JP2011228535A - Nonaqueous electrolyte and electrochemical device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte along with an electrochemical device using the same, capable of suppressing degradation of characteristic of an electrolyte which is caused by the water in the electrolyte, and capable of suppressing expansion and deformation of a film package when put in a reflow furnace for soldering to a circuit-board not to degrade characteristics such as capacitance, relating to the electrochemical device of a film package type.SOLUTION: The nonaqueous electrolyte contains nonaqueous solvent and electrolyte in which the nonaqueous solvent is dissolved. The nonaqueous solvent contains cyclic ortho carbonate. Thanks to the reaction of the cyclic ortho carbonate with the water in the electrolyte, decomposition of propylene carbonate, for example, which is a main component of the nonaqueous solvent, is prevented from reacting with water, thus suppressing degradation of characteristic of the electrolyte.

Description

  The present invention relates to various electrochemical processes such as an electric double layer capacitor, a lithium ion capacitor, a redox capacitor, and a lithium ion secondary battery using a nonaqueous electrolytic solution in which an electrolyte such as an ammonium salt or a lithium salt is dissolved in a nonaqueous solvent. Regarding devices.

  As an example of an electrochemical device using this type of non-aqueous electrolyte, an ammonium salt is used as an electrolyte, and a cyclic carbonate, a mixed organic solvent of a cyclic carbonate and a chain carbonate, etc. are used as a non-aqueous solvent. An electric double layer capacitor using a non-aqueous electrolyte solution in which the electrolyte is dissolved in the non-aqueous solvent, a lithium salt as an electrolyte, and a cyclic carbonate, a cyclic carbonate and a chain carbonate as a non-aqueous solvent A lithium ion capacitor using a non-aqueous electrolytic solution in which a mixed organic solvent or the like is used and the electrolyte is dissolved in the non-aqueous solvent is known.

  As described above, when cyclic carbonate or the like is used as a non-aqueous solvent, the cyclic carbonate is decomposed due to water in the electrolyte while charging and discharging are repeated, and the cyclic carbonate in the electrolyte is reduced by the decomposition. Will do. Here, the non-aqueous solvent containing a cyclic carbonate is a kind of electrochemistry because it has a high dielectric constant, a high boiling point, a solubility of an electrolyte, a reduction in internal resistance of a capacitor, and the like. Often used in devices. For this reason, when the cyclic carbonate is reduced due to the water present in the electrolytic solution, the characteristics of the capacitor related to the advantages of the cyclic carbonate, for example, the electrostatic capacity, are lowered.

  On the other hand, in the lithium ion secondary battery of Cited Document 1, an ortho acid ester selected from the group consisting of orthoformate, orthoacetate and orthocarbonate is added to a non-aqueous solvent composed of propylene carbonate, which is an example of a cyclic carbonate. It is intended to prevent decomposition of propylene carbonate in the electrolytic solution by containing ortho acid ester preferentially with water rather than propylene carbonate. Here, the boiling point of orthocarbonate is about 160 ° C., and the boiling point of propylene carbonate is about 240 ° C.

  On the other hand, in recent years, in order to reduce the thickness of a capacitor, a film package made of a power storage element and a laminate film and encapsulating an electrolytic solution and a power storage element, one end connected to the power storage element and the other end derived from the film package An increasing number of film package type capacitors have a pair of terminals. In addition, reflow furnaces are often used when soldering electronic components to circuit boards, and film package type capacitors are also becoming the target. The temperature profile in the reflow oven varies, but it is often over 250 ° C, and many capacitors with a storage element and electrolyte using a film package are small and have a small volume. When performing, the inside of a film package also becomes the temperature close | similar to the temperature in a reflow furnace. For this reason, propylene carbonate containing ortho carbonate in a non-aqueous solvent of a film package type capacitor is used, and when the capacitor is placed in a reflow furnace, the ortho carbonate in the film package is ahead of propylene carbonate. As a result, the internal pressure in the film package increases, and the increase in the internal pressure may cause expansion and deformation of the film package. Further, since the film package is formed by bending the laminated film and thermally fusing the edge portion, leakage of the electrolyte from the edge portion of the film package is also caused by the increase in the internal pressure and the expansion and deformation of the film package. Can occur.

  Here, in order to increase the boiling point of the ortho acid ester, it is conceivable to lengthen the alkyl chain of the ortho acid ester, but by increasing the alkyl chain, the affinity with the cyclic carbonate, ammonium salt, lithium salt, etc. Since the affinity with the electrolyte is lowered, the characteristics of the electrolytic solution are lowered particularly in terms of high dielectric constant and the solubility of the electrolyte, and the characteristics such as the capacitance of the capacitor are lowered due to the lowered characteristics of the electrolytic solution.

JP 09-199171 A

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress the deterioration of the characteristics of the electrolytic solution caused by the water in the electrolytic solution. For devices, non-aqueous electrolysis that can suppress the expansion and deformation of the film package when put into a reflow furnace for soldering to a circuit board so as not to deteriorate the characteristics such as capacitance. The object is to provide a liquid and an electrochemical device using the same.

  In order to achieve the above object, the present invention provides a nonaqueous electrolytic solution having a nonaqueous solvent and an electrolyte dissolved in the nonaqueous solvent, wherein the nonaqueous solvent contains a cyclic orthocarbonate.

  The present invention also relates to an electrochemical device comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte having a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent. The solvent contains a cyclic orthocarbonate.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

  As will be described in detail below, according to the non-aqueous electrolyte and the electrochemical device using the same according to the present invention, it is possible to suppress deterioration in the characteristics of the electrolyte caused by water in the electrolyte, and a film For package-type electrochemical devices, suppress expansion and deformation of the film package when it is put into a reflow oven for soldering to a circuit board so as not to deteriorate the characteristics such as capacitance. Can do.

Side surface sectional drawing of the electric double layer capacitor of one Embodiment of this invention Plan view of electric double layer capacitor Side sectional view of electric double layer capacitor with film package expanded Diagram showing the general structural formula of cyclic orthocarbonate The figure which shows the example of structural formula of cyclic orthocarbonate which has two rings and the number of ring members of two rings is equal The figure which shows the example of structural formula of cyclic orthocarbonate which has two rings and the number of ring members of two rings differs from each other The figure which shows the example of structural formula of the cyclic ortho carbonate ester which has one ring Table showing experimental results Table showing experimental results Table showing experimental results

  Hereinafter, embodiments of the present invention will be specifically described.

The electric double layer capacitor of this embodiment includes a positive electrode 10, a negative electrode 20, a storage element B having a separator 30 interposed between the positive electrode 10 and the negative electrode 20, and nonaqueous electrolysis obtained by dissolving an electrolyte in a nonaqueous solvent. A liquid package, a film package 40 made of a laminate film and enclosing the electricity storage element B and the non-aqueous electrolyte, and a pair of terminals 50 having one end connected to the electricity storage element B and the other end led out from the film package 40 Have The positive electrode 10 and the negative electrode 20 are each formed by forming polarizable electrode layers 12 and 22 on the surfaces of current collectors 11 and 21 made of metal foil, for example, with a conductive adhesive (not shown). The polarizable electrode layer 12 and the polarizable electrode layer 22 of the negative electrode 20 are disposed so as to face each other. The separator is made of cellulose, polypropylene, polyethylene, fluorine resin, etc., and other materials can be used as long as they can be impregnated with a non-aqueous electrolyte. Further, the separator 30 is disposed between the polarizable electrode layers 12 and 22 of the positive electrode 10 and the negative electrode 20 facing each other as described above, and the storage element B is laminated in the order of the positive electrode 10, the separator 30, and the negative electrode 20. Have a laminated structure. In addition, since the separator 30 between the positive electrode 10 and the negative electrode 20 is impregnated with the non-aqueous electrolyte, an electric two is formed at the contact interface between the polarizable electrode layers 11 and 12 of the positive electrode 10 and the negative electrode 20 and the non-aqueous electrolyte. A multilayer is formed. A known structure used for a film package type electric double layer capacitor can be applied to the storage element B and the film package 40.
[Positive electrode and negative electrode]
The polarizable electrode layers 12 and 22 of the positive electrode 10 and the negative electrode 20 may have a known material and structure used for the polarizable electrode layer of the electric double layer capacitor. For example, polyacene (PAS), polyaniline (PAN) , Activated carbon, carbon black, graphite, carbon nanotubes and the like, and other components such as a conductive agent and a binder as necessary.

Examples of the activated carbon material include sawdust, coconut shell, phenol resin, various heat-resistant resins, pitch, and the like. Examples of the heat-resistant resin include polyimide, polyamide, polyamideimide, polyetherimide, and polyether salsaphone. Preferred examples include resins such as polyether ketone, bismaleimide triazine, aramid, fluororesin, polyphenylene, and polyphenylene sulfide. These can be used alone or in combination of two or more.
[Electrolytes]
The electrolyte may be a known electrolyte used for an electric double layer capacitor. For example, an ammonium salt or a phosphonium salt can be used.

Examples of ammonium salts include tetrabutylammonium tetrafluoroborate ((C ₄ H ₉ ) ₄ NBF ₄ ), 4-ethylammonium tetrafluoroborate ((C ₂ H ₅ ) ₄ NBF ₄ ), tetrafluoroborate 3 Ethylmethylammonium ((C ₂ H ₅ ) ₃ CH ₃ NBF ₄ ), tetrafluoroboric acid-1,1′-spirobipyrrolidinium ((C ₄ H ₈ ) ₂ NBF ₄ ), hexafluorophosphoric acid 4 Examples include butylammonium ((C ₄ H ₉ ) ₄ NPF ₆ ), 4-ethylammonium hexafluorophosphate ((C ₂ H ₅ ) ₄ NPF ₆ ), and the like.

Examples of phosphonium salts include 4-butylphosphonium tetrafluoroborate ((C ₄ H ₉ ) ₄ PBF ₄ ), 4-ethylphosphonium tetrafluoroborate ((C ₂ H ₅ ) ₄ PBF ₄ ), and hexafluorophosphoric acid. Examples thereof include 4-butylphosphonium ((C ₄ H ₉ ) ₄ PPF ₆ ) and 4-ethylphosphonium hexafluorophosphate ((C ₂ H ₅ ) ₄ PPF ₆ ).

The amount of the electrolyte contained is preferably 1.2 mol or more and 1.8 mol or less with respect to 1 liter of the nonaqueous electrolytic solution.
[Nonaqueous solvent]
The non-aqueous solvent is a mixture of one or a plurality of solvents included in any of cyclic carbonate, chain carbonate, cyclic ester, chain ester, cyclic ether, chain ether, nitriles, and sulfur-containing compounds. A solvent is contained as a main component of the non-aqueous solvent.

  Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate, etc. Examples of chain carbonates include dimethyl carbonate, methyl ethyl carbonate, diethyl Examples of the cyclic ester include γ-butyrolactone, γ-valerolactone, 3-methyl-γ-butyrolactone (γBL), and 2-methyl-γ-. Examples include chain esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate, and methyl valerate. Examples of cyclic ethers include 1,4-dioxa 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane and the like. Examples of chain ethers include 1,2 -Dimethoxyethane, 1,2-diethoxyethane, diethyl ether, dimethyl ether, methyl ethyl ether, dipropyl ether and the like. Examples of nitriles include acetonitrile, 3-methoxypropionitrile and the like. Examples of sulfur compounds include sulfolane (SL) and ethyl methyl sulfone (EMS).

  In order to increase the dielectric constant of the non-aqueous electrolyte, at least one selected from the group having a cyclic structure consisting of ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and sulfolane is used as the main component of the non-aqueous solvent. Or a mixed organic solvent in which one or a plurality of those having a chain structure such as the above-mentioned chain ester is mixed as a main component of the nonaqueous solvent, or selected from the group 2 A mixed organic solvent containing a mixture of more than one species as a main component of the non-aqueous solvent, or a mixture organic solvent obtained by mixing one or more of those having a chain structure such as the above-mentioned chain ester with a non-aqueous solvent It is preferable to contain as a main component of a solvent.

  Further, the non-aqueous solvent contains a cyclic orthocarbonate as an additive in an amount of 2 wt% to 60 wt% with respect to the total non-aqueous solvent. The cyclic orthocarbonate contained as an additive has two rings and the same number of ring members of the two rings, for example, each of the following cyclic orthocarbonate esters, two rings and two ring members having the same number of rings. It is possible to select one kind selected from the group consisting of, for example, each cyclic orthocarbonate shown below and each cyclic orthocarbonate shown below having one ring, for example, and two or more kinds are used in combination It is also possible.

  A cyclic orthocarbonate having two rings and the same number of ring members of the two rings is represented by the general structural formula (1) in FIG. The number of members of the ring of the general structural formula (1) in FIG. 4 is preferably 5-8. Examples of this include 1,4,6,9-tetraoxaspiro [4.4] nonane (boiling point: about 190 to 200 ° C.) shown in the structural formula (1) of FIG. 2,7-dimethyl-1,4,6,9-tetraoxaspiro [4.4] nonane (boiling point: about 225 to 235 ° C.), 1,5,7,11− represented by the structural formula (3) Tetraoxaspiro [5.5] undecane (boiling point: about 245 to 255 ° C.), 1,6,8,13-tetraoxaspiro [6.6] tridecane (boiling point: 300 to 310) represented by the structural formula (4) And 1,7,9,15-tetraoxaspiro [7.7] pentadecane (boiling point: about 355 to 365 ° C.) represented by the structural formula (5).

  A cyclic orthocarbonate having two rings and different ring members from each other is represented by the general structural formula (2) in FIG. The number of ring members on one side of the general structural formula (2) in FIG. 4 is preferably 5 to 6, and the number of ring members on the other ring is preferably 6 to 8. As this example, 1,4,6,10-tetraoxaspiro [4.5] decane (boiling point: about 215 to 225 ° C.) represented by the structural formula (6) of FIG. 1,4,6,11-tetraoxaspiro [4.6] undecane (boiling point: about 245 to 255 ° C.), 1,4,6,12-tetraoxa represented by the following structural formula (8) Spiro [4.7] dodecane (boiling point: about 270-280 ° C.), 2-methyl-1,4,6,10-tetraoxaspiro [4.5] decane (boiling point) represented by the following structural formula (9) : About 235 to 245 ° C), 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane (boiling point: about 265 to 275 ° C) represented by the following structural formula (10), 2-methyl-1,4,6, shown in Structural Formula (11) 2-tetraoxaspiro [4.7] dodecane (boiling point: about 290 to 300 ° C.), 1,5,7,12-tetraoxaspiro [5.6] dodecane (boiling point) represented by the following structural formula (12) : 1,270 to 280 ° C.) and 1,5,7,13-tetraoxaspiro [5.7] tridecane (boiling point: about 300 to 310 ° C.) represented by the following structural formula (13).

  A cyclic orthocarbonate having one ring is represented by the general structural formula (3) in FIG. The number of ring members in the general structural formula (3) in FIG. 4 is preferably 5, and the number of ring members in the other ring is preferably 6-8. Further, R in the general structural formula (4) in FIG. 4 is an alkyl group. Examples include 2,2-dimethoxy-4-methyl-1,3-dioxolane (boiling point: about 185 to 195 ° C.) shown in the structural formula (14) of FIG. 7, and the following structural formula (15). 2,2-diethoxy-4-methyl-1,3-dioxolane (boiling point: about 230 to 240 ° C.), 2,2-di-n-propoxy-4-methyl-1 represented by the following structural formula (16) , 3-dioxolane (boiling point: about 275-285 ° C.), 2,2-di-n-butoxy-4-methyl-1,3-dioxolane represented by the following structural formula (17) (boiling point: 320-330 ° C.) Degree).

In the electric double layer capacitor, in order to confirm the effect of including a cyclic orthocarbonate as an additive in a non-aqueous solvent mainly composed of propylene carbonate, the electric double layer capacitors of the following experimental examples and comparative examples were used. An experimental result as shown in FIG. 8 was obtained.
[Experimental Example 1]
In the electric double layer capacitor, PAS is used as the material of the polarizable electrode layer of the positive electrode 10, PAS is used as the material of the polarizable electrode layer of the negative electrode 20, and triethylmethylammonium tetrafluoroborate is used as the electrolyte. A non-aqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (2) as an additive was used.
[Experiment 2]
In Experimental Example 1, a nonaqueous solvent containing 95% by weight of propylene carbonate and 5% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (2) was used.
[Experiment 3]
In Experimental Example 1, a nonaqueous solvent containing 60% by weight of propylene carbonate and 40% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (2) was used.
[Experimental Example 4]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (2) was used.
[Experimental Example 5]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,7,9,15-tetraoxaspiro [7.7] pentadecane of the structural formula (5) was used.
[Experimental Example 6]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,7,9,15-tetraoxaspiro [7.7] pentadecane of the structural formula (5) was used.
[Experimental Example 7]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (1) was used.
[Experimental Example 8]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,4,6,9-tetraoxaspiro [4.4] nonane of the structural formula (1) was used.
[Experimental Example 9]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,4,6,10-tetraoxaspiro [4.5] decane of the structural formula (6) was used.
[Experimental Example 10]
In Experimental Example 1, a nonaqueous solvent containing 95% by weight of propylene carbonate and 5% by weight of 1,4,6,10-tetraoxaspiro [4.5] decane of the structural formula (6) was used.
[Experimental Example 11]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,4,6,10-tetraoxaspiro [4.5] decane of the structural formula (6) was used.
[Experimental example 12]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,4,6,12-tetraoxaspiro [4.7] dodecane of the structural formula (8) was used.
[Experimental Example 13]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,4,6,12-tetraoxaspiro [4.7] dodecane of the structural formula (8) was used.
[Experimental Example 14]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. It was.
[Experimental Example 15]
In Experimental Example 1, a non-aqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. It was.
[Experimental Example 16]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 1,5,7,13-tetraoxaspiro [5.7] tridecane of the structural formula (13) was used.
[Experimental Example 17]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 1,5,7,13-tetraoxaspiro [5.7] tridecane of the structural formula (13) was used.
[Experiment 18]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 2,2-dimethoxy-4-methyl-1,3-dioxolane of the structural formula (14) was used.
[Experimental Example 19]
In Experimental Example 1, a non-aqueous solvent containing 95% by weight of propylene carbonate and 5% by weight of 2,2-dimethoxy-4-methyl-1,3-dioxolane of the structural formula (14) was used.
[Experiment 20]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 2,2-dimethoxy-4-methyl-1,3-dioxolane of the structural formula (14) was used.
[Experiment 21]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of propylene carbonate and 2% by weight of 2,2-di-n-butoxy-4-methyl-1,3-dioxolane of the structural formula (17) was used.
[Experimental example 22]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of propylene carbonate and 60% by weight of 2,2-di-n-butoxy-4-methyl-1,3-dioxolane of the structural formula (17) was used.
[Comparative Example 1]
In Experimental Example 1, an organic solvent composed only of propylene carbonate was used as the non-aqueous solvent.
[Comparative Example 2]
In Experimental Example 1, a nonaqueous solvent containing 80% by weight of propylene carbonate as a main component and 20% by weight of orthocarbonate (C (OCH ₃ ) ₄ ) as an additive was used.

When the main component of the non-aqueous solvent is a mixed organic solvent in which propylene carbonate and diethyl carbonate are mixed at a weight ratio of 3: 2, when ethylene carbonate is used, ethylene carbonate and diethyl carbonate are mixed in a ratio of 3: 2. When mixed organic solvent mixed at a weight ratio, butylene carbonate, butylene carbonate and diethyl carbonate mixed at a weight ratio of 3: 2, mixed organic solvent mixed with γ-butyrolactone, γ− In the case of a mixed organic solvent in which butyrolactone and diethyl carbonate are mixed at a weight ratio of 3: 1, in the case of sulfolane, in the case of a mixed organic solvent in which sulfolane and ethylmethylsulfone are mixed at a weight ratio of 4: 1. In addition, a non-aqueous solvent contains a cyclic orthocarbonate as an additive. In order to confirm the effect of this, electric double layer capacitors of the following experimental examples and comparative examples were manufactured, and experimental results as shown in FIGS. 9 and 10 were obtained.
[Experimental example 23]
In Experimental Example 1, a mixed organic solvent in which propylene carbonate and diethyl carbonate were mixed at a weight ratio of 3: 2 was 98% by weight, and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10). [4.6] A non-aqueous solvent containing 2% by weight of undecane was used.
[Experimental Example 24]
In Experimental Example 1, 95% by weight of a mixed organic solvent obtained by mixing propylene carbonate and diethyl carbonate in a weight ratio of 3: 2 and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10) [4.6] A non-aqueous solvent containing 5% by weight of undecane was used.
[Experiment 25]
In Experimental Example 1, 40% by weight of a mixed organic solvent obtained by mixing propylene carbonate and diethyl carbonate in a weight ratio of 3: 2, 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10) [4.6] A non-aqueous solvent containing 60% by weight of undecane was used.
[Experiment 26]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of ethylene carbonate and 60% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. It was.
[Experiment 27]
In Experimental Example 1, a mixed organic solvent in which ethylene carbonate and diethyl carbonate were mixed at a weight ratio of 3: 2 was 98% by weight, and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10). [4.6] A non-aqueous solvent containing 2% by weight of undecane was used.
[Experiment 28]
In Experimental Example 1, 40% by weight of a mixed organic solvent obtained by mixing ethylene carbonate and diethyl carbonate in a weight ratio of 3: 2 and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10) [4.6] A non-aqueous solvent containing 60% by weight of undecane was used.
[Experimental example 29]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of butylene carbonate and 2% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. It was.
[Experiment 30]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of butylene carbonate and 60% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. It was.
[Experimental example 31]
In Experimental Example 1, a mixed organic solvent obtained by mixing butylene carbonate and diethyl carbonate in a weight ratio of 3: 2 was 98% by weight, and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10). [4.6] A non-aqueous solvent containing 2% by weight of undecane was used.
[Experiment 32]
In Experimental Example 1, 40% by weight of a mixed organic solvent obtained by mixing butylene carbonate and diethyl carbonate in a weight ratio of 3: 2 and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10) [4.6] A non-aqueous solvent containing 60% by weight of undecane was used.
[Experimental Example 33]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of γ-butyrolactone and 2% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) Using.
[Experimental example 34]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of γ-butyrolactone and 60% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) Using.
[Experimental Example 35]
In Experimental Example 1, a mixed organic solvent obtained by mixing γ-butyrolactone and diethyl carbonate at a weight ratio of 3: 1 was 98% by weight, and 2-methyl-1,4,6,11-tetraoxax of the structural formula (10). A non-aqueous solvent containing 2% by weight of spiro [4.6] undecane was used.
[Experimental Example 36]
In Experimental Example 1, 40% by weight of a mixed organic solvent in which γ-butyrolactone and diethyl carbonate were mixed at a weight ratio of 3: 1, 2-methyl-1,4,6,11-tetraoxax of the structural formula (10) A non-aqueous solvent containing 60% by weight of spiro [4.6] undecane was used.
[Experiment 37]
In Experimental Example 1, a nonaqueous solvent containing 98% by weight of sulfolane and 2% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane having the structural formula (10) was used. .
[Experiment 38]
In Experimental Example 1, a nonaqueous solvent containing 40% by weight of sulfolane and 60% by weight of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane of the structural formula (10) was used. .
[Experimental Example 39]
In Experimental Example 1, a mixed organic solvent in which sulfolane and ethylmethylsulfone were mixed at a weight ratio of 4: 1 was 98% by weight, and 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10). [4.6] A non-aqueous solvent containing 2% by weight of undecane was used.
[Experimental Example 40]
In Experimental Example 1, 40% by weight of a mixed organic solvent obtained by mixing sulfolane and ethylmethylsulfone at a weight ratio of 4: 1, 2-methyl-1,4,6,11-tetraoxaspiro of the structural formula (10) [4.6] A non-aqueous solvent containing 60% by weight of undecane was used.
[Comparative Example 3]
In Experimental Example 1, a non-aqueous solvent composed only of a mixed organic solvent in which propylene carbonate and diethyl carbonate were mixed at a weight ratio of 3: 2 was used.
[Comparative Example 4]
In Experimental Example 1, a non-aqueous solvent consisting only of a mixed organic solvent in which ethylene carbonate and diethyl carbonate were mixed at a weight ratio of 3: 2 was used.
[Comparative Example 5]
In Experimental Example 1, an organic solvent composed only of butylene carbonate was used as the non-aqueous solvent.
[Comparative Example 6]
In Experimental Example 1, a non-aqueous solvent composed only of a mixed organic solvent in which butylene carbonate and diethyl carbonate were mixed at a weight ratio of 3: 2 was used.
[Comparative Example 7]
In Experimental Example 1, an organic solvent composed only of γ-butyrolactone was used as a nonaqueous solvent.
[Comparative Example 8]
In Experimental Example 1, a non-aqueous solvent composed only of a mixed organic solvent in which γ-butyrolactone and diethyl carbonate were mixed at a weight ratio of 3: 1 was used.
[Comparative Example 9]
In Experimental Example 1, an organic solvent composed only of sulfolane was used as the non-aqueous solvent.
[Comparative Example 10]
In Experimental Example 1, a non-aqueous solvent composed only of a mixed organic solvent in which sulfolane and ethyl methyl sulfone were mixed at a weight ratio of 4: 1 was used.
[Evaluation methods]
The initial capacitance and resistance values in FIGS. 8 to 10 are obtained by measuring the capacitance and resistance values in an atmosphere of 25 ° C. for each electric double layer capacitor manufactured as described above. In addition, after measuring the initial capacitance and resistance value, a reliability test was performed in which a voltage of 2.75 V was continuously applied to each electric double layer capacitor in an atmosphere of 60 ° C. for 1000 hours. The capacitance and resistance value after the reliability test in FIGS. 8 to 10 are values measured after the reliability test. Further, the thickness before the test after the reliability test in FIGS. 8 to 10 is the reliability test as shown in FIG. 3 with respect to the thickness T1 of the film package 40 before the reliability test as shown in FIG. The thickness T2 of the subsequent film package 40 is shown, and T2 / T1 is expressed as a percentage.
[Evaluation results]
From the measurement result after the initial stage of the electrostatic capacitance shown in FIGS. 8 to 10 and the reliability test, Experimental Examples 1 to 40 containing a cyclic orthocarbonate as an additive in the nonaqueous solvent include the additive in the nonaqueous solvent. Compared with Comparative Examples 1 and 3 to 10 that do not contain, the retention rate of the capacitance is high. Further, from FIGS. 8 to 10, when the content of the cyclic orthocarbonate in the non-aqueous solvent is 2 wt% or more and 60 wt% or less with respect to the total non-aqueous solvent, the comparative example does not contain the additive in the non-aqueous solvent Compared with 1 and 3-10, it was confirmed that the maintenance rate of a capacitance is high.

  From the measurement results after the initial resistance value and reliability test shown in FIGS. 8 to 10, Experimental Examples 1 to 40 containing a cyclic orthocarbonate as an additive in a nonaqueous solvent contain an additive in the nonaqueous solvent. Compared with Comparative Examples 1 and 3 to 10, the resistance increase rate is low. Further, from FIGS. 8 to 10, when the content of the cyclic orthocarbonate in the non-aqueous solvent is 2 wt% or more and 60 wt% or less with respect to the total non-aqueous solvent, the comparative example does not contain an additive in the non-aqueous solvent. Compared with 1 and 3-10, it was confirmed that the rate of increase in resistance of the capacitance was low.

  From the measurement result of the thickness after the reliability test of the film package 40 shown in FIGS. 8 to 10, Experimental Examples 1 to 40 containing a cyclic orthocarbonate as an additive in the non-aqueous solvent are non-aqueous solvents. Compared with Comparative Examples 1 and 3 to 10 that do not contain any additives, the change in thickness of the film package 40 after the reliability test is small. That is, Experimental Examples 1 to 40 containing a cyclic orthocarbonate as an additive in a non-aqueous solvent were compared with Comparative Examples 1 and 3 to 10 that did not contain an additive in a non-aqueous solvent. The amount of gas generated in the package 40 is small. Further, from FIGS. 8 to 10, when the content of the cyclic orthocarbonate in the non-aqueous solvent is 2 wt% or more and 60 wt% or less with respect to the total non-aqueous solvent, the comparative example does not contain an additive in the non-aqueous solvent. Compared with 1 and 3-10, it was confirmed that the thickness change of the film package 40 after a reliability test was small.

  From the initial measurement results of the capacitance shown in FIG. 8 and the measurement results after the reliability test, Experimental Examples 1 to 22 containing a cyclic orthocarbonate as an additive in a nonaqueous solvent are orthocarbonate as an additive in a nonaqueous solvent. Compared with the comparative example 2 containing ester, the maintenance rate of an electrostatic capacitance is high.

  From the measurement results after the initial resistance value and the reliability test shown in FIG. 8, Experimental Examples 1 to 22 containing a cyclic orthocarbonate as an additive in a nonaqueous solvent are orthocarbonates as an additive in a nonaqueous solvent. The rate of increase in resistance is low as compared with Comparative Example 2 containing

  From the measurement result of the thickness after the reliability test of the film package 40 shown in FIG. 8, Experimental Examples 1 to 22 containing a cyclic orthocarbonate as an additive in the nonaqueous solvent were added to the nonaqueous solvent. Compared with Comparative Example 2 containing orthocarbonate as an agent, the change in thickness of the film package 40 after the reliability test is small. That is, Experimental Examples 1 to 22 containing a cyclic orthocarbonate as an additive in a nonaqueous solvent were compared with Comparative Example 2 containing an orthocarbonate as an additive in a nonaqueous solvent, and the film was used during a reliability test. The amount of gas generated in the package 40 is small.

  The reason why these effects can be obtained by including a cyclic orthocarbonate as an additive in a non-aqueous solvent is not clear, but is considered as follows.

  First, for example, when the non-aqueous solvent is composed only of propylene carbonate as in Comparative Example 1, water, which is an impurity, is present in the electrolyte solution in the film package 40, so that water reacts with propylene carbonate to react with glycol. It is presumed that the thickness change of the film package 40 after the reliability test is increased due to the generated carbon dioxide.

  On the other hand, when cyclic orthocarbonate is added to propylene carbonate as the main component of the nonaqueous solvent as in Experimental Examples 1 to 22, water present in the electrolyte solution in the film package 40 reacts with propylene carbonate. It is expected to react with the cyclic orthocarbonate before. Here, propylene carbonate reacts with two molecules of water to produce one molecule of glycol and carbon dioxide as shown in the chemical reaction formula (a) below, but the cyclic orthocarbonate is, for example, of the structural formula (10). As an example, one molecule of 2-methyl-1,4,6,11-tetraoxaspiro [4.6] undecane reacts with four molecules of water as shown in the following chemical reaction formula (b). And one molecule of carbon dioxide. That is, the presence of not only propylene carbonate but also cyclic orthocarbonate in the non-aqueous solvent can reduce the amount of carbon dioxide generated by the reaction with water in the electrolyte during the reliability test. It is speculated that the thickness of the film package 40 after the reliability test can be reduced.

…化学反応式（ａ）

... Chemical reaction formula (a)

…化学反応式（ｂ）

... Chemical reaction formula (b)

Further, even when ortho carbonate is added to propylene carbonate, which is the main component of the nonaqueous solvent as in Comparative Example 2, before the water present in the electrolyte solution in the film package 40 reacts with propylene carbonate. It is expected to react with ortho carbonates. Further, one molecule of C (OCH ₃ ) _4, which is an example of an ortho carbonate, reacts with four molecules of water to generate one molecule of alcohol and carbon dioxide as shown in the following chemical reaction formula (c). Here, the alcohol produced when the ortho carbonate ester reacts with 4 molecules of water is methyl alcohol, whereas the alcohol produced when the cyclic ortho carbonate ester of the present application reacts with 4 molecules of water is glycol, The resulting glycol has a higher boiling point than methyl alcohol. For this reason, it is presumed that when the cyclic orthocarbonate is added, the vaporization of alcohol during the reliability test is less, and the thickness of the film package 40 after the reliability test can be reduced.

…化学反応式（ｃ）

... Chemical reaction formula (c)

  In addition, glycol is higher in polarity than methyl alcohol, and is superior in terms of electrolyte solubility and high dielectric constant of the electrolyte. Therefore, when a cyclic orthocarbonate is added, reliability is improved. It is estimated that the maintenance rate of the capacitance is high.

  Further, as exemplified for the cyclic orthocarbonates of the structural formulas (1) to (17), the cyclic orthocarbonate has a higher boiling point than the chain orthocarbonate, so that the electric double layer capacitor is subjected to reflow soldering. It is considered that the generation of gas in the film package 40 is reduced when it is put into the reflow furnace as compared with the case where ortho carbonate is used as an additive. That is, the expansion and deformation of the film package 40 when the electric double layer capacitor is put into a reflow furnace for soldering to the circuit board can be suppressed.

  Further, since the cyclic orthocarbonate has higher polarity than the orthocarbonate, for example, even if the alkyl chain is lengthened as in structural formulas (5), (11), (13) and (17), non-aqueous It is presumed that the affinity with propylene carbonate, which is the main component of the solvent, and the electrolyte can be maintained. That is, it is possible to increase the boiling point of cyclic orthocarbonate without lowering the affinity with electrolytes such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, etc., which are the main components of the nonaqueous solvent. it is conceivable that.

  Moreover, the cyclic orthocarbonate of the structural formulas (3) to (13) has 6 or more ring members in at least one ring. On the other hand, propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane and the like, which are the main components of the nonaqueous solvent, are 5-membered rings. For this reason, a cyclic orthocarbonate having 6 or more ring members in at least one ring is more likely to react with water than propylene carbonate, which is a 5-membered ring, and the decrease in propylene carbonate contributing to a higher dielectric constant of the electrolyte is reduced. It can be suppressed, and it is considered advantageous for efficient removal of water as an impurity.

  In addition, since the ortho carbonate ester and the cyclic ortho carbonate esters of the structural formulas (1) to (5) have a symmetric structure, once the reaction with water starts, the chemical reaction formula (a) and the chemical reaction formula (b) In many cases, the reaction proceeds to the end as in (1), but the cyclic orthocarbonates of the structural formulas (6) to (13) are cyclic orthocarbonates having two rings and different ring members from each other. When the ring members are different from each other, the two rings have different reactivity with water. Therefore, it is expected that the reaction stops when one ring reacts with water. For example, in the case of the cyclic orthocarbonate of the structural formula (10) in FIG. 6, the ring having 7 ring members is easier to react with water than the ring having 5 ring members, and the following chemical reaction formula (d) Thus, the reaction is expected to stop when the ring having 7 ring members reacts with water, thereby producing propylene carbonate. That is, it is considered that when such a cyclic orthocarbonate reacts with water, propylene carbonate that contributes to the increase in the dielectric constant of the electrolyte and the solubility of the electrolyte is generated, and the deterioration of the capacitor characteristics can be suppressed. In the case of the general structural formula (3), since the reaction is stopped in the middle as described above, ethylene carbonate is produced, so that the same effect is considered.

…化学反応式（ｄ）

... Chemical reaction formula (d)

  In addition, since the cyclic orthocarbonates of the structural formulas (14) to (17) have one 5-membered ring and two alkoxy groups, the two alkoxy groups precede the stable 5-membered ring. It is expected that the reaction will stop there. For example, in the case of the cyclic orthocarbonate of the structural formula (14) in FIG. 7, as shown in the chemical reaction formula (e) below, two methoxy groups react with water before the ring having 5 ring members. The reaction is expected to stop there, thereby producing propylene carbonate. That is, it is considered that such cyclic orthocarbonate reacts with water to produce propylene carbonate that contributes to a high dielectric constant of the electrolytic solution and solubility of the electrolyte, and can suppress deterioration of the capacitor characteristics.

…化学反応式（ｅ）

... Chemical reaction formula (e)

  In the present embodiment, the cyclic ortho carbonate is added to the non-aqueous solvent of the non-aqueous electrolyte of the electric double layer capacitor. However, the cyclic ortho-carbonate is added to the non-aqueous solvent of the non-aqueous electrolyte of the lithium ion capacitor. It is also possible to add esters. That is, the non-aqueous solvent used in the electrolyte of the lithium ion capacitor is a cyclic carbonate such as ethylene carbonate, propylene carbonate, or butylene carbonate, a chain cyclic ester such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, or methyl propyl carbonate, It contains cyclic esters such as γ-butyrolactone, nitriles such as acetonitrile, sulfur-containing compounds such as sulfolane, chain carboxylic acid esters such as ethyl propionate, and chain ethers such as dimethoxyethane. In addition, the non-aqueous solvent contains at least one selected from the group of those having a cyclic structure consisting of, for example, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and sulfolane as a main component of the non-aqueous solvent. Two types selected from the group containing a mixed organic solvent obtained by mixing one or more mixed organic solvents having a chain structure such as the above-mentioned chain ester as a main component of the non-aqueous solvent A mixed organic solvent containing the above mixed organic solvent as a main component of the non-aqueous solvent or a mixed organic solvent obtained by mixing one or more of them having a chain structure such as the above-mentioned chain ester It is preferable to contain as a main component of a non-aqueous solvent. For this reason, the effect similar to the above can be acquired by making the non-aqueous solvent of the electrolyte solution of a lithium ion capacitor contain cyclic ortho carbonate ester as demonstrated in this embodiment.

  It is also possible to add a cyclic orthocarbonate to the nonaqueous solvent of the nonaqueous electrolyte solution of the lithium ion secondary battery. That is, the non-aqueous solvent used for the electrolyte of the lithium ion secondary battery is a cyclic carbonate such as ethylene carbonate, propylene carbonate, or butylene carbonate, or a chain cyclic such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, or methyl propyl carbonate. It contains cyclic esters such as esters, γ-butyrolactone, nitriles such as acetonitrile, sulfur-containing compounds such as sulfolane, chain carboxylic acid esters such as ethyl propionate, chain ethers such as dimethoxyethane, and the like. In addition, the non-aqueous solvent contains at least one selected from the group of those having a cyclic structure consisting of, for example, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and sulfolane as a main component of the non-aqueous solvent. Two types selected from the group containing a mixed organic solvent obtained by mixing one or more mixed organic solvents having a chain structure such as the above-mentioned chain ester as a main component of the non-aqueous solvent A mixed organic solvent containing the above mixed organic solvent as a main component of the non-aqueous solvent or a mixed organic solvent obtained by mixing one or more of them having a chain structure such as the above-mentioned chain ester It is preferable to contain as a main component of a non-aqueous solvent. For this reason, the effect similar to the above can be acquired by making cyclic non-carbonic acid ester contain in the nonaqueous solvent of the electrolyte solution of a lithium ion secondary battery as demonstrated in this embodiment.

  It is also possible to add a cyclic orthocarbonate to the nonaqueous solvent of the nonaqueous electrolyte of the redox capacitor. That is, since the non-aqueous solvent used for the redox capacitor electrolyte contains ethylene carbonate, propylene carbonate, γ-butyrolactone, etc., as described in this embodiment, the non-aqueous solvent for the redox capacitor electrolyte is cyclic orthocarbonate. By containing an ester, the same effect as described above can be obtained.

  In the present embodiment, the description has been made using a film package type electric double layer capacitor in which the storage element B and the non-aqueous electrolyte are enclosed in a film package 40 made of a laminate film, but a metal can or the like is used. It is possible to add a cyclic ortho carbonate to the non-aqueous solvent of the non-aqueous electrolyte of other types of electric double layer capacitors such as button type, cylindrical type, square type, etc. It is possible to maintain the electrostatic capacity over a long period of time and to prevent the resistance value from rising due to the reaction of carbonate with water.

  In this embodiment, the number of ring members in each ring of the general structural formula (1) or (2) is 5 to 8, and one ring number of the general structural formula (3) or (4) is 5 to 6. And the number of ring members of the other ring is 6 to 8 and the ring number of the ring of general structural formula (5) is 5, but each ring of general structural formula (1) or (2) The number of ring members is 9 or more, the number of ring members in one of the general structural formulas (3) or (4) is 7 or more, and the number of ring members in the other ring is 9 or more. Those having 6 or more ring members can be added to the non-aqueous solvent of the non-aqueous electrolyte of the present application if there is no problem in production, and these cyclic orthocarbonates can also achieve the same effects as described above. It is.

  The present invention can be widely applied to various electrochemical devices such as an electric double layer capacitor, a lithium ion capacitor, a redox capacitor, and a lithium ion battery, and the same operation and effect can be obtained by the application.

  DESCRIPTION OF SYMBOLS 10 ... Positive electrode, 11 ... Current collector, 12 ... Polarizable electrode layer, 20 ... Negative electrode, 21 ... Current collector, 22 ... Polarizable electrode layer, 30 ... Separator, 40 ... Film package, 50 ... Terminal, B ... Power storage element.

Claims (8)

A non-aqueous electrolyte having a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent,
The non-aqueous solvent contains a cyclic orthocarbonate. The non-aqueous electrolyte according to claim 1,
The non-aqueous solvent contains a cyclic orthocarbonate having 6 or more ring members in at least one ring. The non-aqueous electrolyte according to claim 1 or 2,
The nonaqueous solvent contains cyclic orthocarbonates having two rings and different ring members from each other. The non-aqueous electrolyte according to claim 1 or 2,
The non-aqueous solvent contains a cyclic orthocarbonate having only one ring. An electrochemical device comprising a positive electrode, a negative electrode, and a nonaqueous electrolytic solution having a nonaqueous solvent and an electrolyte dissolved in the nonaqueous solvent,
The nonaqueous solvent of the nonaqueous electrolytic solution contains a cyclic orthocarbonate. The electrochemical device according to claim 5,
The nonaqueous solvent of the nonaqueous electrolytic solution contains a cyclic orthocarbonate having 6 or more ring members in at least one ring. The electrochemical device according to claim 5 or 6,
The nonaqueous solvent of the nonaqueous electrolytic solution contains cyclic orthocarbonates having two rings and different ring members from each other. The electrochemical device according to claim 5 or 6,
The nonaqueous solvent of the nonaqueous electrolytic solution contains a cyclic orthocarbonate having only one ring.

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