JP2021048006A - Non-aqueous electrolyte for battery and lithium secondary battery - Google Patents

Abstract

To provide a non-aqueous electrolyte for a battery capable of reducing battery resistance.SOLUTION: A non-aqueous electrolyte for a battery includes a compound represented by the formula (1). In the formula (1), R10 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a phenyl group, or a group represented by the formula (S1). R1 to R9 and R11 to R13 independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group, and L1 represents a single bond or an oxygen atom, and * represents a bond position.SELECTED DRAWING: None

Description

The present disclosure relates to a non-aqueous electrolyte solution for a battery and a lithium secondary battery.

Conventionally, various studies have been made on non-aqueous electrolyte solutions for batteries used in batteries such as lithium secondary batteries.
For example, Patent Document 1 describes an electrolytic solution for a lithium secondary battery containing a lithium salt and a non-aqueous solvent as an electrolytic solution for a lithium secondary battery exhibiting excellent output and life characteristics. Disclosed is an electrolytic solution for a lithium secondary battery, characterized in that is added in a content of 0.1 to 20% by weight based on the total weight of the electrolytic solution. In Patent Document 1, the silane-based substance is selected from the group consisting of trimethoxysilylpropylaniline (TMSPA), tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, and a mixture thereof. It is also disclosed that it is preferable to use any one of the above.

Special Table 2015-534707

However, it may be required to further reduce the battery resistance.
An object of one aspect of the present disclosure is to provide a non-aqueous electrolyte solution for a battery capable of reducing battery resistance.
An object of another aspect of the present disclosure is to provide a lithium secondary battery with reduced battery resistance.

Means for solving the above problems include the following aspects.
<1> A non-aqueous electrolytic solution for a battery containing a compound represented by the following formula (1).

In equation (1),
R ^{1 to} R ⁹ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
R ¹⁰ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a phenyl group, or a group represented by the formula (S1).
In equation (S1),
R ^{11 to} R ¹³ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
L ¹ represents a single bond or an oxygen atom
* Represents the bond position.

<2> The non-aqueous electrolyte solution for batteries according to <1>, wherein the content of the compound represented by the formula (1) is 0.001% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolyte solution. ..
<3> The non-aqueous electrolytic solution for a battery according to <1> or <2>, which further contains a compound represented by the following formula (2).

In the formula (2), R ²¹ and R ²² independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms, respectively.

<4> The non-aqueous electrolyte solution for batteries according to <3>, wherein the content of the compound represented by the formula (2) is 0.001% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolyte solution. ..

<5> Positive electrode and
Metallic lithium, lithium-containing alloys, metals or alloys that can be alloyed with lithium, oxides that can be doped and dedoped with lithium ions, transition metal nitrogen compounds that can be doped and dedoped with lithium ions, and lithium. A negative electrode containing at least one selected from the group consisting of a carbon material capable of doping and dedoping ions as a negative electrode active material, and a negative electrode.
The non-aqueous electrolyte solution for batteries according to any one of <1> to <4>.
Lithium secondary battery including.
<6> A lithium secondary battery obtained by charging / discharging the lithium secondary battery according to <5>.

According to one aspect of the present disclosure, a non-aqueous electrolyte solution for a battery capable of reducing battery resistance is provided.
According to another aspect of the present disclosure, a lithium secondary battery with reduced battery resistance is provided.

It is a schematic perspective view which shows an example of the laminated type battery which is an example of the lithium secondary battery of this disclosure. It is schematic cross-sectional view in the thickness direction of the laminated type electrode body housed in the laminated type battery shown in FIG. It is schematic cross-sectional view which shows an example of the coin-type battery which is another example of the lithium secondary battery of this disclosure.

In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.

[Non-aqueous electrolyte for batteries]
The non-aqueous electrolytic solution for batteries (hereinafter, also simply referred to as “non-aqueous electrolytic solution”) of the present disclosure contains a compound represented by the following formula (1).
According to the non-aqueous electrolytic solution of the present disclosure, battery resistance, particularly positive electrode resistance, can be reduced.
Although the reason why such an effect is exhibited is not clear, by incorporating the compound represented by the following formula (1) in the non-aqueous electrolytic solution, the increase of decomposition products of the non-aqueous electrolytic solution on the positive electrode is suppressed. This is thought to be because the increase in resistance can be suppressed.

<Compound represented by formula (1)>

In equation (1),
R ^{1 to} R ⁹ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
R ¹⁰ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a phenyl group, or a group represented by the formula (S1).
In equation (S1),
R ^{11 to} R ¹³ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
L ¹ represents a single bond or an oxygen atom
* Represents the bond position.

In the formula (1), ^{as the alkyl group having 1 to 6 carbon atoms represented by R 1 to} R ¹³ , an alkyl group having 1 to 3 carbon atoms is more preferable, a methyl group or an ethyl group is further preferable, and a methyl group is used. More preferred.

In the formula (1), ^{as the alkenyl group having 2 to 6 carbon atoms represented by R 1 to} R ¹³ , an alkenyl group having 2 or 3 carbon atoms is preferable, and a vinyl group or an allyl group is more preferable.

In the formula (S1), L ¹ represents a single bond or an oxygen atom (in other words, an ether bond (−O−)).
In the group represented by the formula (S1), ^{the embodiment in which L 1} is a single bond is the group represented by the following formula (S1A), and the embodiment in which ^{L 1 is an oxygen atom is represented by the following formula (S1B).} It is the group represented.

Wherein ^R 11 ^{to R 13} in (S1A), respectively, have the same meaning as ^R 11 ^{to R 13} in the formula (S1), ^R 11 ^{to R 13} in the formula (S1B), respectively, the formula (S1) It is synonymous with R ^{11 to} R ^{13 inside.}

^{L 1} in the formula (S1) is preferably a single bond. That is, the group represented by the formula (S1) is preferably the group represented by the formula (S1A).

Hereinafter, specific examples of the compound represented by the formula (1) will be shown, but the compound represented by the formula (1) is not limited to the following specific examples.

The content of the compound represented by the formula (1) is preferably 0.001% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass, based on the total amount of the non-aqueous electrolyte solution. Yes, more preferably 0.1% by mass to 2% by mass, still more preferably 0.1% by mass to 0.6% by mass.

<Compound represented by formula (2)>
The non-aqueous electrolytic solution of the present disclosure preferably contains a compound represented by the following formula (2).

In the formula (2), R ²¹ and R ²² independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms, respectively.

In the formula (2), ^{the hydrocarbon group having 1 to 6 carbon atoms represented by R 21} or R ²² may be a linear hydrocarbon group, or a hydrocarbon group having a branched and / or ring structure. It may be.
As ^{the hydrocarbon group having 1 to 6 carbon atoms represented by R 21} or R ²² , an alkyl group or an aryl group is preferable, and an alkyl group is more preferable.

In the formula (2), ^{the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R 21} or R ²² may be a linear fluorinated hydrocarbon group, and may have a branched and / or ring structure. It may be a fluorinated hydrocarbon group having.
As ^{the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R 21} or R ²² , an alkyl fluorinated group or an aryl fluorinated group is preferable, and an alkyl fluorinated group is more preferable.

In the formula (2), the ^{number of carbon atoms of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R 21} or R ²² is more preferably 1 to 3, further preferably 1 or 2, and particularly preferably 1. ..

Specific examples of the compound represented by the formula (2) include compounds represented by the following formulas (2-1) to (2-11) (hereinafter, compounds (2-1) to compounds (2, respectively). -11)), but the compound represented by the formula (2) is not limited to these specific examples.
Of these, compound (2-1) (vinylene carbonate) is particularly preferable.

When the non-aqueous electrolytic solution of the present disclosure contains a compound represented by the formula (2), the content of the compound represented by the formula (2) with respect to the total amount of the non-aqueous electrolytic solution is 0.001% by mass or more. 10% by mass is preferable, 0.005% by mass to 5% by mass is more preferable, 0.01% by mass to 5% by mass is further preferable, and 0.1% by mass to 3% by mass is particularly preferable.

When the non-aqueous electrolyte solution of the present disclosure contains a compound represented by the formula (2), the ratio of the content mass of the compound represented by the formula (2) to the content mass of the compound represented by the formula (1) ( Hereinafter, the content mass ratio (also referred to as "compound represented by formula (2) / compound represented by formula (1)") is preferably 0.1 to 10, and more preferably 0.2 to 10. It is 5, more preferably 0.3 to 3, and even more preferably 0.5 to 2.

<Other additives>
The non-aqueous electrolytic solution of the present disclosure may contain at least one kind of additives other than the compound represented by the above formula (1) and the compound represented by the above formula (2).
Examples of other additives include known additives that can be contained in a non-aqueous electrolytic solution.
Other additives include, for example,
Oxalato compounds such as lithium difluorobis (oxalate) phosphate, lithium tetrafluoro (oxalate) phosphate, lithium tris (oxalate) phosphate, lithium difluoro (oxalate) borate, and lithium bis (oxalate) borate;
1,3-Propane sultone, 1,4-butane sultone, 1,3-propensultone, 1-methyl-1,3-propensultone, 2-methyl-1,3-propensultone, 3-methyl-1,3- Sultone compounds such as propensultone;
Catechol sulfate, 1,2-cyclohexyl sulfate, 2,2-dioxo-1,3,2-dioxathiolane, 4-methyl-2,2-dioxo-1,3,2-dioxathiolane, 4-ethyl-2,2- Dioxo-1,3,2-dioxathiolane, 4-propyl-2,2-dioxo-1,3,2-dioxathiolane, 4-butyl-2,2-dioxo-1,3,2-dioxathiolane, 4-pentyl- 2,2-Dioxo-1,3,2-dioxathiolane, 4-hexyl-2,2-dioxo-1,3,2-dioxathiolane,
4-Methylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, 4-ethylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, bis ((2,2-dioxo)) Cyclic sulfate compounds such as -1,3,2-dioxathiolan-4-yl) methyl) sulfate, 4,4'-bis (2,2-dioxo-1,3,2-dioxathiolane);
And so on.

In addition, as other additives,
Sulfur compounds such as ethylene sulfite, propylene sulfite, ethylene sulfate, propylene sulfate, butene sulfate, hexene sulfate, vinylene sulfate, 3-sulfolene, divinylsulfone, dimethyl sulfate, diethyl sulfate; dimethyl vinylboronate, diethyl vinylboronate, dipropyl vinylboronate , Vinylboronic acid compounds such as dibutyl vinylboronate;
Amides such as dimethylformamide;
Chain carbamates such as methyl-N, N-dimethyl carbamate;
Cyclic amides such as N-methylpyrrolidone;
Cyclic ureas such as N, N-dimethylimidazolidinone;
Boric acid esters such as trimethyl borate, triethyl borate, tributyl borate, trioctyl borate, tri (trimethylsilyl) borate;
Phosphate esters such as lithium difluorophosphate, lithium monofluorophosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tri (trimethylsilyl) phosphate, triphenyl phosphate;
Ethylene glycol derivatives such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and polyethylene glycol dimethyl ether;
Aromatic hydrocarbons such as biphenyl, fluorobiphenyl, o-terphenyl, toluene, ethylbenzene, fluorobenzene, cyclohexylbenzene, 2-fluoroanisole, 4-fluoroanisole;
A carboxylic acid anhydride having a carbon-carbon unsaturated bond such as maleic anhydride and norbornene dicarboxylic acid anhydride;
And so on.

Next, other components of the non-aqueous electrolyte solution will be described. The non-aqueous electrolyte solution generally contains an electrolyte and a non-aqueous solvent.

<Electrolyte>
The electrolyte in the non-aqueous electrolyte solution of the present disclosure preferably contains a lithium salt, and more preferably contains _{LiPF 6.}
When the electrolyte comprises a LiPF _6, the proportion of LiPF ₆ occupied in the electrolyte is preferably 10 wt% to 100 wt%, more preferably 50 to 100 mass%, more preferably 70 wt% to 100 wt% is there.

The concentration of the electrolyte in the non-aqueous electrolyte solution of the present disclosure is preferably 0.1 mol / L to 3 mol / L, more preferably 0.5 mol / L to 2 mol / L.
_{The concentration of LiPF 6} in the non-aqueous electrolytic solution of the present disclosure is preferably 0.1 mol / L to 3 mol / L, more preferably 0.5 mol / L to 2 mol / L.

When the electrolyte _{contains LiPF 6} , the electrolyte may contain a compound other than _{LiPF 6.}
As a compound other than _{LiPF 6,;}
(C ₂ H ₅ ) ₄ NPF ₆ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NClo ₄ , (C ₂ H ₅ ) ₄ NAsF ₆ , (C ₂ H ₅ ) ₄ N ₂ SiF ₆ , (C ₂ H ₅ ) ₄ NOSO ₂ C _k F _{(2 k + 1)} (integer of k = 1 to 8), (C ₂ H ₅ ) ₄ NPF _n [C _k F _{(2 k + 1)} ] _(6-n) ( Tetraalkylammonium salts such as n = 1 to 5 integers, k = 1 to 8 integers);
LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{(2 k + 1)} (integer of k = 1 to 8), LiPF _n [C _k F _{(2 k + 1)} ] _(6-n) (n = 1-5, k = integer of 1-8), LiC (SO ₂ R ^7X ) (SO ₂ R ^8X ) (SO ₂ R ^9X ), LiN (SO ₂ OR ^10X ) (SO ₂ OR ^11X ), LiN (SO) _{Lithium salts such as 2} R ^12X ) (SO ₂ R ^13X ) (where R ^{7X to} R ^13X may be the same or different from each other and are fluorine atoms or perfluoroalkyl groups with 1 to 8 carbon atoms) (ie, , Lithium salts other than _{LiPF 6);}
And so on.

<Non-aqueous solvent>
The non-aqueous solvent in the non-aqueous electrolytic solution of the present disclosure may be only one type or two or more types.
As the non-aqueous solvent, various known solvents can be appropriately selected.
As the non-aqueous solvent, for example, the non-aqueous solvent described in paragraphs 0069 to 0087 of JP-A-2017-45723 can be used.

The non-aqueous solvent preferably contains a cyclic carbonate compound and a chain carbonate compound.
In this case, the cyclic carbonate compound and the chain carbonate compound contained in the non-aqueous solvent may be only one kind or two or more kinds, respectively.

Examples of the cyclic carbonate compound include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate and the like.
Of these, ethylene carbonate and propylene carbonate having a high dielectric constant are preferable. In the case of a battery using a negative electrode active material containing graphite, it is more preferable that the non-aqueous solvent contains ethylene carbonate.

Examples of the chain carbonate compound include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, dibutyl carbonate, methyl pentyl carbonate, and ethyl pentyl. Examples thereof include carbonate, dipentyl carbonate, methylheptyl carbonate, ethylheptyl carbonate, diheptyl carbonate, methylhexyl carbonate, ethylhexyl carbonate, dihexyl carbonate, methyloctyl carbonate, ethyloctyl carbonate, dioctyl carbonate and the like.

Specific combinations of cyclic carbonate and chain carbonate include ethylene carbonate and dimethyl carbonate, ethylene carbonate and methyl ethyl carbonate, ethylene carbonate and diethyl carbonate, propylene carbonate and dimethyl carbonate, propylene carbonate and methyl ethyl carbonate, and propylene carbonate. Diethyl carbonate, ethylene carbonate and propylene carbonate and methyl ethyl carbonate, ethylene carbonate and propylene carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and methyl ethyl carbonate and diethyl carbonate. , Ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate, ethylene carbonate, propylene carbonate, methyl ethyl carbonate and diethyl Examples thereof include carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate.

The mixing ratio of the cyclic carbonate compound and the chain carbonate compound is expressed by a mass ratio, and the cyclic carbonate compound: the chain carbonate compound is, for example, 5:95 to 80:20, preferably 10:90 to 70:30, more preferably. Is 15:85 to 55:45. By setting such a ratio, it is possible to suppress an increase in the viscosity of the non-aqueous electrolyte solution and increase the degree of dissociation of the electrolyte, so that the conductivity of the non-aqueous electrolyte solution related to the charge / discharge characteristics of the battery can be increased. .. Moreover, the solubility of the electrolyte can be further increased. Therefore, since the non-aqueous electrolytic solution having excellent electrical conductivity at room temperature or low temperature can be obtained, the load characteristics of the battery at room temperature to low temperature can be improved.

The non-aqueous solvent may contain other compounds other than the cyclic carbonate compound and the chain carbonate compound.
In this case, the other compounds contained in the non-aqueous solvent may be only one kind or two or more kinds.
Other compounds include cyclic carboxylic acid ester compounds (for example, γ butyrolactone), cyclic sulfone compounds, cyclic ether compounds, chain carboxylic acid ester compounds, chain ether compounds, chain phosphate ester compounds, amide compounds, and chain carbamate. Examples thereof include compounds, cyclic amide compounds, cyclic urea compounds, boron compounds, polyethylene glycol derivatives, and the like.
For these compounds, the description in paragraphs 0069 to 0087 of JP-A-2017-45723 can be appropriately referred to.

The proportion of the cyclic carbonate compound and the chain carbonate compound in the non-aqueous solvent is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.
The ratio of the cyclic carbonate compound and the chain carbonate compound in the non-aqueous solvent may be 100% by mass.

The ratio of the non-aqueous solvent to the non-aqueous electrolytic solution is preferably 60% by mass or more, and more preferably 70% by mass or more.
The upper limit of the ratio of the non-aqueous solvent to the non-aqueous electrolyte solution depends on the content of other components (electrolyte, additive, etc.), but the upper limit is, for example, 99% by mass, preferably 97% by mass. Yes, more preferably 90% by mass.

[Lithium secondary battery]
The lithium secondary battery of the present disclosure includes a positive electrode, a negative electrode, and a non-aqueous electrolytic solution of the present disclosure.

<Negative electrode>
The negative electrode may include a negative electrode active material and a negative electrode current collector.
Examples of the negative electrode active material in the negative electrode include metallic lithium, lithium-containing alloys, metals or alloys that can be alloyed with lithium, oxides that can be doped / dedoped with lithium ions, and lithium ions that can be doped / dedoped. At least one selected from the group consisting of transition metal nitridates and carbon materials capable of doping and dedoping lithium ions (either alone or in admixture containing two or more of these). Good) can be used.
Examples of the metal or alloy that can be alloyed with lithium (or lithium ion) include silicon, a silicon alloy, tin, and a tin alloy.
Examples of the oxide capable of doping and dedoping lithium ions include lithium titanate, silicon oxide (preferably SiOx (X represents 0.5 or more and less than 1.6), and more preferably SiO). Can be done.
Among these, a carbon material capable of doping and dedoping lithium ions is preferable. Examples of such carbon materials include carbon black, activated carbon, graphite materials (artificial graphite, natural graphite), amorphous carbon materials, and the like. The form of the carbon material may be any of fibrous, spherical, potato-like, and flake-like forms.

Specific examples of the amorphous carbon material include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1500 ° C. or lower, and mesophase pitch carbon fiber (MCF).
Examples of the graphite material include natural graphite and artificial graphite. As the artificial graphite, graphitized MCMB, graphitized MCF and the like are used. Further, as the graphite material, a material containing boron or the like can also be used. Further, as the graphite material, a material coated with a metal such as gold, platinum, silver, copper or tin, a material coated with amorphous carbon, or a mixture of amorphous carbon and graphite can also be used.

These carbon materials may be used alone or in admixture of two or more.
As the carbon material, a carbon material having a surface spacing d (002) of the (002) plane measured by X-ray analysis of 0.340 nm or less is particularly preferable. Further, as the carbon material, graphite having a true density of 1.70 g / cm ³ or more or a highly crystalline carbon material having properties close to the graphite is also preferable. When the carbon material as described above is used, the energy density of the battery can be further increased.

The material of the negative electrode current collector in the negative electrode is not particularly limited, and any known material can be used.
Specific examples of the negative electrode current collector include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. Of these, copper is particularly preferable from the viewpoint of ease of processing.

<Positive electrode>
The positive electrode may include a positive electrode active material and a positive electrode current collector.
Examples of the positive electrode active material in the positive electrode include transition metal oxides or transition metal sulfides such _{as MoS 2} , TiS ₂ , MnO ₂ , and V ₂ O _{5 , LiCoO 2} , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiNi _X Co. _(1-X) O ₂ [0 <X <1], _{Li 1 + α} Me _1-α O _{2 having an α-NaFeO type 2} crystal structure (Me is a transition metal element containing Mn, Ni and Co, 1.0 ≦ (1 + α) / ( 1-α) ≦ 1.6), LiNi x Co y Mn z O 2 [x + y + z = 1,0 < x <1,0 <y <1,0 <z <1 ] (e.g., LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ etc.), LiFePO ₄ , LiMnPO ₄ and other composite oxides consisting of lithium and transition metals, Examples thereof include conductive polymer materials such as polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene, dimercaptothiaizole, and polyaniline complex. Among these, a composite oxide composed of lithium and a transition metal is particularly preferable. When the negative electrode is a lithium metal or a lithium alloy, a carbon material can also be used as the positive electrode. Further, as the positive electrode, a mixture of a composite oxide of lithium and a transition metal and a carbon material can also be used.
The positive electrode active material may be used alone or in combination of two or more. When the positive electrode active material has insufficient conductivity, it can be used together with a conductive auxiliary agent to form a positive electrode. Examples of the conductive auxiliary agent include carbon materials such as carbon black, amorphous whiskers, and graphite.

The material of the positive electrode current collector in the positive electrode is not particularly limited, and any known material can be used.
Specific examples of the positive electrode current collector include metal materials such as aluminum, aluminum alloy, stainless steel, nickel, titanium, and tantalum; carbon materials such as carbon cloth and carbon paper; and the like.

<Separator>
The lithium secondary battery of the present disclosure preferably contains a separator between the negative electrode and the positive electrode.
The separator is a membrane that electrically insulates the positive electrode and the negative electrode and allows lithium ions to pass through, and examples thereof include a porous membrane and a polymer electrolyte.
As the porous film, a microporous polymer film is preferably used, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester and the like.
In particular, porous polyolefin is preferable, and specifically, a porous polyethylene film, a porous polypropylene film, or a multilayer film of a porous polyethylene film and a polypropylene film can be exemplified. The porous polyolefin film may be coated with another resin having excellent thermal stability.
Examples of the polymer electrolyte include a polymer in which a lithium salt is dissolved, a polymer inflated with an electrolytic solution, and the like.
The non-aqueous electrolyte solution of the present disclosure may be used for the purpose of swelling a polymer to obtain a polymer electrolyte.

<Battery configuration>
The lithium secondary battery of the present disclosure can take various known shapes, and can be formed into a cylindrical type, a coin type, a square type, a laminated type, a film type, or any other shape. However, the basic structure of the battery is the same regardless of the shape, and the design can be changed according to the purpose.

An example of the lithium secondary battery of the present disclosure is a laminated battery.
FIG. 1 is a schematic perspective view showing an example of a laminated battery which is an example of the lithium secondary battery of the present disclosure, and FIG. 2 is a thickness of a laminated electrode body housed in the laminated battery shown in FIG. It is a schematic sectional view of a direction.
The laminated battery shown in FIG. 1 contains a non-aqueous electrolytic solution (not shown in FIG. 1) and a laminated electrode body (not shown in FIG. 1), and the peripheral edge thereof is sealed. A laminated exterior body 1 whose inside is hermetically sealed is provided. As the laminated exterior body 1, for example, a laminated exterior body made of aluminum is used.
As shown in FIG. 2, the laminated electrode body housed in the laminated exterior body 1 is a laminated body in which a positive electrode plate 5 and a negative electrode plate 6 are alternately laminated via a separator 7, and a laminated body of the laminated body. A separator 8 that surrounds the periphery is provided. The positive electrode plate 5, the negative electrode plate 6, the separator 7, and the separator 8 are impregnated with the non-aqueous electrolytic solution of the present disclosure.
The plurality of positive electrode plates 5 in the laminated electrode body are all electrically connected to the positive electrode terminal 2 via the positive electrode tab (not shown), and a part of the positive electrode terminal 2 is the laminated exterior body 1. It protrudes outward from the peripheral end (Fig. 1). A portion of the peripheral end of the laminated exterior body 1 from which the positive electrode terminal 2 protrudes is sealed with an insulating seal 4.
Similarly, the plurality of negative electrode plates 6 in the laminated electrode body are all electrically connected to the negative electrode terminal 3 via the negative electrode tab (not shown), and a part of the negative electrode terminal 3 is the laminated exterior. It protrudes outward from the peripheral end of the body 1 (FIG. 1). A portion of the peripheral end of the laminated exterior body 1 on which the negative electrode terminal 3 protrudes is sealed with an insulating seal 4.
In the laminated battery according to the above example, the number of positive electrode plates 5 is 5 and the number of negative electrode plates 6 is 6, and the positive electrode plate 5 and the negative electrode plate 6 are located on both sides of the battery via the separator 7. The outer layers are all laminated so as to be the negative electrode plate 6. However, it goes without saying that the number of positive electrode plates, the number of negative electrode plates, and the arrangement of the laminated battery are not limited to this example, and various changes may be made.

Another example of the lithium secondary battery of the present disclosure is a coin-type battery.
FIG. 3 is a schematic perspective view showing an example of a coin-type battery, which is another example of the lithium secondary battery of the present disclosure.
In the coin-type battery shown in FIG. 3, a disk-shaped negative electrode 12, a separator 15 injected with a non-aqueous electrolyte solution, a disk-shaped positive electrode 11, and, if necessary, spacer plates 17 and 18 made of stainless steel or aluminum are arranged in this order. In a laminated state, it is stored between the positive electrode can 13 (hereinafter, also referred to as “battery can”) and the sealing plate 14 (hereinafter, also referred to as “battery can lid”). The positive electrode can 13 and the sealing plate 14 are caulked and sealed via the gasket 16.
In this example, the non-aqueous electrolytic solution of the present disclosure is used as the non-aqueous electrolytic solution to be injected into the separator 15.

The lithium secondary battery of the present disclosure is obtained by charging / discharging a lithium secondary battery (lithium secondary battery before charging / discharging) containing a negative electrode, a positive electrode, and the non-aqueous electrolyte solution of the present disclosure. It may be a lithium secondary battery.
That is, as the lithium secondary battery of the present disclosure, first, a lithium secondary battery before charging / discharging containing a negative electrode, a positive electrode, and the non-aqueous electrolyte solution of the present disclosure is prepared, and then the lithium secondary battery before charging / discharging is prepared. It may be a lithium secondary battery (charged / discharged lithium secondary battery) manufactured by charging / discharging the lithium secondary battery one or more times.

The use of the lithium secondary battery of the present disclosure is not particularly limited, and it can be used for various known uses. For example, laptops, mobile computers, mobile phones, headphone stereos, video movies, LCD TVs, handy cleaners, electronic organizers, calculators, radios, backup power supplies, motors, automobiles, electric vehicles, bikes, electric bikes, bicycles, electric It can be widely used regardless of whether it is a small portable device or a large device such as a bicycle, a lighting device, a game machine, a clock, an electric tool, or a camera.

Hereinafter, examples of the present disclosure will be shown, but the present disclosure is not limited to the following examples.
In the following examples, "addition amount" means the content of the finally obtained non-aqueous electrolyte solution with respect to the total amount, and "wt%" means mass%, and "formula (1) compound". "" Means the compound represented by the formula (1), and "the compound of the formula (2)" means the compound represented by the formula (2).

[Example 1]
A coin-type lithium secondary battery (hereinafter, also referred to as “coin-type battery”) having the configuration shown in FIG. 3 was produced by the following procedure.

<Cathode preparation>
LiNi _0.5 Mn _0.3 Co _0.2 O ₂ (90 parts by mass), acetylene black (5 parts by mass) and polyvinylidene fluoride (5 parts by mass) are kneaded with N-methylpyrrolidinone as a solvent to form a paste. A positive mixture slurry was prepared.
Next, this positive electrode mixture slurry is applied to a positive electrode current collector of a strip-shaped aluminum foil having a thickness of 20 μm, dried, and then compressed by a roll press to form a sheet-shaped positive electrode composed of the positive electrode current collector and the positive electrode active material layer. Got At this time, the coating density of the positive electrode active material layer was 22 mg / cm ² , and the packing density was 2.5 g / mL.

<Manufacturing of negative electrode>
Amorphous coated natural graphite (97 parts by mass), carboxymethyl cellulose (1 part by mass) and SBR latex (2 parts by mass) were kneaded with an aqueous solvent to prepare a paste-like negative electrode mixture slurry.
Next, this negative electrode mixture slurry is applied to a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm, dried, and then compressed by a roll press to form a sheet-shaped negative electrode composed of a negative electrode current collector and a negative electrode active material layer. Got At this time, the coating density of the negative electrode active material layer was 12 mg / cm ² , and the packing density was 1.5 g / mL.

<Preparation of non-aqueous electrolyte solution>
As a non-aqueous solvent, ethylene carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) were mixed at a ratio of 30:35:35 (mass ratio) to obtain a mixed solvent.
_{LiPF 6} as an electrolyte was dissolved in the obtained mixed solvent so that the electrolyte concentration in the finally prepared non-aqueous electrolyte solution was 1.2 mol / liter.
As an additive to the obtained solution
The content of the compound (1-5), which is a specific example of the compound represented by the formula (1) (hereinafter, also referred to as “the compound of the formula (1)”), with respect to the total mass of the finally prepared non-aqueous electrolyte solution. Is added so as to be 0.5% by mass (that is, added at an addition amount of 0.5% by mass).
A non-aqueous electrolyte was obtained.

<Making coin-type batteries>
The above-mentioned negative electrode had a diameter of 14 mm and the above-mentioned positive electrode had a diameter of 13 mm, and each was punched into a disk shape to obtain a coin-shaped negative electrode and a coin-shaped positive electrode, respectively. Further, a microporous polyethylene film having a thickness of 20 μm was punched into a disk shape having a diameter of 17 mm to obtain a separator.
The obtained coin-shaped negative electrode, separator, and coin-shaped positive electrode were laminated in this order in a stainless steel battery can (2032 size), and then 20 μL of a non-aqueous electrolytic solution was injected into the battery can. It was impregnated in the separator, the positive electrode and the negative electrode.
Next, an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were placed on the positive electrode, and the battery was sealed by crimping the battery can lid via a polypropylene gasket.
As described above, a coin-type battery (that is, a coin-type lithium secondary battery) having a diameter of 20 mm and a height of 3.2 mm and having the configuration shown in FIG. 3 was obtained.

<Evaluation>
The obtained coin-type battery was evaluated as follows.
The evaluation results are shown in Table 1.
In Table 1, the battery resistance (DC resistance) and the positive electrode resistance (positive electrode impedance) in each example are shown as relative values when the value in Comparative Example 1 described later is set to 100, respectively.

In the following
"Conditioning" means that a coin-operated battery is charged and discharged three times between 2.75V and 4.25V at 25 ° C. in a constant temperature bath.
"High temperature storage" means an operation of storing a coin-type battery in a constant temperature bath at 80 ° C. for 2 days.
Hereinafter, the DC resistance was measured under a temperature condition of −20 ° C., and the impedance was measured under a temperature condition of −10 ° C.

(Measurement of battery resistance (DC resistance) before high temperature storage)
The above coin-type battery was conditioned.
The conditioned coin-type battery is charged to a constant voltage of 3.9 V, and then the charged coin-type battery is cooled to -20 ° C in a constant temperature bath and discharged at a constant current of 0.2 mA at -20 ° C. Then, the battery resistance (DC resistance (-20 ° C.)) of the coin-type battery before high-temperature storage was measured by measuring the potential drop in 10 seconds from the start of discharge. The battery resistance (DC resistance (-20 ° C.)) before high-temperature storage was measured in the same manner for the coin-type battery of Comparative Example 1 described later.
Table 1 shows the battery resistance (DC resistance) before high-temperature storage as a relative value when the value in Comparative Example 1 is 100.

(Measurement of battery resistance (DC resistance) after high temperature storage)
A coin-type battery after conditioning and before charging to a constant voltage of 3.9 V is CC-CV charged to 4.25 V at a charging rate of 0.2 C at 25 ° C in a constant temperature bath, and then stored at a high temperature (that is, that is). , Battery resistance (DC resistance) after high temperature storage is measured in the same way as the above-mentioned measurement of battery resistance (DC resistance) before high temperature storage, except that the operation of performing storage at 80 ° C for 2 days) is added. did.
Table 1 shows the battery resistance (DC resistance) after high-temperature storage as a relative value when the value in Comparative Example 1 is 100.

(Measurement of positive electrode resistance (positive electrode impedance) before high temperature storage)
The above coin-type battery was conditioned.
The conditioned coin-type battery was adjusted to 100% SOC (State of Charge), and then the impedance of the coin-type battery was measured at a frequency f in the range of 0.1 Hz to 100,000 Hz. Based on the obtained results, a graph showing the relationship between the frequency f and the impedance was created, and in the obtained graph, the impedance at 0.1 Hz was defined as the positive electrode impedance.
The obtained results are shown in Table 1 as relative values when the value in Comparative Example 1 is 100.

(Measurement of positive electrode resistance (positive electrode impedance) after high temperature storage)
The coin-type battery after conditioning and before adjusting to 100% SOC is charged CC-CV to 4.25 V at a charging rate of 0.2 C at 25 ° C in a constant temperature bath, and then stored at a high temperature (that is, 80 ° C). The positive electrode resistance (positive electrode impedance) after high-temperature storage was measured in the same manner as the above-mentioned measurement of the positive electrode resistance (positive electrode impedance) before high-temperature storage, except that the operation of performing storage for 2 days was added.
The obtained results are shown in Table 1 as relative values when the value in Comparative Example 1 is 100.

[Examples 2 to 6]
The same operation as in Example 1 was carried out except that the type of the compound of formula (1) in the non-aqueous electrolytic solution was changed as shown in Table 1.
The results are shown in Table 1.
The type of the compound of formula (1) in Table 1 corresponds to the compound number of the above-mentioned specific example.

[Comparative Example 1]
The same operation as in Example 1 was carried out except that the compound of formula (1) was not contained in the non-aqueous electrolytic solution.
The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 6 using the non-aqueous electrolyte solution for batteries containing the compound of formula (1), comparative examples using the non-aqueous electrolyte solution for batteries not containing the compound of formula (1). Compared with No. 1, the battery resistance and the positive electrode resistance were reduced.

[Examples 101-107]
The same operation as in Example 1 was performed except that the additive (formula (1) compound) in the non-aqueous electrolyte solution was changed to the additive (formula (1) compound and formula (2) compound) shown in Table 2. It was.
However, each of the battery resistance and the positive electrode resistance is represented by a relative value when the value of Comparative Example 101 described later is set to 100.
The results are shown in Table 2.

[Comparative Example 101]
The same operation as in Example 101 was carried out except that the compound of formula (1) was not contained in the non-aqueous electrolytic solution.
The results are shown in Table 2.

As shown in Table 2, in Examples 101 to 107 using the compound of formula (1) and the non-aqueous electrolytic solution for batteries containing the compound of formula (2), the compound of formula (2) is contained, but the formula (1) is used. Compared with Comparative Example 101 using the non-aqueous electrolytic solution for batteries containing no compound, the battery resistance and the positive electrode resistance were reduced.

1 Laminated exterior 2 Positive electrode terminal 3 Negative electrode terminal 4 Insulation seal 5 Positive electrode plate 6 Negative electrode plate 7, 8 Separator 11 Positive electrode 12 Negative electrode 13 Positive electrode can 14 Seal plate 15 Separator 16 Gasket 17, 18 Spacer plate

Claims (6)

A non-aqueous electrolytic solution for a battery containing a compound represented by the following formula (1).

[In equation (1),
R ^{1 to} R ⁹ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
R ¹⁰ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a phenyl group, or a group represented by the formula (S1).
In equation (S1),
R ^{11 to} R ¹³ independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a phenyl group.
L ¹ represents a single bond or an oxygen atom
* Represents the bond position. ] The non-aqueous electrolytic solution for a battery according to claim 1, wherein the content of the compound represented by the formula (1) is 0.001% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolytic solution. The non-aqueous electrolytic solution for a battery according to claim 1 or 2, further containing a compound represented by the following formula (2).

[In the formula (2), R ²¹ and R ²² independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms. ] The non-aqueous electrolytic solution for a battery according to claim 3, wherein the content of the compound represented by the formula (2) is 0.001% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolytic solution. With the positive electrode
Metallic lithium, lithium-containing alloys, metals or alloys that can be alloyed with lithium, oxides that can be doped and dedoped with lithium ions, transition metal nitrogen compounds that can be doped and dedoped with lithium ions, and lithium. A negative electrode containing at least one selected from the group consisting of a carbon material capable of doping and dedoping ions as a negative electrode active material, and a negative electrode.
The non-aqueous electrolyte solution for a battery according to any one of claims 1 to 4.
Lithium secondary battery including. A lithium secondary battery obtained by charging / discharging the lithium secondary battery according to claim 5.

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