JP2015164109A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which is arranged so as to be able to perform stable charge and discharge over a long period of time and superior in safety while it is a high-energy density battery.SOLUTION: A nonaqueous electrolyte battery comprises: a nonaqueous electrolyte including a silicon-containing compound composed of at least one compound selected from a group consisting of an inorganic acid, an organic acid, an acid amide and amine, provided that in the at least one compound thus selected, at least one hydrogen atom is substituted with a silicon-containing functional group; and a positive electrode including, as a positive electrode active material, a metal oxide expressed by LiNiMO{where M represents at least one metal atom including Co, but not including Mn; "x" is a number satisfying 0.5≤x≤2; and "y" is a number satisfying 1/3<y<1}.

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 this are increasing. As such an electrochemical device, a solar cell etc. are mentioned as an electric power generation device, for example, A secondary battery, a capacitor, a capacitor | condenser etc. are mentioned as an electrical storage device. 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 beginning to be used in large applications such as industrial applications and space satellite industrial applications.

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 formed by covering a positive electrode current collector made of aluminum or the like. The negative electrode is a negative electrode mixture in which coke or graphite or the like as a negative electrode active material and polyvinylidene fluoride, latex or rubber as a binder are mixed, and a lithium metal on a negative electrode current collector made of copper or the like. It is formed by coating. Further, the separator is made of porous polyolefin or the like, and its thickness is very thin, from several μm to several hundred μm. The positive electrode, the negative electrode, and the separator are immersed in the electrolytic solution in the battery. The electrolyte is formed, for example, by dissolving a lithium salt such as LiPF ₆ or LiBF ₄ in an aprotic solvent such as propylene carbonate or ethylene carbonate, or in 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. Further, since new applications are mainly large-scale applications, further improvements in safety and reliability are required.

  In order to respond to such a demand for higher energy density, for example, a positive electrode material having a high lithium content that can be occluded / desorbed has been developed. For this purpose, various additives have been studied, and in order to improve safety and reliability, studies have been made to include a flame retardant in the electrolyte or to form an insulating layer on the electrode or separator. It has been broken.

  In particular, recently, a battery using a high-capacity positive electrode or a battery driven at a high voltage using a high-potential positive electrode has been demanded as a measure for increasing the energy density. However, when the potential of the positive electrode is increased, due to the strength of the oxidizing power, the battery is remarkably deteriorated and the performance is lowered, and it is difficult to manufacture a high-quality battery.

Therefore, in the conventional lithium ion secondary battery, the potential of the positive electrode when fully charged is set to 4.2 V (vsLi / Li ⁺ ) or less. In the use of a lithium ion secondary battery using such a high potential positive electrode, the carbonate solvent contained in the electrolytic solution may be oxidized and decomposed on the surface of the positive electrode, resulting in a problem that the cycle life of the battery is reduced. 4.2 V (vsLi / Li ⁺ ) was the upper limit potential that can be stably charged.

  In order to achieve a high-quality lithium ion secondary battery using a positive electrode of high potential, an electrolytic solution can be obtained 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 electrolyte solution component. Studies have been made to suppress battery deterioration (see, for example, Patent Documents 1 to 4). However, even if these additives are used, a battery that can be charged and discharged stably over a long period has not been achieved.

Conventionally, LiCoO ₂ is often used as the positive electrode active material. However, the capacity of the positive electrode single electrode that can be charged and discharged in the potential range of 4.2 V to 3.0 V is as low as 150 mAh / g or less. Therefore, in order to further increase the energy density, it is necessary to improve the material itself. On the other hand, in the positive electrode active material, Ni, Mn, or the like can be used instead of Co in LiCoO ₂ . Since LiNiO ₂ using Ni has a capacity of about 200 mAh / g in the potential range of 4.3 V to 3.0 V, it is effective for increasing the capacity of the positive electrode.

However, since LiNiO ₂ has low thermal stability and high reactivity, it is affected by carbon dioxide or water, and Li ₂ CO ₃ or the like is generated on the electrode surface layer or the decomposition of the electrolytic solution is promoted. It has been known. When these reactions occur, there arises a problem that gas is generated in the battery.

  When gas is generated inside the battery, the battery expands and it is difficult to ensure safety. In addition, this problem appears more noticeably in prismatic or pouch-type batteries than in cylindrical batteries. Therefore, in order to apply a Ni-based positive electrode to these batteries, it is necessary to further reduce the amount of gas generated.

Therefore, an attempt has been made to improve the thermal stability of the positive electrode by using Ni and another metal, for example, a metal such as Co or Mn. For example, a LiNi _1/3 Mn _1/3 Co _1/3 O ₂ positive electrode active material using the same amount of Ni, Mn and Co has been developed and used.

However, when LiNi _1/3 Mn _1/3 Co _1/3 O ₂ is used, since Ni is less than LiNiO ₂ , the energy density of the battery is small, but Ni is contained in the positive electrode, so the heat is low. Stability could not be overcome completely.

Further, when these positive electrode materials are used at a high voltage such that the positive electrode potential at full charge exceeds 4.2 V (vsLi / Li ⁺ ), for example, the crystal structure collapses or is distorted, or the metal element is electrolyzed. There is a limit to driving at a high voltage because it elutes into the liquid, reduces the repeated durability of the battery, or causes a short circuit of the battery and reduces safety.

JP 2012-123989 A JP 2010-244502 A International Publication No. 2012/77712 JP 2000-223152 A

  As described above, various battery materials for achieving a battery with high safety, reliability, and energy density have been studied, but a battery having these performances has not been achieved. In particular, a battery with a high energy density is more likely to generate a gas or elute a metal than a conventional battery, thereby reducing repeated charge / discharge durability and safety. Tended to be.

  Accordingly, an object of the present invention is to provide a battery that can be stably charged / discharged over a long period of time and is excellent in safety even for a battery having a high energy density.

As a result of intensive studies to solve the above problems, the present inventors have used the above-described problems by using a positive electrode material configured with a predetermined metal atomic ratio and an electrolyte solution including a predetermined silicon-containing compound. As a result, the present invention has been completed. That is, the present invention is as follows:
[1] A nonaqueous 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 inorganic acids, organic acids, acid amides and amines are substituted with silicon-containing functional groups And as a positive electrode active material, Li _x Ni _y M _1-y O ₂ {wherein M is one or more metal atoms including Co and not including Mn, and x is 0.5 ≦ x ≦ 2 and y is a positive electrode containing a metal oxide represented by 1/3 <y <1.
Non-aqueous electrolyte battery containing.
[2] The silicon-containing compound is one of 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. The nonaqueous electrolyte battery according to [1], wherein the above is a silicon-containing compound substituted with a silicon-containing functional group.
[3] The non-aqueous electrolyte battery according to [1] or [2], wherein the non-aqueous electrolyte further includes one or more carbonate solvents and one or more lithium salts.
[4] The non-aqueous electrolyte battery according to any one of [1] to [3], wherein the positive electrode active material has a layered crystal structure.
[5] The metal oxide is Li _x Ni _y Co _1-yz M ′ _z O ₂ {wherein x is a number satisfying 0.5 ≦ x ≦ 2, and y is 1/3. <A number satisfying y <1, z is a number satisfying 0.0001 <z <0.2, and M ′ is one or more metal atoms not containing Mn}. The nonaqueous electrolyte battery according to any one of [1] to [4].
[6] The nonaqueous electrolyte battery according to [5], wherein the metal atom M ′ includes one or more of Al, Mg, Ti, and Zr.
[7] The non-aqueous electrolyte battery according to any one of [1] to [6], wherein the positive electrode active material is a mixture of two or more positive electrode active materials.
[8] The nonaqueous electrolyte battery according to any one of [1] to [7], wherein the positive electrode active material is a mixture of the metal oxide and a positive electrode active material containing Mn.
[9] The nonaqueous electrolysis according to any one of [1] to [8], 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 ⁺ ). Liquid battery.
[10] The non-aqueous electrolysis according to any one of [1] to [9], 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 ⁺ ). Liquid battery.
[11] The non-aqueous electrolyte battery according to any one of [1] to [10], wherein the positive electrode has a lithium-based positive electrode potential of 4.3 V (vsLi / Li ⁺ ) when fully charged. .
[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, it is possible to achieve a high energy density battery with improved long-term characteristics of the battery.

  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 a non-aqueous electrolyte and a positive electrode. The non-aqueous electrolyte 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 positive electrode is Li _x Ni _y M _1-y O ₂ as the positive electrode active material {wherein M is one or more metal atoms including Co and not including Mn, and x is 0.5 ≦ x ≦ 2 and y includes a metal oxide represented by 1/3 <y <1. The nonaqueous electrolyte battery may also include a negative electrode. The nonaqueous electrolyte battery is preferably a lithium ion secondary battery.

The positive electrode preferably contains a positive electrode active material having a lithium-based potential at full charge exceeding 4.2 V (vsLi / Li ⁺ ).

  The nonaqueous electrolytic solution according to the present embodiment is excellent in reliability and safety so that stable charging and discharging can be performed over a long period of time because decomposition of the nonaqueous electrolytic solution is suppressed during charging and discharging or storage. A battery can be formed.

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

[Non-aqueous electrolyte]
In the present embodiment, the non-aqueous electrolyte contains a silicon-containing compound. If desired, the electrolytic solution may contain other components such as a lithium salt, a non-aqueous solvent, an additive, hydrofluoric acid, and water. Therefore, the silicon-containing compound, lithium salt, non-aqueous solvent, additive, hydrofluoric acid, and water will be described below.

[Silicon-containing compound]
The silicon-containing compound can be 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. The compound having such a structure exhibits an effect of protecting the positive electrode due to the effect of the silicon-containing functional group and other sites, and is effective in oxidizing and adsorbing a non-aqueous solvent, a lithium salt and other additives on the positive electrode. Reaction and elution of the positive electrode active material component into the electrolyte can be suppressed. Thereby, a battery characteristic improves more.

(Inorganic acid)
The inorganic acid is not particularly limited, and examples thereof include inorganic acids containing nonmetallic elements such as boron, fluorine, chlorine, bromine, iodine, sulfur, selenium, tellurium, nitrogen, phosphorus, and arsenic. Among these, an inorganic acid containing boron, sulfur, phosphorus, or nitrogen is preferable, an inorganic acid containing boron or phosphorus is more preferable, and an inorganic acid containing phosphorus is more preferable. Specifically, as the inorganic acid, for example, phosphoric acid, phosphorous acid, polyphosphoric acid or boric acid is preferable. By using a compound in which one or more hydrogen atoms of an inorganic acid formed by the bond of a base containing boron or phosphorus and hydrogen are substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and It tends to be possible to further suppress oxidation and side reactions of the nonaqueous solvent, lithium salt and other additives on the positive electrode, and elution of the positive electrode active material component into the electrolyte. 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. By using a compound in which one or more hydrogen atoms of these compounds are substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and a non-aqueous solvent, a lithium salt, and other additives It tends to be possible to further suppress oxidation and side reactions on the positive electrode and elution of the positive electrode active material component into the electrolyte. Thereby, the battery characteristics tend to be further improved. As the organic acid, a compound having at least one carboxylic acid moiety is preferable.

  The compound having one or more sulfonic acid moieties 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, fluorosulfonic acid and the like.

  The compound having at least one carboxylic acid moiety is not particularly limited. Examples include phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, and itaconic acid. Of 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 and succinic acid are preferred. 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 monoamides, N-alkyl-substituted or unsubstituted phosphoric acid diamides, and phosphoric acid amides represented by 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 one or more hydrogen atoms of the N-alkyl-substituted carboxylic acid amide or phosphoric acid amide are substituted with a silicon-containing functional group, the effect of protecting the positive electrode is further improved, and a non-aqueous solvent, There is a tendency that oxidation and side reaction of the lithium salt and other additives 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 and 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 reactions on a positive electrode of a nonaqueous solvent, a lithium salt, and an additive, and a positive electrode The ability to suppress elution of the active material component into the electrolyte solution tends to be 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, at least one of R ^{1 to} R ³ is preferably a halogen-substituted or unsubstituted, saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, and 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.

Further, at least two of R ^{1 to} R ³ may be bonded to form a ring. When forming a ring, for example, at least two of R ^{1 to} R ³ represent a halogenated or unsubstituted, saturated or unsaturated, common alkylene group.

Among R ^{1 to} R ³ , a functional group other than a 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)
Although it does not specifically limit as a silicon-free functional group, For example, a halogen-substituted or unsubstituted, saturated or unsaturated C1-C20 hydrocarbon group is mentioned. 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.

  The silicon-containing compound is not particularly limited, but is preferably 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, and includes an inorganic acid or a carboxylic acid containing boron or phosphorus. More preferable is a compound in which one or more hydrogen atoms are substituted with a silicon-containing functional group, and two or more hydrogen atoms of a boron or phosphorus-containing inorganic acid or carboxylic acid are substituted with a silicon-containing functional group. More preferred are compounds.

  Such a silicon-containing compound is not particularly limited. For example, tris (trimethylsilyl) phosphoric acid, tris (trimethylsilyl) phosphorous acid, trimethylsilylpolyphosphoric acid, tris (trimethylsilyl) phosphonic 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) silane C acid, N, etc. O- bis (trimethylsilyl) acetamide and the like.

The content of the silicon-containing compound in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.1% by mass to 20% by mass, and 0.1% by mass to 15% by mass with respect to 100% by mass of the nonaqueous electrolytic solution. % Is more preferable, and 0.5% by mass to 10% by mass is more preferable. When this 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. The content of the silicon-containing compound can be calculated by, for example, measuring the nuclear magnetic resonance spectroscopy (NMR spectroscopy) and analyzing the peak of the nuclide even when mixed with the electrolytic solution. . As the nuclide for NMR measurement, for example, ¹ H, ¹¹ B, ¹³ C, ¹⁹ F, ²⁹ Si, ³¹ P or the like can be selected depending on the structure of the silicon-containing compound.

[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, the organic lithium salt which contains a carbon atom in an anion, etc. 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), 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 (m is LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) _2, etc. organic lithium salt represented by an integer of 1 to _{8); LiPF 5 (CF 3)} LiPF such _{n (C p F 2p + 1} ) 6-n (n is an integer of from 1 to 5, p is an integer of 1 to 8) An organic lithium salt represented by LiBF _q (C _s F _{2s + 1} ) _4-q (where q is an integer of 1 to 3, s is an integer of 1 to 8) such as LiBF ₃ (CF ₃ ) Salt: Lithium bis (oxalato) borate represented by LiB (C ₂ O ₄ ) ₂ (LiBOB); Halogenation represented by lithium oxalatodifluoroborate (LiODFB) represented by LiBF ₂ (C ₂ O ₄ ) L _{BOB; LiB (C 3 O 4} H 2) lithium bis represented by ₂ (malonate) borate _{(LiBMB); LiPF 4 (C} 2 O 2) lithium tetrafluoro-oxa Lato phosphate represented by; formula (1a ), Organolithium salts represented by (1b) and (1c), and the like.
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 formulas (1a) to (1c), R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a perfluoroalkyl group having 1 to 8 carbon atoms. }

  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 nonaqueous electrolytic solution is preferably from 0.1 mol / L to 5 mol / L, more preferably from 0.5 mol / L to 3 mol / L, still more preferably from 0.8 mol / L 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.

  Although it does not specifically limit as a nonaqueous solvent, For example, Alcohols, such as methanol, ethanol, isopropanol; Methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, (gamma) -butyrolactone, (gamma) -valerolactone, (delta)- Acid esters such as 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, fluorobenzene, hexafluorobenzene Hydrocarbons such as dimethyl ether, diethyl ether, 1,2-dimethoxyethane, 1,4-dioxane, crown ethers, glymes, tetrahydrofuran, etc .; N, N-dimethylacetamide Amides such as 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 Carbonates such as isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate; acetonitrile, propylene Nitriles such as onitrile, adiponitrile, succinonitrile, malononitrile, acrylonitrile, methoxyacetonitrile; lactams such as N-methylpyrrolidone (NMP); sulfones such as sulfolane, 3-methylsulfolane, dimethylsulfone, and ethylmethylsulfone; propane Examples thereof include sulfonic acid esters such as 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 two or more hydrogen atoms of a carbonate compound are substituted with a fluorine atom or a chlorine atom, one hydrogen atom of a nitrile or Compound in which 2 or more are substituted with fluorine atom or chlorine atom, Compound in which 1 or 2 or more of hydrogen atoms of sulfones are substituted with fluorine atom or chlorine atom, 1 of hydrogen atoms in ester compound Examples thereof include compounds in which one or two or more of them are 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) ) Imide anion, bis (pentafluoroethanesulfonyl) imide anion, dicyanoamine anion, halide anion, and the like can be used.

  The non-aqueous solvent preferably contains at least one of acid esters, lactones, carbonates, ethers, and nitriles, and contains at least one of acid esters, lactones, and carbonates. Is more preferable, and it is particularly preferable that one or more carbonates are included.

  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, at least one of them is preferably a carbonate solvent. 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.

(Hydrofluoric acid)
Moreover, the non-aqueous electrolyte according to the present embodiment may contain hydrofluoric acid. The content of hydrofluoric acid is preferably 0.5 to 50 ppm, more preferably 1 to 30 ppm, and still more preferably 2 to 20 ppm. When the content of hydrofluoric acid is in the above range, continuous repair and formation of the SEI film tend to be easier.

(water)
The nonaqueous electrolytic solution according to the present embodiment preferably does not contain moisture, but may contain a very small amount of moisture as long as the solution of the problem of the present embodiment is not hindered. Such water content is preferably 0 to 100 ppm, more preferably 1 to 50 ppm, and still more preferably 1 to 30 ppm with respect to the total amount of the nonaqueous electrolytic solution.

[Positive electrode]
The positive electrode acts as a positive electrode of a lithium ion secondary battery, and Li _x Ni _y M _1-y O ₂ {wherein M includes Co and does not include Mn as a positive electrode active material. A metal oxide represented by the above metal atom, wherein x is a number satisfying 0.5 ≦ x ≦ 2 and y is a number satisfying 1/3 <y <1}. Include as a substance. A high battery capacity can be achieved by selecting a value of x within the range and adjusting y to exceed 1/3. Further, by combining Ni and the metal atom M, the instability based on Ni can be improved and the reliability and safety of the battery can be enhanced. As such a metal oxide, Li _x Ni _y Co _1-yz M ′ _z O ₂ {wherein x is a number satisfying 0.5 ≦ x ≦ 2 and y is 1/3 <A number satisfying y <1, z is a number satisfying 0.0001 <z <0.2, and M ′ is one or more metal atoms not containing Mn} Oxides are preferred. The metal atom M ′ preferably further contains at least one of Al, Mg, Ti, and Zr, and most preferably Al. When such a positive electrode active material is used, the capacity of the battery can be increased without deteriorating safety and reliability.

Although the positive electrode active material is not particularly limited, for example, the following formula (3):
Li _0.5 Ni _y Co _1-yz M ′ _z O ₂ (3)
{In Formula (3), y is 1/3 <y <1, z is 0.0001 <z <0.2, and M ′ is one or more metal atoms not containing Mn. }
An oxide represented by
Following formula (4):
LiNi _y Co _1-yz M ′ _z O ₂ (4)
{In Formula (4), y is 1/3 <y <1, z is 0.0001 <z <0.2, and M ′ is one or more metal atoms not containing Mn. }
An oxide represented by
Following formula (5):
_{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 containing Co and not containing Mn, and z is 0.1 ≦ z ≦ 0.9. It is. }
It is preferable that it is 1 or more types chosen from the group which consists of complex oxide represented by these. By using such a positive electrode active material, the structural stability of the positive electrode active material tends to be more excellent.

  It is a spinel type positive electrode active material which is an oxide represented by the above formula (3). By using such an active material, for example, when the positive electrode is used at a higher potential exceeding 4.5V. However, the stability tends to be superior.

  Here, the spinel oxide represented by the above formula (3) is within the range of 10 mol% or less with respect to the number of moles of Co 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.

  The layered oxide positive electrode active material which is an oxide represented by the above formula (4) is not particularly limited, but from the viewpoint of stability at a high potential, the metal atom M ′ is Al, Mg, Ti and Zr. It is more preferable that it is any one or more of these, and among these, Al is preferable.

The layered oxide represented by the formula (4) is not particularly limited, for _{example, LiNi 0.8 Co 0.15 Al 0.05 O} 2, LiNi 0.53 Co 0.3 Al 0.17 O ₂ etc. are mentioned. By using the oxide represented by the above formula (4), the stability tends to be more excellent. The oxide represented by the above formula (4) is used singly or in combination of two or more, or used in combination with the compound represented by the above 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 a part having the structure of the above formula (3) in one particle and the above formula ( It may be a structure in which a part having the structure of 4) is recognized together.

Although it does not specifically limit as a composite layered oxide which is a complex oxide represented by the said Formula (5), For example, 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. }
It is preferable that it is complex oxide represented by these.

  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 singly or in combination of two or more.

  In the present embodiment, the positive electrode active material may be a mixture of two or more positive electrode active materials.

Further, the positive electrode active material may be a mixture of the metal oxide described above and a positive electrode active material containing Mn. In that case, the positive electrode active material containing Mn is Li _x Ni _y Mn _z M ′ _1-yz O ₂ {wherein x is a number satisfying 0.5 ≦ x ≦ 2, and y is A number satisfying 0 ≦ y <1, z is a number satisfying 0 <z ≦ 1, and M ′ is a metal oxide represented by one or more metal atoms other than Mn}. It is preferable.

In the present embodiment, the positive electrode active material preferably has a discharge capacity of 10 mA / 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 a discharge capacity higher than 10 mAh / g. Even when a positive electrode containing a positive electrode active material having the above discharge capacity is provided, the battery of this 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. Thus, positive electrode active material, 4.2V (vsLi / Li ⁺⁾ as long as it has 10 mAh / g or more discharge capacity at potentials greater than, the discharge capacity at 4.2V (vsLi / Li ⁺⁾ potential below You may have.

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.

Also, as the positive electrode active material, 4.2V (vsLi / Li ⁺⁾ and the positive electrode active material having a 10 mAh / g or more discharge capacity at potentials greater ^{than, 4.2V (vsLi / Li +)} 10mAh / g at the potential of more than A positive electrode active material having no discharge capacity as described above can also be used in combination. The 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.

(Lithium standard positive electrode potential at full charge)
The positive electrode potential of the lithium reference when fully charged lithium ion secondary battery according to the present embodiment is preferably greater than 4.3V (vsLi / Li ^+), that exceeds 4.4V (vsLi / Li ⁺⁾ Further preferred. When the positive electrode potential at full charge exceeds 4.2 V (vsLi / Li ⁺ ), the charge / discharge capacity of the positive electrode active material of the lithium ion secondary battery tends to be efficiently utilized. Moreover, when the positive electrode potential at the time of full charge exceeds 4.2 V (vsLi / Li ⁺ ), the energy density of the lithium ion secondary battery tends to be further improved. The positive electrode potential based on lithium at the time of full charge can be controlled by controlling the voltage of the battery at the time of full charge.

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. Further, when a carbon negative electrode active material is used for the negative electrode, the potential of the lithium ion secondary battery at the time of full charge (Va) since the potential of the carbon negative electrode active material at the time of full charge is 0.05 V (vsLi / Li ⁺ ). ) 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.

The positive electrode active materials of the present embodiment can be used singly or in combination of two or more, but when two or more are combined, different ones can be used even if they combine the same positive electrode potential at full charge. May be combined. Moreover, it does not prevent that the positive electrode active material to combine includes what has a full charge potential of 4.2V (vsLi / Li ⁺ ) or less.

  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.

(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.

[Negative electrode]
A negative electrode will not be specifically limited if it acts as a negative electrode of a lithium ion secondary battery, A well-known thing may be used. The negative electrode contains one or more materials selected from the group consisting of a material capable of inserting and extracting lithium ions as a negative electrode active material and metallic lithium. The negative electrode preferably contains, as the negative electrode active material, one or more selected from the group consisting of metallic lithium, a carbon material, a silicon material, a material containing an element capable of forming an alloy with lithium, and a lithium-containing compound. Among these, it is more preferable to contain one or more materials selected from the group consisting of metallic lithium, carbon materials, silicon materials, and materials containing elements capable of forming an alloy with lithium. By using such a negative electrode active material, the battery capacity tends to be further improved.

  The carbon material is not particularly limited, for example, hard carbon, soft carbon, artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, organic polymer compound fired body, mesocarbon microbeads, Examples thereof include carbon fiber, activated carbon, 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 those obtained by firing and carbonizing a polymer material such as phenol resin and furan resin 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.

  Although it does not specifically limit as said silicon material, For example, a crystalline silicon compound, an amorphous silicon compound, an organic silicon compound, the blend composition of a silicon material and a metal, a polymer alloy, or an alloy is mentioned. In addition, various forms of silicon materials such as nano silicon materials and fibrous silicon materials can be used.

  Furthermore, the material containing an element capable of forming an alloy with lithium is not particularly limited. For example, the material may be a metal or a semimetal alone, an alloy, or a compound. Alternatively, it may have at least a part of two or more phases.

  In the present specification, the “alloy” includes an alloy having one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Further, the alloy may have a nonmetallic element as long as it has metal properties as a whole. In the structure of the alloy, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of these coexist.

  Such metal elements and metalloid elements are not particularly limited. For example, titanium (Ti), tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon (Si), zinc (Zn), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr), yttrium (Y), etc. Can be mentioned. Among these, metal elements and metalloid elements of Group 4 or 14 in the long-period periodic table are preferable, and titanium, silicon, and tin are more preferable.

  Although it does not specifically limit as an alloy of silicon, For example, as a 2nd element other than silicon, tin, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony And those having one or more elements selected from the group consisting of chromium.

  The tin alloy is not particularly limited. For example, as the second constituent element other than tin, silicon, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony And one having one or more elements selected from the group consisting of chromium (Cr).

  The titanium compound, the tin compound, and the silicon compound are not particularly limited, and examples thereof include those having oxygen (O) or carbon (C). In addition to titanium, tin, or silicon, the second compound described above is used. It may have a constituent element.

  Although it does not specifically limit as a lithium containing compound, For example, the same thing as what was illustrated as a positive electrode material can be used.

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

  The number average particle diameter (primary particle diameter) of the negative electrode active material is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the negative electrode active material is measured in the same manner as the number average particle size of the positive electrode active material.

(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% by mass to 80% by mass, and more preferably 40% by mass 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.

  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]
In the present embodiment, a non-aqueous electrolyte battery such as a lithium ion battery can include a separator between the positive electrode and the negative electrode in order to give the battery safety such as prevention of a 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, a cellulose etc. 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 formed by sequentially forming a layer on another layer, that is, by sequentially multilayering, and a plurality of films prepared separately are 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.

<Method for manufacturing 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, or the battery manufacturing time may be shortened.

  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 examples thereof include a cylindrical shape, an oval shape, a rectangular tube shape, a button shape, a coin shape, a flat shape, and a laminate shape. Among these, a coin type, a cylindrical type, a rectangular tube type, a flat type and a laminate type are 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. In addition, a laminated battery has a battery case (exterior) configured by laminating an aluminum film and a resin like an aluminum laminate material from the viewpoints of lightness, durability, handleability, and cost. More preferably it is.

  The lithium ion secondary battery of this embodiment can function as a battery by initial 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 0.001C-0.5C, It is more preferable to be performed at 0.002C-0.3C, 0.003C 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, a SEI (Solid Electrolyte Interface) film 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 23]
(1) Preparation of Nonaqueous Electrolyte Solution As shown in Table 1 below, a predetermined amount of components constituting the nonaqueous electrolyte solution are prepared and stirred in an argon atmosphere to produce nonaqueous electrolyte solutions of Production Examples 1 to 23 Got. The nonaqueous electrolytic solutions of Production Examples 1 to 23 are referred to as electrolytic solutions (A) to (W), respectively.

[Production Examples 24-28]
(2) Preparation of positive electrode As shown in Table 2 below, using a composite oxide in which the metal element ratio is changed as a positive electrode active material, acetylene black and PVDF binder are mixed, NMP solvent is added, and a slurry is prepared. 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 with a diameter of 16 mm to obtain positive electrodes (a1) to (d1), and the positive electrode plate was punched into a rectangular shape of 3 cm × 4 cm to obtain positive electrodes (a2) to (d2). It was. The positive electrode active materials (a) to (c) that are layered oxides were synthesized using the synthesis method described in Example 1 of Japanese Patent Application Laid-Open No. 2008-166269, and (d), which is a spinel oxide, It was synthesized by a conventional method.

[Production Examples 29 to 33]
As shown in Table 3 below, a positive electrode plate was produced in the same manner as in Production Example 24 using a composition obtained by mixing a composite oxide and lithium manganate as a positive electrode active material. In addition to punching the positive electrode plate into a disk shape having a diameter of 16 mm to obtain positive electrodes (f1) to (j1), the positive electrode plate was punched into a rectangular shape of 3 cm × 4 cm to obtain positive electrodes (f2) to (j2).

(3) Preparation of negative electrode 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 Co.), styrene Butadiene rubber and carboxymethylcellulose were mixed and water was added as a solvent to prepare a slurry. 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 (k1) and a rectangular shape of 3 cm × 4 cm to obtain a negative electrode (k2).

(Production example 1 of lithium ion secondary battery)
The positive electrodes (a1) to (j1) and the negative electrode (k1) produced as described above were superposed on both sides of a polyethylene separator (film thickness 25 μm, porosity 50%) to obtain a laminate. This laminate was inserted into a disk-type battery case made of SUS. 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 battery was kept in a thermostatic bath set at 25 ° C. for 24 hours, and the non-aqueous electrolyte was sufficiently adapted to the laminated body so that 1C = 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 4.4V. 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. Was also 4.45V.

(Production example 2 of a lithium ion secondary battery)
An electrode tab is welded to the positive electrodes (a2) to (j2) and the negative electrode (k2) produced 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 a resin, and the three pieces were heat-sealed to obtain a laminate type battery. Next, 0.5 mL of the electrolytes (A) to (W) are injected into the battery case, the laminate is immersed in the electrolyte, and then the battery case is sealed to produce a lithium ion secondary battery (small battery). did. This battery was kept in a thermostat set at 25 ° C. for 24 hours, and the non-aqueous electrolyte solution was sufficiently adapted to the laminate so that 1C = 40.0 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 0.1 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 4.4V.

(4) 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.

[Discharge temperature characteristics test]
Evaluation was performed using the battery manufactured in Production Example 1 of a lithium ion secondary battery. 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. Thereafter, the battery was discharged at a constant current of 2.0 mA to 3.0 V at various temperatures, and the discharge capacity retention rate at various temperatures relative to the discharge capacity at 25 ° C. was measured. The results are shown in Table 4 below.

[High temperature storage test]
Evaluation was performed using the battery manufactured in Manufacturing Example 2 of a lithium ion secondary battery. The battery was charged at a constant current of 40.0 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. Thereafter, discharging to 3.0 V was performed at a constant current of 40.0 mA. Subsequently, the battery is charged at a constant current of 40.0 mA, reaches a constant voltage of 4.4 V, is charged at a constant voltage of 4.4 V, and is charged for a total of 8 hours. Store (float) at 45 ° C for 7 days while maintaining a fully charged state, measure the remaining capacity and recovery capacity when discharged to 3.0 V at a constant current of 20 mA, and maintain the discharge capacity against the discharge capacity before storage. Was measured. The results are shown in Table 4 below. The measurement was performed at 25 ° C.

Claims (12)

A non-aqueous electrolyte containing 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; and positive electrode As an active material, Li _x Ni _y M _1-y O ₂ {wherein M is one or more metal atoms including Co and not including Mn, and x satisfies 0.5 ≦ x ≦ 2. A positive electrode including a metal oxide represented by the following formula: y is a number satisfying 1/3 <y <1;
Non-aqueous electrolyte battery containing.   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 non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte further includes one or more carbonate solvents and one or more lithium salts.   The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode active material has a layered crystal structure. The metal oxide is Li _x Ni _y Co _1-yz M ′ _z O ₂ {wherein x is a number satisfying 0.5 ≦ x ≦ 2, and y is 1/3 <y <. 1 is a number satisfying 1, z is a number satisfying 0.0001 <z <0.2, and M ′ is one or more metal atoms not containing Mn}. The nonaqueous electrolyte battery as described in any one of -4.   The non-aqueous electrolyte battery according to claim 5, wherein the metal atom M ′ includes at least one of Al, Mg, Ti, and Zr.   The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode active material is a mixture of two or more positive electrode active materials.   The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode active material is a mixture of the metal oxide and a positive electrode active material containing Mn. The non-aqueous electrolyte battery according to any one of claims 1 to 8, 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 1 to 9, wherein the positive electrode active material has a discharge capacity of 10 mA / g or more at a potential exceeding 4.3 V (vsLi / Li ⁺ ). 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.   It is a lithium ion secondary battery, The nonaqueous electrolyte battery as described in any one of Claims 1-11.