JP5601576B2 - Non-aqueous electrolyte composition and non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a secondary battery used as a power source for driving a motor of, for example, an electric vehicle or a hybrid electric vehicle. The present invention relates to a composition and a non-aqueous electrolyte secondary battery to which such an electrolyte composition is applied.

In recent years, the development of electric vehicles (EV), hybrid electric vehicles (HEV), fuel cell vehicles (FCV) and the like has been promoted against the background of the increasing environmental protection movement.
A secondary battery that can be repeatedly charged and discharged is suitable as a power source for driving motors in these automobiles, and nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries that can be expected to have high capacity and high output are attracting attention. Yes.

Such a nonaqueous electrolyte secondary battery is formed on the surface of the positive electrode current collector and has a positive electrode active material layer containing a positive electrode active material such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , for example. Further, it is formed on the surface of a negative electrode current collector different from the above current collector, for example, metallic lithium, carbonaceous materials such as coke and natural / artificial graphite, metals such as Sn and Si, oxides of these metals, etc. A negative electrode active material layer containing the negative electrode active material.
Further, the non-aqueous electrolyte secondary battery includes a supporting electrolyte (supporting salt) made of a lithium salt such as LiPF ₆ or LiN (CF ₃ CF ₂ SO ₂ ) ₂ between the positive electrode active material layer and the negative electrode active material layer. The positive electrode active material layer and the negative electrode active material layer are separated by this.

In such a non-aqueous electrolyte secondary battery, a chemical reaction or decomposition of the electrolyte layer may occur on the surface of the positive electrode or the negative electrode, or on both electrode surfaces.
When such a chemical reaction or decomposition reaction occurs, problems such as deterioration in storage characteristics of the battery at high temperatures, deterioration in cycle characteristics of the secondary battery, and generation of gas due to decomposition products arise.

  In order to prevent the occurrence of these problems, a compound having a protective film generating function is added to the electrolytic solution contained in the electrolyte layer.

Specifically, a protection provided with a function that intentionally promotes decomposition of a compound added to the electrolyte solution on the surface of the negative electrode active material during initial charging, and the decomposition product prevents decomposition of a new electrolyte layer. It is known to form a coating, ie SEI (Solid Electrolyte Interface).
And by forming such a protective film, the chemical reaction and decomposition | disassembly of the electrolyte layer in the electrode surface in a negative electrode are suppressed appropriately, As a result, there exists an effect which maintains the battery performance of a secondary battery. Various reports have been made.

  For example, Patent Document 1 contains a cyclic sulfonic acid ester having at least two sulfonyl groups in a nonaqueous electrolytic solution, and forms a stable protective film on the negative electrode to suppress solvent decomposition of the electrolytic solution. Therefore, it is disclosed that the cycle characteristics and storage characteristics of the battery are improved.

JP 2004-281368 A

The sulfonic acid ester compound contained in the electrolytic solution is reductively decomposed on the negative electrode surface to form a stable film, thereby improving cycle life and storage characteristics.
However, since the high-temperature storage stability as a single compound is low, the generation of decomposition products thereof may lead to an increase in internal resistance due to clogging of the separator or a decrease in the coating repair function due to a decrease in absolute amount. In addition, quality control may be complicated when storing the electrolyte.

  The present invention has been made to solve the above-described problems in conventional secondary batteries using a non-aqueous electrolyte containing the sulfonic acid ester compound as described above. An object of the present invention is to provide a non-aqueous electrolyte composition that can suppress decomposition and improve battery cycle characteristics and high-temperature storage stability. Another object of the present invention is to provide a non-aqueous electrolyte secondary battery using such an electrolyte composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by allowing a sulfonate ester and a phosphazene compound to coexist in a non-aqueous electrolyte. It came to be completed.

That is, the present invention is based on the above knowledge, and the non-aqueous electrolyte composition of the present invention contains a supporting electrolyte, a non-aqueous solvent , a cyclodisone that is a sulfonate ester , and a phosphazene compound. The content of is characterized by being 0.5 to 1% by mass ratio with respect to the total of the supporting electrolyte and the nonaqueous solvent .

  According to the present invention, since the non-aqueous electrolyte composition in which the sulfonate ester and the phosphazene compound coexist is obtained, the high-temperature decomposition of the sulfonate ester can be suppressed by the phosphazene compound, and such an electrolyte composition is used as a secondary battery. By applying to, the cycle characteristics and high-temperature storage stability of the battery can be improved.

  Hereinafter, the nonaqueous electrolyte composition of the present invention and the nonaqueous electrolyte secondary battery using the composition will be described in more detail. In the present specification, “%” represents mass percentage unless otherwise specified.

As described above, the nonaqueous electrolyte composition of the present invention is a nonaqueous electrolyte composition containing a supporting electrolyte in a nonaqueous solvent, and further includes a sulfonic acid that forms a stable protective film on the negative electrode. Along with the ester, a phosphazene compound is contained.
It is considered that the presence of moisture and acid affects the high-temperature decomposition of sulfonic acid esters. In the present invention, caustic substances such as H ₂ O and acids, such as HF, are phosphazenes having a —P═N— bond. It is made to suppress by addition of a compound. That is, the —P═N— site of the phosphazene compound can be trapped by the bond with hydrogen in H ₂ O, HF, and the absolute amount capable of attacking the sulfonate ester is reduced. Can be suppressed.

Next, the supporting electrolyte, the non-aqueous solvent, the sulfonate ester, and the phosphazene compound constituting the non-aqueous electrolyte composition of the present invention will be specifically described.
The non-aqueous electrolyte composition of the present invention is typified by a liquid non-aqueous electrolyte, that is, an electrolytic solution, but not only such a non-aqueous electrolytic solution but also a polymer skeleton as described later. It is also possible to obtain a gel electrolyte by impregnating it. That is, in the present invention, the “non-aqueous electrolyte composition” means a general term for non-aqueous electrolytes including not only liquid electrolytes but also gels.

  The liquid electrolyte (electrolytic solution) is in a state in which the supporting electrolyte (supporting salt) is dissolved in a non-aqueous solvent (organic solvent). In the present invention, a sulfonate ester and a phosphazene compound are further added thereto. .

[Supporting electrolyte]
The supporting electrolyte is not particularly limited, and a known supporting salt (lithium salt) can be used. From the viewpoint of cell characteristics, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , Li (CF ₃ SO ₂ ) ₂ N, It is desirable to use Li (CF ₃ CF ₂ SO ₂ ) ₂ N and Li (FSO ₂ ) ₂ N. In addition, LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ SO _3, etc. can be used. These supporting electrolytes may be used alone or in combination of two or more.

[Nonaqueous solvent]
As the non-aqueous solvent, a high dielectric constant solvent or a low viscosity solvent can be used, and these can be used alone or in combination.
Here, examples of the high dielectric constant solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC). As the low viscosity solvent, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), or the like can be used.

Besides the above, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, 1,3-dioxolane, diethyl ether, γ-butyrolactone Lactones such as acetonitrile, nitriles such as acetonitrile, esters such as methyl propionate, amides such as dimethylformamide, esters such as methyl acetate and methyl formate, sulfolane, dimethyl sulfoxide, 3-methyl-1,3-oxazolidine -2-one and the like.
These solvents may be used alone or in combination of two or more. Among the various solvents, since the SEI film is easily formed on the surface of the negative electrode active material, it is at least one selected from the group consisting of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, and vinylene carbonate. It is preferable.

[Sulfonate]
The sulfonate ester contributes to the formation of a protective film on the electrode surface and has a function of suppressing the decomposition of solvent molecules.
As such a sulfonate ester, it is desirable to use at least one compound selected from the group consisting of a cyclic sulfonate ester and a chain sulfonate ester represented by the following formula (3) from the viewpoint of life characteristics. .

式（３）におけるＺは、炭素数１〜５のアルキレン基を示し、これにさらに第２のスルホニル基を含んでいてもよい。

Z in Formula (3) represents an alkylene group having 1 to 5 carbon atoms, and may further contain a second sulfonyl group.

  Specific examples of such a compound include 1,3-propane sultone, 1,4-butane sultone, and 2,4-butane sultone. Moreover, as what has a 2nd sulfonyl group, a cyclodisone etc. can be mentioned, for example.

As content of the said sulfonic acid ester, it is preferable that it is 0.01 to 10% by mass ratio with respect to the sum total of a supporting electrolyte and a nonaqueous solvent.
That is, when the content of the sulfonic acid ester is less than 0.01%, the effect of the addition may not be sufficiently exhibited. On the other hand, when the content exceeds 10%, the resistance increases or becomes irreversible. There is a risk that cell characteristics may be deteriorated due to an increase in capacity.

[Phosphazene compounds]
As described above, the phosphazene compound has a function of trapping H ₂ O and HF, suppressing hydrolysis of the sulfonate ester, and maintaining the original protective film forming function of the sulfonate ester.
As such a phosphazene compound, from the viewpoint of cell characteristics, at least one compound selected from the group consisting of a cyclic phosphazene represented by the following formula (1) and a chain phosphazene represented by the following formula (2) is used. It is preferable to use it.

However, the side chain R 1 is an alkyl group such as —CH ₃ or —CH ₂ CH ₃ (however, part or all of hydrogen may be substituted with a halogen element such as fluorine), or —OCH ₃ , _{-OCH 2 CH 3, -OC 6 H} 5, alkoxy groups such as -OCH 2 _OCH 2 CH ₃ (although some hydrogen or all may be substituted with a halogen element such as fluorine), or, - _{COOCH 3, -COOCH 2 CH 3,} -COOC 6 H 5 carboxyl group (provided that part of hydrogen or all may be substituted with a halogen element such as fluorine), such as, _or, -COCH 3, -COCH ₂ CH _3, a carbonyl group, such as -COC ₆ H ₅ (although some hydrogen or all may be substituted with a halogen element such as fluorine), also _{, -C 6 H 5, -C 6} H 4 CH 3, -C 6 H 5 (CH 3) 2 aryl group (such as, even if some of the hydrogen or all substituted by a halogen element such as fluorine Or a alkenyl group such as —CH═CH ₂ , —CH═CH ₂ C ₂ H ₅ , —CH═CH ₂ C ₆ H ₅ (wherein part or all of hydrogen is a halogen element such as fluorine). Which may be substituted) or a halogen element such as fluorine or chlorine, and each R may be the same as or different from each other. N represents an integer of 0 or more and 10 or less.

  Specific examples of such compounds include ethoxypentafluorocyclotriphosphazene, diethoxytetrafluorocyclotriphosphazene, triethoxytrifluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, diphenoxytetrafluorocyclotriphosphazene, triphenoxy. And trifluorocyclotriphosphazene.

As content of the said phosphazene compound, it is 0.5 to 1% by mass ratio with respect to the sum total of a supporting electrolyte and a nonaqueous solvent .
That is, when the content of the phosphazene compound is less than 0.1%, the effect of suppressing the decomposition of the sulfonic acid ester may not be sufficiently obtained. This tends to cause a decline.

The liquid electrolyte can also be used as a gel electrolyte by being injected into a matrix polymer made of an ion conductive polymer.
Examples of the ion conductive polymer used as the matrix polymer include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. In such polyalkylene oxide polymers, electrolyte salts such as lithium salts are well dissolved.

The matrix polymer of gel electrolyte can express excellent mechanical strength by forming a crosslinked structure.
In order to form a crosslinked structure, thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte using an appropriate polymerization initiator. A polymerization treatment may be performed.

The liquid electrolyte and gel electrolyte described above can also be used in a state of being impregnated in a separator made of a porous sheet or a nonwoven fabric.
The separator has a function to prevent internal short circuit by interposing between the positive electrode and the negative electrode. Natural, cotton, rayon, acetate, polyamide, polyester, polyethylene (PE), polypropylene (PP), polyimide, aramid, etc. An insulating material having a high ion permeability and a predetermined mechanical strength, such as a nonwoven fabric made of synthetic fiber or ceramic fiber, or a porous sheet made of a polymer such as polyethylene, polypropylene, polyimide, or aramid, is used. It is also possible to adopt a laminated structure of two or more kinds of porous sheets.

  The separator can be provided with a shutdown function, that is, when an excessive current flows through the battery, the heat generation closes the pores of the porous sheet and shuts off the current. A laminated structure composed of a three-layer porous sheet of PE / PP / PE having different melting points is preferably used.

Next, the nonaqueous electrolyte secondary battery of the present invention will be described together with its configuration and materials.
A non-aqueous electrolyte secondary battery is provided with one or more sets of single battery layers formed by laminating a positive electrode, an electrolyte layer, and a negative electrode in this order. This single cell layer has a structure in which a positive electrode active material layer formed on the surface of the positive electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector are opposed to each other through the electrolyte layer. The non-aqueous electrolyte secondary battery of the present invention is characterized by applying the non-aqueous electrolyte composition of the present invention as an electrolyte layer.

The positive electrode has a structure in which a positive electrode active material layer is formed on one side or both sides of a current collector (positive electrode current collector) made of a conductive material such as an aluminum foil, a copper foil, a nickel foil, or a stainless steel foil. The thickness of the current collector is not particularly limited, but generally it is preferably about 1 to 30 μm.
A positive electrode active material layer can contain a conductive support agent and a binder (binder) with a positive electrode active material as needed.

In the nonaqueous electrolyte secondary battery of the present invention, the positive electrode active material is not particularly limited, and a conventionally known positive electrode active material can be used. For example, a lithium-transition metal composite oxide can be preferably used. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li-Ni-based composite oxide such as LiNiO _2, LiMn composite oxide such as spinel LiMn ₂ O _4, such as LiFeO ₂ Li- Examples thereof include Fe-based composite oxides. In addition, transition metal oxides such as LiFePO ₄ and lithium phosphate compounds and sulfate compounds, transition metal oxides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , sulfides, PbO ₂ , AgO, NiOOH etc. are mentioned. These positive electrode active materials are excellent in output characteristics, capacity, reactivity, cycle durability, and low in cost. It is also possible to use two or more positive electrode active materials in combination.

  On the other hand, the negative electrode has a structure in which a negative electrode active material layer is formed on one side or both sides of a current collector (negative electrode current collector) made of a conductive material as described above, as in the case of the positive electrode. As with the positive electrode, the layer may contain a conductive additive or a binder as necessary.

In the present invention, the negative electrode active material is not particularly limited, and a conventionally known negative electrode active material can be used. Suitable examples include carbon materials, alloy-based negative electrode materials, lithium-transfer metal composite oxides such as lithium-titanium composite oxide (lithium titanate: Li ₄ Ti ₅ O ₁₂ ), potassium titanate, titanium carbide, and dioxide. Titanium, magnesium oxide, etc. are exemplified, but from the viewpoint of output characteristics, capacity, reactivity, and cycle durability, carbon materials and alloy-based negative electrode materials are preferable. These may be used alone or in combination of two or more.

  Specific examples of the carbon material include graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, and hard carbon. Of these, graphite is more preferred. These carbon materials can be used alone or in combination of two or more.

The alloy-based negative electrode material described above preferably includes at least one selected from the group consisting of silicon, tin, aluminum, zinc, germanium, lead, magnesium, sodium, gallium, and indium, and includes silicon or tin. Is more preferable.
Specific examples include silicon, silicon monoxide, tin dioxide, silicon carbide, and tin, and silicon and silicon monoxide are more preferable. These may be used individually by 1 type and may use 2 or more types together.

  The average particle diameter of the positive electrode active material and the negative electrode active material is not particularly limited, but is preferably in the range of 1 to 20 μm from the viewpoint of increasing the output.

As the binder added to the positive electrode active material or the negative electrode active material layer as necessary, for example, polyvinylidene fluoride (PVdF), polyimide, polyamideimide, a synthetic rubber binder, or the like can be used.
Similarly, the conductive auxiliary agent contained in the active material layer as necessary is an additive compounded to improve the conductivity of the positive electrode active material layer or the negative electrode active material layer, and is a carbon such as acetylene black. Examples thereof include carbon materials such as black, graphite, and vapor grown carbon fiber. When the active material layer contains such a conductive additive, an electronic network inside the active material layer is effectively formed, which contributes to improvement of the output characteristics of the battery.

The compounding ratio of the components contained in the positive electrode active material layer and the negative electrode active material layer is not particularly limited, and these compounding ratios may be adjusted by appropriately referring to known information on the nonaqueous electrolyte secondary battery. Can do.
Moreover, although there is no limitation in particular also about the thickness of a positive electrode and a negative electrode active material layer, generally it is about 2-150 micrometers.

  In the above description, the positive electrode active material layer and the negative electrode active material layer are formed on one surface or both surfaces of each current collector, but the positive electrode active material layer on one surface of one current collector, A negative electrode active material layer can be formed on each of the other surfaces, and such an electrode can be applied to a bipolar battery.

Further, the shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. For example, a laminated flat shape, a wound cylindrical shape, a rectangular flat shape obtained by deforming a wound shape, and a coin shape Etc.
Furthermore, a laminated film, a metal can, etc. can be used also about an exterior material.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to these Examples.

[Preparation of non-aqueous electrolyte]
A solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70 was used as a non-aqueous solvent, and LiPF ₆ was dissolved as a supporting electrolyte to a concentration of 1.0 M for electrolysis. A liquid base was used.
Then, a cyclodison represented by the following formula (4), which is a sulfonate ester, was added at a concentration of 1.5% with respect to the obtained electrolytic solution base, that is, the total mass of the mixed solvent and the supporting electrolyte. Furthermore, to this, cyclic phosphazene compounds represented by the formulas (5) to (7) were respectively 0 (comparative example), 0.1, 0.5, 0.75, 1, 5, By adding at each concentration of 10%, non-aqueous electrolytes of Examples , Reference Examples and Comparative Examples were obtained.

[Evaluation of deterioration resistance of electrolyte]
About each non-aqueous electrolyte obtained by the above, immediately after preparing electrolyte solution, after preserve | saving for 7 days in the thermostat hold | maintained at 55 degreeC, the state of electrolyte solution was observed visually. The results are shown in Table 1.

[Production of positive electrode]
85% LiMn ₂ O ₄ (average particle size: 15 μm) as a positive electrode active material, 5% acetylene black as a conductive assistant, and 10% PVdF as a binder were mixed, and N-methyl-2- An appropriate amount of pyrrolidone (NMP) was added as a slurry viscosity adjusting solvent to obtain a positive electrode slurry.
Next, the obtained positive electrode slurry was applied to one side of an aluminum foil (20 μm) as a current collector and dried to produce a positive electrode.

(Production of negative electrode)
MCMB (mesocarbon microbeads, average particle size: 20 μm) 85% as a negative electrode active material, 5% acetylene black as a conductive additive, and 10% PVdF as a binder are mixed. An appropriate amount of NMP was added to obtain a negative electrode slurry.
Next, the obtained negative electrode slurry was applied to one side of a copper foil (15 μm) as a current collector and dried to prepare a negative electrode.

[Assembly of single cells]
Each of the positive electrode and the negative electrode obtained as described above is subjected to a heating roll press, and pressed to such an extent that the electrode does not break through the current collector, whereby the thickness of the positive electrode active material layer and the negative electrode active material layer is 75 μm and 65 μm, respectively. It pressed so that it might become.
Thereafter, the positive electrode and the negative electrode were each cut into a 90 × 90 mm square shape, and the positive electrode and the negative electrode were bonded together via a 95 × 95 mm separator (polyolefin microporous film, thickness 20 μm).

  A tab was welded to each of these positive electrodes and negative electrodes, and sealed with each of the previously prepared non-aqueous electrolytes in an exterior made of an aluminum laminate film to complete a single cell.

[Battery performance evaluation]
The nonaqueous electrolyte secondary battery (single cell) produced as described above was evaluated by a charge / discharge performance test. The results are also shown in Table 1.
That is, in a thermostatic chamber maintained at 55 ° C., the battery temperature is set to 55 ° C., then constant current charging (CC) is performed to 4.2 V at a current rate of 1 C, and then constant voltage charging (CV) is performed for 3 hours. Charged. Then, after providing a 10-minute rest period, a charge / discharge test was performed in which a charge / discharge process of discharging to 2.5 V at a current rate of 1 C and resting for 10 minutes after the discharge was performed as one cycle. The ratio of the discharge capacity after 100 cycles to the initial discharge capacity was defined as the capacity maintenance rate.

As a result, in non-aqueous electrolytes containing cyclodisone as the sulfonate ester, the occurrence of precipitates due to the high-temperature decomposition of the sulfonate ester is caused by the addition of a predetermined cyclic phosphazene compound, especially by adding a small amount of 0.1%. It was confirmed that it could be almost completely prevented and the high temperature storage stability could be improved.
Further, in the secondary battery using such a non-aqueous electrolyte, although a slight deterioration tendency of the cycle characteristics is observed due to an increase in the amount of the phosphazene compound added, as long as the amount added does not exceed 10%, It was confirmed that almost the same cycle characteristics were exhibited.

Claims (5)

It contains a supporting electrolyte, a non-aqueous solvent, cyclodisone which is a sulfonate ester , and a phosphazene compound, and the content of the phosphazene compound is 0.5 to 1% by mass ratio with respect to the total of the supporting electrolyte and the non-aqueous solvent. non-aqueous electrolyte composition, characterized in that. To claim 1, wherein the phosphazene compound is characterized in that at least one compound selected from the group consisting of linear phosphazene represented by cyclic phosphazene and the following equation represented by the following formula (1) (2) The nonaqueous electrolyte composition described.

(In the formula, the side chain R is an alkyl group such as —CH ₃ or —CH ₂ CH ₃ (however, part or all of hydrogen may be substituted with a halogen element such as fluorine), or —OCH ₃ , an alkoxy group such as —OCH ₂ CH ₃ , —OC ₆ H ₅ , —OCH ₂ OCH ₂ CH ₃ (however, part or all of hydrogen may be substituted with a halogen element such as fluorine), or _{, -COOCH 3, -COOCH 2 CH 3} , -COOC 6 H 5 carboxyl group (provided that part of hydrogen or all may be substituted with a halogen element such as fluorine), such as, or, -COCH _3, -COCH ₂ CH _3, a carbonyl group, such as -COC ₆ H ₅ (although some hydrogen or all may be substituted with a halogen element such as fluorine), also _{, -C 6 H 5, -C 6} H 4 CH 3, -C 6 H 5 (CH 3) 2 aryl group (such as, even if some of the hydrogen or all substituted by a halogen element such as fluorine Or a alkenyl group such as —CH═CH ₂ , —CH═CH ₂ C ₂ H ₅ , —CH═CH ₂ C ₆ H ₅ (wherein part or all of hydrogen is a halogen element such as fluorine). Any of halogen elements such as fluorine and chlorine, and each R may be the same as or different from each other, and n is 0 or more and 10 or less. Indicates an integer ) 3. The non-aqueous electrolyte composition according to claim 1 , wherein the cyclodison content is 0.01 to 10% by mass ratio with respect to the total of the supporting electrolyte and the non-aqueous solvent. The support electrolyte is at least one compound selected from the group consisting of LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N, Li (CF ₃ CF ₂ SO ₂ ) ₂ N and Li (FSO ₂ ) ₂ N The non-aqueous electrolyte composition according to claim 1 , wherein the non-aqueous electrolyte composition is a non-aqueous electrolyte composition. A non-aqueous electrolyte secondary battery using the non-aqueous electrolyte composition according to claim 1 .