JP2021018911A - Electrolyte additive, electrolyte, and lithium battery - Google Patents

Abstract

To provide an electrolyte additive capable of further improving the potential stability with respect to repeated charging and discharging.SOLUTION: An electrolyte additive, which is a mixture of an amide compound represented by CH2=CH-C(=O)-NR1R2 (R1 and R2 are the same or different to indicate hydrogen atoms or hydrocarbon groups that may be substituted) and a naphthalene derivative having 1 to 3 (same or different) hydroxy groups or alkyl groups as substituents, is used so as to be added to a non-aqueous electrolytic solution of a lithium ion secondary battery.SELECTED DRAWING: None

Description

The present invention relates to an additive for an electrolytic solution, an electrolytic solution, a lithium battery, and the like.

In recent years, there has been a demand for technology for more effectively utilizing electric power against the background of energy problems and environmental problems. For that purpose, an electric storage means capable of storing a large amount of electric power in a small size and efficiently extracting the electric power is required. Since metallic lithium has a large discharge capacity and a high discharge voltage, it is attracting attention as a next-generation material.

Metallic lithium batteries that use metallic lithium as the negative electrode are attracting attention because they can produce high capacity. Lithium has a low density of 0.54 g / cm ³ and a very low standard reduction potential of -3.045 V (SHE: based on the standard hydrogen electrode), so it is attracting attention as an electrode material for high energy density batteries. ..

Patent Document 1 reports that an electrolytic solution containing a specific base agent and a specific leveling agent can be suitably used as an electrolytic solution for a metallic lithium battery. More specifically, by using such an electrolytic solution, it is possible to suppress the precipitation of metallic lithium dendrites on the surface of the negative electrode, and to suppress the formation of lithium dendrites and the growth of nuclei during the charge / discharge cycle. It has been reported.

Japanese Unexamined Patent Publication No. 2018-11186

In the course of research, the present inventor focused on the problem that the potential rises when the metallic lithium battery is repeatedly charged and discharged. Then, it was noted that the potential stability with respect to repeated charging and discharging was insufficient depending on the combination of additives.

Therefore, an object of the present invention is to provide a technique capable of further improving the potential stability with respect to repeated charging and discharging.

As a result of diligent research in view of the above problems, the present inventor has obtained a combination of an amide compound specified by a specific general formula and an aromatic compound specified by a specific general formula in an electrolytic solution. It has been found that the potential stability with respect to repeated charging and discharging can be further improved. As a result of further research based on this finding, the present invention has been completed. That is, the present invention includes the following aspects.

Item 1. General formula (1):

[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
The amide compound represented by, and the general formula (2):

[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
An additive for an electrolytic solution containing an aromatic compound represented by.

Item 2. The amide compound is acrylamide, N- [3- (dimethylamino) propyl] acrylamide, N, N-diethylacrylamide, N, N'-ethylenebisacrylamide, N, N'-methylenebisacrylamide, N-isopropylacrylamide, Item 2. The additive for an electrolytic solution according to Item 1, which is at least one selected from the group consisting of N-tert-butyl acrylamide, diacetone acrylamide, N-dodecyl acrylamide, and N- (butoxymethyl) acrylamide.

Item 3. The aromatic compounds are 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1 , 7-Dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene , 1,4-Dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 2-methyl-1-naphthol, 3-methyl-1- Naphthal, 4-methyl-1-naphthol, 5-methyl-1-naphthol, 6-methyl-1-naphthol, 7-methyl-1-naphthol, 1-methyl-2-naphthol, 1-methyl-3-naphthol, Item 2. The additive for an electrolytic solution according to Item 1 or 2, which is at least one selected from the group consisting of 1-methyl-6-naphthol and 1-methyl-7-naphthol.

Item 4. General formula (1):

[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
The general formula (2): containing the amide compound represented by

[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
Additive for electrolytic solution to be used for addition to the electrolytic solution together with the aromatic compound represented by.

Item 5. General formula (2):

[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
General formula (1): containing an aromatic compound represented by

[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
Additive for electrolytic solution to be used for addition to the electrolytic solution together with the amide compound represented by.

Item 6. Item 2. The additive for an electrolytic solution according to any one of Items 1 to 5, which is for a lithium battery.

Item 7. It contains a lithium salt, a solvent, and the additive for an electrolytic solution according to any one of Items 1 to 3, or the additive for an electrolytic solution according to Item 4 and the additive for an electrolytic solution according to Item 5. Electrolyte.

Item 8. Item 2. The electrolytic solution according to Item 7, wherein the content of the amide compound in the electrolytic solution is 0.01 to 10 g / L.

Item 9. Item 7. The electrolytic solution according to Item 7 or 8, wherein the content of the aromatic compound in the electrolytic solution is 0.01 to 10 g / L.

Item 10. Item 2. The electrolytic solution according to any one of Items 7 to 8, wherein the content of the lithium salt in the electrolytic solution is 0.1 to 10 mol / L.

Item 11. Item 2. The electrolytic solution according to any one of Items 7 to 10, which is for a lithium battery.

Item 12. A lithium battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer arranged between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer contains the electrolytic solution according to any one of Items 7 to 11.

According to the present invention, it is possible to provide a technique capable of further improving the potential stability with respect to repeated charging and discharging. Specifically, for example, an additive for an electrolytic solution, an electrolytic solution, a lithium battery and the like can be provided.

A representative example (result of Example 2) of the charge / discharge test result of the Example is shown. The vertical axis shows the potential, and the horizontal axis shows the elapsed time from the start of the test. A representative example of the charge / discharge test result of the comparative example (result of the comparative example 1) is shown. The vertical axis shows the potential, and the horizontal axis shows the elapsed time from the start of the test.

In the present specification, the expressions "contains" and "contains" include the concepts of "contains", "contains", "substantially consists" and "consists of only".

1. 1. Additives for electrolytes In one aspect of the present invention, the general formula (1):

[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
The amide compound represented by, and the general formula (2):

[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
It relates to an additive for an electrolytic solution containing an aromatic compound represented by (in the present specification, it may be referred to as "additive for an electrolytic solution 1 of the present invention"). This will be described below.

The amide compound represented by the general formula (1) (hereinafter, may be referred to as “amide compound”) is not particularly limited as long as it can be blended in the electrolytic solution.

R ¹ and R ² are preferably hydrocarbon groups, one of which is a hydrogen atom and the other of which may be substituted.

The hydrocarbon group represented by R ¹ or R ² is not particularly limited, and is, for example, an alkyl group, an aryl group, or a group formed by arbitrarily combining these (for example, an aralkyl group, an alkylaryl group, an alkylaralkyl group). Group) and the like. From the viewpoint of potential stability with respect to repeated charging and discharging, the hydrocarbon group is preferably an alkyl group.

The alkyl group represented by R ¹ or R ² includes any of linear, branched, and cyclic (preferably linear or branched chain, more preferably branched chain). To. The number of carbon atoms of the alkyl group (in the case of a linear or branched chain) is not particularly limited, and is, for example, 1 to 18. The number of carbon atoms is preferably 1 to 12, more preferably 2 to 8, still more preferably 2 to 6, still more preferably 3 to 5, and particularly preferably 4. The number of carbon atoms of the alkyl group (in the case of a cyclic group) is not particularly limited, and is, for example, 3 to 7, preferably 4 to 6. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, n-pentyl group, neopentyl group and n. Examples thereof include −hexyl group, 3-methylpentyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group and n-dodecyl group.

The aryl group represented by R ¹ or R ² is not particularly limited, but preferably has 6 to 12 carbon atoms, and more preferably 6 to 8 carbon atoms. The aryl group can be either monocyclic or polycyclic (for example, bicyclic, tricyclic, etc.), but is preferably monocyclic. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, a pentarenyl group, an indenyl group, an anthranyl group, a tetrasenyl group, a pentasenyl group, a pyrenyl group, a peryleneyl group, a fluorenyl group, a phenanthryl group and the like. However, a phenyl group is preferable.

The aralkyl group represented by R ¹ or R ² is not particularly limited, but for example, an aralkyl group in which a hydrogen atom (for example, 1 to 3 or preferably 1 hydrogen atom) of the alkyl group is substituted with the aryl group or the like. Can be mentioned. Specific examples of the aralkyl group include a benzyl group and a phenethyl group.

The alkylaryl group represented by R ¹ or R ² is not particularly limited, but is, for example, an alkylaryl in which the hydrogen atom of the aryl group (for example, 1 to 3 or preferably 1 hydrogen atom) is substituted with the alkyl group. The basis etc. can be mentioned. Specific examples of the alkylaryl group include a tolyl group and a xsilyl group.

The alkyl aralkyl group represented by R ¹ or R ² is not particularly limited, but for example, hydrogen atoms on the aromatic ring of the aralkyl group (for example, 1 to 3 hydrogen atoms, preferably 1 hydrogen atom) are substituted with the alkyl group. Examples thereof include an alkyl aralkyl group obtained from the above.

As the substituent of the hydrocarbon group represented by R ¹ or R ² , for example, an acetyl group, -NR ⁴ R ⁵ (R ⁴ and R ⁵ are the same or different, and indicate a hydrogen atom, a hydrocarbon group, or an acryloyl group. ), An alkoxy group and the like. From the viewpoint of potential stability with respect to repeated charging and discharging, the substituent is preferably an acetyl group.

Examples of the hydrocarbon group represented by R ⁴ or R ⁵ include the same hydrocarbon groups as those represented by R ¹ or R ² .

In one embodiment, R ⁴ and R ⁵ are hydrogen atoms on one side and hydrocarbon groups on the other side.

The alkoxy group is not particularly limited, and is linear or branched (preferably linear) having 1 to 8 carbon atoms, preferably 2 to 6, more preferably 3 to 5, and even more preferably 4. The group is mentioned. Examples of such an alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a t-butoxy group and the like.

The number of substituents of the hydrocarbon group represented by R ¹ or R ² is not particularly limited, and is, for example, 0 to 3, 0 to 2, 0 to 1, or 1.

Specifically, the amide compound is preferably acrylamide, N- [3- (dimethylamino) propyl] acrylamide, N, N-diethylacrylamide, N, N'from the viewpoint of potential stability with respect to repeated charging and discharging. Examples thereof include -ethylenebisacrylamide, N, N'-methylenebisacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, diacetoneacrylamide, N-dodecylacrylamide, and N- (butoxymethyl) acrylamide. Among these, diacetone acrylamide is particularly preferable from the viewpoint of further improving the potential stability with respect to repeated charging and discharging.

The amide compound may be used alone or in combination of two or more.

The aromatic compound represented by the general formula (2) (hereinafter, may be referred to as “aromatic compound”) is not particularly limited as long as it can be blended in the electrolytic solution.

The alkyl group represented by R ³ includes any of linear, branched, and cyclic (preferably linear or branched chain, more preferably linear). The number of carbon atoms of the alkyl group (in the case of a linear or branched chain) is not particularly limited, and is, for example, 1 to 6. The carbon number is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. The number of carbon atoms of the alkyl group (in the case of a cyclic group) is not particularly limited, and is, for example, 3 to 7. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, n-pentyl group, neopentyl group, n. -Hexyl group, 3-methylpentyl group and the like can be mentioned.

n is preferably 1 or 2 from the viewpoint of potential stability with respect to repeated charging and discharging.

From the viewpoint of potential stability with respect to repeated charging and discharging, when n is 1, R ³ is preferably a hydroxy group, and when n is plural (particularly 2), at least one of R ³ is hydroxy. Is the basis.

The substitution position of R ³ is preferably the 1st or 2nd position on the naphthalene ring from the viewpoint of potential stability with respect to repeated charging and discharging.

From the viewpoint of potential stability with respect to repeated charging and discharging, the aromatic compound is preferably the general formula (2A):

[In the formula, R ³¹ and R ³² are the same or different and represent a hydrogen atom, a hydroxy group, or an alkyl group. However, at least one of R ³¹ and R ³² is a hydroxy group. ]
Examples thereof include aromatic compounds represented by.

The alkyl group represented by R ³¹ or R ³² is the same as that of the alkyl group represented by R ³ .

Specific examples of the aromatic compound include 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, and 1,4 from the viewpoint of potential stability with respect to repeated charging and discharging. -Dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1-methylnaphthalene , 2-Methylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2, 7-Dimethylnaphthalene, 2-methyl-1-naphthol, 3-methyl-1-naphthol, 4-methyl-1-naphthol, 5-methyl-1-naphthol, 6-methyl-1-naphthol, 7-methyl-1 Examples thereof include −naphthol, 1-methyl-2-naphthol, 1-methyl-3-naphthol, 1-methyl-6-naphthol, 1-methyl-7-naphthol and the like. Among these, 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene, 1-methyl-2-naphthol and the like are particularly preferable from the viewpoint of further enhancing the potential stability with respect to repeated charging and discharging.

The aromatic compound may be used alone or in combination of two or more.

By blending the amide compound and the aromatic compound in the electrolytic solution, the potential stability with respect to repeated charging and discharging can be further improved. From this point of view, the present invention, in one aspect thereof, is an additive for an electrolytic solution for use in addition to an electrolytic solution together with an aromatic compound containing an amide compound (in the present specification, "electrolysis of the present invention". Liquid additive 2A ”), and an electrolytic solution additive for use in addition to an amide compound containing an aromatic compound (in the present specification, the present invention). (In the present specification, the electrolyte solution 1 of the present invention, the electrolyte solution additive 2A of the present invention, and the electrolyte solution additive 2A of the present invention). Agent 2B may be collectively referred to as "additive for electrolytic solution of the present invention").

The additive for an electrolytic solution of the present invention may contain other components as long as the effect of the present invention is not significantly reduced. From the viewpoint of potential stability with respect to repeated charging and discharging, it is preferable that the additive for an electrolytic solution of the present invention does not contain a compound having sulfur and / or a triple bond. Examples of such a compound include saccharin, 1,2-benzoisothiazole-3 (2H) -one, 2-propin-1-ol, 1,4-butynediol and the like. In particular, compounds having sulfur such as saccharin and 1,2-benzoisothiazole-3 (2H) -one are preferably not included in the additives for the electrolytic solution of the present invention.

2. 2. Electrolyte In one aspect of the present invention, a lithium salt, a solvent, an additive 1 for an electrolytic solution of the present invention, an additive 2A for an electrolytic solution of the present invention, and an additive 2B for an electrolytic solution of the present invention are used. It relates to an electrolytic solution (sometimes referred to as "the electrolytic solution of the present invention" in the present specification) to be contained. This will be described below.

The content of the amide compound in the electrolytic solution of the present invention is not particularly limited, but is, for example, 0.01 to 10 g / L from the viewpoint of potential stability with respect to repeated charging and discharging. From the same viewpoint, the content is preferably 0.1 to 5 g / L, more preferably 0.1 to 2 g / L.

The content of the aromatic compound in the electrolytic solution of the present invention is not particularly limited, but is, for example, 0.01 to 10 g / L from the viewpoint of potential stability with respect to repeated charging and discharging. From the same viewpoint, the content is preferably 0.1 to 5 g / L, more preferably 0.1 to 2 g / L.

In the electrolytic solution of the present invention, the content of the aromatic compound relative to the content of the amide compound is not particularly limited. From the viewpoint of potential stability with respect to repeated discharges, the amount of the aromatic compound is, for example, 1 to 5000 parts by mass, preferably 2 to 3000 parts by mass, and more preferably 5 to 2000 parts by mass with respect to 100 parts by mass of the amide compound.

The lithium salt is not particularly limited as long as it can be blended in the electrolytic solution (particularly in the electrolytic solution of the lithium battery). As the lithium salt, a lithium salt which exhibits sufficient solubility in the solvent contained in the electrolytic solution of the present invention and can impart suitable conductivity can be preferably used. Specific examples of the lithium salt include lithium halide such as lithium chloride and lithium fluoride; lithium oxide; lithium nitrate; a lithium salt of a boron complex such as lithium tetrafluoroborate; a phosphorus complex such as lithium hexafluorophosphate. Lithium salt; Lithium salt of an arsenic complex such as lithium hexafluorohydrate; Lithium perchlorate; Lithium trifrate; Lithium imide; Lithium bis (trifluoromethanesulfonyl) imide (Li [TFSI]); Can be mentioned. Among these, lithium bis (trifluoromethanesulfonyl) imide is preferable from the viewpoint of potential stability against repeated charging and discharging.

One type of lithium salt can be used alone, or two or more types can be used in combination.

The content of the lithium salt in the electrolytic solution of the present invention is not particularly limited, but is, for example, 0.1 to 10 mol / L from the viewpoint of potential stability with respect to repeated charging and discharging. From the same viewpoint, the content is preferably 0.2 to 2 mol / L, more preferably 0.5 to 1.5 mol / L.

The solvent is not particularly limited as long as it can be used as a solvent for an electrolytic solution (particularly an electrolytic solution for a lithium battery). As such a solvent, a non-aqueous solvent can be preferably used, and for example, an ester compound, an ether compound, a carbonate compound, a heterocyclic compound, an aromatic compound and the like can be preferably used.

Examples of the ester compound include fatty acid esters of monocarboxylic acids. The monocarboxylic acid preferably has 1 to 12 carbon atoms. Specific examples of such ester compounds include ethyl acetate, methyl propionate, methyl butyrate, ethyl butyrate, methyl formate and the like.

Examples of the ether compound include linear ether and cyclic ether. Examples of the linear ether include methylene dimethyl ether (DMM), ethylene dimethyl ether (monoglyme), ethylene diethyl ether (DEE), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme). Can be mentioned. As the cyclic ether, for example, tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane can be used.

Examples of the carbonate compound include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Among them, lactones such as γ-butyrolactone and γ-valerolactone can be preferably used.

Examples of the heterocyclic compound include furans and pyridines. Examples of the furans include tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4,4-dimethyl-1,3-dioxane and the like. Examples of pyridines include pyridine, 2-vinylpyridine, 4-vinylpyridine, polyvinylpyridine and the like.

Examples of the aromatic compound include benzene, toluene, xylene and fluorobenzene. Examples of the fluorobenzenes include monofluorobenzene, difluorobenzene, trifluorobenzene, monofluorotoluene, difluorotoluene, monofluoronaphthalene and the like.

As the solvent, an ether compound can be preferably used from the viewpoint of potential stability with respect to repeated charging and discharging.

The solvent may be used alone or in combination of two or more.

The content of the solvent in the electrolytic solution of the present invention is, for example, preferably 25 to 97% by mass, more preferably 60 to 93% by mass, still more preferably 67 to 85% by mass.

The electrolytic solution of the present invention may contain other components as long as the effects of the present invention are not significantly reduced. From the viewpoint of potential stability with respect to repeated charging and discharging, it is preferable that the electrolytic solution of the present invention does not contain sulfur and / or a compound having a triple bond. Examples of such a compound include saccharin, 1,2-benzoisothiazole-3 (2H) -one, 2-propin-1-ol, 1,4-butynediol and the like. In particular, compounds having sulfur such as saccharin and 1,2-benzoisothiazole-3 (2H) -one are preferably not contained in the electrolytic solution of the present invention.

The content of other components is not particularly limited, and is, for example, 20% by mass or less, preferably 3% by mass or less, more preferably 1.5% by mass or less, and 1% by mass with respect to 100% by mass of the electrolytic solution of the present invention. % Or less, 0.5% by mass or less, 0.1% by mass or less, 0.01% by mass or less.

The method for producing the electrolytic solution of the present invention is not particularly limited as long as it can mix a lithium salt, an amide compound, an aromatic compound, and a solvent. For example, the solvent contains a lithium salt, an amide compound, and an aromatic compound. Can be mentioned as a method of sequentially adding. The order in which the lithium salt, the amide compound, the aromatic compound, and the solvent are added is not particularly limited, and may be added in any order.

3. 3. Lithium Battery In one embodiment, the present invention has a positive electrode layer, a negative electrode layer, and an electrolyte layer arranged between the positive electrode layer and the negative electrode layer, and the electrolyte layer contains the electrolytic solution of the present invention. It relates to a battery (in the present specification, it may be referred to as "the lithium battery of the present invention").

A typical example of the lithium battery is a lithium metal battery (particularly, a lithium metal secondary battery). This will be described below.

The positive electrode layer contained in the lithium metal battery produced by using the electrolytic solution of the present invention can contain a material that can be used as the positive electrode active material of the lithium metal battery. Examples of the positive electrode active material include lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , Li. Dissimilar element substitution Li-Mn spinel having a composition represented by _{1 + x} Mn _{2- xy My} O ₄ (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn). , lithium titanate _(Li x _TiO y), phosphate metal lithium (LiMPO _4, M is Fe, Mn, Co or Ni,), vanadium oxide _(V 2 _{O 5)} and molybdenum oxide (MoO ₃₎ transition metal such oxide, titanium sulfide _(TiS 2), carbon materials such as graphite and hard carbon, lithium-cobalt nitride (LiCoN), lithium silicon oxide _{(Li x Si y O z)} , lithium storage intermetallic compound _(Mg x M Alternatively, N _y Sb, M is Sn, Ge, or Sb, N is In, Cu, or Mn) and the like, and derivatives thereof.

The positive electrode layer may contain a binder. Binder materials include polytetrafluoroethylene, polytrifluoroethylene, polyethylene, nitrile rubber, polybutadiene rubber, butyl rubber, hydrogenated butylene rubber, polystyrene, styrene butadiene rubber, styrene butadiene latex, polysulfide rubber, nitrocellulose, and acrylonitrile butadiene rubber. , Polyvinyl fluoride, polyvinylidene fluoride, fluororubber, etc. are desirable, but are not particularly limited.

The positive electrode layer may contain conductive auxiliary material particles, if desired. The conductive auxiliary material particles are not particularly limited, and graphite, carbon black, or the like can be used.

As the negative electrode active material, for example, a lithium metal or a lithium alloy can be used alone or in combination. Examples of the substance capable of forming an alloy with the lithium metal include Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, Sn, In, and Zn.

In addition, the lithium battery of the present invention can also include a separator that prevents a short circuit between the positive electrode and the negative electrode. The separator is not particularly limited, but a material conventionally used for lithium metal batteries can be used. For example, a polymer non-woven fabric such as a polypropylene non-woven fabric or a polyphenylene sulfide non-woven fabric, an olefin resin such as polyethylene or polypropylene, etc. A microporous film or a combination thereof can be used. The separator may be impregnated with an electrolyte such as a liquid electrolyte to form an electrolyte layer.

A positive electrode current collector can be arranged adjacent to the positive electrode layer. The material of the positive electrode current collector is not particularly limited as long as it has conductivity and functions as a positive electrode current collector, for example, SUS, aluminum, copper, nickel, iron, titanium, and carbon. Etc., and SUS and aluminum are preferable. Further, as the shape of the positive electrode current collector, for example, a foil shape, a plate shape, a mesh shape and the like can be mentioned.

A negative electrode current collector can be arranged adjacent to the negative electrode layer. The material of the negative electrode current collector is not particularly limited as long as it has conductivity and functions as a negative electrode current collector, and examples thereof include SUS, copper, nickel, and carbon. Yes, SUS and copper are preferred. Further, as the shape of the negative electrode current collector, for example, a foil shape, a plate shape, a mesh shape and the like can be mentioned.

As the battery case for wrapping the lithium metal battery, a known laminated film or the like that can be used in the lithium metal battery can be used.

The lithium metal battery can have a desired shape such as, but is not limited to, a cylindrical type, a square type, a button type, a coin type, or a flat type.

The electrolyte layer may contain components other than the electrolytic solution of the present invention as long as the effects of the present invention are not significantly reduced. From the viewpoint of potential stability with respect to repeated charging and discharging, it is preferable that the electrolyte layer does not contain sulfur and / or a compound having a triple bond. Examples of such a compound include saccharin, 1,2-benzoisothiazole-3 (2H) -one, 2-propin-1-ol, 1,4-butynediol and the like. In particular, compounds having sulfur such as saccharin and 1,2-benzoisothiazole-3 (2H) -one are preferably not contained in the electrolyte layer.

The lithium battery of the present invention can be formed by any conventional method.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

(1) Preparation of Electrolyte Solution Lithium bis (trifluoromethanesulfonyl) imide (Li [TFSI]) was dissolved as a lithium-containing electrolyte in 30 ml of the solvent shown in Tables 1 to 6. Then, additives were added according to the formulations shown in Tables 1 to 6 to prepare an electrolytic solution.

(2) Charge / Discharge Test Using the electrolytic solutions of Examples and Comparative Examples prepared as described above, metallic lithium was electrodeposited by passing an electric current for 30 minutes under the following conditions. After that, discharging for 3 minutes and charging for 3 minutes were repeatedly carried out, and the number of cycles until the potential reached 1 V was measured.
Working electrode: Nickel plate (1 cm in diameter)
Counter electrode: Lithium plate (20 mm x 5 mm x t0.3 mm)
Reference electrode: Lithium plate (20 mm x 5 mm x t0.3 mm)
Liquid volume: 5 ml
Electrolyte temperature: 25 ° C
Atmosphere: Ar gas (dew point: <-60 ° C, oxygen concentration: <5 ppm)
Current density: 0.127 mA / cm ² .

(3) Results The results are shown in Tables 1-6. Further, a representative example of the test result of the example (result of the second example) is shown in FIG. 1, and a representative example of the test result of the comparative example (result of the comparative example 1) is shown in FIG.

The number of cycles is increased by adding both the amide compound and the aromatic compound (Examples 1 to 28) as compared with the case where the amide compound and the aromatic compound are not added or one of them (Comparative Examples 1 to 10). It turned out.

Claims (12)

General formula (1):
[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
The amide compound represented by, and the general formula (2):
[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
An additive for an electrolytic solution containing an aromatic compound represented by. The amide compound is acrylamide, N- [3- (dimethylamino) propyl] acrylamide, N, N-diethylacrylamide, N, N'-ethylenebisacrylamide, N, N'-methylenebisacrylamide, N-isopropylacrylamide, The additive for an electrolytic solution according to claim 1, which is at least one selected from the group consisting of N-tert-butyl acrylamide, diacetone acrylamide, N-dodecyl acrylamide, and N- (butoxymethyl) acrylamide. The aromatic compounds are 1-naphthol, 2-naphthol, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1 , 7-Dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene , 1,4-Dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 2-methyl-1-naphthol, 3-methyl-1- Naphthal, 4-methyl-1-naphthol, 5-methyl-1-naphthol, 6-methyl-1-naphthol, 7-methyl-1-naphthol, 1-methyl-2-naphthol, 1-methyl-3-naphthol, The additive for an electrolytic solution according to claim 1 or 2, which is at least one selected from the group consisting of 1-methyl-6-naphthol and 1-methyl-7-naphthol. General formula (1):
[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
The general formula (2): containing the amide compound represented by
[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
Additive for electrolytic solution to be used for addition to the electrolytic solution together with the aromatic compound represented by. General formula (2):
[In the formula, R ³ is the same or different and represents a hydroxy group or an alkyl group. n represents an integer of 1 to 3. ]
General formula (1): containing an aromatic compound represented by
[In the formula, R ¹ and R ² represent the same or different hydrocarbon atoms or optionally substituted hydrocarbon groups. ]
Additive for electrolytic solution to be used for addition to the electrolytic solution together with the amide compound represented by. The additive for an electrolytic solution according to any one of claims 1 to 5, which is for a lithium battery. The lithium salt, the solvent, and the electrolyte solution additive according to any one of claims 1 to 3, or the electrolyte solution additive according to claim 4 and the electrolyte solution additive according to claim 5. Containing electrolyte. The electrolytic solution according to claim 7, wherein the content of the amide compound in the electrolytic solution is 0.01 to 10 g / L. The electrolytic solution according to claim 7 or 8, wherein the content of the aromatic compound in the electrolytic solution is 0.01 to 10 g / L. The electrolytic solution according to any one of claims 7 to 8, wherein the content of the lithium salt in the electrolytic solution is 0.1 to 10 mol / L. The electrolytic solution according to any one of claims 7 to 10, which is for a lithium battery. A lithium battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer arranged between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer contains the electrolytic solution according to any one of claims 7 to 11.