JP2015118859A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which never suffers the worsening of a large-current performance even in the case of using a high-potential positive electrode, and is superior in long-term characteristics and safety.SOLUTION: A nonaqueous electrolyte battery comprises: an electrolyte including a silicon-containing compound consisting of at least one compound selected from a group consisting of an inorganic acid, an organic acid, an acid amide and an amine with at least one hydrogen atom substituted with a silicon-containing functional group; a negative electrode including, as a negative electrode active material, a metal oxide, of which the lithium occlusion/release potential is 1-3 V (vs. Li/Li); and a positive electrode, of which the positive electrode potential based on lithium is over 4.2 V (vs. Li/Li) on condition that the nonaqueous electrolyte battery is full charged.

Description

  The present invention relates to a secondary battery containing a non-aqueous electrolyte.

  With the recent development of electronic technology and increasing interest in environmental technology, various electrochemical devices have been developed. In particular, there is a strong demand for the development of electrochemical devices for the purpose of energy saving, and expectations for electrochemical devices that can contribute to energy saving are increasing. Examples of such electrochemical devices include solar cells as power generation devices, and secondary batteries, capacitors, capacitors, and the like as power storage devices. Lithium ion secondary batteries, which are typical examples of power storage devices, have been used mainly as rechargeable batteries for portable devices, but in recent years, they have been used as batteries for hybrid and electric vehicles, or stationary storage batteries, aircraft It is also used for large applications such as industrial applications and space satellite industrial applications. Therefore, the use and market of the lithium ion secondary battery tend to further expand.

A lithium ion secondary battery generally has a configuration in which a positive electrode and a negative electrode mainly composed of an active material capable of inserting and extracting lithium are arranged via a separator. The positive electrode of the lithium ion secondary battery includes LiCoO ₂ , LiNiO ₂ or LiMn ₂ O ₄ as a positive electrode active material, carbon black or graphite as a conductive agent, and polyvinylidene fluoride, latex or rubber as a binder. Is mixed with a positive electrode current collector made of aluminum or the like. The negative electrode is a negative electrode mixture in which coke or graphite as a negative electrode active material and polyvinylidene fluoride, latex or rubber as a binder are mixed, on a negative electrode current collector made of copper or the like. It is formed by coating. Furthermore, the separator is made of porous polyolefin or the like, and its thickness is several μm to several hundred μm and is very thin. The positive electrode, the negative electrode, and the separator are immersed in the electrolytic solution in the battery. Examples of the electrolytic solution include an electrolytic solution in which a lithium salt such as LiPF ₆ or LiBF ₄ is dissolved in an aprotic solvent such as propylene carbonate or ethylene carbonate, or a polymer such as polyethylene oxide. .

  Compared to other storage batteries, lithium ion secondary batteries have features such as high electromotive force, high energy density, and repeated charge / discharge durability, and are widely used, but automobiles that are expected to expand in the future In the use of lithium ion secondary batteries such as stationary ones, higher energy density and repeated durability are required than before. In addition, since new applications are mainly large-scale applications, improvement in safety is also required.

  In order to respond to such demands for higher energy density, for example, the development of positive electrode materials with a high lithium content that can be occluded / desorbed and the density of electrodes in the battery has been developed. In order to improve the above, studies have been made to contain a flame retardant in the electrolytic solution or to form an insulating layer on the electrode or the separator.

  In recent years, in particular, as a response to higher energy density, a battery driven at a high voltage using a positive electrode having a high potential has been demanded. Various positive electrodes have been studied, and various positive electrodes can be selected according to the potential. However, when the potential of the positive electrode is increased, the problem is that a battery using the positive electrode is significantly deteriorated or deteriorated in performance because of its strong oxidizing power. Therefore, it has been studied to reduce the oxidative decomposition of the electrolytic solution and suppress the degradation by using a fluorine-containing carbonate compound, a sulfur-containing compound, a nitrile compound, a phosphoric acid compound, a silicon-containing compound, etc. as an electrolytic solution component ( For example, see Patent Documents 1 to 4). However, there are few single compounds that have reached a practical level, and it is necessary to design a complicated additive composition.

  On the other hand, it is also known that a silicon-containing compound is useful for suppressing decomposition of the non-aqueous electrolyte in a battery using a positive electrode having a high potential (see, for example, Patent Document 4 and Patent Document 5). It is considered that the silicon-containing compound has a silicon-containing functional group and / or a residue of the silicon-containing functional group exhibiting excellent SEI (solid electrolyte interface) forming ability with respect to the positive electrode. When such a silicon-containing compound is used as a constituent component of the electrolytic solution, the driving voltage can be significantly increased.

  Although it has been known for a long time that SEI is formed on the negative electrode, forming SEI on the positive electrode is a relatively new concept proposed in, for example, Patent Document 8 and Patent Document 9. is there. In this connection, when a high-quality SEI is formed on the positive electrode, the oxidative decomposition of the electrolytic solution in a high voltage environment can be reduced.

  Further, from the viewpoint of safety, it is required to cope with an internal short circuit caused by foreign matters mixed in the battery manufacturing process or the like. An internal short circuit cannot be prevented by an external protection circuit, and must be handled by the battery itself.

  In order to suppress the internal short circuit, for example, a method of forming a flame retardant layer on an electrode or a separator (for example, Patent Document 6), a method of forming an inorganic insulating layer (for example, Patent Document 7), and the like are known. , Have a certain effect. However, the battery using a positive electrode with a high potential is not only rarely used, but also has a resistance component depending on the layer structure, and the large current performance characteristic of the lithium ion battery may be lowered.

JP 2012-123989 A JP 2010-244502 A International Publication No. 2012/77712 JP 2000-223152 A International Publication 2012/170688 International Publication No. 2013/035720 JP 2005-183179 A JP 2008-97954 A JP 2008-34334 A

  As described above, various types of batteries using a positive electrode having a high potential or a battery having excellent safety have been studied, but a battery that achieves both has not been achieved. In particular, a battery using a positive electrode with a high potential is required to improve safety at a high level as compared with a conventional battery, and it is difficult to achieve both.

  An object of the present invention is to provide a battery that is excellent in long-term characteristics and safety without impairing a large current performance even when a positive electrode having a high potential is used.

As a result of intensive research in order to solve the above problems, the inventors of the present invention have achieved high performance by using a negative electrode agent having a predetermined lithium occlusion / release potential and an electrolyte containing a predetermined silicon-containing compound. The present invention has been completed by finding that the above problem can be solved even with a battery using a positive electrode of potential. That is, the present invention is as follows:
[1]
An electrolytic solution containing a silicon-containing compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid, an organic acid, an acid amide, and an amine are substituted with a silicon-containing functional group;
A negative electrode containing a metal oxide having a lithium storage / release potential of 1 V (vsLi / Li ⁺ ) or more and 3 V (vsLi / Li ⁺ ) or less as a negative electrode active material;
A non-aqueous electrolyte battery comprising: a positive electrode having a lithium standard positive electrode potential of 4.2 V (vsLi / Li ⁺ ) when fully charged.
[2]
In the silicon-containing compound, one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid, a carboxylic acid, and a phosphoric acid amide formed by combining a base containing boron or phosphorus and hydrogen are silicon. The nonaqueous electrolyte battery according to [1], which is a silicon-containing compound substituted with a containing functional group.
[3]
The non-aqueous electrolyte battery according to [1] or [2], wherein the electrolytic solution further includes at least one carbonate solvent and at least one lithium salt.
[4]
Any one of [1] to [3], wherein the metal oxide includes at least one selected from the group consisting of titanium oxide, titanium metal composite oxide, molybdenum metal composite oxide, and niobium metal composite oxide. The nonaqueous electrolyte battery according to Item.
[5]
The non-aqueous electrolyte battery according to [4], wherein the metal oxide includes a titanium metal composite oxide.
[6]
The non-aqueous electrolyte battery according to [5], wherein the titanium metal composite oxide includes one or more lithium titanium composite oxides.
[7]
The non-aqueous electrolyte battery according to any one of [1] to [6], wherein the positive electrode has a lithium-based positive electrode potential of 4.3 V (vsLi / Li ⁺ ) when fully charged.
[8]
The non-aqueous electrolyte battery according to any one of [1] to [7], wherein the positive electrode includes a positive electrode active material.
[9]
The nonaqueous electrolyte battery according to [8], wherein the positive electrode active material has at least one structure selected from the group consisting of layered, spinel, and olivine types.
[10]
The nonaqueous electrolyte battery according to [8] or [9], wherein the positive electrode active material has a discharge capacity of 10 mA / g or more at a potential higher than 4.2 V (vsLi / Li ⁺ ).
[11]
The non-aqueous electrolyte battery according to any one of [8] to [10], wherein the positive electrode active material has a discharge capacity of 10 mA / g or more at a potential higher than 4.3 V (vsLi / Li ⁺ ).
[12]
The nonaqueous electrolyte battery according to any one of [1] to [11], which is a lithium ion secondary battery.

  According to the present invention, even when a positive electrode having a high potential is used for a battery, the long-term characteristics and safety of the battery can be improved.

  Hereinafter, a mode for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. Deformation is possible.

[Nonaqueous electrolyte battery]
In the present embodiment, the non-aqueous electrolyte battery includes an electrolytic solution, a negative electrode, and a positive electrode. Here, the electrolytic solution contains a silicon-containing compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of inorganic acids, organic acids, acid amides, and amines are substituted with silicon-containing functional groups. . The negative electrode includes a metal oxide having a lithium insertion / release potential of 1 V (vsLi / Li ⁺ ) or more and 3 V (vsLi / Li ⁺ ) or less as a negative electrode active material. The positive electrode includes a positive electrode active material in which the lithium-based potential at full charge exceeds 4.2 V (vsLi / Li ⁺ ).

  In the non-aqueous electrolyte battery according to the present embodiment, by using the negative electrode containing the metal oxide and the electrolyte containing the silicon-containing compound, the decomposition of the electrolyte is suppressed even when a high potential positive electrode is used. And since the battery excellent in safety | security can be formed without impairing large current performance, the reliable battery which can perform the stable charging / discharging over a long period of time can be achieved.

  Further, if desired, the non-aqueous electrolyte battery can include a separator. Therefore, constituent elements such as an electrolytic solution, a negative electrode, a positive electrode, and a separator will be described below.

[Electrolyte]
In the present embodiment, the electrolytic solution contains a silicon-containing compound. Moreover, if desired, the electrolytic solution may contain other components such as a lithium salt, a non-aqueous solvent, and an additive. Accordingly, the silicon-containing compound, lithium salt, non-aqueous solvent, and additive will be described below.

[Silicon-containing compound]
The nonaqueous electrolytic solution according to the present embodiment includes a silicon-containing compound. The silicon-containing compound is a silicon-containing compound obtained by substituting one or more hydrogen atoms of one or more compounds selected from the group consisting of inorganic acids, organic acids, acid amides, and amines with silicon-containing functional groups. is there. The compound having such a structure shows the effect of protecting the positive electrode by the effect of the silicon-containing functional group and other sites, and the oxidation and side reaction of the electrolyte solvent, salt and other additives on the positive electrode, In addition, elution of the positive electrode active material component into the electrolytic solution can be suppressed. Thereby, a battery characteristic improves more.

(Inorganic acid)
Although it does not specifically limit as an inorganic acid, For example, the inorganic acid containing nonmetallic elements, such as a boron, a fluorine, chlorine, a bromine, an iodine, sulfur, selenium, tellurium, nitrogen, phosphorus, or arsenic, is mentioned. Among these, an inorganic acid containing boron, sulfur, phosphorus, or nitrogen is preferable, an inorganic acid containing boron or phosphorus is more preferable, an inorganic acid containing phosphorus is more preferable, phosphoric acid, phosphorous acid, polyphosphoric acid or More preferred is boric acid. By using a compound in which one or more hydrogen atoms of an inorganic acid containing boron or phosphorus are substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and the electrolyte solvent, salt, and other additives Oxidation and side reactions on the positive electrode and elution of the positive electrode active material component into the electrolyte solution tend to be further suppressed. Thereby, the battery characteristics tend to be further improved.

(Organic acid)
Although it does not specifically limit as an organic acid, For example, the compound which has 1 or more types of sulfonic acid or a carboxylic acid site | part is mentioned. Among these, carboxylic acid is preferable. By using a compound in which one or more of the hydrogen atoms of the carboxylic acid is substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and the electrolyte solvent, salt and other additives can be positively controlled. It tends to be possible to further suppress oxidation and side reactions at the finest and elution of the positive electrode active material component into the electrolyte. Thereby, the battery characteristics tend to be further improved.

  The sulfonic acid is not particularly limited. For example, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, acrylic acid sulfonic acid, vinylsulfonic acid, benzenesulfonic acid, alkylbenzenesulfonic acid, toluenesulfonic acid, fluoro Examples thereof include sulfonic acid.

  The carboxylic acid is not particularly limited. For example, acetic acid, trifluoroacetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, methacrylic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, phthalic acid, isophthalic acid, Examples include terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, and itaconic acid. Among these, dicarboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, and itaconic acid are preferred, and adipic acid, itaconic acid, Succinic acid, malonic acid, benzoic acid, isophthalic acid, and terephthalic acid are more preferable, and adipic acid, itaconic acid, succinic acid, isophthalic acid, and terephthalic acid are more preferable.

(Acid amide)
The acid amide is not particularly limited, but examples thereof include N-alkyl substituted or unsubstituted acetamide and carboxylic acid amides represented by N-alkyl substituted or unsubstituted formamide; sulfonic acid amide, N-alkyl substituted or unsubstituted Examples thereof include phosphoric acid amides represented by phosphoric acid monoamides, N-alkyl-substituted or unsubstituted phosphoric acid diamides, and N-alkyl-substituted or unsubstituted phosphoric acid triamides. Among these, phosphoric acid amides such as N-alkyl-substituted carboxylic acid amides or N-alkyl-substituted phosphoric acid triamides are preferable. By using a compound in which at least one hydrogen atom of phosphoric acid amide is substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and the electrolyte solution solvent, salt and other additives There is a tendency that oxidation and side reactions on the positive electrode and elution of the positive electrode active material component into the electrolytic solution can be further suppressed. This compound also has a function of removing unnecessary acid content in the battery. Thereby, the battery characteristics tend to be further improved.

(Amine)
Although it does not specifically limit as an amine, For example, a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium salt are mentioned. Among these, a secondary amine or a tertiary amine is preferable.

  Among inorganic acids, organic acids, acid amides or amines, inorganic acids or organic acids are preferable. By using a compound in which one or more hydrogen atoms of an inorganic acid or an organic acid are substituted with a silicon-containing functional group, oxidation and side reaction of the electrolyte solution solvent, salt and additive on the positive electrode, and positive electrode activity There is a tendency that the ability to suppress elution of substance components into the electrolyte is more excellent.

  The silicon compound of this embodiment may contain one or two or more inorganic acid, organic acid, acid amide, or amine sites.

(Silicon-containing functional group)
Although it does not specifically limit as a silicon-containing functional group, For example, the functional group which has one or more site | parts represented by -Si (R < ¹ >) (R < ² >) (R < ³ >) is mentioned. Here, one or more of R ¹ to R ³ is a halogen-substituted or unsubstituted, saturated or unsaturated, preferably a hydrocarbon group having 1 to 20 carbon atoms, two of R ¹ to R ³ The above is more preferably a halogen-substituted or unsubstituted, saturated or unsaturated, hydrocarbon group having 1 to 20 carbon atoms.

  The halogen-substituted or unsubstituted saturated or unsaturated hydrocarbon group is not particularly limited, and examples thereof include alkyl groups, alkenyl groups, alkynyl groups, allyl groups, alkoxy groups, alkylthio groups, N-substituted alkyl groups, and F-substituted alkyls. Group, F-substituted alkoxy group, vinyl group, acrylic group, methacryl group and the like.

Two or more Rs out of R ^{1 to} R ³ may be bonded to form a ring. In the case of forming a ring, for example, two of R ^{1 to} R ³ represent a halogen-substituted or unsubstituted, saturated or unsaturated, common alkylene group.

Among R ^{1 to} R ³ , the functional group other than the halogen-substituted or unsubstituted saturated or unsaturated hydrocarbon group is not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, Examples thereof include a sulfide group.

  The silicon-containing compound is not particularly limited. For example, among the hydrogen atoms possessed by inorganic acids, organic acids, acid amides or amines, the remaining hydrogen atoms not substituted with silicon-containing functional groups are silicon-free functional groups. It may be a substituted compound.

(Functional group containing no silicon)
Such a silicon-free functional group is not particularly limited, and examples thereof include halogen-substituted or unsubstituted, saturated or unsaturated, hydrocarbon groups having 1 to 20 carbon atoms. Such hydrocarbon groups are not particularly limited, and examples thereof include alkyl groups, alkenyl groups, alkynyl groups, allyl groups, alkoxy groups, alkylthio groups, N-substituted alkyl groups, F-substituted alkyl groups, F-substituted alkoxy groups, vinyls. Group, acrylic group, methacryl group and the like.

  Further, a silicon-free functional group that replaces two or more hydrogen atoms may be bonded to form a ring. In the case of forming a ring, for example, two silicon-free functional groups represent a substituted or unsubstituted, saturated or unsaturated, common alkylene group.

  Although it does not specifically limit as a silicon-containing compound, The compound by which one or more of the hydrogen atoms which an inorganic acid or an organic acid has is substituted with the siliconization containing functional group is preferable, An inorganic acid containing boron or phosphorus, or a carboxylic acid More preferred is a compound in which one or more of the hydrogen atoms contained in is substituted with a silicon-containing substituent, and two or more of the hydrogen atoms of an inorganic acid or carboxylic acid containing boron or phosphorus are substituted with a silicon-containing substituent. More preferred are the compounds.

  Such a silicon-containing compound is not particularly limited. For example, tris (trimethylsilyl) phosphoric acid, tris (trimethylsilyl) phosphorous acid, trimethylsilylpolyphosphoric acid, tris (trimethylsilyl) boric acid, tris (triethylsilyl) phosphoric acid, Trimethylsilylacetic acid, bis (trimethylsilyl) succinic acid, bis (trimethylsilyl) malonic acid, bis (trimethylsilyl) adipic acid, bis (trimethylsilyl) isophthalic acid, bis (trimethylsilyl) terephthalic acid, bis (triethylsilyl) malonic acid, bis (triethylsilyl) ) Adipic acid, bis (triethylsilyl) itaconic acid, bis (triethylsilyl) fumaric acid, bis (trimethylsilyl) succinic acid, bis (trimethylsilyl) oxalic acid, N, O-bis (trimethylsilyl) Acetamide and the like.

  Although content of a silicon-containing compound is not specifically limited, 0.1-20 mass% is preferable with respect to 100 mass% of non-aqueous electrolyte, 0.1-15 mass% is more preferable, 0.5-10 mass % Is more preferable. When the content is within the above range, it tends to be possible to obtain a battery that is more excellent in oxidation resistance and has a higher positive electrode potential and battery voltage.

[Lithium salt]
The nonaqueous electrolytic solution according to the present embodiment can include an electrolyte. When the non-aqueous electrolyte is used for a lithium ion battery or a lithium ion capacitor, a lithium salt is used as the electrolyte. Although it does not specifically limit as lithium salt, For example, the inorganic lithium salt which does not contain a carbon atom in an anion, and the organic lithium salt which contains a carbon atom in an anion are mentioned. In addition, as lithium salt, inorganic lithium salt or organic lithium salt may be used individually by 1 type, or these may be used together.

Although it does not specifically limit as said inorganic lithium salt, For example, what is used as a normal nonaqueous electrolyte can be used. Such an inorganic lithium salt is not particularly limited. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , Li ₂ B ₁₂ F _b H _{12 -b} (b is an integer of 0 to 3), a lithium salt bonded to a polyvalent anion, and the like. These inorganic lithium salts may be used alone or in combination of two or more. Among these, one or more inorganic lithium salts selected from the group consisting of LiPF ₆ and LiBF ₄ are more preferable, and LiPF ₆ is more preferable. By using an inorganic lithium salt having a fluorine atom, the balance of battery characteristics tends to be more excellent. Further, by using an inorganic lithium salt having a phosphorus atom or a boron atom, ion conductivity and handleability tend to be more excellent.

Although it does not specifically limit as said organic lithium salt, For example, what is used as a normal nonaqueous electrolyte can be used. Such an organic lithium salt is not particularly limited. For example, LiN (SO ₂ C _m F _{2m + 1} ) ₂ (LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) _2, etc. m organolithium salt represented by an integer of 1 to _{8); LiPF n (C p F} 2p + 1) 6-n (n is an integer of from 1 to 5 such as LiPF ₅ (CF _3), p is 1 An organic lithium salt represented by LiBF _q (C _s F _{2s + 1} ) _4-q (q is an integer of 1 to 3, s is an integer of 1 to 8), such as LiBF ₃ (CF ₃ ) Lithium oxalate difluoroborate (LiODFB) represented by LiBF ₂ (C ₂ O ₄ ); Lithium bis (oxalato) borate (LiBOB) represented by LiB (C ₂ O ₄ ) ₂ Halogenated LiBOB typified by: LiB (C ₃ O ₄ H ₂ ) ₂ Malonate) borate (LiBMB); lithium tetrafluorooxalatophosphate represented by LiPF ₄ (C ₂ O ₂ ); organic lithium salts represented by the following formulas (1a), (1b) and (1c) It is done.
LiC (SO ₂ R ⁴ ) (SO ₂ R ⁵ ) (SO ₂ R ⁶ ) (1a)
LiN (SO ₂ OR ⁷ ) (SO ₂ OR ⁸ ) (1b)
LiN (SO ₂ R ⁹ ) (SO ₂ OR ¹⁰ ) (1c)
(In the formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a C 1-8 perfluoroalkyl group.)

  Among these, an organic lithium salt having a boron atom is preferable. Such an organic lithium salt is structurally stable.

  In addition, the said lithium salt may be used individually by 1 type, or may use 2 or more types together.

  The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.1 to 5 mol / L, more preferably 0.5 to 3 mol / L, and still more preferably 0.8 to 2 mol / L. When the concentration of the lithium salt is within the above range, the non-aqueous electrolyte has a higher conductivity, and the charge / discharge efficiency of the non-aqueous secondary battery using the non-aqueous electrolyte tends to be higher. It is in.

[Nonaqueous solvent]
The nonaqueous electrolytic solution according to this embodiment can contain a nonaqueous solvent.

  Such a non-aqueous solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, and isopropanol; methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, γ-butyrolactone, γ-valero Acid esters such as lactone, δ-valerolactone, and ε-caprolactone; ketones such as dimethyl ketone, diethyl ketone, methyl ethyl ketone, 3-pentanone, and acetone; pentane, hexane, octane, cyclohexane, benzene, toluene, xylene, Hydrocarbons such as fluorobenzene and hexafluorobenzene; ethers such as dimethyl ether, diethyl ether, 1,2-dimethoxyethane, 1,4-dioxane, crown ethers, glymes, and tetrahydrofuran Amides such as N, N-dimethylacetamide and N, N-dimethylformamide; Amines such as ethylenediamine and pyridine; Propylene carbonate, ethylene carbonate, vinylene carbonate, 1,2-butylene carbonate, trans-2,3-butylene carbonate Cis-2,3-butylene carbonate, 1,2-pentylene carbonate, trans-2,3-pentylene carbonate, cis-2,3-pentylene carbonate, vinyl ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl Carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate, etc. Carbonates; nitriles such as acetonitrile, propionitrile, adiponitrile, succinonitrile, malononitrile, acrylonitrile and methoxyacetonitrile; lactams such as N-methylpyrrolidone (NMP); sulfolane and 3-methylsulfolane, dimethyl sulfone and ethylmethyl Examples include sulfones such as sulfone; sulfonic acid esters such as propane sultone and butane sultone; sulfoxides such as dimethyl sulfoxide; industrial oils such as silicon oil and petroleum; and edible oils.

  In addition, as the non-aqueous solvent, a solvent in which one or more hydrogen atoms in the solvent molecule are substituted with a halogen atom or a functional group can be used. Such a solvent is not particularly limited. For example, a compound in which one or more hydrogen atoms of a carbonate compound are substituted with a chlorine atom, one or more hydrogen atoms of a nitrile In which is substituted with a fluorine atom or a chlorine atom, a compound in which one or more hydrogen atoms of sulfones are substituted with a fluorine atom or a chlorine atom, one or two hydrogen atoms of an ester compound Examples thereof include compounds in which at least one atom is substituted with a fluorine atom or a chlorine atom.

  Moreover, an ionic liquid can also be used as a non-aqueous solvent. Here, the “ionic liquid” refers to a liquid composed of ions obtained by combining an organic cation and an anion.

  The organic cation is not particularly limited, and examples thereof include imidazolium ions such as dialkylimidazolium cation and trialkylimidazolium cation; tetraalkylammonium ion; alkylpyridinium ion; dialkylpyrrolidinium ion; and dialkylpiperidinium ion. .

The anion serving as a counter for these organic cations is not particularly limited. For example, PF ₆ anion, PF ₃ (C ₂ F ₅ ) ₃ anion, PF ₃ (CF ₃ ) ₃ anion, BF ₄ anion, BF ₂ ( CF ₃ ) ₂ anion, BF ₃ (CF ₃ ) anion, bisoxalatoborate anion, Tf (trifluoromethanesulfonyl) anion, Nf (nonafluorobutanesulfonyl) anion, bis (fluorosulfonyl) imide anion, bis (trifluoromethanesulfonyl) ) Anion anion, bis (pentafluoroethanesulfonyl) imide anion, dicyanoamine anion, halide anion, and the like.

  Of the non-aqueous solvents, acid esters, lactones, carbonates, ethers, or nitriles are preferably used, acid esters, lactones, and carbonates are more preferably used, and carbonates are particularly used. It is preferable.

  The said non-aqueous solvent may be used individually by 1 type, or may use 2 or more types together.

  When two or more kinds of non-aqueous solvents are used in combination, one or more of them are preferably carbonate solvents. As the carbonate solvent, at least one of a cyclic carbonate solvent and a chain carbonate solvent is used.

  Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, vinylene carbonate, vinyl ethylene carbonate, 4,5-difluoro-1,3-dioxolane- 2-one etc. can be mentioned.

  The chain carbonate compound is not particularly limited, and examples thereof include ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, and ethyl propyl carbonate. be able to.

  The chain ether compound is not particularly limited, and examples thereof include dimethyl ether, diethyl ether, 1,2-dimethoxyethane, 1,4-dioxane, crown ethers, glymes, and tetrahydrofuran.

  Examples of the chain ester solvent include methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, dimethyl oxalate, dimethyl succinate, and dimethyl malonate.

(Additive)
The non-aqueous electrolyte according to the present embodiment may further contain an additive as necessary. Although it does not specifically limit as an additive used by this embodiment, For example, the substance which plays the role as a solvent which melt | dissolves lithium salt is mentioned. Such materials may substantially overlap with the non-aqueous solvent described above. Further, the additive is preferably a substance that contributes to improving the performance of the non-aqueous electrolyte and the non-aqueous secondary battery according to this embodiment, and a substance that does not directly participate in the electrochemical reaction can also be used. . Or the additive which improves safety | security or improves the handleability of battery preparation can also be used. In addition, an additive may be used individually by 1 type, or may use 2 or more types together.

  Although it does not specifically limit as an additive, For example, unsaturated bond containing cyclic carbonate represented by vinylene carbonate and vinyl ethylene carbonate; (gamma) -butyrolactone, (gamma) -valerolactone, (gamma) -caprolactone, (delta) -valerolactone, (delta) -caprolactone Lactone represented by ε-caprolactone; cyclic ether represented by 1,2-dioxane; methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl formate, ethyl acetate, ethyl propionate, Ethyl butyrate, n-propyl formate, n-propyl acetate, n-propyl propionate, n-propyl butyrate, isopropyl formate, isopropyl acetate, isopropyl propionate, isopropyl butyrate n-butyl formate, n-butyl acetate, n-butyl propionate, n-butyl butyrate, isobutyl formate, isobutyl acetate, isobutyl propionate, isobutyl butyrate, sec-butyl formate, sec-butyl acetate , Sec-butyl propionate, sec-butyl butyrate, tert-butyl formate, tert-butyl acetate, tert-butyl propionate, tert-butyl butyrate, methyl pivalate, n-butyl pivalate, n-hexylpi Carboxyl represented by barate, n-octyl pivalate, dimethyl oxalate, ethyl methyl oxalate, diethyl oxalate, diphenyl oxalate, malonic acid ester, fumaric acid ester, maleic acid ester Esters; amides represented by N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide; ethylene sulfite, propylene sulfite, butylene sulfite, pentene sulfite, sulfolane, 3-methylsulfolane, 3 -Cyclic sulfur compounds represented by sulfolene, 1,3-propane sultone, 1,4-butane sultone, 1,3-propanediol sulfate, tetramethylene sulfoxide, thiophene 1-oxide; monofluorobenzene, biphenyl, fluorinated biphenyl A nitro compound represented by nitromethane; a Schiff base; a Schiff base complex; an oxalate complex, an aromatic compound represented by substituted or unsubstituted benzene, biphenyl, naphthalene, and terphenyl; Trimethyl phosphate, triethyl phosphate, trimethyl phosphite, triethyl phosphite, phosphoric acid ester or phosphite represented by fluorine-substituted phosphoric acid or phosphite; difluorophosphate, monofluorophosphoric acid Examples of the salt structure include salts, nitrates, and carbonates. These may be used individually by 1 type, or may use 2 or more types together.

[Negative electrode]
The negative electrode functions as a negative electrode of a lithium ion secondary battery, and includes a metal oxide having a lithium occlusion / release potential of 1 V (vsLi / Li ⁺ ) or more and 3 V (vsLi / Li ⁺ ) or less as a negative electrode active material. . Note that (vsLi / Li ⁺ ) represents a lithium-based potential.

  When the lithium occlusion / release potential is in the above range, it is excellent in that reductive decomposition of the electrolytic solution or lithium electrodeposition on the negative electrode hardly occurs during charging and discharging. As a result, not only can the battery life be extended, but also short circuiting, exothermic ignition, and the like can be suppressed, contributing to improved safety.

  The metal oxide is also characterized by a small volume change at the time of charging / discharging and a point that it is easily formed into fine particles, which can be expected to extend the life of the battery and improve the high-speed charging / discharging characteristics.

  Examples of the metal oxide whose lithium occlusion / release potential is 1 V (vsLi / Li +) or more and 3 V (vsLi / Li +) or less include, for example, titanium oxide, titanium metal composite oxide, molybdenum metal composite oxide, and niobium metal composite oxide. You can list things.

_Examples of the titanium oxide include compounds having an anatase type, rutile type, brookite type, or bronze type structure as shown by TiO ₂ or H _x Ti _y O _z . Titanium oxide does not contain Li in advance and can be expected to achieve a high capacity.

The titanium metal composite oxide is a spinel type lithium titanium composite oxide represented by Li _{4 + x} Ti ₅ O ₁₂ (wherein −1 ≦ x ≦ 3), Li _{2 + y} Ti ₃ O ₇ (where 0 ≦ Lithium titanium composite oxide having a ramsdellite structure such as y ≦ 3), a titanium-containing composite containing at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Fe and Co and Ti Oxides can be mentioned. In addition, the value of the molar ratio of oxygen in the spinel-type lithium-titanium composite oxide can change due to the influence of non-stoichiometry and the like.

  In such a lithium titanium composite oxide, a plurality of crystal phases may be mixed, a crystal phase and an amorphous phase may coexist, or an amorphous phase may exist alone. In particular, a lithium-titanium composite oxide having a microstructure exhibits a high discharge capacity even at high-speed charge / discharge, and is excellent in terms of high cycle performance.

Examples of the molybdenum metal composite oxide include Li _x MoO ₂ or Li _x MoO ₃ , and examples of the niobium metal composite oxide include Li _x Nb ₂ O ₃ .

  Among these substances, it is preferable to use a ramsdellite type or bronze type titanium oxide because of its high electric capacity.

Further, in charge / discharge of a battery using a spinel type titanium-based oxide, a reversible reaction occurs between a phase in which lithium is occluded and a phase in which lithium is occluded, but Li ₄ Ti ₅ O that does not occlude lithium. ₁₂ is substantially insulative. This phase is preferable in order to cut off the current flow when the battery is internally short-circuited, to suppress battery runaway and to contribute to safety.

  Such a metal oxide having a lithium occlusion / release potential of 1 V (vsLi / Li +) or more and 3 V (vsLi / Li +) or less may be used alone or in combination with a plurality of compounds. . Alternatively, core-shell type particles can be prepared, and different metal oxides can be used for the core phase and the shell phase. For example, a lithium titanium composite oxide other than the spinel structure can be used for the core phase, and a spinel lithium titanium composite oxide can be used for the shell phase. When such particles are used, it is possible to achieve both high capacity and current interruption capability at the time of internal short circuit at a high level.

  Furthermore, the metal oxide and other negative electrode active materials can be mixed or combined. The other negative electrode active material is selected from the group consisting of a material capable of inserting and extracting lithium ions as the negative electrode active material and metallic lithium. Examples of other negative electrode active materials include metallic lithium and carbon materials.

  Examples of the carbon material include hard carbon, soft carbon, artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, a fired body of an organic polymer compound, mesocarbon microbeads, carbon fiber, activated carbon, Examples include graphite, carbon colloid, and carbon black. Among these, the coke is not particularly limited, and examples thereof include pitch coke, needle coke, and petroleum coke. Further, the fired body of the organic polymer compound is not particularly limited, and examples thereof include a carbonized material obtained by firing a polymer material such as a phenol resin, a furan resin, or polyacrylonitrile at an appropriate temperature. In the present embodiment, a battery employing metallic lithium as the negative electrode active material is also included in the lithium ion secondary battery.

  In the case of using a negative electrode active material in which a carbon material and a metal oxide are combined, for example, core-shell structured particles using a carbon material as a core phase and a metal oxide as a shell phase can be produced. In addition, carbon-doped particles can be produced, and carbon material-doped particles can be produced.

  A negative electrode active material is used individually by 1 type or in combination of 2 or more types.

  A metal-containing compound or an organic or inorganic compound may be coated or coated on a part or the whole of the negative electrode active material surface. The properties of the negative electrode material can be changed by performing various coatings or coatings on the negative electrode surface.

(Method for producing negative electrode)
A negative electrode is obtained as follows, for example. That is, first, a negative electrode mixture-containing paste is prepared by dispersing, in a solvent, a negative electrode mixture obtained by adding a conductive additive, a binder, and the like to the negative electrode active material as necessary. Next, the negative electrode mixture-containing paste is applied to a negative electrode current collector and dried to form a negative electrode mixture layer, which is pressurized as necessary and the thickness can be adjusted to produce a negative electrode. it can.

  Here, the solid content concentration in the negative electrode mixture-containing paste is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass.

  Although a negative electrode collector is not specifically limited, For example, metal foils, such as aluminum foil, copper foil, nickel foil, or stainless steel foil, are mentioned.

[Positive electrode]
The positive electrode functions as a positive electrode of a lithium ion secondary battery, and has a lithium-based positive electrode potential at full charge exceeding 4.2 V (vsLi / Li ⁺ ). When the positive electrode potential at full charge exceeds 4.2 V (vsLi / Li ⁺ ), not only can the charge / discharge capacity of the positive electrode active material of the lithium ion secondary battery be efficiently utilized, but also the lithium ion secondary battery The energy density also tends to improve. The positive electrode potential is preferably greater than 4.3V (vsLi / Li ^+), and more preferably greater than 4.4V (vsLi / Li ^+). In addition, by controlling the voltage of the battery at the time of full charge, the positive electrode potential based on lithium at the time of full charge can be adjusted to exceed 4.2 V (vsLi / Li ⁺ ).

Lithium-based positive electrode potential at full charge is to disassemble a fully charged lithium ion secondary battery in an Ar glove box, take out the positive electrode, reassemble the battery using metallic lithium as the counter electrode, and measure the voltage Can be measured easily. For example, when a carbon negative electrode active material is used for the negative electrode, since the potential of the carbon negative electrode active material at full charge is 0.05 V (vsLi / Li ⁺ ), the voltage of the lithium ion secondary battery at full charge (Va ) To 0.05V, the potential of the positive electrode at full charge can be easily calculated. For example, in a lithium ion secondary battery using a carbon negative electrode active material for the negative electrode, when the voltage (Va) of the lithium ion secondary battery at full charge is 4.4 V, the potential of the positive electrode at full charge is It can be calculated as 4.4V + 0.05V = 4.45V.

Note that in the conventional lithium ion secondary battery, the potential of the positive electrode at full charge is set to 4.2 V (vsLi / Li ⁺ ) or less. In a lithium ion secondary battery application using a positive electrode having a high potential, a problem may occur in that the carbonate solvent contained in the electrolyte solution is oxidized and decomposed on the surface of the positive electrode, and the cycle life of the battery is reduced. (VsLi / Li ⁺ ) was the upper limit potential that can be stably charged. Therefore, in applications that require higher reliability, the potential at full charge is sometimes designed to be lower than 4.2 V (vsLi / Li ⁺ ), but the potential at full charge is 4.2 V (vs Li / Li). It was very difficult to make a design exceeding Li ⁺ ). A lithium ion secondary battery in which the potential of the positive electrode at full charge exceeds 4.2 V (vsLi / Li ⁺ ) has a higher voltage than a conventional lithium ion secondary battery. Such a problem is unlikely to occur in a conventional lithium ion secondary battery application that is used at a positive electrode potential of 4.2 V (vsLi / Li ⁺ ) or less when fully charged. The lithium ion secondary battery according to the present embodiment has the above-described configuration, thereby solving the problem that occurs when the positive electrode potential at the time of full charge exceeds 4.2 V (vsLi / Li ⁺ ). Therefore, it can operate at a high voltage and has a high cycle life.

The positive electrode active materials of the present embodiment can be used alone or in combination of two or more. However, when two or more types are combined, even when two or more positive electrode potentials at the time of full charge are combined, they are different. You may combine things. Moreover, what has a full charge potential of 4.2V (vsLi / Li ^<+> ) or less may be contained in the positive electrode active material to combine.

The positive electrode active material of the present embodiment preferably has a discharge capacity of 10 mAh / g or more at a potential exceeding 4.2 V (vsLi / Li ⁺ ) from the viewpoint of realizing a higher voltage. / Li ⁺ ) at a potential higher than 10 mAh / g, more preferably at a potential higher than 4.4 V (vsLi / Li ⁺ ), more preferably higher than 10 mAh / g. Even when such a positive electrode is provided, the battery according to the present embodiment is useful in that it operates at a high voltage and can improve the recycling life. Here, 4.2 V and a positive electrode active material having a 10 mAh / g or more discharge capacity (vsLi / Li ⁺⁾ above the potential, 4.2V (vsLi / Li ⁺⁾ of the above lithium ion secondary battery at a potential A positive electrode active material capable of causing a charge and discharge reaction as a positive electrode, and a discharge capacity at a constant current discharge of 0.1 C is 10 mAh or more with respect to 1 g of mass of the active material. Further, as long as such condition is satisfied, as the positive electrode active material, a cathode active material having a 10 mAh / g or more discharge capacity at potentials greater than ^{4.2V (vsLi / Li +),} 4.2V (vsLi / Li + ) And a positive electrode active material that does not have a discharge capacity of 10 mAh / g or more can be used in combination. A positive electrode active material that does not have a discharge capacity of 10 mAh / g or more at a potential higher than 4.2 V (vsLi / Li ⁺ ) is not particularly limited.

  These positive electrode active materials may be doped with various elements on the particle surface and inside, or may be coated with a compound containing various elements. Thereby, the crystallinity and crystal structure of the positive electrode active material can be controlled, and the reactivity of the particle surface can be controlled.

The discharge capacity of the positive electrode active material used in this embodiment is preferably 10 mAh / g or more, more preferably 15 mAh / g or more, and even more preferably 20 mAh / g or more at a potential exceeding 4.2 V (vsLi / Li ⁺ ). When the discharge capacity of the positive electrode active material is within the above range, a high energy density can be achieved by driving at a high voltage. The discharge capacity of the positive electrode active material can be measured by the method described in the examples.

Although it does not specifically limit as such a positive electrode active material, For example, the oxide represented by following formula (3), the oxide represented by following formula (4), the composite represented by following formula (5) It is preferably at least one selected from the group consisting of oxides, compounds represented by the following formula (6), and compounds represented by the following formula (7). By using such a positive electrode active material, the structural stability of the positive electrode active material tends to be more excellent.
_{LiMn 2-x Ma x O 4} (3)
(In formula (3), Ma represents one or more selected from the group consisting of transition metals, and x is 0.2 ≦ x ≦ 0.7.)
LiMeO ₂ (4)
(In formula (4), Me represents one or more selected from the group consisting of transition metals.)
zLi ₂ McO _{3- (1-z)} LiMdO ₂ (5)
(In Formula (5), Mc and Md each independently represent one or more selected from the group consisting of transition metals, and z is 0.1 ≦ z ≦ 0.9.)
LiMb _1-y Fe _y PO ₄ (6)
(In the formula (6), Mb represents one or more selected from the group consisting of Mn and Co, and y is 0 ≦ y ≦ 0.9.)
Li ₂ MfPO ₄ F (7)
(In formula (7), Mf represents one or more selected from the group consisting of transition metals.)

Although it does not specifically limit as a spinel type positive electrode active material which is an oxide represented by the said Formula (3), For example, the oxide represented by the following formula (3a) or the following formula (3b) is preferable.
LiMn _2-x Ni _x O ₄ (3a)
(In formula (3a), 0.2 ≦ x ≦ 0.7.)
LiMn _2-x Ni _x O ₄ (3b)
(In formula (3b), 0.3 ≦ x ≦ 0.6.)

The oxide represented by the formula (3a) or formula (3b), is not particularly limited, for example, LiMn _1.5 Ni _0.5 O ₄ and LiMn _1.6 Ni _0.4 O ₄ and the like. By using the spinel type oxide represented by the formula (3), the stability tends to be more excellent even when the positive electrode is used at a higher potential, for example, exceeding 4.5V.

  Here, the spinel type oxide represented by the above formula (3) is within the range of 10 mol% or less with respect to the number of moles of Mn atoms from the viewpoint of stability of the positive electrode active material, electronic conductivity, and the like. In addition to the structure, it may further contain a transition metal or a transition metal oxide. The compounds represented by the above formula (3) are used singly or in combination of two or more.

Although it does not specifically limit as a layered oxide positive electrode active material which is an oxide represented by the said Formula (4), From a viewpoint of stability in high potential, for example, following formula (4a) to (4c) It is preferable that it is an oxide represented, and it is more preferable that it is an oxide represented by (4a) or (4c).
_{LiMn 1-vw Co v Ni w} O 2 (4a)
(In formula (4a), 0.1 ≦ v ≦ 0.4 and 0.1 ≦ w ≦ 0.8.)
LiMnO ₂ (4b)
LiCoO ₂ (4c)

The layered oxide represented by the above formula (4a) is not particularly limited. For example, LiMn _1/3 Co _1/3 Ni _1/3 O ₂ , LiMn _0.1 Co _0.1 Ni _0.8 O ₂ , LiMn _0.3 Co _0.2 Ni _0.5 O _{2 and the} like can be mentioned. By using the compound represented by the formula (4), the stability tends to be more excellent. The compound represented by Formula (4) is used individually by 1 type or in combination of 2 or more types, or is used in combination with the compound shown by the said Formula (3). In that case, a mixture of the compound represented by the above formula (3) and the compound represented by the above formula (4) may be used, and the part having the structure of the above formula (3) in one particle and the above formula (4) It may be a structure in which a part having a structure of

Although it does not specifically limit as a complex layered oxide which is complex oxide represented by the said Formula (5), For example, it is preferable that it is complex oxide represented by following formula (5a).
_{zLi 2 MnO 3- (1-z} ) LiNi a Mn b Co c O 2 (5a)
(In formula (5a), 0.3 ≦ z ≦ 0.7, a + b + c = 1, 0.2 ≦ a ≦ 0.6, 0.2 ≦ b ≦ 0.6, and 0.05 ≦ c ≦ 0. 4)

  In the above formula (5a), 0.4 ≦ z ≦ 0.6, a + b + c = 1, 0.3 ≦ a ≦ 0.4, 0.3 ≦ b ≦ 0.4, and 0.2 ≦ c ≦ 0. 3 is more preferable. By using the composite oxide represented by the above formula (5), the stability tends to be more excellent. The composite layered oxide represented by the above formula (5) is used alone or in combination of two or more.

Although it does not specifically limit as an olivine type positive electrode active material which is a compound represented by the said Formula (6), For example, the compound represented by following formula (6a) and following formula (6b) is preferable.
LiMn _1-y Fe _y PO ₄ (6a)
(In formula (6a), 0.05 ≦ y ≦ 0.8.)
LiCo _1-y Fe _y PO ₄ (6b)
(In the formula (6b), 0.05 ≦ y ≦ 0.8.)

  By using the compound represented by the above formula (6), stability and electronic conductivity tend to be more excellent. The compounds represented by the above formula (6) are used singly or in combination of two or more.

The fluoride olivine-type positive electrode active material is a compound represented by the above formula (7) is not particularly limited, for _{example, Li 2 FePO 4 F, Li} 2 MnPO 4 F and Li ₂ CoPO ₄ F are preferred. By using the compound represented by the formula (7), the stability tends to be more excellent. The compound represented by Formula (7) is used individually by 1 type or in combination of 2 or more types.

(Method for producing positive electrode active material)
The positive electrode active material can be produced by the same method as that for producing a general inorganic oxide. The method for producing the positive electrode active material is not particularly limited. For example, inorganic oxide is obtained by firing a mixture in which metal salts (for example, sulfate and / or nitrate) are mixed at a predetermined ratio in an atmosphere containing oxygen. A method of obtaining a positive electrode active material containing a product; or by subjecting a carbonate and / or hydroxide salt to a solution in which a metal salt is dissolved to precipitate a hardly soluble metal salt, and extracting and separating the salt. A method of obtaining a positive electrode active material containing an inorganic oxide by mixing lithium carbonate and / or lithium hydroxide as a lithium source and firing in an atmosphere containing oxygen can be given.

(Production method of positive electrode)
Here, an example of the manufacturing method of a positive electrode is shown below. First, a paste containing a positive electrode mixture is prepared by dispersing, in a solvent, a positive electrode mixture obtained by adding a conductive auxiliary agent, a binder, and the like to the positive electrode active material as necessary. Next, this paste is applied to a positive electrode current collector and dried to form a positive electrode mixture layer, which is pressurized as necessary, and the thickness can be adjusted to produce a positive electrode.

  Although it does not specifically limit as a positive electrode electrical power collector, For example, what is comprised with metal foil, such as aluminum foil or stainless steel foil, is mentioned.

  Here, the solid content concentration in the positive electrode mixture-containing paste is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass.

  In the production of the positive electrode and the negative electrode, the conductive aid used as necessary is not particularly limited, and examples thereof include carbon black typified by graphite, acetylene black and ketjen black, and carbon fibers. The number average particle size (primary particle size) of the conductive assistant is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm, and is measured in the same manner as the number average particle size of the positive electrode active material. Examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, styrene butadiene rubber, and fluorine rubber.

[Separator]
The lithium ion battery of the present embodiment can be provided with a separator between the positive electrode and the negative electrode in order to provide the battery with safety such as prevention of short circuit between the positive and negative electrodes. As the separator, an insulating thin film having high ion permeability and excellent mechanical strength is preferable.

  Although the material of the separator in this embodiment is not specifically limited, For example, a ceramic, glass, resin, and a cellulose are mentioned. The resin may be a synthetic resin or a natural resin (natural polymer), and may be an organic resin or an inorganic resin. From the viewpoint of excellent performance as a separator, An organic resin is preferred.

  Although it does not specifically limit as organic resin, For example, heat resistant resins, such as polyolefin, polyester, polyamide, liquid crystal polyester, and aramid, are mentioned.

  Moreover, it does not specifically limit as inorganic resin, For example, a silicone resin etc. are mentioned.

  The material of the separator is preferably ceramic and glass from the viewpoint of heat resistance, and polyester, polyamide, liquid crystal polyester, aramid, and cellulose are preferable from the viewpoint of handling properties and heat resistance. Further, from the viewpoint of cost and processability, polyolefin is preferable. Among these materials, when a resin is employed, it may be a homopolymer or a copolymer, and a mixture of a plurality of types of resins and an alloy may be used.

  Further, the separator may be a laminated body in which films made of a plurality of materials are laminated. When the separator is a laminate, the material of each layer may be the same or different.

(Manufacturing method of separator)
In the case of manufacturing a separator of a laminated body, it may be manufactured by sequentially stacking a certain layer on another layer, that is, by sequentially multilayering, and a plurality of separate films may be bonded together. Thus, a laminate may be produced.

  As the form of the separator in the present embodiment, for example, a synthetic resin microporous film produced by forming a synthetic resin film, a fiber spun from a synthetic resin or a natural polymer, a woven fabric processed from glass fiber or ceramic fiber, Nonwoven fabrics, knitted fabrics, papermaking, and films prepared by arranging synthetic resin, ceramic particles, and glass fine particles are listed.

  The separator in the present embodiment is a component other than the above, for example, an organic filler, an inorganic filler, an organic particle, and an inorganic particle on the surface and / or inside of the separator from the viewpoints of membrane reinforcement, charge / discharge assist, heat resistance improvement, and the like. May be included.

[Production method of lithium ion secondary battery]
A general method may be used as a method for manufacturing the lithium ion secondary battery in the present embodiment, and is not particularly limited. For example, the following method can be selected.

  First, a battery structure is produced by housing a laminate produced using a positive electrode, a negative electrode, and a separator in a battery case (exterior). And a battery can be produced by injecting the non-aqueous electrolyte of the present embodiment into it.

  For example, the laminated body is formed by alternately winding a positive electrode and a negative electrode in a laminated state with a separator interposed therebetween to form a laminated structure having a wound structure, or bending them, laminating a plurality of layers, etc. It can produce by shape | molding into the laminated body in which a separator interposes between the some positive electrode and negative electrode which were laminated | stacked.

  The battery manufacturing method according to the present embodiment may include a step of pressurizing or depressurizing the inside of the battery. The method of pressurization and pressure reduction is not particularly limited, and the heating and the pressure reduction and pressurization may be performed simultaneously or separately. By passing through these steps, the impregnation property of the electrolyte into the electrode and separator of the battery structure may be improved.

  After passing through the above steps, if necessary, the remaining members are incorporated into the battery structure, and if the battery case (exterior) is not completely sealed (sealed), the battery is sealed. Can be obtained. If necessary, after passing through the above-described steps, the shape of the battery may be adjusted by removing an excess part of the battery, or the battery may be retightened or resealed.

  The shape of the battery in the present embodiment is not particularly limited, and for example, a cylindrical shape, an oval shape, a rectangular tube shape, a button shape, a coin shape, a flat shape, and a laminate shape are preferable. Among these, a coin type, a cylindrical type, a rectangular tube type, a flat type and a laminate type are more preferable, and a coin type, a cylindrical type, a flat type and a laminate type are more preferable. The battery having such a shape can further enhance the affinity between the electrolytic solution and the battery structure, expresses various performances of the electrolytic solution in the present embodiment to a higher level, and is relatively easy to manufacture the battery. Easy. Also, the size of the battery is not particularly limited, and a structure in which a plurality of batteries are stacked or arranged can be used in combination with many kinds of batteries. Also, among laminated batteries, the battery case (exterior) is constructed by laminating an aluminum film and a resin like an aluminum laminate material from the viewpoint of lightness, durability, handleability, cost, etc. More preferably.

  Although the lithium ion secondary battery of this embodiment can function as a battery by the first charge, it is stabilized when a part of the electrolytic solution is decomposed during the first charge. Although there is no restriction | limiting in particular about the method of the initial charge in this embodiment, It is preferable that initial charge is performed at 0.001-0.5C, It is more preferable to be performed at 0.002-0.3C, 0.003 More preferably, it is carried out at ~ 0.2C. In addition, it is also preferable that the initial charging is performed via the constant voltage charging in the middle. In addition, the constant current which discharges rated capacity in 1 hour is 1C. By setting the voltage range in which the lithium salt is involved in the electrochemical reaction to be long, SEI is formed on the electrode surface, which has an effect of suppressing an increase in internal resistance including the positive electrode. It is very effective to perform the first charge in consideration of such an electrochemical reaction.

  In addition, the non-aqueous secondary battery of this embodiment can also be used by connecting in series or in parallel.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Various characteristics of the nonaqueous secondary battery were measured and evaluated as follows.

[Production Examples 1 to 27]
(1) Preparation of Nonaqueous Electrolyte As shown in Tables 1 and 2 below, a predetermined amount of the components constituting the nonaqueous electrolyte is prepared and stirred in an argon atmosphere to produce electrolytes of Production Examples 1 to 27 Got.

(2) Preparation of lithium ion secondary battery

  Using lithium cobaltate as a positive electrode active material (layered compound), acetylene black and PVDF binder were mixed to prepare a slurry with an NMP solvent. The prepared slurry was applied to an aluminum foil (thickness: 15 μm) and dried, followed by roll press treatment to obtain a positive electrode plate. The obtained positive electrode plate was punched into a disk shape having a diameter of 16 mm to obtain a positive electrode (a).

  NMP solvent mixed with acetylene black and PVDF binder using lithium / nickel / manganese / cobalt composite oxide (element ratio of nickel / manganese / cobalt = 1/1/1) as positive electrode active material (layered compound) A slurry was prepared. The prepared slurry was applied to an aluminum foil (thickness: 15 μm) and dried, followed by roll press treatment to obtain a positive electrode plate. The obtained positive electrode plate was punched into a disk shape having a diameter of 16 mm to obtain a positive electrode (a2).

Using lithium / nickel / manganese composite oxide (LiNi _0.5 Mn _1.5 O ₄ ) (spinel compound) as a positive electrode active material, acetylene black and a PVDF binder were mixed to prepare a slurry with an NMP solvent. The prepared slurry was applied to an aluminum foil (thickness: 15 μm) and dried, followed by roll press treatment to obtain a positive electrode plate. The obtained positive electrode plate was punched into a disk shape having a diameter of 16 mm and punched into a positive electrode (b) and a 3 cm × 4 cm rectangular shape to obtain a positive electrode (b2).

  Using lithium titanate as a negative electrode active material, acetylene black and PVDF binder were mixed and a slurry was prepared with an NMP solvent. The prepared slurry was applied to an aluminum foil (thickness 15 μm, dried, and then subjected to a roll press treatment to obtain a negative electrode plate. The obtained negative electrode sheet was punched into a disk shape having a diameter of 16 mm, and the negative electrode (c) And punched into a 3 cm × 4 cm rectangular shape to obtain a negative electrode (c2).

  Using graphite powder (trade name “OMAC1.2H / SS” manufactured by Osaka Gas Chemical Co., Ltd.) as a negative electrode active material, other graphite powder (trade name “SFG6” manufactured by TIMCAL), styrene butadiene rubber and carboxymethylcellulose And a slurry was prepared with an aqueous solvent. The prepared slurry was applied to one side of a copper foil (thickness: 18 μm), the solvent was removed by drying, and then rolled with a roll press to obtain a negative electrode plate. The obtained negative electrode sheet was punched into a disk shape having a diameter of 16 mm and punched into a negative electrode (d) and a 3 cm × 4 cm rectangular shape to obtain a negative electrode (d2).

(Production example 1 of lithium ion secondary battery)
The positive electrode (a), (a2) or positive electrode (b) and negative electrode (c) or (d) produced as described above are stacked on both sides of a polyethylene separator (film thickness 25 μm, porosity 50%). The combined laminate was inserted into a SUS disk type battery case. Next, 0.4 mL of the electrolytic solution was injected into the battery case, and the laminate was immersed in the electrolytic solution. Then, the battery case was sealed to produce a lithium ion secondary battery (small battery). This was kept for 24 hours in a thermostatic bath set at 25 ° C., and the non-aqueous electrolyte was sufficiently adapted to the laminate, and produced so that 1 C = 6.0 mA. The produced battery was connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.), charged for 8 hours at a constant current of 0.2 C-constant voltage, and 3 at a constant current of 0.3 C. It was completed by initial conditioning by discharging to 0.0V.

Charging was performed up to 4.5V when using the positive electrode (a), up to 4.4V when using the positive electrode (a2), and up to 4.8V when using the positive electrode (b). . In addition, after charging the lithium ion secondary battery of this example to full charge, it was disassembled in an Ar glove box, the positive electrode was taken out, the battery was assembled again using metallic lithium as the counter electrode, and the potential of the positive electrode was measured. The positive electrode potential based on lithium when fully charged is 4.55 V (vsLi / Li ⁺ ) when the positive electrode (a) is used, and 4.45 V when the positive electrode (a2) is used. When the positive electrode (b) was used, all were 4.85 V (vsLi / Li ⁺ ).

(Production example 2 of a lithium ion secondary battery)
An electrode tab is welded to the positive electrode (b2) and the negative electrode (c2) or (d2) manufactured as described above, and a microporous film made of polyethylene (film thickness 25 μm, porosity 50%) is used as the separator. Thus, a laminate of the electrode and the separator was produced. Next, the laminate was sandwiched between exterior bodies composed of a laminate of aluminum and resin, and the three pieces were heat-sealed to obtain a laminate type battery. Next, 0.5 mL of the electrolyte solution was injected into the battery case and the laminate was immersed in the electrolyte solution, and then the battery case was sealed to produce a lithium ion secondary battery (small battery). This was kept for 24 hours in a thermostatic bath set at 25 ° C., and the non-aqueous electrolyte solution was sufficiently adapted to the laminate to produce 1C = 30.0 mA. The produced battery was connected to a charging / discharging device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.), charged to 4.8 V for 8 hours at a constant current-constant voltage of 0.1 C, and charged with 0.3 C. It was completed by performing initial conditioning by discharging to 3.0 V at a constant current.

(3) Evaluation The following battery evaluation was performed using the electrolytic solution obtained as described above. These evaluations were performed using a charge / discharge device ACD-01 (trade name) manufactured by Asuka Electronics Co., Ltd. and a thermostat PLM-63S (trade name) manufactured by Futaba Kagaku Co., Ltd.

[High temperature cycle test 1]
After charging with a constant current of 6.0 mA and reaching 4.5 V, charging was performed with a constant voltage of 4.5 V, and charging was performed for a total of 8 hours. Then, it discharged to 3.0V with the constant current of 6.0mA, and let it be 1 cycle charging / discharging cycle. This charge / discharge cycle was carried out 60 cycles at 50 ° C., and the value of the discharge capacity at the 100th cycle relative to the second cycle was calculated as the discharge capacity retention rate (A). This measurement was performed in an environment of 50 ° C. Table 2 shows the results. In this test, the positive electrode (a) was used, and a predetermined test was performed after initial conditioning when the positive electrode (a) was used.

[High temperature cycle test 2]
The battery was charged at a constant current of 6.0 mA and reached 4.4 V, and then charged at a constant voltage of 4.4 V, and charged for a total of 8 hours. Then, it discharged to 3.0V with the constant current of 6.0mA, and let it be 1 cycle charging / discharging cycle. This charge / discharge cycle was carried out 60 cycles at 50 ° C., and the value of the discharge capacity at the 100th cycle relative to the second cycle was calculated as the discharge capacity retention rate (A). This measurement was performed in an environment of 60 ° C. Table 2 shows the results. In this test, the positive electrode (b) was used, and a predetermined test was performed after initial conditioning when the positive electrode (b) was used.

[High temperature cycle test 3]
After charging at a constant current of 6.0 mA and reaching 4.8 V, charging was performed at a constant voltage of 4.8 V, and charging was performed for a total of 8 hours. Then, it discharged to 3.0V with the constant current of 6.0mA, and let it be 1 cycle charging / discharging cycle. This charge / discharge cycle was carried out at 50 ° C. for 50 cycles, and the value of the discharge capacity at the 50th cycle relative to the second cycle was calculated as the discharge capacity retention rate (B). This measurement was performed in an environment of 50 ° C. Table 2 shows the results. In this test, the positive electrode (b) was used, and a predetermined test was performed after initial conditioning when the positive electrode (b) was used.

[High temperature storage test]
After charging at a constant current of 30.0 mA and reaching 4.8 V, charging was performed at a constant voltage of 4.8 V, and charging was performed for a total of 8 hours. Thereafter, discharging was performed up to 3.0 V at a constant current of 30.0 mA. Subsequently, the battery is charged at a constant current of 30.0 mA, reaches a constant voltage of 4.8 V, is charged at a constant voltage of 4.8 V, and is charged for a total of 8 hours. It was stored (float) at 50 ° C. for 10 days while maintaining a fully charged state. About the lithium ion secondary battery before and behind holding | maintenance, the gas amount in a battery was measured using the Archimedes method, and the amount of generated gas at the time of a full charge holding | maintenance was calculated | required. This measurement was performed in an environment of 50 ° C. Table 2 shows the results. In this test, the positive electrode (b2) was used, and a predetermined test was performed after initial conditioning.

[Safety / Reliability Test]
After charging with a constant current of 6.0 mA and reaching 4.5 V, charging was performed with a constant voltage of 4.5 V, and charging was performed for a total of 8 hours. Thereafter, the battery was further charged to 6.0 V with a constant current of 6.0 mA. Then, the battery after charging was disassembled in an Ar glove box and the state was observed. At this time, the battery was short-circuited in the middle of charging and became unchargeable in the middle, and the battery after charging was found to have deposits on the negative electrode surface x, although the short-circuit was not performed △ Those that showed unstable charging behavior and those that generated gas when disassembling the battery after charging, can be charged without abnormal behavior, and even after disassembling the battery after charging A sample in which no abnormality was found was marked with a circle. In this test, the positive electrode (a) was used, and a predetermined test was performed after initial conditioning when the positive electrode (a) was used.

[Examples 1 to 20] [Comparative Examples 1 to 7]
As shown in Tables 3 and 4 below, an electrolyte solution, a negative electrode, and a positive electrode were prepared, and the above evaluation was performed using the battery obtained as described above. The obtained results are shown in Tables 3 and 4 below.

Claims (12)

An electrolytic solution containing a silicon-containing compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid, an organic acid, an acid amide, and an amine are substituted with a silicon-containing functional group;
A negative electrode containing a metal oxide having a lithium storage / release potential of 1 V (vsLi / Li ⁺ ) or more and 3 V (vsLi / Li ⁺ ) or less as a negative electrode active material;
A non-aqueous electrolyte battery comprising: a positive electrode having a lithium standard positive electrode potential of 4.2 V (vsLi / Li ⁺ ) when fully charged.   In the silicon-containing compound, one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid, a carboxylic acid, and a phosphoric acid amide formed by a bond of a base containing boron or phosphorus and hydrogen are silicon. The nonaqueous electrolyte battery according to claim 1, which is a silicon-containing compound substituted with a containing functional group.   The nonaqueous electrolyte battery according to claim 1, wherein the electrolytic solution further includes one or more carbonate solvents and one or more lithium salts.   The metal oxide includes at least one selected from the group consisting of titanium oxide, titanium metal composite oxide, molybdenum metal composite oxide, and niobium metal composite oxide. The nonaqueous electrolyte battery described.   The non-aqueous electrolyte battery according to claim 4, wherein the metal oxide includes a titanium metal composite oxide.   The non-aqueous electrolyte battery according to claim 5, wherein the titanium metal composite oxide includes one or more lithium titanium composite oxides. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode has a lithium-based positive electrode potential of 4.3 V (vsLi / Li ⁺ ) when fully charged.   The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode includes a positive electrode active material.   The non-aqueous electrolyte battery according to claim 8, wherein the positive electrode active material has at least one structure selected from the group consisting of a layered type, a spinel type, and an olivine type. The nonaqueous electrolyte battery according to claim 8 or 9, wherein the positive electrode active material has a discharge capacity of 10 mA / g or more at a potential exceeding 4.2 V (vsLi / Li ⁺ ). The non-aqueous electrolyte battery according to any one of claims 8 to 10, wherein the positive electrode active material has a discharge capacity of 10 mA / g or more at a potential higher than 4.3 V (vsLi / Li ⁺ ).   The nonaqueous electrolyte battery according to claim 1, which is a lithium ion secondary battery.