical substrate 12 and the upper surface of the lid 26 were sandwiched by a clamping member (not shown), and fixed by applying a force in the direction in which the cylindrical substrate 12 and the lid 26 approach each other. Finally, the height of the reference electrode 42 was adjusted so that the tip of the reference electrode 42 was in contact with the nonaqueous electrolytic solution 36 to obtain the electricity storage device 10. In the electricity storage device 10, the current collecting member 32, the cylindrical base 12, and the negative electrode 16 are integrated to become the negative electrode side, and the current collecting member 37, the lid 26, the pressing spring 34, the pressing member 33, and the positive electrode 20 are integrated. And the reference electrode 42 is on the reference electrode side. At this time, the pressing force applied to the pressing member 33, the positive electrode 20, the separator 18, and the negative electrode 16 is adjusted to an appropriate force by the pressing spring 34. In the electricity storage device 10, the negative electrode 16, the positive electrode 20, and the reference electrode 42 are insulated by the insulating ring 22 and the insulating ring 29. In addition, a polyethylene separator (Asahi Kasei Co., Ltd.) was used as the separator, and a nonaqueous solvent-based reference electrode (Ag / Ag ⁺ ) (manufactured by BAS) was used as the reference electrode. The cell was produced in an argon-substituted glove box.

2. Measurement of cyclic voltammetry (CV) CV measurement was performed using an electrochemical measurement system (HZ-3000, manufactured by Hokuto Denko). In order to investigate the electrostatic capacity of the negative electrode, the measurement was performed between a natural potential and a potential range of 1.5 V in terms of Li standard. The scanning speed was 0.5 mV / s. Then, the capacitance of the negative electrode was calculated by dividing the passing electricity amount in the CV measurement at the 10th cycle by the scanning potential range.

[Examples 2 and 3]
A cell of Example 2 was produced in the same manner as Example 1 except that N-butyldimethylamine was changed to 1-ethylpyrrolidine (Wako Pure Chemical Industries), and CV measurement was performed. A cell of Example 3 was produced in the same manner as in Example 1 except that N-butyldimethylamine was changed to 1- (3-cyanopropyl) pyrrolidine (Tokyo Chemical Industry), and CV measurement was performed.

[Examples 4 and 5]
A cell of Example 4 was prepared in the same manner as in Example 1 except that N-butyldimethylamine was changed to 4-methylmorpholine (Tokyo Chemical Industry), and CV measurement was performed. Moreover, Example 4 was performed in the same manner as Example 4 except that the amount of 4-methylmorpholine (Tokyo Chemical Industry) was changed from 1 molar equivalent to 2 molar equivalents with respect to the supporting salt in the nonaqueous electrolytic solution. A cell was prepared and CV measurement was performed.

[Example 6]
A cell of Example 6 was prepared in the same manner as in Example 1 except that the amount of N-butyldimethylamine was changed from 1 molar equivalent to 0.5 molar equivalent with respect to the supporting salt in the nonaqueous electrolytic solution. CV measurement was performed.

[Example 7]
A cell of Example 7 was produced in the same manner as in Example 1 except that N-butyldimethylamine was changed to 1-methylpyrrole (Tokyo Chemical Industry), and CV measurement was performed.

[Example 8]
1M LiBF ₄ PC solution was changed to 1M triethylmethylammonium tetrafluoroborate (TEMA BF ₄ ) PC solution (Toyama Pharmaceutical), and N-butyldimethylamine was changed to 4-methylmorpholine (Tokyo Chemical Industry) A cell of Example 8 was produced in the same manner as in Example 1 except that it was changed to CV measurement.

[Example 9]
A cell of Example 9 was produced in the same manner as in Example 1 except that N-butyldimethylamine was changed to N, N-diisopropylethylamine (Tokyo Chemical Industry), and CV measurement was performed. In Example 9, the non-aqueous electrolyte was prepared by stirring overnight. However, the solubility of N, N-diisopropylethylamine in the PC solvent was low, and the lithium salt was dissolved because it was separated into two layers. The layer was used as a non-aqueous electrolyte.

[Comparative Examples 1 and 2]
A cell of Comparative Example 1 was produced in the same manner as in Example 1 except that a nonaqueous electrolytic solution containing no N-butyldimethylamine was used, and CV measurement was performed. Moreover, the cell of the comparative example 2 was produced similarly to Example 8 except having used the non-aqueous electrolyte solution which does not contain 4-methylmorpholine, and CV measurement was performed.

[Experimental result]
Table 1 shows the capacitance (10th cycle) of the negative electrodes of Examples 1 to 9 and Comparative Examples 1 and 2. Table 1 also shows the type of amine in the non-aqueous electrolyte, the structural formula, the molar equivalent to the supporting salt, and the type of supporting salt. FIG. 2 shows the cyclic voltammograms of the 10th cycle of Example 1 and Comparative Examples 1 and 2. FIG. 3 is a graph showing the relationship between the capacitance and voltage of the negative electrode in the 10th cycle of Example 1 and Comparative Examples 1 and 2. FIG. 4 shows a cyclic voltammogram of the 16th to 20th cycles of Example 1.

First, comparing Examples 1 to 7, 9 and Comparative Example 1 using LiBF ₄ as the supporting salt, the negative electrode had a capacitance of 90 F / g in Comparative Example 1 in which no amine was added. In Examples 1 to 7 and 9 containing amine, the capacitance of the negative electrode was as high as 122 to 260 F / g. From this, it was found that the capacitance of the negative electrode can be increased by adding amine.

  Among these, when Examples 1 to 4 and 7 having the same amine dissolution amount (1 molar equivalent with respect to the supporting salt) and different types of amines were compared, N-butyldimethylamine having a pKa of 9.84 was obtained. In Example 1 used and Examples 2 and 3 using 1-ethylpyrrolidine or 1- (3-cyanopropylpyrrolidine) whose pKa is considered to be equal to or higher than that of N-butyldimethylamine, the capacitance of the negative electrode is high. It was particularly expensive. In Example 4 using 4-methylmorpholine having a pKa of 7.4, the negative electrode has the next highest capacitance, and in Example 7 using 1-methylpyrrole considered to have a pKa of about 0.4. The negative electrode had the next highest capacitance. From the above, it was speculated that the amine has a pKa of, for example, preferably 0.1 or more, more preferably 7 or more, and even more preferably 9 or more. Further, the amine of Example 1 in which the capacitance of the negative electrode was particularly high was an aliphatic amine, and the amines of Examples 2 and 3 in which the capacitance of the negative electrode was particularly high and the next comparative example 4 were alicyclic. It was a group amine. From this, it was speculated that the amine is preferably an aliphatic amine or an alicyclic amine.

  Further, when Examples 4 and 5 having the same amine type (4-methylmorpholine) and different addition amounts were compared, Example 5 having a higher addition amount had a higher capacitance of the negative electrode. Further, when Examples 1 and 6 having the same amine type (N-butyldimethylamine) and different addition amounts were compared, Example 1 having a larger addition amount had a higher capacitance of the negative electrode. From the above, it was speculated that the capacitance of the negative electrode could be increased by increasing the amount of amine dissolved.

  Further, in Example 9, N, N-diisopropylethylamine having a pKa of 11 was used, but the capacitance of the negative electrode was low. This is presumably because N, N-diisopropylethylamine has low solubility in the non-aqueous electrolyte and the amount of amine dissolved in the non-aqueous electrolyte is small. From this, it was speculated that the amine preferably has a high solubility in the non-aqueous electrolyte.

Next, comparing Example 8 and Comparative Example 2 using TEMA · BF ₄ as the supporting salt, in Comparative Example 2 in which no amine was added, the capacitance of the negative electrode was 130 F / g. In Example 8 containing amine, the capacitance of the negative electrode was as high as 170 F / g. From this, it was found that the cation contained in the supporting salt is not limited to alkali metal ions or alkaline earth metal ions but may be onium ions.

  As shown in FIGS. 2 and 4, the cyclic voltammogram was very stable in the example 1. Moreover, it was the same also about Examples 2-9. From this, it was speculated that the power storage device of the present invention also has good cycle characteristics.

  DESCRIPTION OF SYMBOLS 10 Power storage device, 12 Cylindrical base | substrate, 14 Cavity, 16 Negative electrode, 18 Separator, 20 Positive electrode, 22 Insulating ring, 26 Lid, 28 Packing, 29 Insulating ring, 32, 37 Current collecting member, 33 Pressing member, 34 Pressing spring, 36 Nonaqueous electrolyte, 42 reference electrode.

Claims (8)

A non-aqueous electrolyte containing ions and amines;
A negative electrode capable of adsorbing and desorbing ions contained in the non-aqueous electrolyte;
A positive electrode facing the negative electrode through the non-aqueous electrolyte,
An electricity storage device.   The electricity storage device according to claim 1, wherein the amine has an acid dissociation constant pKa of 0.1 or more and 13 or less.   The electricity storage device according to claim 1, wherein the amine is a tertiary amine.   The electricity storage device according to any one of claims 1 to 3, wherein the ions are one or more selected from the group consisting of alkali metal ions, alkaline earth metal ions, and onium ions.   5. The electricity storage device according to claim 1, wherein in the non-aqueous electrolyte, the amine is dissolved in an amount of 0.5 molar equivalent or more and 2 molar equivalents or less with respect to the ion dissolution amount. .   The electricity storage device according to claim 1, wherein the amine is at least one of an aliphatic amine and an alicyclic amine.   The electricity storage device according to any one of claims 1 to 6, wherein all of the chain hydrocarbon groups bonded to nitrogen are linear in the amine.   The electricity storage device according to claim 1, wherein the electricity storage device is an electrochemical capacitor.

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