JP2018060652A - Power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage element which is hard to cause the decrease in discharge capacity even if suffering the repetition of charge and discharge.SOLUTION: A power storage element 10 comprises: a positive electrode 11 including a positive electrode active material allowing an anion to go thereinto and go out thereof; a negative electrode 12 including a negative electrode active material allowing a cation to go thereinto and go out thereof; and a nonaqueous electrolyte solution with an electrolyte salt dissolved in nonaqueous solvent. The nonaqueous electrolyte solution contains cycloalkane and/or a cycloalkane derivative.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage element.

  Conventionally, as a storage element using a nonaqueous electrolyte, a positive electrode containing a positive electrode active material such as lithium cobalt composite oxide, a negative electrode containing a negative electrode active material such as carbon, and a lithium salt dissolved in a nonaqueous solvent Many lithium ion secondary batteries having a nonaqueous electrolyte solution are used (see, for example, Patent Document 1).

  In recent years, power storage elements are used in a wide range of applications from portable devices to electric vehicles, and power storage elements having a high input / output density are required.

  As an energy storage device having a large input / output density, carbon is used for the positive electrode active material and the negative electrode active material, and anions in the nonaqueous electrolyte are inserted into or removed from the positive electrode, and lithium ions in the nonaqueous electrolyte are inserted into the negative electrode. There is a dual carbon battery (Dual Carbon Battery: DCB) that is detached and charged / discharged (see, for example, Non-Patent Document 1).

  The discharge capacity of the dual carbon battery is determined by the anion storage amount of the positive electrode, the anion release amount of the positive electrode, the cation storage amount of the negative electrode, the cation release amount of the negative electrode, and the anion and cation contents in the non-aqueous electrolyte.

  In the dual carbon battery, since ions are inserted between the positive electrode active material and the negative electrode active material, the internal resistance of the battery is very small and the input / output density is very large.

  However, when charging / discharging is repeated, there is a problem that the discharge capacity decreases.

  An object of this invention is to provide the electrical storage element in which discharge capacity does not fall easily even if charging / discharging is repeated.

  According to one embodiment of the present invention, in a power storage element, a positive electrode including a positive electrode active material capable of inserting or desorbing anions, a negative electrode including a negative electrode active material capable of inserting or desorbing a cation, A non-aqueous electrolyte solution in which an electrolyte salt is dissolved in an aqueous solvent, and the non-aqueous electrolyte solution contains cycloalkane and / or a cycloalkane derivative.

  According to the present invention, it is possible to provide a power storage element in which the discharge capacity is less likely to decrease even when charging and discharging are repeated.

It is the schematic which shows an example of the electrical storage element of this embodiment.

(Storage element)
The power storage device of this embodiment includes a positive electrode including a positive electrode active material capable of inserting or desorbing anions, a negative electrode including a negative electrode active material capable of inserting or desorbing cations, and a non-aqueous solvent. It has a non-aqueous electrolyte solution in which an electrolyte salt is dissolved, and further has other members as necessary.

  Hereafter, each component of the electrical storage element of this embodiment is demonstrated in detail.

<Positive electrode>
The positive electrode is not particularly limited as long as it contains a positive electrode active material, and can be appropriately selected according to the purpose. For example, a positive electrode including a positive electrode material layer containing a positive electrode active material on a positive electrode current collector Etc.

  There is no restriction | limiting in particular as a shape of a positive electrode, According to the objective, it can select suitably, For example, flat form, a sheet form, etc. are mentioned.

[Positive electrode material layer]
The positive electrode material layer includes a positive electrode active material, and further includes a conductive agent, a binder, a thickener, and the like as necessary.

  There is no restriction | limiting in particular in the average thickness of a positive electrode material layer, Although it can select suitably according to the objective, It is preferable that they are 20 micrometers or more and 300 micrometers or less, and it is more preferable that they are 40 micrometers or more and 200 micrometers or less. When the average thickness of the positive electrode material layer is 20 μm or more, a power storage element with sufficient input / output density can be obtained, and when the average thickness is 300 μm or less, a power storage element with good load characteristics can be obtained.

[Positive electrode active material]
The positive electrode active material is not particularly limited as long as it can insert or desorb anions, and can be appropriately selected according to the purpose. Examples thereof include carbonaceous materials and conductive polymers. It is done. These may be used individually by 1 type and may use 2 or more types together. Among these, a carbonaceous material is particularly preferable because of its high input / output density.

  Examples of the carbonaceous material include graphite (graphite) such as coke, artificial graphite, and natural graphite, soft carbon, and thermal decomposition products of organic substances under various thermal decomposition conditions. Among these, artificial graphite, natural graphite, and soft carbon are particularly preferable.

The carbonaceous material is preferably a carbonaceous material having high crystallinity. The crystallinity of the carbonaceous material can be evaluated by X-ray diffraction, Raman analysis, or the like. For example, the carbonaceous material has a diffraction peak intensity I _{2θ = 22.3 ° at 2θ = 22.3 °} and a diffraction peak intensity I _2θ at 2θ = 26.4 ° in a powder X-ray diffraction pattern using CuKα rays. _{= 26.4 °} to the intensity ratio _{I 2θ = 22.3 ° / I 2θ} = 26.4 ° of is preferably 0.4 or less.

The carbonaceous material preferably has a BET specific surface area of 1 m ² / g or more and 100 m ² / g or less by nitrogen adsorption, and a median diameter measured by a laser diffraction / scattering method is 0.1 μm or more and 100 μm or less. preferable.

  Soft carbon, for example, is a generic term for carbon in which a hexagonal network surface composed of carbon atoms is easy to form a regular laminated structure by heat treatment in an inert atmosphere.

In the present embodiment, for example, when heat treatment is performed in an inert atmosphere, a crystal structure in which an average interplanar spacing d ₀₀₂ of (002) plane is 3.50 mm or less, preferably 3.35 mm or more and 3.45 mm or less. The soft carbon that forms is used.

  Examples of the raw material for soft carbon include graphitizable carbon such as petroleum pitch, coal pitch, coke, and anthracene. These may be used alone or in combination of two or more.

  Examples of the conductive polymer include polyaniline, polypyrrole, polyparaphenylene, and the like.

[Binder]
The binder is not particularly limited as long as it is a material that is stable with respect to the solvent and non-aqueous electrolyte used in manufacturing the positive electrode, and can be appropriately selected according to the purpose. For example, polyvinylidene fluoride (PVDF ), Fluorine-based binders such as polytetrafluoroethylene (PTFE), acrylic binders, styrene-butadiene rubber (SBR), and isoprene rubber. These may be used alone or in combination of two or more.

[Thickener]
The thickener is not particularly limited and may be appropriately selected depending on the intended purpose. For example, carboxymethylcellulose (CMC), polyethylene glycol (PEO), methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorus Examples include oxidized starch, casein, and sodium alginate. These may be used alone or in combination of two or more.

[Conductive agent]
There is no restriction | limiting in particular as a electrically conductive agent, According to the objective, it can select suitably, For example, carbonaceous materials, such as metal materials, such as copper and aluminum, carbon black, and acetylene black, etc. are mentioned. These may be used alone or in combination of two or more.

[Positive electrode current collector]
There is no restriction | limiting in particular as a material, a shape, a magnitude | size, and a structure of a positive electrode electrical power collector, According to the objective, it can select suitably.

  The material of the positive electrode current collector is not particularly limited as long as it is a conductive material that is stable with respect to an applied potential, and can be appropriately selected according to the purpose. For example, stainless steel, nickel, aluminum, Examples include titanium and tantalum. Among these, stainless steel and aluminum are particularly preferable.

  There is no restriction | limiting in particular as a shape of a positive electrode electrical power collector, According to the objective, it can select suitably.

  The size of the positive electrode current collector is not particularly limited as long as it is a size that can be used for a power storage element, and can be appropriately selected according to the purpose.

<Method for producing positive electrode>
The positive electrode, after adding a binder, a thickener, a conductive agent, a solvent, etc. to the positive electrode active material as necessary, and applying a slurry-like coating material for the positive electrode material layer on the positive electrode current collector, It can be produced by drying to form a positive electrode material layer.

  There is no restriction | limiting in particular as a solvent, According to the objective, it can select suitably, For example, an aqueous solvent, an organic solvent, etc. are mentioned.

  Examples of the aqueous solvent include water and alcohol.

  Examples of the organic solvent include N-methyl-2-pyrrolidone (NMP) and toluene.

  In addition, the composition for positive electrode material layers which added the binder, the electrically conductive agent, etc. to the positive electrode active material as needed can be roll-molded into a sheet electrode, or compression-molded into a pellet electrode.

<Negative electrode>
The negative electrode is not particularly limited as long as it contains a negative electrode active material, and can be appropriately selected according to the purpose. For example, a negative electrode including a negative electrode material layer containing a negative electrode active material on a negative electrode current collector Etc.

  There is no restriction | limiting in particular as a shape of a negative electrode, According to the objective, it can select suitably, For example, flat form etc. are mentioned.

[Negative electrode layer]
The negative electrode material layer includes a negative electrode active material, and further includes a binder, a conductive agent, and the like as necessary.

  There is no restriction | limiting in particular in the average thickness of a negative electrode material layer, Although it can select suitably according to the objective, It is preferable that they are 10 micrometers or more and 450 micrometers or less, and it is more preferable that they are 20 micrometers or more and 200 micrometers or less. When the average thickness of the negative electrode material layer is 10 μm or more, the battery element has good cycle characteristics, and when it is 450 μm or less, the battery element with sufficient input / output density can be obtained.

[Negative electrode active material]
The negative electrode active material is not particularly limited as long as it can insert or desorb cations, and can be appropriately selected according to the purpose. For example, an alkali metal ion, alkaline earth metal, or the like Metal oxides capable of occluding or releasing metal; metals capable of alloying with alkali metal ions, alkaline earth metals, alloys containing these metals, composite alloy compounds; carbonaceous materials having a large specific surface area, etc. Examples include non-reactive electrodes by physical adsorption of ions. Among these, in terms of input / output density of the power storage element, a substance capable of inserting or desorbing at least one of lithium and lithium ions is preferable, and in terms of cycle characteristics of the power storage element, a non-reactive electrode is used. More preferred.

  Specific examples of the negative electrode active material include carbonaceous materials, antimony tin oxide, metal oxides capable of inserting and extracting lithium such as silicon monoxide, and alloys such as lithium, such as aluminum, tin, silicon, and zinc. A metal that can be formed, an alloy containing the metal, a composite alloy compound of a metal that can be alloyed with lithium and an alloy containing the metal and lithium, lithium metal nitride such as cobalt lithium nitride, and the like. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, lithium titanate is particularly preferable because of the high input / output density of the power storage element.

  Examples of the carbonaceous material include coke, artificial graphite, natural graphite, soft carbon, hard carbon, and pyrolysis products of organic substances under various pyrolysis conditions. Among these, artificial graphite, natural graphite, soft carbon, or hard carbon is particularly preferable.

In the present embodiment, for example, when it is heat treated in an inert atmosphere, hard carbon is used in which the average spacing d ₀₀₂ of (002) plane to form a crystal structure of greater than 3.50 Å.

  Examples of the raw material for hard carbon include thermosetting resins such as phenol resin, melamine resin, urea resin, epoxy resin, and urethane resin, and carbon black such as acetylene black and furnace black.

[Binder]
The binder is not particularly limited as long as it is a material that is stable with respect to the solvent and non-aqueous electrolyte used in manufacturing the negative electrode, and can be appropriately selected according to the purpose. For example, polyvinylidene fluoride (PVDF ), Fluorine-based binders such as polytetrafluoroethylene (PTFE), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), isoprene rubber, carboxymethylcellulose (CMC), polyethylene glycol (PEO) and the like. It is done. These may be used alone or in combination of two or more.

[Conductive agent]
There is no restriction | limiting in particular as a electrically conductive agent, According to the objective, it can select suitably, For example, carbonaceous materials, such as metal materials, such as copper and aluminum, carbon black, and acetylene black, etc. are mentioned. These may be used alone or in combination of two or more.

[Negative electrode current collector]
There is no restriction | limiting in particular as a material, a shape, a magnitude | size, and a structure of a negative electrode collector, According to the objective, it can select suitably.

  The material of the negative electrode current collector is not particularly limited as long as it is a conductive material that is stable with respect to an applied potential, and can be appropriately selected according to the purpose. For example, stainless steel, nickel, aluminum, Examples include copper. Among these, stainless steel and copper are particularly preferable.

  There is no restriction | limiting in particular as a shape of a negative electrode electrical power collector, According to the objective, it can select suitably.

  The size of the negative electrode current collector is not particularly limited as long as it is a size that can be used for a power storage element, and can be appropriately selected according to the purpose.

<Method for producing negative electrode>
The negative electrode is coated with a negative electrode material layer coating solution, which is made into a slurry by adding a binder, a conductive agent, a solvent, and the like to the negative electrode active material, if necessary, and then dried. It can be produced by forming a material layer.

  As the solvent, a solvent similar to that of <Method for manufacturing positive electrode> can be used.

  Moreover, the composition for negative electrode material layers which added the binder, the electrically conductive agent, etc. to the negative electrode active material as needed can be roll-molded into a sheet electrode, or can be compressed into a pellet electrode. In addition, a thin film electrode of a negative electrode active material can be formed on the negative electrode current collector by a method such as vapor deposition, sputtering, or plating.

<Non-aqueous electrolyte>
In the nonaqueous electrolytic solution, an electrolyte salt is dissolved in a nonaqueous solvent.

[Nonaqueous solvent]
There is no restriction | limiting in particular as a non-aqueous solvent, Although it can select suitably according to the objective, An aprotic organic solvent is preferable.

  As the aprotic organic solvent, carbonate-based organic solvents such as cyclic carbonates and chain carbonates can be used.

  The aprotic organic solvent preferably contains a cyclic carbonate. Thereby, the solubility of electrolyte salt can be improved.

  Examples of the cyclic carbonate include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC). Among these, propylene carbonate (PC) is particularly preferable because of its high input / output density and discharge capacity of the electricity storage device.

  Examples of the chain carbonate include ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl propionate (MP). Among these, ethyl methyl carbonate (EMC) is particularly preferable.

  The content of the chain carbonate in the non-aqueous solvent can be appropriately selected according to the purpose, but is preferably 50% by mass or more, and more preferably 67% by mass or more. When the content of the chain carbonate in the non-aqueous solvent is 50% by mass or more, the discharge capacity of the electricity storage device can be improved, and the input / output density of the electricity storage device can be reduced by reducing the resistance of the non-aqueous electrolyte. Can be improved.

  As the aprotic organic solvent other than the chain carbonate and the cyclic carbonate, an ester organic solvent such as a cyclic ester and a chain ester, an ether organic solvent such as a cyclic ether and a chain ether, and the like are used as necessary. Can do.

  Examples of the cyclic ester include γ-butyrolactone (γBL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.

  Examples of the chain ester include propionic acid alkyl ester, malonic acid dialkyl ester, acetic acid alkyl ester (methyl acetate (MA), ethyl acetate, etc.), formic acid alkyl ester (methyl formate (MF), ethyl formate, etc.) and the like. It is done.

  Examples of the cyclic ether include tetrahydrofuran, alkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, 1,4-dioxolane and the like.

  Examples of the chain ether include 1,2-dimethoxyethane (DME), diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether.

[Electrolyte salt]
The electrolyte salt is not particularly limited as long as it is dissolved in a nonaqueous solvent and ionized cations exhibit high ionic conductivity.

  Examples of the cation constituting the electrolyte salt include alkali metal ions, alkaline earth metal ions, tetraalkylammonium ions, spiro quaternary ammonium ions, and the like.

Examples of the anion constituting the electrolyte salt include Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ). _{^{2N -, (C 2 F 5}} SO 2) 2N - , and the like.

  One electrolyte salt may be used alone, or two or more electrolyte salts may be used in combination. Among electrolyte salts, lithium salt is particularly preferable from the viewpoint of improving the initial capacity of the electricity storage device.

The lithium salt is not particularly limited and may be appropriately selected depending on the purpose. For example, lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium chloride (LiCl), borofluoride Lithium fluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF6), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide (LiN (C ₂ F ₅ SO ₂ ) ₂ ), lithium bis And furfluoroethylsulfonylimide (LiN (CF ₂ F ₅ SO ₂ ) ₂ ). These may be used individually by 1 type and may use 2 or more types together. Among these, LiPF ₆ or a combination of LiPF ₆ and LiBF ₄ is particularly preferable from the viewpoint of the amount of occlusion of anions in the carbonaceous material.

  The concentration of the electrolyte salt in the nonaqueous electrolytic solution is not particularly limited and can be appropriately selected according to the purpose, but is preferably 2 mol / L or more, and is 2 mol / L or more and 4 mol / L or less. Is more preferable. When the concentration of the electrolyte salt in the non-aqueous electrolyte is 2 mol / L or more, an electricity storage device with high charge / discharge efficiency is obtained, and when it is 4 mol / L or less, an electricity storage device with good large current charge / discharge characteristics is obtained.

[Derivatives of cycloalkane and / or cycloalkane]
The nonaqueous electrolytic solution contains cycloalkane and / or a derivative of cycloalkane. For this reason, even if charging / discharging is repeated, the discharge capacity of an electrical storage element does not fall easily.

The cycloalkane derivative of this embodiment has the general formula C _m H _2m-n X _n
(In the formula, X is a substituent, m is 3 to 10, and n is 0 to 20.)
It is a compound represented by these.

  X is not particularly limited, and examples thereof include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alkoxy group, an arylcarbonyl group, an oxocycloalkyl group, and a cyano group.

  Examples of the cycloalkane derivative of the present embodiment include a chemical formula

で表される１−フェニルシクロプロパンカルボニトリル、化学式

1-phenylcyclopropanecarbonitrile represented by the chemical formula

で表されるシクロプロピルアセチレン、化学式

Cyclopropylacetylene represented by the chemical formula

で表されるシクロブチルフェニルケトン、化学式

Cyclobutyl phenyl ketone represented by the chemical formula

で表される２−シクロペンチルシクロペンタノン、化学式

2-Cyclopentylcyclopentanone represented by the chemical formula

で表されるメトキシシクロペンタン、化学式

Methoxycyclopentane represented by the chemical formula

で表されるアリルシクロヘキサン、化学式

Allylcyclohexane represented by the chemical formula

で表されるシクロヘキシルベンゼン、化学式

Cyclohexylbenzene represented by the chemical formula

で表されるアミルシクロヘキサン等が挙げられる。

And amylcyclohexane represented by the formula:

  Examples of the cycloalkane of this embodiment include a chemical formula

で表されるシクロヘプタン、化学式

Cycloheptane represented by the chemical formula

で表されるシクロオクタン、化学式

Cyclooctane represented by the chemical formula

で表されるシクロデカン等が挙げられる。

The cyclodecane etc. which are represented by these are mentioned.

  When charging and discharging of the storage element are repeated, the cycloalkane and / or the cycloalkane derivative of the present embodiment is decomposed on the electrode before the non-aqueous electrolyte is decomposed to form a thin film. Thereby, decomposition | disassembly of a non-aqueous electrolyte is suppressed, generation | occurrence | production of the gas in an electrical storage element decreases, and the discharge capacity of an electrical storage element does not fall easily.

  The cycloalkane and / or cycloalkane derivative of the present embodiment is not particularly limited, but it is preferable to add it after dissolving the electrolyte salt in a non-aqueous solvent.

  The content of cycloalkane and / or cycloalkane derivative in the non-aqueous electrolyte is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 3.0% by mass. . When the content of the cycloalkane and / or cycloalkane derivative in the non-aqueous electrolyte solution is 0.1% by mass or more, when charging and discharging are repeated, the discharge capacity of the electricity storage device is further less likely to be reduced. By being 5.0 mass% or less, an excessive side reaction in an electrical storage element can be suppressed to the minimum.

<Other members>
There is no restriction | limiting in particular as another member, According to the objective, it can select suitably, For example, a separator, an armored can, a lead wire etc. are mentioned.

[Separator]
The separator is provided between the positive electrode and the negative electrode in order to prevent a short circuit between the positive electrode and the negative electrode.

  There is no restriction | limiting in particular as a material of a separator, a shape, a magnitude | size, and a structure, According to the objective, it can select suitably.

  Examples of the separator include paper such as kraft paper, vinylon mixed paper and synthetic pulp mixed paper, cellophane, polyethylene graft film, polyolefin nonwoven fabric such as polypropylene melt flow nonwoven fabric, polyamide nonwoven fabric, and glass fiber nonwoven fabric.

  Examples of the shape of the separator include a sheet shape.

  The size of the separator is not particularly limited as long as it is a size that can be used for a power storage element, and can be appropriately selected according to the purpose.

  The separator preferably has a porosity of 50% or more. Thereby, the retention amount of a non-aqueous electrolyte can be improved.

  The separator is preferably a nonwoven fabric rather than a thin film having micropores because of its high porosity.

  There is no restriction | limiting in particular in the average thickness of a separator, Although it can select suitably according to the objective, It is preferable that they are 20 micrometers or more and 100 micrometers or less. When the average thickness of the separator is 20 μm or more, the retention amount of the nonaqueous electrolyte can be improved, and when it is 100 μm or less, the input / output density of the electricity storage device can be improved.

  In this embodiment, a thin film having micropores with an average thickness of 30 μm or less is arranged on the negative electrode side, and a nonwoven fabric with an average thickness of 20 μm or more and 100 μm or less and a porosity of 50% or more is arranged on the positive electrode side. It is preferable to do. Thereby, the positive / negative short circuit by precipitation of the alkali metal in the negative electrode side and alkaline-earth metal can be prevented.

<Method for manufacturing power storage element>
The electrical storage element of this embodiment can be manufactured by assembling a positive electrode, a negative electrode, a nonaqueous electrolytic solution, and a separator into an appropriate shape, for example. When manufacturing an electrical storage element, an outer can etc. can further be used as needed.

  There is no restriction | limiting in particular as a method of assembling an electrical storage element, It can select suitably from the methods employ | adopted normally.

<Shape of power storage element>
There is no restriction | limiting in particular as a shape of the electrical storage element of this embodiment, According to the use, it can select suitably from the various shapes generally employ | adopted.

  Examples of the shape of the electricity storage element include a laminate type, a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a coin type in which a pellet electrode and a separator are stacked, and the like. It is done.

  In FIG. 1, an example of the electrical storage element of this embodiment is shown.

  In the electricity storage device 10, a positive electrode 11, a negative electrode 12, and a separator 13 are accommodated in an outer can 14, and the separator 13 is filled with a nonaqueous electrolyte. In addition, lead wires 15 and 16 are provided on the positive electrode 1 and the negative electrode 2, respectively.

<Applications of power storage elements>
There is no restriction | limiting in particular as a use of the electrical storage element of this embodiment, For example, it can use for various uses, For example, a notebook personal computer, pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a portable fax, a portable copy, a portable Printer, Headphone Stereo, Video Movie, LCD TV, Handy Cleaner, Portable CD, Mini Disc, Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Motor, Lighting Equipment, Toy, Game Equipment, Clock, Strobe, Examples include power supplies for cameras, electric bicycles, electric tools, and backup power supplies.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Preparation of positive electrode A>
After adding and kneading 10.0 g of graphite powder KS-6 (manufactured by TIMCAL) as a positive electrode active material and 0.75 g of acetylene black as a conductive agent, carboxymethylcellulose (CMC) as a thickener. ) Was added and kneaded. Subsequently, 0.75 g of binder TRD-202A (manufactured by JSR) was added and kneaded to prepare a positive electrode material layer slurry.

Here, graphite powder KS-6 (manufactured by TIMCAL) has a BET specific surface area of 20 m ² / g by nitrogen adsorption, and a median diameter measured by a laser diffraction particle size distribution analyzer SALD-2200 (manufactured by Shimadzu Corporation) is 3. .4 μm.

  Next, a positive electrode material layer slurry was applied on an aluminum foil as a positive electrode current collector, and then vacuum dried at 120 ° C. for 5 minutes to form a positive electrode material layer. The aluminum foil on which the positive electrode material layer was formed was punched into a coated part (76 mm × 83 mm) and a non-coated part (76 mm × 13 mm) to produce a positive electrode A.

<Preparation of negative electrode A>
Lithium titanate LTO (manufactured by Ishihara Sangyo Co., Ltd.) 10 g as a negative electrode active material and 0.5 g of acetylene black as a conductive agent were kneaded with water, and then carboxymethyl cellulose (CMC) as a thickener. 10 g of 2 mass% aqueous solution was added and kneaded. Subsequently, 0.6 g of a 50.2 mass% aqueous solution of binder EX-1215 (manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to prepare a slurry for the negative electrode material layer.

  Next, after applying a slurry for a negative electrode material layer on a copper foil as a negative electrode current collector, the negative electrode material layer was formed by vacuum drying at 120 ° C. for 5 minutes. The copper foil on which the negative electrode material layer was formed was punched into a coated part (80 mm × 89 mm) and a non-coated part (80 mm × 13 mm) to produce a negative electrode A.

<Preparation of non-aqueous electrolyte 1>
Content after dissolving LiPF ₆ and LiBF ₄ in a mixed solvent of 1: 1: 1 mass ratio of PC / DMC / EMC so that the concentration becomes 1.8 mol / L and 0.2 mol / L, respectively. 1-phenylcyclopropanecarbonitrile was added so that the amount of the nonaqueous electrolyte solution 1 was 20 g.

<Preparation of non-aqueous electrolytes 2 and 3>
20 g of non-aqueous electrolytes 2 and 3 were prepared in the same manner as non-aqueous electrolyte 1 except that the content of 1-phenylcyclopropanecarbonitrile was changed to 1.0% by mass and 5.0% by mass, respectively. did.

<Preparation of non-aqueous electrolytes 4-6>
20 g of nonaqueous electrolytic solutions 4 to 6 were prepared in the same manner as the nonaqueous electrolytic solutions 1 to 3, respectively, except that cyclopropylacetylene was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of non-aqueous electrolytes 7-9>
20 g of non-aqueous electrolytes 7 to 9 were prepared in the same manner as the non-aqueous electrolytes 1 to 3, respectively, except that cyclobutylphenyl ketone was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of non-aqueous electrolytes 10-12>
20 g of non-aqueous electrolytes 10 to 12 were prepared in the same manner as non-aqueous electrolytes 1 to 3, respectively, except that 2-cyclopentylcyclopentanone was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of nonaqueous electrolytic solutions 13-15>
20 g of nonaqueous electrolytes 13 to 15 were prepared in the same manner as nonaqueous electrolytes 1 to 3, respectively, except that methoxycyclopentane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of non-aqueous electrolytes 16-18>
20 g of nonaqueous electrolytes 16 to 18 were prepared in the same manner as nonaqueous electrolytes 1 to 3, respectively, except that allylcyclohexane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of nonaqueous electrolytic solutions 19 to 21>
20 g of nonaqueous electrolytes 19 to 21 were prepared in the same manner as nonaqueous electrolytes 1 to 3, respectively, except that cyclohexylbenzene was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of nonaqueous electrolyte solutions 22-24>
20 g of non-aqueous electrolytes 22 to 24 were prepared in the same manner as non-aqueous electrolytes 1 to 3, respectively, except that amylcyclohexane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of non-aqueous electrolyte 25-27>
20 g of non-aqueous electrolytes 25 to 27 were prepared in the same manner as non-aqueous electrolytes 1 to 3, respectively, except that cycloheptane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of nonaqueous electrolytic solution 28-30>
20 g of nonaqueous electrolytic solutions 28 to 30 were prepared in the same manner as nonaqueous electrolytic solutions 1 to 3, respectively, except that cyclooctane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of non-aqueous electrolytes 31-33>
20 g of non-aqueous electrolytes 31 to 33 were prepared in the same manner as non-aqueous electrolytes 1 to 3, respectively, except that cyclodecane was used instead of 1-phenylcyclopropanecarbonitrile.

<Preparation of nonaqueous electrolytic solution 34>
20 g of nonaqueous electrolyte solution 34 was prepared in the same manner as nonaqueous electrolyte solution 1 except that 1-phenylcyclopropanecarbonitrile was not added.

  Tables 1 and 2 show the configurations of the non-aqueous electrolytes 1 to 34.

＜実施例１＞
負極Ａと、平均厚みが２５μｍのセルロースからなるセパレータと、正極Ａとを、この順序で繰り返し積層して、電極群を作製した。このとき、３枚の正極Ａ、３枚のセパレータ及び４枚の負極Ａを用いて、負極Ａが最も外側に位置するようにした。得られた電極群を外装缶内に収容した。外装缶は、厚さが４０μｍのアルミニウム箔の両面に、厚さが０．１ｍｍのポリプロピレンからなるラミネートフィルムが形成されている。次に、外装缶内に非水電解液１を１０ｇ充填した後、ラミネートフィルムをシールし、蓄電素子を作製した。

<Example 1>
A negative electrode A, a separator made of cellulose having an average thickness of 25 μm, and a positive electrode A were repeatedly laminated in this order to produce an electrode group. At this time, using three positive electrodes A, three separators, and four negative electrodes A, the negative electrode A was positioned on the outermost side. The obtained electrode group was accommodated in an outer can. In the outer can, a laminate film made of polypropylene having a thickness of 0.1 mm is formed on both surfaces of an aluminum foil having a thickness of 40 μm. Next, 10 g of the non-aqueous electrolyte 1 was filled in the outer can, and then the laminate film was sealed to produce a power storage device.

<Examples 2-33>
A power storage device was produced in the same manner as in Example 1 except that the nonaqueous electrolytic solutions 2 to 33 were used instead of the nonaqueous electrolytic solution 1, respectively.

<Comparative Example 1>
A power storage device was produced in the same manner as in Example 1 except that the nonaqueous electrolytic solution 34 was used instead of the nonaqueous electrolytic solution 1.

<Charge / discharge cycle test>
A charge / discharge cycle in which a storage element is charged to 3.5 V in about 1 hour at room temperature (25 ° C.) using a charge / discharge evaluation apparatus TOSCAT3001 (manufactured by Toyo System Co., Ltd.) and then discharged to 1.7 V in about 1 hour. Was repeated 1000 cycles to carry out a charge / discharge cycle test.

<Discharge capacity>
In the charge / discharge cycle test, the discharge capacities of the electricity storage elements at the first and 1000th cycles were measured.

<Gas generation>
The volume of the electricity storage element was measured before and after the charge / discharge cycle test, and the amount of gas generated in the charge / discharge cycle test was determined. Specifically, the volume of the electricity storage element was measured by completely immersing the electricity storage element in a beaker of full water and measuring the volume of overflowing water.

  Table 3 shows the measurement results of the discharge capacity of the electricity storage element and the amount of gas generated.

表３から、実施例１〜３３の蓄電素子は、充放電サイクル試験後の放電容量の維持率が高く、ガスの発生量が少ないことがわかる。

From Table 3, it turns out that the electrical storage element of Examples 1-33 has a high maintenance rate of the discharge capacity after a charging / discharging cycle test, and there is little generation amount of gas.

  On the other hand, since the nonaqueous electrolytic solution 34 does not contain cycloalkane or a derivative thereof, the storage element of Comparative Example 1 has a low discharge capacity retention rate after the charge / discharge cycle test and a large amount of gas generation.

DESCRIPTION OF SYMBOLS 10 Power storage element 11 Positive electrode 12 Negative electrode 13 Separator 14 Outer can 15, 16 Lead wire

JP 2004-63367 A

Journal of The Electrochemical Society, 147 (3) 899-901 (2000)

Claims (11)

A positive electrode comprising a positive electrode active material capable of inserting or removing anions;
A negative electrode comprising a negative electrode active material capable of inserting or removing cations; and
A non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent,
The non-aqueous electrolyte includes a cycloalkane and / or a cycloalkane derivative.   2. The electricity storage device according to claim 1, wherein the non-aqueous electrolyte has a content of the cycloalkane and / or cycloalkane derivative of 0.1 to 5.0 mass%.   The electricity storage device according to claim 1, wherein the negative electrode active material is lithium titanate.   The storage element according to any one of claims 1 to 3, wherein a maximum initial charging voltage is 3.5 V or more.   The power storage element according to claim 1, wherein the non-aqueous solvent includes a cyclic carbonate.   The electrical storage element according to claim 5, wherein the cyclic carbonate contains propylene carbonate.   The electrical storage element in any one of Claim 1 to 6 in which the said electrolyte salt contains lithium salt.   The electricity storage device according to claim 7, wherein the lithium salt includes lithium hexafluorophosphate.   The electricity storage device according to claim 8, wherein the lithium salt further contains lithium tetrafluoroborate.   The electric storage element according to claim 1, wherein the nonaqueous electrolytic solution has a concentration of the electrolyte salt of 2 mol / L or more.   The electric storage element according to claim 1, wherein the positive electrode active material includes a carbonaceous material.

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