JP6967473B2 - Non-aqueous electrolyte storage element - Google Patents

Description

The present invention relates to a non-aqueous electrolyte storage device.

In recent years, with the miniaturization and high performance of mobile devices, the characteristics of non-aqueous electrolyte storage elements having high energy density have improved and become widespread. Development of a non-aqueous electrolyte storage element with a larger capacity and excellent safety is also underway, and installation in electric vehicles and the like has begun.

Under such circumstances, it is expected that a so-called dual intercalation type non-aqueous electrolyte storage element will be put into practical use as a storage element having a high energy density and suitable for high-speed charging / discharging. Since the dual intercalation type power storage element uses a carbonaceous material for the positive electrode, it can be operated stably without elution of elements from the positive electrode even under high voltage, but it is a charge / discharge cycle. As a result, there is a problem that a large amount of gas is generated. It is considered that this is because the electrolytic solution is decomposed at the interface between the electrode and the electrolytic solution.

In order to suppress such decomposition of the electrolytic solution, the development of an electrolytic solution having high oxidizing property in a high voltage region is being studied.

For example, in order to improve the oxidation resistance performance of the electrolytic solution, a secondary battery using dimethyl malonate as the electrolytic solution has been proposed in a lithium secondary battery system (see, for example, Patent Document 1).
Further, in order to improve the battery capacity, a dinitrile compound and an S = O group-containing compound are added to the electrolytic solution of a lithium secondary battery using a lithium cobalt oxide for the positive electrode, and lithium is operated at an upper limit voltage of 4.2 V. A non-aqueous electrolyte solution for a secondary battery has been proposed (see, for example, Patent Document 2).
Further, in order to improve the battery capacity and cycle characteristics, at least one of a cyclic sulfonic acid ester, a disulfonic acid ester, and a nitrile compound is contained in the electrolytic solution of a lithium secondary battery using a lithium cobalt oxide for the positive electrode. Further, in a battery system to which fluorinated ethylene carbonate is added, a non-aqueous electrolyte solution used for a high-voltage secondary battery operated at an upper limit voltage of 4.35 V has been proposed (see, for example, Patent Document 3).

Being able to operate at a higher voltage not only improves the energy density, but also reduces the number of series connections even when a large voltage is required, such as when applied to large machines. There are advantages. Further, considering the application to automobile applications, it is necessary not only to improve the energy density but also to improve the input / output characteristics. In order to improve the input / output characteristics, a secondary battery in which the element resistance is reduced by thinning the electrodes has been proposed (see, for example, Patent Document 4).

An object of the present invention is to provide a non-aqueous electrolyte storage element capable of suppressing gas generation without deteriorating the characteristics of the power storage element and improving input / output characteristics without deteriorating the energy density.

The non-aqueous electrolyte storage element of the present invention as a means for solving the above-mentioned problems includes a positive electrode containing a positive electrode active material into which an anion can be inserted and removed, a negative electrode containing a negative electrode active material, and a non-aqueous electrolytic solution. The non-aqueous electrolytic solution contains a dinitrile compound, and the content of the dinitrile compound is the above. It is 33% by mass or less with respect to the non-aqueous electrolytic solution.

According to the present invention, it is possible to provide a non-aqueous electrolyte storage element capable of suppressing gas generation without deteriorating the characteristics of the power storage element and improving input / output characteristics without deteriorating the energy density.

FIG. 1 is a schematic cross-sectional view showing an example of the non-aqueous electrolyte storage device of the present invention. FIG. 2 is a schematic diagram showing an example of a basic configuration of a three-dimensional network structure in a non-aqueous electrolyte storage element. FIG. 3 is a diagram showing cyclic voltammetry measurement results of the non-aqueous electrolyte storage element of Example 1 and Comparative Example 1.

(Non-water electrolyte storage element)
The non-aqueous electrolytic solution power storage element of the present invention has a positive electrode containing a positive electrode active material capable of inserting or removing anions, a negative electrode containing a negative electrode active material, a non-aqueous electrolytic solution, and between the positive electrode and the negative electrode. It has a separator which is arranged and holds the non-aqueous electrolytic solution, the non-aqueous electrolytic solution contains a dinitrile compound, and the content of the dinitrile compound is 33 mass with respect to the non-aqueous electrolytic solution. % Or less, and further have other members as needed.

In the conventional technique, the non-aqueous electrolyte storage element of the present invention uses a conventional positive electrode active material for a lithium secondary battery represented by a lithium cobalt oxide, and the positive electrode active material for a lithium secondary battery is used. It is based on the finding that when a dinitrile compound is added to the system prepared by using it, there is a problem that the capacity is lowered from the initial stage of charge / discharge and the cycle characteristics are remarkably lowered. It is considered that this is because the transition metal in the positive electrode active material and the dinitrile compound are reacting with each other. Therefore, it is based on the finding that the conventional technique is not yet satisfactory in terms of safety and long-term cycleability.

As a result of diligent studies to solve the above problems, the present inventors have used an electrolytic solution having high voltage resistance in a dual intercalation type non-aqueous electrolytic solution power storage element in a high voltage region. It was found that it is possible to provide a highly safe power storage element without deteriorating the battery characteristics due to the elution of the transition metal and generating gas due to the decomposition of the electrolytic solution.

Hereinafter, each component of the non-aqueous electrolyte storage element of the present invention will be described in detail.

<Positive electrode>
The positive electrode is not particularly limited as long as it contains a positive electrode storage material (positive electrode active material, etc.) and can be appropriately selected depending on the intended purpose. For example, a positive electrode material having a positive electrode active material on a positive electrode current collector can be selected. Examples include the provided positive electrode.
The shape of the positive electrode is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a flat plate shape.

-Positive material-
The positive electrode material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it contains at least a positive electrode active material, and further contains a conductive auxiliary agent, a binder, a thickener and the like, if necessary.

--Positive electrode active material ---
The positive electrode active material is not particularly limited as long as it is a substance capable of inserting or removing anions, and can be appropriately selected depending on the intended purpose. Examples thereof include carbon materials.

--- Carbon material ---
Examples of the carbon material include graphite (graphite) such as coke, artificial graphite, and natural graphite, and pyrolyzed products of organic substances under various pyrolysis conditions. Among these, it is preferable to use porous carbon having communicating pores (mesopores) having a three-dimensional network structure capable of suppressing expansion or contraction of the electrode cross section when anion is inserted or removed.
When the porous carbon has a three-dimensional network structure, ions can move smoothly and the surface area is expanded, so that high-speed charge / discharge characteristics can be improved.

The positive electrode active material having the mesopores of the three-dimensional network structure is charged by the presence of a pair of positive and negative electrolyte ions on both sides of the surface where the mesopores (cavities) and the carbon material portion are in contact with each other. It is a capacitor in which multiple layers are formed. Therefore, the movement of the electrolyte ions existing in pairs is faster than the movement of the generated electrolyte ions after the sequential chemical reaction with the polar active material, and the power supply capacity is the volume of the cavity. It is understood that it depends on the surface area of the mesopores in which positive and negative electrolyte ion pairs are present, as well as the size of.
The mesopores preferably form a three-dimensional network structure. If the mesopores have a three-dimensional network structure, ions move smoothly.
The mesopores are preferably open pores.
It is preferable that the open pores have a structure in which the pore portions are continuous. With the above configuration, the ions move smoothly.

The BET specific surface area of the carbon material, preferably at least ^{50 m} 2 / g, more preferably ^{50 m} 2 / g or more 2,000 m ² / g or less, more preferably 800 m ² / g or more 1,800 m ² / g or less.
When the BET specific surface area is 50 m ² / g or more, a sufficient amount of pores are formed and ions are sufficiently inserted, so that the capacity can be increased. Further, when the BET specific surface area is 2,000 m ² / g or less, mesopores are sufficiently formed and the insertion of ions is not hindered, so that the capacity can be increased.
The BET specific surface area can be obtained, for example, by using the BET (Brunauer, Emmett, Teller) method from the measurement results of the adsorption isotherm by an automatic specific surface area / pore distribution measuring device (TriStarII3020, manufactured by Shimadzu Corporation). can.

The pore volume of the carbon material is preferably 0.2 mL / g or more and 2.3 mL / g or less. When the pore volume is 0.2 mL / g or more, the mesopores rarely become independent pores, and a large discharge capacity can be obtained without inhibiting the movement of anions. On the other hand, when the pore volume of the carbon material is 2.3 mL / g or less, the carbon structure is not bulky, the energy density is increased as an electrode, and the discharge capacity per unit volume can be increased. Further, the carbonaceous wall forming the pores is not thinned, and the shape of the carbonaceous wall can be maintained even if the anion is repeatedly occluded and released, which is advantageous in that the charge / discharge characteristics are improved. ..
The pore volume of the carbon material is determined by using the BJH (Barrett, Joiner, Hallender) method from the measurement results of the adsorption isotherm by, for example, an automatic specific surface area / pore distribution measuring device (TriStarII3020, manufactured by Shimadzu Corporation). Can be asked.

As the carbon material, an appropriately manufactured one may be used, or a commercially available product may be used. Examples of the commercially available product include Knobel (registered trademark) (manufactured by Toyo Tanso Co., Ltd.).

--Binder and thickener ---
The binder and the thickener are not particularly limited as long as they are a solvent and an electrolytic solution used at the time of manufacturing the electrode and a material stable to the applied potential, and can be appropriately selected depending on the intended purpose, for example. Fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), isoprene rubber, acrylate-based latex, carboxymethyl cellulose (CMC) , Methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyacrylic acid, polyvinyl alcohol, alginic acid, oxidized starch, phosphate starch, casein and the like. These may be used alone or in combination of two or more. Among these, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), acrylate-based latex, and carboxymethyl cellulose (CMC) are preferable.

--Conductive aid ---
Examples of the conductive auxiliary agent include metal materials such as copper and aluminum, carbon materials such as carbon black, acetylene black, and carbon nanotubes. These may be used alone or in combination of two or more.

-Positive current collector-
The material, shape, size, and structure of the positive electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
The material of the positive electrode current collector is formed of a conductive material, and is not particularly limited as long as it is stable with respect to the applied potential, and can be appropriately selected depending on the intended purpose, for example. Examples include stainless steel, nickel, aluminum, titanium and tantalum. Among these, stainless steel and aluminum are preferable.
The shape of the positive electrode current collector is not particularly limited and may be appropriately selected depending on the intended purpose.
The size of the positive electrode current collector is not particularly limited as long as it can be used for a non-aqueous electrolyte storage element, and can be appropriately selected depending on the intended purpose.

<Method of manufacturing positive electrode>
For the positive electrode, a positive electrode material made into a slurry by adding the binder, the thickener, the conductive auxiliary agent, a solvent, etc. to the positive electrode active material, if necessary, is applied onto the positive electrode current collector. It can be manufactured by drying. The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an aqueous solvent and an organic solvent. Examples of the aqueous solvent include water, alcohol and the like. Examples of the organic solvent include N-methyl-2-pyrrolidone (NMP) and toluene.
The positive electrode active material may be roll-molded as it is to be a sheet electrode, or may be compression-molded to be a pellet electrode.

<Negative electrode>
The negative electrode is not particularly limited as long as it contains a negative electrode storage material (negative electrode active material, etc.) and can be appropriately selected depending on the intended purpose. For example, a negative electrode material having a negative electrode active material on a negative electrode current collector can be selected. The negative electrode provided, and the like can be mentioned.
The shape of the negative electrode is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a flat plate shape.

-Negative electrode material-
The negative electrode material contains at least a negative electrode active material, and further contains a conductive auxiliary agent, a binder, a thickener, and the like, if necessary.

-Negative electrode active material-
The negative electrode active material is not particularly limited as long as it can occlude and release cations in a non-aqueous solvent system, and can be appropriately selected depending on the intended purpose. For example, lithium ions as cations can be occluded and released. Examples thereof include carbon materials, metal oxides, metals or metal alloys that can be alloyed with lithium, composite alloy compounds of alloys containing lithium and metals that can be alloyed with lithium and lithium, and lithium nitride.

The carbon material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include graphite and thermally decomposed organic substances under various thermal decomposition conditions.
Examples of the graphite include coke, artificial graphite, and natural graphite. Among these, artificial graphite and natural graphite are preferable.
Examples of the metal oxide include antimony oxide, silicon monoxide and the like.
Examples of the metal or metal alloy include lithium, aluminum, tin, silicon, zinc and the like.
Examples of the composite alloy compound with lithium include lithium titanate and the like.
Examples of the lithium metal chloride include lithium cobalt oxide and the like.
As the negative electrode active material, one type may be used alone, or two or more types may be used in combination. Among these, at least one of a carbon material and lithium titanate is preferable from the viewpoint of safety and cost.

--Binder and thickener ---
The binder and the thickener are not particularly limited as long as they are a solvent and an electrolytic solution used at the time of manufacturing the electrode and a material stable to the applied potential, and can be appropriately selected depending on the intended purpose, for example. Fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), isoprene rubber, acrylate-based latex, carboxymethyl cellulose (CMC) , Methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyacrylic acid, polyvinyl alcohol, alginic acid, oxidized starch, phosphate starch, casein and the like. These may be used alone or in combination of two or more. Among these, fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) are preferable.

--Conductive aid ---
Examples of the conductive auxiliary agent include metal materials such as copper and aluminum, carbon materials such as carbon black, acetylene black, and carbon nanotubes. These may be used alone or in combination of two or more.

-Negative electrode current collector-
The material, shape, size, and structure of the negative electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
The material of the negative electrode current collector is formed of a conductive material, and is not particularly limited as long as it is stable with respect to the applied potential, and can be appropriately selected depending on the intended purpose. For example, stainless steel. Examples include steel, nickel, aluminum and copper. Among these, stainless steel, copper and aluminum are preferable.
The shape of the negative electrode current collector is not particularly limited and may be appropriately selected depending on the intended purpose.
The size of the negative electrode current collector is not particularly limited as long as it can be used for a non-aqueous electrolyte storage element, and can be appropriately selected depending on the intended purpose.

<Method of manufacturing negative electrode>
For the negative electrode, a negative electrode material formed into a slurry by adding the binder, a thickener, a conductive auxiliary agent, a solvent, etc. to the negative electrode active material, if necessary, is applied onto the negative electrode current collector. It can be manufactured by drying. As the solvent, the same solvent as in the method for producing the positive electrode can be used.
Further, the negative electrode active material to which the binder, the thickener, the conductive auxiliary agent, etc. are added is directly rolled to form a sheet electrode, or a pellet electrode is formed by compression molding, and methods such as vapor deposition, sputtering, and plating are performed. It is also possible to form a thin film of the negative electrode active material on the negative electrode current collector.

<Non-water electrolyte>
The non-aqueous electrolytic solution contains a dinitrile compound, preferably contains an electrolyte salt in a non-aqueous solvent, and further contains other components, if necessary.

-Dinitrile compound-
Examples of the dinitrile compound include succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanooctane, and 1,9-. Dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaro Nitrile, 1,4-dicyanopentane, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane And so on. These may be used alone or in combination of two or more. Among these, the dinitrile compound may be aromatic, and glutaronitrile, adiponitrile, and 2-methylglutaronitrile are preferable from the viewpoint of high voltage resistance and cycleability.

The content of the dinitrile compound is 33% by mass or less, particularly preferably 1% by mass or less, based on the non-aqueous electrolytic solution. When the content is 33% by mass or less, gas generation can be suppressed without deteriorating the characteristics of the power storage element. When the content is 1% by mass or less, gas generation can be suppressed without deteriorating the characteristics of the power storage element even in a high voltage region.

-Non-aqueous solvent-
The non-aqueous solvent is not particularly limited and may be appropriately selected depending on the intended purpose, but an aprotic organic solvent is preferable.
As the aprotic organic solvent, a carbonate-based organic solvent such as a chain carbonate or a cyclic carbonate is used, and a solvent having a low viscosity is preferable. Among these, chain carbonate is preferable because it has a high dissolving power of the electrolyte salt.

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

Examples of the cyclic carbonate include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), vinylene carbonate (VC), fluoroethylene carbonate (FEC) and the like.

When a mixed solvent in which ethylene carbonate (EC) is used as the cyclic carbonate and dimethyl carbonate (DMC) is used as the chain carbonate, the mixing ratio of ethylene carbonate (EC) and dimethyl carbonate (DMC) is particularly high. There are no restrictions, and it can be selected as appropriate according to the purpose.

As the non-aqueous solvent, an ester-based organic solvent such as a cyclic ester or a chain ester, an ether-based organic solvent such as a cyclic ether or a chain ether, or the like can be used, if necessary.
Examples of the cyclic ester include γ-butyrolactone (γ-BL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, γ-valerolactone and the like.
Examples of the chain ester include propionic acid alkyl ester, malonic acid dialkyl ester, acetate alkyl ester (methyl acetate (MA), ethyl acetate, etc.), formic acid alkyl ester (methyl formate (MF), ethyl formate, etc.) and the like. Can be mentioned.
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-dimethoschiietan (DME), diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, tetraethylene glycol dialkyl ether and the like.

-Electrolyte salt-
As the electrolyte salt, it is preferable to use a lithium salt.
The lithium salt is not particularly limited as long as it is soluble in a non-aqueous solvent and exhibits high ionic conductivity, and can be appropriately selected depending on the intended purpose. For example, lithium hexafluorophosphate (LiPF ₆ ). , Lithium perchlorate (LiClO ₄ ), lithium chloride (LiCl), lithium borofluoride (LiBF ₄ ), lithium hexafluorophosphate (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoro Examples thereof include methyl sulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ) and lithium bispentafluoroethyl sulfonylimide (LiN (C ₂ F ₅ SO ₂ ) ₂ ). These may be used alone or in combination of two or more. Among these, at least one of _{LiPF 6} and LiBF ₄ is preferable from the viewpoint of the amount of anion occluded in the carbon electrode.

The concentration of the electrolyte salt is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.5 mol / L or more and 6 mol / L or less in the non-aqueous solvent, and the capacity and output of the power storage element. From the viewpoint of compatibility between the above, 2 mol / L or more and 4 mol / L or less are more preferable.

<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.
The material, shape, size, and structure of the separator are not particularly limited and may be appropriately selected depending on the intended purpose.
Examples of the material of the separator include kraft paper, vinylon mixed paper, synthetic pulp mixed paper and other papers, cellophane, polyethylene graft film, polypropylene melt blown non-woven fabric and other polyolefin non-woven fabrics, polyamide non-woven fabrics, glass fiber non-woven fabrics, micropore films and the like. Can be mentioned. Among these, those having a porosity of 50% or more are preferable from the viewpoint of retaining the electrolytic solution.
As the shape of the separator, a non-woven fabric having a high porosity is preferable to a thin film type having micropores.
The average thickness of the separator is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 μm or more, and more preferably 20 μm or more and 100 μm or less. If the average thickness is less than 20 μm, the holding amount of the electrolytic solution may be small.
The size of the separator is not particularly limited as long as it can be used for a non-aqueous electrolyte storage element, and can be appropriately selected depending on the intended purpose.
The structure of the separator may be a single-layer structure or a laminated structure.

<Manufacturing method of non-aqueous electrolyte power storage element>
The non-aqueous electrolytic solution power storage element of the present invention is manufactured by assembling the positive electrode, the negative electrode, the non-aqueous electrolytic solution, and the separator into an appropriate shape. Further, if necessary, other components such as an outer can can be used. The method for assembling the non-aqueous electrolytic solution power storage element is not particularly limited, and can be appropriately selected from the commonly adopted methods.

The shape of the non-aqueous electrolyte storage element of the present invention is not particularly limited, and can be appropriately selected from various generally adopted shapes according to the intended use. Examples of the shape include a cylinder type in which a sheet electrode and a separator are spirally formed, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, and a coin type in which a pellet electrode and a separator are laminated.

Here, an embodiment of the present invention will be described with reference to the drawings.
An outline of the configuration of the non-aqueous electrolytic solution power storage element 10 of the present invention will be described with reference to FIG. The non-aqueous electrolyte storage element 10 shown in FIG. 1 includes a positive electrode 11, a negative electrode 12, a separator 13 holding a non-aqueous electrolytic solution, an outer can 14, a positive electrode lead wire 15, and a negative electrode lead wire 16. And have other members as needed. Specific examples of the non-aqueous electrolyte storage element 10 include a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte capacitor, and the like.

FIG. 2 is a schematic diagram showing an example of a basic configuration of a three-dimensional network structure in a non-aqueous electrolyte storage element.
The positive electrode 11 is, for example, conductive between a positive electrode current collector 20 made of aluminum, carbon 21 as a positive electrode active material fixed on the positive electrode current collector 20, a binder 22 that holds the carbons 21 together, and carbon 21. It has a conductive auxiliary agent 23 and the like indicated by a black circle to give a pass.
The negative electrode 12 includes, for example, a negative electrode current collector 24 made of copper, a negative electrode active material 25 made of a carbon material fixed on the negative electrode current collector 24, a binder 22 for connecting the negative electrode active materials 25 to each other, and a negative electrode activity. It has a conductive auxiliary agent 23 and the like indicated by a black circle that imparts a conductive path between the substances 25.
A separator 13 is arranged between the positive electrode 11 and the negative electrode 12, and a non-aqueous electrolytic solution 26 is arranged. Reference numeral 27 indicates an ion. Charging and discharging are performed by inserting and removing ions between the carbon layers.
In the charge / discharge reaction of the dual intercalation type non-aqueous electrolyte storage element, for example, when LiPF _{6 is used as the electrolyte, PF 6} ⁻ is inserted into the positive electrode from the non-aqueous electrolyte solution ^{and Li +} is inserted into the negative electrode. Is inserted to charge, and PF ₆ ⁻ is desorbed from the positive electrode and Li ⁺ is desorbed from the negative electrode to the non-aqueous electrolyte solution to discharge.

<Use>
The non-aqueous electrolyte storage element of the present invention is not particularly limited and can be used for various purposes. For example, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a mobile fax, and a portable device. Copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini disk, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, motor, lighting equipment, toys, game equipment, clock , Power sources for strobes, cameras, electric bicycles, electric tools, etc., backup power sources, etc.

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

(Example 1)
<Manufacturing of positive electrode>
Porous carbon (Knobel (registered trademark), manufactured by Toyo Carbon Co., Ltd.) is used as the positive electrode active material, acetylene black (Denka Black powder, manufactured by Denka Co., Ltd.) as the conductive auxiliary agent, and carboxymethyl cellulose (Daicel 2200) as the thickener. , Made by Daicel Corporation), and acrylate-based latex (TRD202A, manufactured by JSR Corporation) as a binder so that the mass ratio of solid content is 85.0: 6.2: 6.3: 2.5, respectively. The slurry mixed and adjusted to an appropriate viscosity by adding water was applied to one side of an aluminum foil having a thickness of 20 μm using a doctor blade.
The average basis weight (mass of carbon active material powder in the coated positive electrode) after drying was 3 mg / cm ² . This was punched to a diameter of 16 mm to obtain a positive electrode.
The porous carbon (Knobel, manufactured by Toyo Tanso Co., Ltd.) has a plurality of pores forming a three-dimensional network structure, has a BET specific surface area of 1,730 m ² / g, and a pore volume of 2.27 mL / g. Is.

<Manufacturing of negative electrode>
Artificial graphite (MAGD, manufactured by Hitachi Kasei Kogyo Co., Ltd.) is used as the negative electrode active material, acetylene black (Denka Black powder, manufactured by Denka Co., Ltd.) as the conductive auxiliary agent, and styrene-butadiene rubber (SBR) -based (EX1215) as the binder. Denka Co., Ltd.) and carboxymethyl cellulose (Daicel 2200, manufactured by Daicel Co., Ltd.) as a thickener so that the mass ratio of solid content is 90.9: 4.5: 2.7: 1.8, respectively. The slurry, which was mixed with water and adjusted to an appropriate viscosity by adding water, was applied to one side of a copper foil having a thickness of 18 μm using a doctor blade.
The average basis weight (mass of carbon active material powder in the coated positive electrode) after drying was 10 mg / cm ² . This was punched to a diameter of 16 mm to obtain a negative electrode.

<Separator>
As the separator, two sheets of glass filter paper (GA100, manufactured by ADVANTEC) punched out to a diameter of 16 mm were prepared.

<Non-water electrolyte>
As the non-aqueous electrolyte, a volume ratio of ethylene carbonate (EC) and methylethyl carbonate (EMC) 1: using a mixed solvent of 3, was prepared LiBF ₄ solution 2 mol / L. 2-Methylglutaronitrile was added to the prepared LiBF ₄ solution to a concentration of 33% by mass to prepare a non-aqueous electrolytic solution.

<Manufacturing of non-aqueous electrolyte storage element>
After vacuum-drying the positive electrode, the negative electrode, and the separator at 150 ° C. for 4 hours, a 2032 type coin cell was assembled in a dry argon glove box to obtain a non-aqueous electrolyte storage element.

Using the obtained non-aqueous electrolyte storage device, "cyclic voltammetry (CV)" was measured as follows.

<Cyclic voltammetry (CV) evaluation>
Cyclic voltammetry (CV) swept to 5.5 V at 23 ° C. was measured using an electrochemical analyzer ALS660C (manufactured by BAS (Bioanalytic Systems)) and a spectroscope USB4000 (manufactured by Ocean Optics).

(Comparative Example 1)
In Example 1, a non-aqueous electrolyte storage device was obtained in the same manner as in Example 1 except that 2-methylglutaronitrile was not added to _{the LiBF 4 solution.}
Using the obtained non-aqueous electrolyte storage device, "cyclic voltammetry (CV)" was measured in the same manner as in Example 1.

The results of cyclic voltammetry (CV) measurement for Example 1 and Comparative Example 1 are shown in FIG.

As shown in FIG. 3, in the non-aqueous electrolyte storage device of Comparative Example 1 to which the dinitrile compound is not added, the current value starts to increase from around 5.0 V, and the electrolyte is decomposed from around this voltage. You can see that. On the other hand, in the non-aqueous electrolyte storage device of Example 1 to which the dinitrile compound was added, the increase in the current value did not occur up to around 5.3 V, and it can be seen that the withstand voltage resistance was improved. The reason for this may be the influence of the high oxidation potential of the dinitrile compound. The dinitrile compound has a significantly higher oxidation potential than the cyclic carbonates and chain carbonates which are electrolyte solvent molecules. Further, since the nitrile group has an extremely high electron attracting property, the dinitrile compound having two nitrile groups has a structure in which it is extremely difficult to separate electrons. Therefore, it is considered that the addition of the dinitrile compound to the carbonic acid esters improved the oxidation potential of the entire electrolyte, and as shown in FIG. 3, the withstand voltage resistance was improved.
From this result, by adding a nitrile compound to the dual intercalation type non-aqueous electrolyte storage element, the lithium secondary battery can be charged and discharged without decomposition of the electrolyte and elution of the positive electrode active material at high voltage. Can be found to be obtained.

(Example 2)
A non-aqueous electrolytic solution power storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed to 1% by mass in Example 1. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured as follows.

<Measurement of capacity and discharge capacity retention rate>
An automatic battery evaluation device of 1024B-7V0.1A-4 (manufactured by Electrofield) was used for the charge / discharge test.
The obtained non-aqueous electrolyte storage element was charged to 4.4 V at a rate of 10 C at 23 ° C., then paused for 5 minutes, and the operation of discharging to 2.0 V was repeated 200 times. The discharge capacity at the 10th time was used as a capacity value (“capacity”), and the “discharge capacity retention rate” at the 200th time with respect to the initial capacity was calculated.

<Measurement of gas generation>
The obtained non-aqueous electrolyte storage element is charged to 4.4 V at a rate of 10 C at 23 ° C. using a cell for measuring discharge gas pressure (device name: ECC-Press-DL, manufactured by EL-CELL). Then, after resting for 5 minutes and repeating the operation of discharging to 2.0 V 200 times, the pressure converted into volume was measured as the amount of gas generated.

(Example 3)
A non-aqueous electrolytic solution power storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed to 5% by mass in Example 1. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Example 4)
In Example 1, a non-aqueous electrolytic solution power storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 10% by mass. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Example 5)
In Example 1, a non-aqueous electrolyte storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 20% by mass. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Example 6)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 1. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Example 7)
In Example 1, a non-aqueous electrolyte storage element was obtained in the same manner as in Example 1 except that 2-methylglutaronitrile having an added concentration of 33% by mass was changed to glutaronitrile having an added concentration of 10% by mass. rice field. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Example 8)
In Example 1, a non-aqueous electrolyte storage element was obtained in the same manner as in Example 1 except that 2-methylglutaronitrile having an added concentration of 33% by mass was changed to adiponitrile having an added concentration of 10% by mass. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Comparative Example 2)
A non-aqueous electrolyte storage element was obtained in the same manner as in Comparative Example 1. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Comparative Example 3)
In Example 1, a non-aqueous electrolyte storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 50% by mass. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

(Comparative Example 4)
In Example 1, a non-aqueous electrolyte storage device was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 34% by mass. Next, the "capacity", the "discharge capacity retention rate", and the "gas generation amount" were measured in the same manner as in Example 2.

The results of "capacity", "discharge capacity retention rate", and "gas generation amount" in Examples 2 to 8 and Comparative Examples 2 to 4 are shown in Table 1 below.

As shown in Table 1, it can be seen that Examples 2 to 8 significantly reduce the amount of gas generated as compared with Comparative Example 2. This result indicates that the addition of the dinitrile compound suppressed the decomposition of the electrolytic solution in the high voltage region. Further, when the volume was confirmed, the same volume as that of Comparative Example 2 in which the dinitrile compound was not added was obtained. Further, when the discharge capacity retention rate is confirmed, it can be seen that although a slight decrease is observed in Example 6, the retention rate is 60% or more even in the 200th cycle of 10C charge / discharge. These results indicate that the addition of a predetermined amount of the dinitrile compound does not interfere with the charge / discharge process.
On the other hand, in Comparative Example 3 in which 50% by mass of the dinitrile compound was added and Comparative Example 4 in which 34% by mass was added, a decrease in the capacity retention rate was observed. It is considered that this is because the addition of a certain amount or more of the dinitrile compound to the electrolytic solution inhibited the intercalation of the anion between the positive electrode layers or the cation of lithium to the negative electrode. Be done.
Further, in Examples 7 and 8 in which glutaronitrile or adiponitrile was used as the type of the dinitrile compound, a significant decrease in the amount of gas generated was also observed. Therefore, the addition of the dinitrile compound resulted in a significant decrease in the amount of gas generated. It can be seen that the withstand voltage resistance of the compound is improved and the decomposition reaction can be suppressed.

(Example 9)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 2.

(Example 10)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 6.

(Comparative Example 5)
A non-aqueous electrolyte storage element was obtained in the same manner as in Comparative Example 2.

Using the obtained non-aqueous electrolyte storage element, the "rate characteristics" were evaluated as follows.

<Rate characteristics>
The prepared non-aqueous electrolyte storage element was charged to 4.4 V at a rate of 1 C at 23 ° C., then paused for 5 minutes, and the operation of discharging to 2.0 V was repeated 20 times. Next, the operation of charging to 4.4 V at a 5 C rate, resting for 5 minutes, and discharging to 2.0 V was repeated 50 times. Further, the operation of charging to 4.4 V at a 10 C rate, resting for 5 minutes, and discharging to 2.0 V was repeated 100 times. The discharge capacity at the 10th discharge at each rate was used as the capacity value, and the appearance rate of the capacity at the 10C rate with respect to the capacity at the 1C rate was calculated as the "rate characteristic". The results are shown in Table 2 below.

From the results in Table 2 above, Examples 9 and 10 to which the dinitrile compound was added showed the same capacity at each charge / discharge rate as compared with Comparative Example 5 which was a non-added system, and the rate characteristics were changed. The comparison was about the same. From this, the addition of the dinitrile compound does not cause a reaction to form a decomposition product that increases the battery resistance, and it is possible to suppress the decomposition of the electrolytic solution while maintaining the low resistance of the battery. Became clear.

(Example 11)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 1.

(Example 12)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 4.

(Example 13)
A non-aqueous electrolyte storage element was obtained in the same manner as in Example 2.

(Example 14)
In Example 1, a non-aqueous electrolytic solution power storage element was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 0.5% by mass.

(Example 15)
In Example 1, a non-aqueous electrolytic solution power storage element was obtained in the same manner as in Example 1 except that the addition concentration of 2-methylglutaronitrile was changed from 33% by mass to 0.2% by mass.

(Comparative Example 6)
A non-aqueous electrolyte storage element was obtained in the same manner as in Comparative Example 2.

(Comparative Example 7)
A non-aqueous electrolyte storage element was obtained in the same manner as in Comparative Example 3.

<Measurement of capacity, discharge capacity retention rate and gas generation amount in high voltage region>
Using the manufactured power storage element, the "capacity", "discharge capacity retention rate", and "gas generation amount" were measured in the same manner as in Example 2 except that the upper limit voltage was set to 4.5V. The results are shown in Table 3.

<Measurement of input / output characteristics>
The prepared power storage element was charged to 4.5 V at a rate of 0.2 C at 23 ° C., then paused for 5 minutes, and the operation of discharging to 2.0 V was repeated 10 times. Next, the operation of charging to 4.5 V at a 1 C rate, resting for 5 minutes, and discharging to 2.0 V was repeated 20 times. The resistance of the charged / discharged laminated cell was measured using the AC four-terminal method of 1 kHz, and this value was evaluated as "input / output characteristics". Since the resistance value is small, it is possible to suppress the decrease in input / output. The results are shown in Table 3.

表３の結果から、上限電圧を４．４Ｖから４．５Ｖに上げることで、いずれの蓄電素子系においても、容量の向上がみられる。しかし、ジニトリル化合物を添加していない比較例６では、容量は向上しているものの、ガス発生量が非常に多いことに加えて、放電容量維持率が非常に低い。これは、４．５Ｖという高電圧領域では電解液の分解が促進されてしまうことを示しており、高電圧では電池としての特性を著しく損なってしまうことがわかった。
一方で、ジニトリル化合物を添加した実施例１１から１５では、いずれにおいてもガス発生量が抑制されている。これは、ジニトリル化合物が電解液構成成分である炭酸エステル類と相互作用することで酸化電位が向上し、耐電圧性が向上したためと考えられる。特に１質量％以下で添加した実施例１３から１５では、特に高い放電容量維持率を維持しながらも、ガス発生量が抑制されている。
一方、ジニトリル化合物を５０質量％添加した比較例７では、容量維持率の低下が見られる。これは、上限電圧４．４Ｖで使用した比較例３と同様に、電解液中に一定量以上のジニトリル化合物を添加することにより、アニオンの正極層間へのインターカレート、又はカチオンであるリチウムの負極へのインターカレートが阻害されたことによるものと考えられる。
上限電圧４．５Ｖの高電圧領域においても、ジニトリル化合物を３３質量％以下添加することで、電池特性を損なうことなく、ガス発生量を抑制することが可能になる。

From the results in Table 3, by increasing the upper limit voltage from 4.4V to 4.5V, the capacity is improved in any of the power storage element systems. However, in Comparative Example 6 to which the dinitrile compound is not added, although the capacity is improved, the amount of gas generated is very large and the discharge capacity retention rate is very low. This indicates that the decomposition of the electrolytic solution is promoted in the high voltage region of 4.5 V, and it was found that the characteristics of the battery are significantly impaired at the high voltage.
On the other hand, in Examples 11 to 15 to which the dinitrile compound was added, the amount of gas generated was suppressed in each of the examples. It is considered that this is because the dinitrile compound interacts with carbonic acid esters, which are constituents of the electrolytic solution, to improve the oxidation potential and the withstand voltage. In particular, in Examples 13 to 15 added in an amount of 1% by mass or less, the amount of gas generated is suppressed while maintaining a particularly high discharge capacity retention rate.
On the other hand, in Comparative Example 7 in which 50% by mass of the dinitrile compound was added, a decrease in the capacity retention rate was observed. This is the same as in Comparative Example 3 used at the upper limit voltage of 4.4 V. By adding a certain amount or more of the dinitrile compound to the electrolytic solution, the anion can be intercalated between the positive electrode layers or the cation lithium can be used. It is considered that this was due to the inhibition of intercalation to the negative electrode.
Even in the high voltage region of the upper limit voltage of 4.5 V, by adding 33% by mass or less of the dinitrile compound, it is possible to suppress the amount of gas generated without impairing the battery characteristics.

(Example 16)
<Making laminated cells>
An aluminum positive electrode terminal was attached to the positive electrode according to Example 1, and a nickel negative electrode terminal was attached to the negative electrode by ultrasonic welding. The positive electrode and the negative electrode to which each terminal was attached were laminated via a cellulose separator and vacuum dried at 150 ° C. for 4 hours. This laminate was enclosed in an aluminum laminate in a dry argon glove box. Next, the electrolytic solution prepared in the same manner as in Example 1 was injected, and the aluminum laminate was heat-sealed under reduced pressure to obtain a laminated cell.

(Example 17)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Example 4 was used.

(Example 18)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Example 2 was used.

(Example 19)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Example 14 was used.

(Example 20)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Example 15 was used.

(Comparative Example 8)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Comparative Example 2 was used.

(Comparative Example 9)
In Example 16, a laminated cell was produced in the same manner as in Example 16 except that the same electrolytic solution as in Comparative Example 3 was used.

<Measurement of input / output characteristics>
The prepared laminated cell was charged at 23 ° C. at a rate of 0.2 C to 4.5 V, then paused for 5 minutes, and the operation of discharging to 2.0 V was repeated 10 times. Next, the operation of charging to 4.5 V at a 1 C rate, resting for 5 minutes, and discharging to 2.0 V was repeated 20 times. The resistance of the charged / discharged laminated cell was measured using the AC four-terminal method of 1 kHz, and this value was evaluated as "input / output characteristics". Since the resistance value is small, it is possible to suppress the decrease in input / output. The results are shown in Table 4.

表４の結果から、ジニトリル化合物を添加した実施例１６から２０は、未添加の系である比較例８と比較して、入出力特性として記載した抵抗値が低下していることがわかった。特に添加量が少ない実施例１８、１９及び２０では、著しく低下していることが分かった。この理由として、少量のジニトリル化合物の添加により、電解液中に存在するジニトリル化合物がアニオン及びカチオンの移動を阻害することなく、電解液の分解が抑制されたことで、充放電に伴う被膜の形成が緩和され、ジニトリル化合物を未添加の系よりもより緻密で薄い被膜となり、蓄電素子としての抵抗が低下したものと考えられる。
高電圧領域でのガス発生量抑制効果、放電容量維持率及び入出力特性の結果を鑑みると、ジニトリル化合物の添加量は、１質量％以下が特に好ましい。

From the results in Table 4, it was found that Examples 16 to 20 to which the dinitrile compound was added had a lower resistance value described as input / output characteristics as compared with Comparative Example 8 which was a non-added system. In particular, in Examples 18, 19 and 20 in which the addition amount was small, it was found that the amount was significantly reduced. The reason for this is that by adding a small amount of the dinitrile compound, the dinitrile compound present in the electrolytic solution does not inhibit the movement of anions and cations, and the decomposition of the electrolytic solution is suppressed, so that a film is formed due to charging and discharging. It is considered that the film was more dense and thinner than the system without the addition of the dinitrile compound, and the resistance as a power storage element was reduced.
Considering the effect of suppressing the amount of gas generated in the high voltage region, the discharge capacity retention rate, and the results of the input / output characteristics, the amount of the dinitrile compound added is particularly preferably 1% by mass or less.

From the above results, in the dual intercalation type non-aqueous electrolyte storage element, by using the electrolytic solution having high voltage resistance, the battery characteristics are deteriorated due to the elution of the transition metal even when used in the high voltage region. It was found that a highly safe power storage element can be provided without causing gas generation due to electrolyte decomposition.

Aspects of the present invention are, for example, as follows.
<1> A positive electrode containing a positive electrode active material into which an anion can be inserted or removed, a negative electrode containing a negative electrode active material, a non-aqueous electrolytic solution, and the non-aqueous electrolytic solution arranged between the positive electrode and the negative electrode. Has a separator, and has
The non-aqueous electrolytic solution contains a dinitrile compound and contains
The non-aqueous electrolytic solution power storage element is characterized in that the content of the dinitrile compound is 33% by mass or less with respect to the non-aqueous electrolytic solution.
<2> The non-aqueous electrolytic solution power storage element according to <1>, wherein the content of the dinitrile compound is 1% by mass or less with respect to the non-aqueous electrolytic solution.
<3> The non-aqueous electrolyte storage device according to any one of <1> to <2>, wherein the dinitrile compound is 2-methylglutaronitonyl.
<4> The positive electrode active material contains a carbon material, and the positive electrode active material contains a carbon material.
Any of the above <1> to <3> in which the BET specific surface area of the carbon material is 50 m ² / g or more and the pore volume of the carbon material is 0.2 mL / g or more and 2.3 mL / g or less. The non-aqueous electrolyte storage element according to the above.
<5> The non-aqueous electrolyte storage device according to <4>, wherein the carbon material is at least one of graphite and a thermal decomposition product of an organic substance.
<6> The non-aqueous electrolyte storage device according to <5>, wherein the graphite is porous carbon.
<7> The non-aqueous electrolyte storage device according to <6>, wherein the porous carbon has a three-dimensional network structure in which the pores are communicated with each other.
<8> The non-aqueous electrolytic solution storage element according to any one of <1> to <7>, wherein the non-aqueous electrolytic solution _{contains LiBF 4.}
<9> The non-aqueous electrolytic solution power storage element according to any one of <1> to <8>, wherein the negative electrode active material is a carbon material.
<10> The non-aqueous electrolyte storage element according to any one of <1> to <9>, wherein the positive electrode further includes a binder.
<11> The non-aqueous electrolyte storage element according to <10>, wherein the binder is an acrylate-based latex.
<12> The non-aqueous electrolyte storage element according to any one of <1> to <11>, wherein the positive electrode further contains a thickener.
<13> The non-aqueous electrolyte storage device according to <12>, wherein the thickener is carboxymethyl cellulose.
<14> The non-aqueous electrolyte storage element according to any one of <1> to <13>, wherein the positive electrode further contains a conductive auxiliary agent.
<15> The non-aqueous electrolyte storage element according to <14>, wherein the conductive auxiliary agent is acetylene black.
<16> The non-aqueous electrolyte storage element according to any one of <1> to <15>, wherein the negative electrode further includes a binder.
<17> The non-aqueous electrolyte storage element according to <16>, wherein the binder is a styrene-butadiene rubber.
<18> The non-aqueous electrolyte storage element according to any one of <1> to <17>, wherein the negative electrode further contains a thickener.
<19> The non-aqueous electrolyte storage device according to <18>, wherein the thickener is carboxymethyl cellulose.
<20> The non-aqueous electrolyte storage element according to any one of <1> to <19>, wherein the negative electrode further contains a conductive auxiliary agent.
<21> The non-aqueous electrolyte storage element according to <20>, wherein the conductive auxiliary agent is acetylene black.

According to the non-aqueous electrolyte storage device according to any one of <1> to <21>, the conventional problems can be solved and the object of the present invention can be achieved.

10 Non-aqueous electrolyte storage element 11 Positive electrode 12 Negative electrode 13 Separator

Japanese Unexamined Patent Publication No. 8-162154 Japanese Patent No. 5645144 Japanese Patent No. 5896010 Japanese Patent No. 5097415

Claims (6)

A positive electrode containing a positive electrode active material into which an anion can be inserted or removed, a negative electrode containing a negative electrode active material, a non-aqueous electrolytic solution, and the positive electrode and the negative electrode are arranged between the positive electrode and the negative electrode to hold the non-aqueous electrolytic solution. With a separator,
The non-aqueous electrolytic solution contains a dinitrile compound and contains
A non-aqueous electrolytic solution power storage element characterized in that the content of the dinitrile compound is 33% by mass or less with respect to the non-aqueous electrolytic solution. The non-aqueous electrolytic solution power storage element according to claim 1, wherein the content of the dinitrile compound is 1% by mass or less with respect to the non-aqueous electrolytic solution. The non-aqueous electrolyte storage device according to any one of claims 1 to 2, wherein the dinitrile compound is 2-methylglutaronitonyl. The positive electrode active material contains a carbon material and
The invention according to any one of claims 1 to 3, wherein the carbon material has a BET specific surface area of 50 m ² / g or more, and the pore volume of the carbon material is 0.2 mL / g or more and 2.3 mL / g or less. Non-aqueous electrolyte storage element. The non-aqueous electrolytic solution power storage element according to any one of claims 1 to 4, wherein the non-aqueous electrolytic solution _{contains LiBF 4.} The non-aqueous electrolytic solution power storage element according to any one of claims 1 to 5, wherein the negative electrode active material is a carbon material.

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