JP2017224428A - Battery electrolyte solution and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery electrolyte solution having high ion conductivity and durability, which has been demanded in the prior art.SOLUTION: A battery electrolyte solution comprises: a nitrile solvent (R-CN, where R is a saturated or unsaturated aliphatic group) as a main solvent; and a metal fluoride (Me-Fwhere Me is a monovalent or divalent metal cation, and x is 1 or 2) as an additive agent. This enables the achievement of a battery electrolyte solution having high ion conductivity and durability. A battery comprises: the electrolyte solution; a positive electrode; and a negative electrode. This enables the materialization of a battery having high input and output characteristics and reliability.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a battery electrolyte and a battery.

  Patent Document 1 discloses a method using an electrolytic solution containing a nitrile solvent as a method for improving the ionic conductivity of a battery electrolytic solution.

JP 2004-303437 A

  In the prior art, battery electrolytes having high ionic conductivity and durability are desired.

The battery electrolyte in one embodiment of the present disclosure includes a nitrile solvent (R—CN: R is a saturated or unsaturated aliphatic group) as a main solvent, and a metal fluoride (Me—F _x : Me is monovalent or A divalent metal cation, x, contains 1 or 2) as an additive.

  According to the present disclosure, a battery electrolyte having high ionic conductivity and durability can be realized.

FIG. 1 is a schematic sketch showing an example of the battery in the second embodiment. FIG. 2 is a schematic cross-sectional view showing an example of the battery in the second embodiment. FIG. 3 is a diagram showing an electrode processing procedure in the production of the sheet-type battery of Example 1. 4 is a schematic sketch showing the electrode group of the sheet type battery in Example 1. FIG.

A first aspect of the present disclosure includes a nitrile solvent (R—CN: R is a saturated or unsaturated aliphatic group) as a main solvent, and a metal fluoride (Me—F _x : Me is a monovalent or divalent metal) A cation, x, provides an electrolytic solution for a battery containing 1 or 2) as an additive.

  The electrolytic solution of the first aspect has high ionic conductivity and durability.

  According to a second aspect of the present disclosure, in addition to the first aspect, the Me includes at least one selected from the group consisting of Cs, Rb, K, Na, Li, Ba, Sr, Ca, and Mg. I will provide a.

  The electrolytic solution of the second aspect has higher ionic conductivity and durability.

  The third aspect of the present disclosure provides the battery electrolyte, in addition to the second aspect, wherein the Me includes at least one selected from the group consisting of Cs and Rb.

  The electrolyte solution of the third aspect has higher ionic conductivity and durability.

  According to a fourth aspect of the present disclosure, in addition to the third aspect, the Me includes Cs.

  The electrolyte solution of the fourth aspect has higher ionic conductivity and durability.

  In a fifth aspect of the present disclosure, in addition to any one of the first aspect to the fourth aspect, the content of the additive with respect to the entire electrolytic solution is 0.01 wt% or more and 0.1 wt% or less. An electrolyte for a battery is provided.

  The electrolyte solution of the fifth aspect has higher ionic conductivity and durability.

  According to a sixth aspect of the present disclosure, in addition to the fifth aspect, there is provided a battery electrolyte in which the content of the additive with respect to the entire electrolyte is 0.05 wt% or more and 0.1 wt% or less. To do.

  The electrolyte solution of the sixth aspect has higher ionic conductivity and durability.

  A seventh aspect of the present disclosure provides a battery electrolyte containing a fluorine-containing cyclic carbonate in addition to any one of the first to sixth aspects.

  The electrolyte solution of the seventh aspect has higher ionic conductivity and durability.

The eighth aspect of the present disclosure is at least selected from the group consisting of LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ and LiN (SO ₂ F) ₂ in addition to any one of the first to seventh aspects. Provided is a battery electrolyte containing one lithium salt.

  The electrolyte solution of the eighth aspect has higher ionic conductivity and durability.

  A ninth aspect of the present disclosure provides a battery including the battery electrolyte solution of any one of the first aspect to the eighth aspect, a positive electrode, and a negative electrode.

  The battery of the ninth aspect has high input / output characteristics and reliability.

  A tenth aspect of the present disclosure provides a battery in which the negative electrode active material in the negative electrode is carbon in addition to the ninth aspect.

  The battery of the tenth aspect has higher input / output characteristics and reliability.

  In an eleventh aspect of the present disclosure, in addition to the ninth aspect or the tenth aspect, the positive electrode active material in the positive electrode includes at least one selected from the group consisting of Ni, Co, and Mn, and Li. A battery is provided.

  The battery according to the eleventh aspect has higher input / output characteristics and reliability.

  The electrolytic solution of the present disclosure has high ionic conductivity and durability by including a nitrile solvent as a main solvent and a metal fluoride as an additive. This factor is not necessarily clear, but can be explained as follows.

  In general, since a nitrile group has a high polarity, it has a high coordination ability with respect to alkali metal ions such as lithium ions. Therefore, the ability to dissolve alkali metal salts such as lithium salts is high. Furthermore, it has a low viscosity as compared with a carbonate-based solvent that is a conventional solvent. Therefore, lithium ions can move quickly in the electrolytic solution containing the nitrile solvent. By using the electrolytic solution having a high ion conductivity, the input / output characteristics of the battery are improved.

  However, in a nitrile solvent such as butyronitrile, the nitrile group portion undergoes one-electron reduction as shown in the general formula (1), and molecular splitting occurs. Since this reaction product has a low molecular weight and is easily dissolved in a solvent, this reductive decomposition reaction continuously occurs on the negative electrode. Therefore, a nitrile solvent has a low ability to form a passive film called Solid Electrolyte Interface (SEI).

  On the other hand, when a metal fluoride such as CsF or RbF is added to the nitrile solvent, it is directly deposited on the negative electrode as SEI, or is replaced with Li to become LiF, and is deposited on the negative electrode as good SEI. Therefore, the continuous reductive decomposition reaction of the nitrile solvent on the negative electrode is suppressed.

  Therefore, an electrolytic solution obtained by adding a metal fluoride to a nitrile solvent has high ionic conductivity and durability. A battery using the electrolytic solution has high input / output characteristics and reliability.

  Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure is not limited to the following embodiment.

(Embodiment 1)
Hereinafter, as the first embodiment, the battery electrolyte in the present disclosure will be described.

The battery electrolyte in Embodiment 1 contains a nitrile solvent (R-CN: R is a saturated or unsaturated aliphatic group) as a main solvent, and a metal fluoride (Me- _Fx : Me is monovalent or divalent). A valent metal cation, x, contains 1 or 2) as an additive.

  According to the above configuration, a battery electrolyte having high ionic conductivity and durability can be realized.

  As the nitrile solvent used in the electrolytic solution, acetonitrile, propionitrile, butyronitrile, valeronitrile, isobutyronitrile, pivalonitrile, adiponitrile, pimelonitrile, and derivatives thereof can be used.

  As the derivative, a compound in which a part of the hydrogen group is substituted with a fluoro group is preferable from the viewpoint of oxidation resistance.

  These may be used alone or in combination of two or more.

Me of the metal fluoride (Me- _Fx ) which is an additive is a monovalent or divalent metal cation. x is 1 or 2. _{Me-F x} is specifically a _{CsF, RbF, KF, NaF,} LiF, BaF 2, SrF 2, CaF 2, MgF 2 or the like.

  Moreover, CsF and RbF are preferable from the viewpoint of the deposition potential.

  Furthermore, CsF is particularly preferable from the viewpoint of solubility in the electrolytic solution.

  Further, the content of Me—F is preferably 0.01 wt% or more and 0.1 wt% or less with respect to the entire electrolyte solution.

  Furthermore, from the viewpoint of improving the durability of the lithium secondary battery, 0.05 wt% or more and 0.1 wt% or less is particularly preferable.

  Moreover, as electrolyte solution, in addition to the said nitrile solvent, the other nonaqueous solvent may be included.

  Other non-aqueous solvents may include known solvents for non-aqueous electrolytes.

  Specifically, cyclic carbonates, chain carbonates, cyclic carboxylic acid esters, chain carboxylic acid esters, cyclic ethers, chain ethers, and the like can be used.

  Moreover, it is preferable to contain cyclic carbonate from a soluble viewpoint of lithium salt.

  As the cyclic carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate, and derivatives thereof can be used.

  From the viewpoint of the ionic conductivity of the electrolytic solution, ethylene carbonate, fluoroethylene carbonate, and propylene carbonate are preferable.

  Furthermore, it is particularly preferable to use a fluorine-containing cyclic carbonate such as fluoroethylene carbonate from the viewpoint of stability on the negative electrode.

  As the chain carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and derivatives thereof can be used.

  As the cyclic carboxylic acid ester, γ-butyrolactone, γ-valerolactone, and derivatives thereof can be used.

  Examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and derivatives thereof.

  As the cyclic ether, 1,3-dioxolane, 1,4-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, and derivatives thereof can be used.

  As the chain ether, 1,2-dimethoxyethane, dimethyl ether, diethyl ether, dipropyl ether, ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and derivatives thereof can be used.

  As the above-mentioned derivative in the non-aqueous solvent, a compound in which a part of the hydrogen group is substituted with a fluoro group is preferable from the viewpoint of oxidation resistance.

  Moreover, the above non-aqueous solvent may be contained alone in the electrolytic solution. Alternatively, two or more of the non-aqueous solvents described above may be combined and included in the electrolytic solution.

Examples of the metal salt dissolved in the electrolyte include lithium salts such as LiClO ₄ , LiBF ₄ , LiPF ₆ , LiN (SO ₂ F) ₂ , LiN (SO ₂ CF ₃ ) ₂ , lithium bisoxalate borate (LiBOB), and the like. , NaClO ₄ , NaBF ₄ , NaPF ₆ , sodium salts such as NaN (SO ₂ F) ₂ , NaN (SO ₂ CF ₃ ) ₂ , and the like can be used.

  In addition, lithium salts are preferable from the viewpoint of overall characteristics when used in lithium ion secondary batteries.

Furthermore, from the viewpoint of ion conductivity and the like, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ F) ₂ are particularly preferable.

  As the lithium salt, one or more selected from these may be used.

  The molar content of the lithium salt in the electrolytic solution is not particularly limited, but is preferably 0.5 mol / L or more and 2.0 mol / L or less.

(Embodiment 2)
Hereinafter, a battery according to the present disclosure will be described as a second embodiment. In addition, the description which overlaps with the above-mentioned Embodiment 1 is abbreviate | omitted suitably.

  The battery in the second embodiment includes the battery electrolyte solution of the first embodiment, a positive electrode, and a negative electrode.

  According to the above configuration, a battery having high input / output characteristics and reliability can be realized.

  The battery in the second embodiment can be configured as, for example, a lithium ion secondary battery.

  That is, the battery according to the second embodiment includes, for example, the battery electrolyte according to the first embodiment, a positive electrode including a positive electrode active material capable of inserting and extracting lithium ions, and a negative electrode active material capable of inserting and extracting lithium ions. And a negative electrode.

  FIG. 1 is a schematic sketch showing an example of the battery in the second embodiment.

  FIG. 2 is a schematic cross-sectional view showing an example of the battery in the second embodiment.

  As shown in FIGS. 1 and 2, the battery 100 includes an electrode group 4 and an exterior 5. The electrode group 4 is accommodated in the exterior 5. The electrode group 4 includes a positive electrode 10, a negative electrode 20, and a separator 30. The positive electrode 10 includes a positive electrode current collector 1b and a positive electrode mixture layer 1a. The negative electrode 20 includes a negative electrode current collector 2b and a negative electrode mixture layer 2a. The surface of the positive electrode mixture layer 1 a and the surface of the negative electrode mixture layer 2 a are opposed to each other with the separator 30 interposed therebetween. Thus, the electrode group 4 is formed. The electrode group 4 is impregnated with a non-aqueous electrolyte (not shown). A positive electrode tab lead 1c is connected to the positive electrode current collector 1b. A negative electrode tab lead 2c is connected to the negative electrode current collector 2b. Each of the positive electrode tab lead 1 c and the negative electrode tab lead 2 c extends to the outside of the exterior 5. An insulating tab film 6 is disposed between the positive electrode tab lead 1 c and the exterior 5. An insulating tab film 6 is also disposed between the negative electrode tab lead 2 c and the exterior 5.

  The positive electrode mixture layer 1a includes a positive electrode active material that can occlude and release alkali metal ions. The positive electrode mixture layer 1a may contain a conductive additive, an ionic conductor, and a binder as necessary. For the positive electrode active material, the conductive additive, the ionic conductor, and the binder, known materials can be used without any particular limitation.

The positive electrode active material is not particularly limited as long as it is a material that occludes and releases alkali metal ions. For example, lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, and the like can be given. Specifically, Li _x Me _y O ₂ and Li _{1 + x} Me _y O ₃ (0 <x ≦ 1, 0.95 ≦ y <1.05, Me is Co, Ni, Mn, Fe, Cr, Cu, Including at least one selected from the group consisting of Mo, Ti, Al, and Sn), Li _x Me _y PO ₄ and Li _x Me _y P ₂ O ₇ (0 < x ≦ 1, 0.95 ≦ y <1.05, Me preferably includes at least one selected from the group consisting of Co, Ni, Mn, Fe, Cu, and Mo). Can do.

  As the positive electrode current collector 1b, a porous or non-porous sheet or film made of a metal material such as aluminum, aluminum alloy, stainless steel, titanium, or titanium alloy can be used. Aluminum and its alloys are desirable as materials for the positive electrode current collector 1b because they are inexpensive and easily thin. As the sheet or film, a metal foil, a metal mesh or the like is used. A carbon material such as carbon may be applied to the surface of the positive electrode current collector 1b for the purpose of reducing the resistance value, imparting a catalytic effect, and strengthening the bond between the positive electrode mixture layer 1a and the positive electrode current collector 1b. .

  The negative electrode mixture layer 2a includes a negative electrode active material that can occlude and release alkali metal ions. The negative electrode mixture layer 2a may contain a conductive additive, an ionic conductor, and a binder as necessary. The same conductive assistant, ion conductor and binder as those used in the positive electrode 10 can be used.

The negative electrode active material is not particularly limited as long as it is a material that absorbs and releases alkali metal ions. For example, lithium metal alloy, carbon, transition metal oxide, silicon material, and the like can be given. Specifically, an alloy of metal and lithium selected from the group consisting of Zn, Al, Sn, Si, Pb, Na, Ca, In, and Mg, artificial graphite, natural graphite, non-graphitized amorphous carbon Carbon such as graphitizable amorphous carbon, transition metal oxides such as Li ₄ Ti ₅ O ₁₂ , TiO ₂ , V ₂ O ₅ , SiO _x (0 <x ≦ 2), lithium metal, etc. Can do.

  As the negative electrode current collector 2b, a porous or non-porous sheet or film made of a metal material such as aluminum, aluminum alloy, stainless steel, nickel, nickel alloy, copper, or copper alloy can be used. Aluminum and its alloys are desirable as a material for the negative electrode current collector 2b because they are inexpensive and easily thin. As the sheet or film, a metal foil, a metal mesh or the like is used. A carbon material such as carbon may be applied to the surface of the negative electrode current collector 2b for the purpose of reducing the resistance value, imparting a catalytic effect, and strengthening the bond between the negative electrode mixture layer 2a and the negative electrode current collector 2b. .

  As the separator 30, a porous film made of polyethylene, polypropylene, glass, cellulose, ceramics, or the like is used. The pores of the separator 30 are impregnated with a nonaqueous electrolytic solution.

  As the conductive assistant, carbon materials such as carbon black, graphite, and acetylene black, conductive polymers such as polyaniline, polypyrrole, and polythiophene can be preferably used.

  As the ionic conductor, a gel electrolyte such as polymethyl methacrylate and polymethyl methacrylate, a solid electrolyte such as polyethylene oxide, and the like can be used.

  As the binder, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, styrene-butadiene copolymer rubber, polypropylene Polyethylene, polyimide, etc. can be used.

  The battery according to the second embodiment is not limited to the sheet type shown in FIGS. 1 and 2, but may be various types of batteries such as a coin type, a button type, a laminated type, a cylindrical type, a flat type, and a square type. Can be configured. The battery of Embodiment 2 can be used for a portable information terminal, a portable electronic device, a household power storage device, an industrial power storage device, a motorcycle, an EV, a PHEV, and the like, but the application is not limited thereto.

<Example 1>
[Preparation of electrolyte]
Fluoroethylene carbonate (CAS number: 114435-02-8) and butyronitrile (CAS number: 109-74-0) were mixed so that the volume ratio was 1: 4. Furthermore, 1.0 mol / L LiPF ₆ (CAS number: 21324-40-3) was dissolved. Furthermore, as an additive, 0.1 wt% CsF was added and dissolved in the entire electrolyte solution. Thus, an electrolytic solution was obtained.

[Production of positive electrode plate]
First, Li (Ni _, Co _, Al) O ₂ was prepared as a positive electrode active material (for example, Li (Ni _0.82 Co _0.15 Al _0.03 ) O ₂ ). 90 parts by weight of the positive electrode active material was mixed with 5 parts by weight of acetylene black as a conductive agent and 5 parts by weight of polyvinylidene fluoride resin as a binder. These were dispersed in dehydrated N-methyl-2-pyrrolidone to obtain a slurry-like positive electrode mixture. This positive electrode mixture was applied to only one surface of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm and dried. Then, it rolled and obtained the positive electrode plate. The coating amount of the positive electrode mixture after drying was 10 mg / cm ² .

[Production of negative electrode plate]
98 parts by weight of artificial graphite powder, 1 part by weight of styrene-butadiene rubber, and 1 part by weight of carboxymethylcellulose were mixed. These were dispersed in water to obtain a slurry-like negative electrode mixture. This negative electrode mixture was applied to only one surface of a negative electrode current collector made of a copper foil having a thickness of 10 μm and dried. Then, it rolled and the negative electrode plate was obtained. The coating amount of the negative electrode mixture after drying was 6.5 mg / cm ² .

[Production of sheet battery]
A sketch and a sectional view of the produced sheet battery are shown in FIG. 1 and FIG.

  FIG. 3 is a diagram showing an electrode processing procedure in the production of the sheet-type battery of Example 1.

  4 is a schematic sketch showing the electrode group of the sheet type battery in Example 1. FIG.

First, the positive electrode plate and the negative electrode plate were processed as shown in FIG. The electrode area was 24 cm ² for both positive and negative electrodes. The tab lead was made of aluminum for the positive electrode and nickel made for the negative electrode. As shown in FIG. 3, a heat welding resin is welded to the tab lead. The positive electrode plate and negative electrode plate processed as shown in FIG. 3 were opposed to each other so that the electrodes just overlap each other with a separator (made of polypropylene, thickness 30 μm) as shown in FIG. Next, the aluminum laminate (thickness 100 μm) cut into a 120 × 120 mm square was folded. The 120 mm end face was heat-sealed at 230 ° C. to form a cylinder of 120 × 60 mm. As shown in FIG. 4, a group of electrodes facing each other was inserted from the end face of 60 mm. Then, as shown in FIG. 1, the end face of the aluminum laminate and the position of the heat welding resin of the tab lead were aligned and heat sealed at 230 ° C. Next, 0.8 cc of electrolyte was injected from the side of the laminate that was not sealed. After pouring, the mixture was allowed to stand for 15 minutes under a vacuum of 0.06 MPa, and the electrode mixture was impregnated with the electrolytic solution. Finally, the end surface of the injected laminate was heat sealed at 230 ° C.

[Battery evaluation]
At the time of evaluation, the produced battery was sandwiched between 80 × 80 cm stainless steel plates (thickness 2 mm) and the electrode plate from above the laminate, and was pressurized by 0.2 MPa with a U-shaped clamp. Moreover, all evaluation was performed in a 25 degreeC thermostat.

  First, the electrolyte solution was completely impregnated inside the positive electrode / negative electrode mixture. For the purpose of forming SEI on the negative electrode, charging / discharging 1 cycle (1) was repeated at a constant current of 5 mA, and charging / discharging was repeated 4 cycles at a constant current of 20 mA. Charging was terminated at a battery voltage of 4.2V, and discharging was terminated at a battery voltage of 2.5V. Between charging and discharging, it was left in an open circuit for 20 minutes.

  Next, another cycle charge / discharge (2) was performed under the same conditions. Furthermore, after making a thermostat 60 degreeC, it charged with the constant current of 20 mA, and hold | maintained at 20 mA and 4.2V for 3 days. Then, the thermostat was returned to 25 ° C., and one cycle charge / discharge (3) was performed under the same conditions as before the holding test. The discharge capacity retention rate after the retention test (3) relative to the discharge capacity before the retention test (2) was used as an index of durability. It shows in Table 1 together with the discharge capacity of the first time (1).

<Example 2>
A battery was prepared in the same manner as in Example 1 except that 0.05 wt% RbF was used instead of CsF as an additive, and evaluation was performed in the same manner. The results are shown in Table 1.

<Comparative Example 1>
A battery was prepared and evaluated in the same manner as in Example 1 except that no additive was used. The results are shown in Table 1.

<Discussion>
From Table 1, the batteries of Examples 1 and 2 have a higher discharge capacity retention rate after the holding test with respect to the discharge capacity before the holding test than the battery of Comparative Example 1. That is, it has been shown that an electrolytic solution containing a metal fluoride such as CsF or RbF as an additive and using a nitrile solvent as a main solvent has higher durability than an electrolytic solution containing no additive.

  In a nitrile solvent such as butyronitrile, a portion of the nitrile group undergoes one-electron reduction, resulting in molecular splitting. Since this reaction product has a low molecular weight and is easily dissolved in a solvent, this reduction reaction occurs continuously. On the other hand, when CsF and RbF are added as in Examples 1 and 2, SEI is deposited on the negative electrode as it is, or Li is replaced with LiF, and good SEI is deposited on the negative electrode. Therefore, it is considered that the continuous reductive decomposition reaction of the nitrile solvent on the negative electrode is suppressed and the durability is improved.

  Further, from Table 1, the battery of Example 1 has a higher discharge capacity retention rate after the holding test than the battery of Example 2 with respect to the discharge capacity before the holding test. The reason for this is that the CsF content of Example 1 is 0.1 wt% with respect to the entire electrolyte solution, whereas the RbF content of Example 2 is 0.05 wt% with respect to the entire electrolyte solution. It can be considered. That is, it was shown that a battery having higher durability can be realized when CsF having excellent solubility in an electrolytic solution is used as an additive.

  From the above results, it was found that the battery electrolyte of the present disclosure has high ionic conductivity and durability. Further, it was found that the battery of the present disclosure has high input / output characteristics and reliability.

  The battery electrolyte of the present disclosure is useful as, for example, a non-aqueous electrolyte for a lithium ion secondary battery.

DESCRIPTION OF SYMBOLS 10 Positive electrode 1a Positive electrode mixture layer 1b Positive electrode collector 1c Positive electrode tab lead 20 Negative electrode 2a Negative electrode mixture layer 2b Negative electrode collector 2c Negative electrode tab lead 30 Separator 4 Electrode group 5 Exterior 6 Insulation tab film 100 Battery

Claims (11)

A nitrile solvent (R-CN: R is a saturated or unsaturated aliphatic group) as a main solvent,
Metal fluoride (Me-F _x : Me is a monovalent or divalent metal cation, x is 1 or 2) as an additive,
Battery electrolyte. The Me includes at least one selected from the group consisting of Cs, Rb, K, Na, Li, Ba, Sr, Ca, Mg,
The battery electrolyte according to claim 1. The Me includes at least one selected from the group consisting of Cs and Rb.
The battery electrolyte according to claim 2. The Me includes Cs;
The battery electrolyte solution according to claim 3. The content of the additive with respect to the entire electrolytic solution is 0.01 wt% or more and 0.1 wt% or less.
The battery electrolyte according to any one of claims 1 to 4. The content of the additive with respect to the entire electrolyte solution is 0.05 wt% or more and 0.1 wt% or less.
The battery electrolyte according to claim 5. Including a fluorine-containing cyclic carbonate,
The battery electrolyte solution according to any one of claims 1 to 6. Including at least one lithium salt selected from the group consisting of LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ and LiN (SO ₂ F) ₂ ;
The battery electrolyte solution according to any one of claims 1 to 7. A positive electrode;
A negative electrode,
An electrolyte for a battery according to any one of claims 1 to 8,
battery. The negative electrode active material in the negative electrode is carbon,
The battery according to claim 9. The positive electrode active material in the positive electrode is a metal oxide containing at least one selected from the group consisting of Ni, Co, and Mn and Li.
The battery according to claim 9 or 10.

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