JP2016058163A - Lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which can be charged and discharged with stability over a long period of time even if it is a high-energy density battery, and which is superior in safety.SOLUTION: A lithium ion secondary battery comprises: a nonaqueous electrolyte; a separator having a layer including an inorganic substance partially or totally in a base film; a positive electrode; and a negative electrode. The nonaqueous electrolyte includes: a silicon-containing compound; a lithium salt; and a nonaqueous solvent. The silicon-containing compound includes at least one compound selected from a group consisting of an inorganic acid, an organic acid, acid amide and amine, in which at least one hydrogen atom is substituted with a silicon-containing functional group.SELECTED DRAWING: None

Description

  The present invention relates to a lithium ion secondary battery.

  With the recent development of electronic technology and increasing interest in environmental technology, various electrochemical devices have been developed. This is based on the diversification of scale, usage, and specifications of energy creation (power generation) and energy storage (storage). For this reason, the request | requirement with respect to the electrochemical device development corresponding to them is strong, and the expectation for this is 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 for 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. Since such new applications are mainly large-scale applications, further improvements in safety and reliability are required. In addition, since the amount of information handled by devices is increasing in conventional small device applications, batteries with high capacity and high energy density 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 produce a battery that maintains high quality over a long period of time. Even a battery using a high-capacity positive electrode needs to be driven at a higher voltage and have a higher positive electrode potential than conventional batteries.

That is, in the use of a lithium ion secondary battery using such a high potential positive electrode, there is a problem that the carbonate-based solvent or the like contained in the electrolytic solution is oxidized and decomposed on the surface of the positive electrode, thereby reducing the cycle life of the battery. Since it may occur, 4.2 V (vsLi / Li ⁺ ) was the upper limit potential that can be stably charged. 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 order to achieve a high-quality lithium ion secondary battery using a positive electrode at a high potential, the use of 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 Studies have been made to suppress deterioration (see, for example, Patent Documents 1 to 4).

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

  However, even if these additives are used, a battery that can be charged and discharged stably over a long period of time has not been achieved.

  Further, studies have been made to form a layer of inorganic particles on a part or the whole of the separator. The battery is driven at a high voltage by using a positive electrode having a high potential. Particularly, accelerated deterioration of the separator can be suppressed by the inorganic particle layer. However, this alone has not led to a battery that can be charged and discharged stably over a long period of time.

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 . LiNiO ₂ using Ni is effective for increasing the capacity of the positive electrode because a capacity of about 200 mAh / g is obtained in the potential range of 4.3 V to 3.0 V.

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, attempts have 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 Ni, Mn and Co in the same amount 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 battery has a low energy density, so that Ni is contained in the positive electrode, so the heat is low. Stability could not be overcome completely.

In addition, 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.

  Therefore, positive electrode active materials in which the ratios of Ni, Co, and Mn are changed, positive electrode active materials formed by coating or doping a small amount of different metals with respect to various positive electrode active materials, and the like have been studied. A positive electrode material capable of being driven at a high voltage of about 0.05 V to 0.2 V is being proposed. As described above, attempts have been made to increase the voltage of each member, but it has not been possible to achieve an optimum high-voltage drive battery as a whole battery.

  As described above, various battery materials for achieving a battery with high safety, reliability, and energy density have been studied, but a battery that achieves an effective synergistic effect of the performance of each battery member 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. Tend to.

  The present invention has been made in view of the above problems, and provides a lithium ion secondary battery that can be stably charged and discharged over a long period of time even in a high energy density battery and is excellent in safety. The purpose is to do.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using an electrolytic solution containing a predetermined silicon-containing compound and a separator having a layer of inorganic particles. Thus, the present invention has been completed.

That is, the present invention is as follows.
[1]
A non-aqueous electrolyte, a separator having a layer containing an inorganic substance in a part or the whole of the base film, a positive electrode, and a negative electrode,
The non-aqueous electrolyte includes a silicon-containing compound, a lithium salt, and a non-aqueous solvent,
The silicon-containing compound includes a 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. Lithium ion secondary battery.
[2]
In the silicon-containing compound, one or more hydrogen atoms of one or more compounds selected from the group consisting of inorganic acids containing boron or phosphorus, carboxylic acids, sulfonic acids, and phosphoric acid amides are substituted with silicon-containing functional groups. The lithium ion secondary battery as described in the above item [1], which contains a compound that has been prepared.
[3]
The silicon-containing compound is a compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid containing phosphorus, a carboxylic acid, and a phosphoric acid amide are substituted with a silicon-containing functional group. The lithium ion secondary battery according to [1] or [2] above.
[4]
The lithium ion secondary battery according to any one of [1] to [3], wherein the silicon-containing compound further includes a compound having a Si—F bond.
[5]
The lithium ion secondary battery according to any one of [1] to [4], wherein the inorganic-containing layer is present on one side or both sides of the base film.
[6]
The lithium ion 2 according to any one of [1] to [5], wherein the inorganic substance includes one or more selected from the group consisting of metal oxides, metal hydroxides, carbonates, and clay minerals. Next battery.
[7]
The lithium ion secondary battery according to any one of [1] to [6], wherein the layer containing the inorganic substance further contains an organic substance.
[8]
The lithium ion secondary battery according to any one of [1] to [7] above, wherein the potential of the positive electrode based on lithium at full charge is 4.1 V (vsLi / Li ⁺ ) or more.
[9]
The positive electrode is
Following formula (1):
_{LiMn 2-x Ma x O 4} (1)
(In formula (1), Ma represents one or more selected from the group consisting of transition metals, and x satisfies 0.2 ≦ x ≦ 0.7.)
An oxide represented by
Following formula (2):
LiMn _1-u Me _u O ₂ (2)
(In formula (2), Me represents one or more selected from the group consisting of transition metals excluding Mn, and u satisfies 0.1 ≦ u ≦ 0.9.)
An oxide represented by
Following formula (3):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (3)
(In Formula (3), Mc and Md each independently represent one or more selected from the group consisting of transition metals, and z satisfies 0.1 ≦ z ≦ 0.9.)
A composite oxide represented by
Following formula (4):
LiMb _1-y Fe _y PO ₄ (4)
(In the formula (4), Mb represents one or more selected from the group consisting of Mn and Co, and y satisfies 0 ≦ y ≦ 0.9.)
And a compound represented by the following formula (5):
Li ₂ MfPO ₄ F (5)
(In formula (5), Mf represents one or more selected from the group consisting of transition metals.)
A compound represented by
The lithium ion secondary battery according to any one of [1] to [8] above, comprising at least one positive electrode active material selected from the group consisting of:
[10]
The lithium ion according to any one of [1] to [9], wherein the positive electrode includes a positive electrode active material having a discharge capacity of 10 mAh / g or more at a potential of 4.3 V (vsLi / Li ⁺ ) or more. Secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a battery of a high energy density, the charging / discharging stable over the long term is possible, and the lithium ion secondary battery excellent in safety | security can be achieved.

  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.

<Lithium ion secondary battery>
The lithium ion secondary battery of the present embodiment includes a non-aqueous electrolyte, a separator having a layer containing an inorganic substance in a part or the whole of the base film, a positive electrode, and a negative electrode, and the non-aqueous electrolyte includes: A silicon-containing compound, a lithium salt, and a non-aqueous solvent, wherein the silicon-containing compound is a hydrogen atom of one or more compounds selected from the group consisting of inorganic acids, organic acids, acid amides, and amines. Including compounds in which one or more is substituted with a silicon-containing functional group.

  Components such as the non-aqueous electrolyte, separator, positive electrode, and negative electrode will be described below.

[Non-aqueous electrolyte]
The nonaqueous electrolytic solution contains a silicon-containing compound, a lithium salt, and a nonaqueous solvent. Moreover, the non-aqueous electrolyte may contain other components such as an additive, hydrofluoric acid, and water, if necessary. Hereinafter, the silicon-containing compound, lithium salt, non-aqueous solvent, additive, hydrofluoric acid, and water will be described.

[Silicon-containing compound]
The silicon-containing compound includes a 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. As the silicon-containing compound, one or more hydrogen atoms of one or more compounds selected from the group consisting of inorganic acids containing boron or phosphorus, carboxylic acids, sulfonic acids, and phosphoric acid amides are substituted with silicon-containing functional groups. A compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid containing phosphorus, a carboxylic acid, and a phosphoric acid amide are substituted with a silicon-containing functional group Is more preferable. The compound having such a structure exhibits an effect of protecting the positive electrode even in a battery having a high energy density due to the effect of the silicon-containing functional group and other sites, and is a non-aqueous solvent, a lithium salt, and other components. Oxidation and side reaction of the additive on the positive electrode and elution of the positive electrode active material component into the non-aqueous 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 nonaqueous electrolytic solution. 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 one or more sulfonic acid groups or carboxylic acid groups 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 non-aqueous electrolyte. Thereby, the battery characteristics tend to be further improved. As the organic acid, a compound having at least one carboxylic acid group is preferable.

  The compound having one or more sulfonic acid groups is not particularly limited. For example, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, acrylic acid sulfonic acid, vinylsulfonic acid, benzenesulfonic acid, alkylbenzenesulfone. An acid, toluenesulfonic acid, fluorosulfonic acid etc. are mentioned.

  The compound having one or more carboxylic acid groups 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, terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, itaconic acid and the like. 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 the oxidation and side reaction of the lithium salt and other additives on the positive electrode and the elution of the positive electrode active material component into the non-aqueous electrolyte 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 non-aqueous electrolyte tends to be more excellent.

  A silicon compound may be used individually by 1 type, or may use 2 or more types together.

(Silicon-containing functional group)
The silicon-containing functional group is not particularly limited as long as it contains silicon, and examples thereof include a functional group represented by the following formula.
-Si (R ¹ ) (R ² ) (R ³ )
(In the above formula, R ^{1 to} R ³ each independently represents a halogen-substituted or unsubstituted, saturated or unsaturated hydrocarbon group, hydrogen atom, halogen atom, hydroxyl group, amino group, mercapto group, sulfide group. (At least two of R ^{1 to} R ³ may be bonded to form a ring.)

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 an alkyl group, alkenyl group, alkynyl group, allyl group, alkoxy group, alkylthio group, N-substituted alkyl group, and F-substituted. Examples thereof include an alkyl group, an F-substituted alkoxy group, a vinyl group, an acrylic group, and a methacryl group.

Further, at least two of R ^{1 to} R ³ may be bonded to form a ring. In the case of 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 , 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 not containing silicon)
The 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.

  In addition, 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 common alkylene group, which is substituted or unsubstituted, saturated or unsaturated.

  Examples of such silicon-containing compounds include, but are not limited to, tris (trimethylsilyl) phosphoric acid, tris (trimethylsilyl) phosphorous acid, trimethylsilylpolyphosphoric acid, ethyl bis (trimethylsilyl) phosphonate, butyl bis (trimethylsilyl) phosphonate Allyl, bis (trimethylsilyl) phosphonate, vinyl bis (trimethylsilyl) phosphonate, 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, Sus (triethylsilyl) itaconic acid, bis (triethylsilyl) fumaric acid, bis (trimethylsilyl) succinic acid, bis (trimethylsilyl) oxalic acid, N, O-bis (trimethylsilyl) acetamide, 1,3-bis (trimethylsiloxy)- Examples include 1,3-dimethyldisiloxane and trimethylsilyl isocyanate.

  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 measured by, for example, nuclear magnetic resonance spectroscopy (NMR spectroscopy), gas chromatography or the like even when mixed with the non-aqueous electrolyte. In nuclear magnetic resonance spectroscopy, silicon, boron, phosphorus, fluorine, hydrogen, or the like can be selected as a measurement nuclide.

  It is preferable that the silicon-containing compound further includes a compound having a Si—F bond in addition to the above compound. Although it does not specifically limit as a compound which has a Si-F bond, For example, a fluoro trialkylsilane, a difluoro dialkylsilane, a trifluoroalkylsilane etc. can be mentioned. The alkyl group of these compounds may be saturated, unsaturated, or have a substituent. The unsaturated alkyl group may have an aromatic group.

  A compound having a Si-F bond tends to stabilize the protective film on the negative electrode surface of the battery. For this reason, it exists in the tendency which can suppress the decomposition | disassembly of electrolyte solution, suppress the fall of the ionic conductivity in a battery even if it decomposes | disassembles, and can improve the lifetime of a battery.

[Lithium salt]
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, lithium salt may be used individually by 1 type, or may use 2 or more types 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 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.

  The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.10 mol / L to 5.0 mol / L, more preferably 0.50 mol / L to 3.0 mol / L, and 0.80 mol / L to 2.0 mol. / L is more preferable. When the concentration of the lithium salt is within the above range, the conductivity of the non-aqueous electrolyte is kept higher, and the charge / discharge efficiency of the lithium ion secondary battery using the non-aqueous electrolyte tends to be kept higher. It is in.

[Nonaqueous solvent]
The non-aqueous solvent is not particularly limited. For example, alcohols such as methanol, ethanol, isopropanol; methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, dimethyl oxalate Chain esters such as dimethyl succinate and dimethyl malonate; cyclic esters such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone; dimethyl ketone, diethyl ketone, methyl ethyl ketone, 3-pentanone, Ketones such as acetone; hydrocarbons such as pentane, hexane, octane, cyclohexane, benzene, toluene, xylene, fluorobenzene, hexafluorobenzene; dimethyl ether, diethyl ether, 1,2-dimethoxyethane, Chain ethers such as limes; Cyclic ethers such as 1,4-dioxane, crown ethers 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- Cyclic rings such as pentylene carbonate, cis-2,3-pentylene carbonate, vinyl ethylene carbonate, 4-fluoro-1,3-dioxolan-2-one, 4,5-difluoro-1,3-dioxolan-2-one Carbonate; ethyl methyl car Chain carbonates such as sulfonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, ethyl propyl carbonate; acetonitrile, propionitrile, adiponitrile, succinonitrile, malononitrile Nitriles such as acrylonitrile and methoxyacetonitrile; lactams such as N-methylpyrrolidone (NMP); sulfones such as sulfolane, 3-methylsulfolane, dimethylsulfone and ethylmethylsulfone; 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 It is.

  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 contains at least one selected from the group consisting of cyclic esters, chain esters, lactones, cyclic carbonates, chain carbonates, cyclic ethers, chain ethers, and nitriles. It is more preferable that it contains at least one selected from the group consisting of esters, lactones, and carbonates, and it is particularly preferable that carbonates are included.

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

  When using 2 or more types of non-aqueous solvents together, it is preferable that 1 or more types is a carbonate solvent among them. As the carbonate solvent, it is preferable to use one or more of a cyclic carbonate solvent and a chain carbonate solvent, and it is more preferable to use both.

〔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 the performance improvement of the non-aqueous electrolyte and the lithium ion secondary battery according to the present 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 1,3-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, iso Propylbutyrate, n-butylformate, n-butylacetate, n-butylpropionate, n-butylbutyrate, isobutylformate, isobutylacetate, isobutylpropionate, isobutylbutyrate, sec-butylformate, 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- For hexyl pivalate, n-octyl pivalate, dimethyl oxalate, ethyl methyl oxalate, diethyl oxalate, diphenyl oxalate, malonic acid ester, fumaric acid ester, maleic acid ester Carboxylic acid esters represented: N-methylformamide, N, N-dimethylformamide, amides represented by N, N-dimethylacetamide; ethylene sulfite, propylene sulfite, butylene sulfite, pentene sulfite, sulfolane, 3 -Cyclic sulfur compounds represented by methylsulfolane, 3-sulfolene, 1,3-propane sultone, 1,4-butane sultone, 1,3-propanediol sulfate, tetramethylene sulfoxide, thiophene 1-oxide; monofluorobenzene, Aromatic compounds typified by difluorobenzene, hexafluorobenzene, biphenyl, fluorinated biphenyl; nitro compounds typified by nitromethane; Schiff base; Schiff base complex; oxalato complex, substituted or unsubstituted benzene, Aromatic compounds typified by biphenyl, naphthalene, terphenyl; phosphate esters typified by trimethyl phosphate, triethyl phosphate, trimethyl phosphite, triethyl phosphite, fluorine-substituted phosphoric acid or phosphite Phosphites: those having a salt structure typified by difluorophosphate, monofluorophosphate, nitrate and carbonate. These may be used alone or in combination of two or more.

(Hydrofluoric acid)
Moreover, the nonaqueous electrolytic solution may contain hydrofluoric acid. The content of hydrofluoric acid is preferably 0.50 to 50 ppm, more preferably 1.0 to 30 ppm, and still more preferably 2.0 to 20 ppm. When the content of hydrofluoric acid is in the above range, continuous repair and formation of a SEI (solid electrolyte interface) film tends to be easier.

(water)
The non-aqueous electrolyte 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 1.0 to 50 ppm, and still more preferably 1.0 to 30 ppm with respect to the total amount of the nonaqueous electrolytic solution.

[Separator]
The lithium ion secondary battery of this embodiment includes a separator having a layer containing an inorganic substance in a part or the whole of a base film between a positive electrode and a negative electrode. Although it does not specifically limit as a base film, For example, it is preferable to select the insulating film | membrane with large ion permeability and excellent mechanical strength.

[Base membrane]
The material of the base film is not particularly limited, and examples thereof include ceramic, glass, resin, and cellulose. Among these, ceramic and glass are preferable from the viewpoint of heat resistance. Moreover, the film | membrane containing polyester, polyamide, liquid crystal polyester, aramid, and a cellulose is preferable from a viewpoint of handling property and heat resistance. Furthermore, from the viewpoint of cost, processability, and shutdown performance, a film containing polyolefin is preferable.

  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, Organic resins are preferably used. The resin may be a homopolymer or a copolymer, and a compound containing a mixture of plural kinds of resins, a polymer alloy, and an additive may be used.

Although it does not specifically limit as organic resin, For example, heat resistant resins, such as polyolefin, polyester, polyamide, a polyimide, liquid crystal polyester, and aramid, are mentioned. Polyethylene or polypropylene is used as the polyolefin.
The molecular weight of the organic resin is not particularly limited, but if a resin having a higher molecular weight is used, a film having excellent heat resistance and mechanical strength tends to be formed.

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

  When ceramic or glass is used for the base film, the base film and the inorganic material may be substantially the same or different.

  Hereinafter, the case where polyolefin is used as the base film will be described. In this case, the content of the polyolefin constituting the base film is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass with respect to the total amount of the film, from the viewpoint of shutdown performance and the like. % Or less, and more preferably 70% by mass or more and 100% by mass or less.

  Although it does not specifically limit as polyolefin which comprises a base film, For example, homopolymers, copolymers, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene, Or a multistage polymer etc. are mentioned. Moreover, these polyolefin resin may be used individually by 1 type, or may use 2 or more types together. Specific examples of polyolefin include low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ultra high molecular weight polyethylene, isotactic polypropylene, atactic polypropylene, ethylene-propylene random copolymer, polybutene, ethylene Examples include propylene rubber.

  From the viewpoint of shutdown properties and high strength, it is preferable to use a resin composition mainly composed of high-density polyethylene as the polyolefin resin.

  Moreover, it is preferable that it is a resin composition of a polypropylene and other resin from a heat resistant viewpoint.

  Further, the base film 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.

  In the case of manufacturing a film of a laminated body, it may be formed in order by repeating the formation of one layer on another layer, that is, sequentially multilayered, and a plurality of films prepared separately are bonded together. Thus, a laminate may be produced.

  Examples of the form of the base membrane in the present embodiment include a synthetic resin microporous membrane manufactured by forming a synthetic resin, a fiber spun from a synthetic resin or a natural polymer, a woven fabric processed from a glass fiber or a ceramic fiber. , Nonwoven fabrics, knitted fabrics, papermaking, and films prepared by arranging fine particles of synthetic resin, ceramic particles and glass.

[Inorganic layer]
The separator in the present embodiment has a layer containing an inorganic substance in part or all of the film, so that a battery having excellent durability can be achieved even when the battery is driven at a high voltage, and the film is reinforced or heat resistance is improved. Can also be achieved. The layer containing an inorganic substance may be present inside the base film, on the surface, or both. In the case where a layer containing an inorganic substance is formed on the surface of the base film, the layer containing an inorganic substance may be present on one side or both sides of the base film. Among these, from the viewpoint of the effect of the present invention, it is preferable that an inorganic porous layer is formed on at least one surface of the surface of the base film.

(Inorganic)
The kind of the inorganic substance is not particularly limited as long as it does not inhibit charging / discharging of the lithium ion secondary battery, but those having a high melting point and high electrical insulation are preferable. Inorganic particles include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, chromium hydroxide, zirconium hydroxide, nickel hydroxide, boron hydroxide; silica, alumina, titania, zirconia, magnesia, ceria , Yttria, zinc oxide, metal oxides such as iron oxide and ITO; metal nitrides such as silicon nitride, titanium nitride, boron nitride and aluminum nitride; carbonates such as calcium carbonate and magnesium carbonate; barium sulfate, aluminum sulfate and sulfuric acid Sulfates such as calcium; calcium silicate, magnesium silicate, talc, kaolin, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, apatite, zeolite, boehmite, mullite, spinel, dica Clay minerals such as calcium, barium fluoride, carbon materials such as carbon black and graphite; silicon carbide, potassium titanate, titanium Examples include barium acid, silicon, diamond, and glass fiber. These inorganic substances can be used alone or in combination of two or more. A plurality of inorganic substances of the same type and having different shapes and properties can be used in combination.

  From the viewpoint of electrical and thermal stability, the inorganic substance is preferably a metal oxide, metal hydroxide, carbonate, sulfate or clay mineral, more preferably a metal oxide, hydroxide, carbonate or clay mineral. More preferred are metal oxides or clay minerals. Among metal oxides or clay minerals, compounds containing aluminum are preferred. In consideration of availability, calcined kaolin and boehmite are preferably used.

  The shape of the inorganic substance is not particularly limited, and various shapes such as a spherical shape, a polyhedral shape, a columnar shape, a fiber shape, a plate shape, a needle shape, and a spindle shape can be used. From the viewpoint of short circuit prevention, plate-like particles are preferably used, and from the viewpoint of ion permeability, a polyhedral shape having a plurality of faces, a columnar shape, and a spindle shape are preferably used.

  Moreover, the surface of the inorganic substance may be surface-treated. For example, a coupling agent such as a silane coupling agent may be used, or a hydrophilic or hydrophobic treatment may be performed. By performing such treatment, it is possible to control the adhesion between the inorganic material and the base film or the binder and the cohesiveness between the inorganic materials.

  The average primary particle diameter of the inorganic substance in the present embodiment is preferably 1 nm or more and 15 μm or less, more preferably 10 nm or more and 10 μm or less, and further preferably 30 nm or more and 5 μm or less.

  In addition, in the layer actually formed in the separator, the primary particles are often agglomerated secondary particles. Secondary particles have a particle size of about 3 to 30 times that of primary particles.

  When the average particle diameter of the inorganic material is in the above range, it has heat resistance and voltage resistance such as suppression of thermal shrinkage under high temperature and high voltage environment regardless of the thickness of the base film and the pore structure.

  In addition, as a method for controlling the particle size of the inorganic material, there is a method of reducing the particle size by pulverizing the inorganic material using a ball mill, a bead mill, a jet mill or the like.

  The content of the inorganic substance is preferably 50% by mass or more and less than 100% by mass, and more preferably 60% by mass or more and 90% by mass or less, with respect to the total amount of the layer containing the inorganic substance. When the content of the inorganic material is within the above range, the binding property of the inorganic material, the permeability of the separator, the heat resistance and the like tend to be further improved.

(organic matter)
The layer containing an inorganic substance may further have an organic substance in addition to the inorganic substance. Although it does not specifically limit as an organic substance, For example, the organic binder used in order to form the layer containing an inorganic substance can be mentioned. In the case where an inorganic porous layer is formed on the surface of the base film, the layer containing an inorganic substance preferably contains an organic binder. Although it does not specifically limit as an organic binder, For example, it is electrochemically stable on the use conditions of a lithium ion secondary battery, and a thing insoluble with respect to nonaqueous electrolyte solution is mentioned.

  Such an organic binder is not particularly limited. For example, polyolefin such as polyethylene and polypropylene; fluorine-containing polymer such as polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and fluorine-based rubber; Rubbers such as vinyl acetate, polyvinyl alcohol, polyvinyl butyral (PVB); ethylene-acrylic acid ester copolymer, methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester Copolymers containing acrylic esters such as copolymers; Styrene-butadiene rubber (SBR) and hydrides thereof; Acrylonitrile-butadiene-styrene copolymers and hydrides thereof; Ethylcellulose, Methyl Cell Cellulose derivatives such as cellulose, carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC); polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, polyamide, polyester, polyvinylpyrrolidone (PVP), crosslinked acrylic Resins, polyurethane, epoxy resins and the like can be mentioned.

  Among these, a heat-resistant binder having a heat-resistant temperature of 150 ° C. or higher is particularly preferable, and a heat-resistant binder having a heat-resistant temperature of 180 ° C. or higher is more preferably used. An organic binder may be used individually by 1 type, and may use 2 or more types together.

  A latex binder can also be used as the organic binder. Latex binders are emulsion polymerized from aliphatic conjugated diene monomers, unsaturated carboxylic acid monomers, and other monomers copolymerizable with these from the viewpoints of electrochemical stability and binding properties. What is obtained is preferable. Emulsion polymerization can be performed by a conventional method.

  Although it does not specifically limit as a conjugated diene type compound, For example, 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene Substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and the like.

  The unsaturated carboxylic acid monomer is not particularly limited, and examples thereof include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Acid is preferred.

  The layer containing an inorganic substance may further contain materials other than the materials described above.

[Positive electrode]
A positive electrode will not be specifically limited if it acts as a positive electrode of a lithium ion secondary battery, A well-known thing can be used. The positive electrode preferably contains one or more selected from the group consisting of materials capable of inserting and extracting lithium ions as a positive electrode active material.

(Positive electrode active material)
Further, the discharge capacity of the positive electrode active material at a potential of 4.4 V (vsLi / Li ⁺ ) or more is preferably 10 mAh / g or more, more preferably 15 mAh / g or more, and further preferably 20 mAh / g or more. is there. When the discharge capacity of the positive electrode active material at a potential of 4.3 V (vsLi / Li ⁺ ) or higher is within the above range, a lithium ion secondary battery can be driven at a higher voltage to achieve a high energy density. It tends to be possible. Furthermore, even if it is a case where this positive electrode is provided, if it is the lithium ion secondary battery of this embodiment, it exists in the tendency which can improve a cycle life more. The discharge capacity of the positive electrode active material can be measured by the method described in the examples.

Here, 4.3 V and a positive electrode active material having a 10 mAh / g or more discharge capacity in (vsLi / Li ⁺⁾ or more potential, 4.3V (vsLi / Li ⁺⁾ of the lithium ion secondary battery in the above potential It is a positive electrode active material capable of causing charge and discharge reactions as a positive electrode, and has a discharge capacity at a constant current discharge of 0.1 C of 10 mAh or more with respect to 1 g of mass of the active material. Therefore, it is sufficient that the positive electrode active material has a discharge capacity of 10 mAh / g or more at a potential of 4.3 V (vsLi / Li ⁺ ) or higher, and a discharge capacity at a potential of 4.3 V (vsLi / Li ⁺ ) or lower. There is no problem even if it has.

Although it does not specifically limit as a positive electrode active material which can be used by this embodiment, For example, a lithium containing compound is mentioned, More specifically,
Following formula (1):
_{LiMn 2-x Ma x O 4} (1)
(In formula (1), Ma represents one or more selected from the group consisting of transition metals, and x satisfies 0.2 ≦ x ≦ 0.7.)
An oxide represented by
Following formula (2):
LiMn _1-u Me _u O ₂ (2)
(In formula (2), Me represents one or more selected from the group consisting of transition metals excluding Mn, and u satisfies 0.1 ≦ u ≦ 0.9.)
An oxide represented by
Following formula (3):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (3)
(In Formula (3), Mc and Md each independently represent one or more selected from the group consisting of transition metals, and z satisfies 0.1 ≦ z ≦ 0.9.)
A composite oxide represented by
Following formula (4):
LiMb _1-y Fe _y PO ₄ (4)
(In the formula (4), Mb represents one or more selected from the group consisting of Mn and Co, and y satisfies 0 ≦ y ≦ 0.9.)
And a compound represented by the following formula (5):
Li ₂ MfPO ₄ F (5)
(In formula (5), Mf represents one or more selected from the group consisting of transition metals.)
A compound represented by
It is preferable that it is 1 or more types chosen from the group which consists of. These positive electrode active materials tend to be more excellent in structural stability.

The oxide represented by the formula (1) may be a spinel positive electrode active material. Although it does not specifically limit as a spinel type positive electrode active material, following formula (1a):
LiMn _2-x Ni _x O ₄ (1a)
(In the formula (1a), x satisfies 0.2 ≦ x ≦ 0.7.)
An oxide represented by the following formula (1b):
LiMn _2-x Ni _x O ₄ (1b)
(In the formula (1b), x satisfies 0.3 ≦ x ≦ 0.6.)
Is more preferable.

The oxide represented by the formula (1a) or formula (1b), 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 (1), the stability of the positive electrode active material tends to be more excellent.

  From the viewpoint of stability of the positive electrode active material, electronic conductivity, and the like, the spinel oxide represented by the formula (1) is within a range of 10 mol% or less with respect to the number of moles of Mn atoms, in addition to the above structure. Further, a transition metal or a transition metal oxide may be contained. The compound represented by Formula (1) is used individually by 1 type or in combination of 2 or more types.

The oxide represented by the formula (2) may be a layered oxide positive electrode active material. Although it does not specifically limit as a layered oxide positive electrode active material, For example, following formula (2a):
_{LiMn 1-vw Co v Ni w} O 2 (2a)
(In the formula (2a), v satisfies 0.1 ≦ v ≦ 0.4, and w satisfies 0.1 ≦ w ≦ 0.8.)
The oxide represented by these is preferable.

The layered oxide represented by the formula (2a) 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 or the like. By using the compound represented by Formula (2), the stability of the positive electrode active material tends to be more excellent. The compound represented by Formula (2) is used individually by 1 type or in combination of 2 or more types.

The composite oxide represented by the formula (3) may be a composite layered oxide. Although it does not specifically limit as a composite layered oxide, For example, following formula (3a):
_{zLi 2 MnO 3 - (1-} z) LiNi a Mn b Co c O 2 (3a)
(In the formula (3a), z satisfies 0.3 ≦ z ≦ 0.7, a satisfies 0.2 ≦ a ≦ 0.6, and b satisfies 0.2 ≦ b ≦ 0.6. And c satisfies 0.05 ≦ c ≦ 0.4, and a, b, and c satisfy the relationship of a + b + c = 1.)
A composite oxide represented by

  In Formula (3a), 0.4 ≦ z ≦ 0.6, a + b + c = 1, 0.3 ≦ a ≦ 0.4, 0.3 ≦ b ≦ 0.4, 0.2 ≦ c ≦ 0.3 A certain complex oxide is more preferable. By using the composite oxide represented by the formula (3), the stability of the positive electrode active material tends to be more excellent. The composite layered oxide represented by the formula (3) is within a range of 10 mol% or less with respect to the total number of moles of Mn, Ni and Co atoms from the viewpoint of stability of the positive electrode active material, electronic conductivity and the like. In addition to the above structure, a transition metal or a transition metal oxide may be further contained. The composite oxide represented by the formula (3) is used alone or in combination of two or more.

The compound represented by the formula (4) may be an olivine type positive electrode active material. Although it does not specifically limit as an olivine type positive electrode active material, For example, following formula (4a):
LiMh _1-y Fe _y PO ₄ (4a)
(In formula (4a), y satisfies 0.05 ≦ y ≦ 0.8, Mh represents a transition metal such as Mn and Co), or the following formula (4b):
LiMh _1-y Co _y PO ₄ (4b)
(In formula (4b), y satisfies 0.05 ≦ y ≦ 0.8, and Mh represents a transition metal such as Mn or Ti.)
The compound represented by these is preferable.

  By using the compound represented by the formula (4), the stability and electronic conductivity of the positive electrode active material tend to be more excellent. The compound represented by Formula (4) is used individually by 1 type or in combination of 2 or more types.

The compound represented by the formula (5) may be a fluorinated olivine type positive electrode active material. The fluoride olivine-type positive electrode active material 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 Formula (5), the stability of the positive electrode active material tends to be more excellent. The compound represented by the formula (5) has the above structure in a range of 10 mol% or less with respect to the total number of moles of Mn, Fe and Co atoms from the viewpoint of stability of the positive electrode active material, electronic conductivity and the like. In addition, a transition metal or a transition metal oxide may be further contained. The compound represented by Formula (5) is used individually by 1 type or in combination of 2 or more types.

The positive electrode active materials having a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vsLi / Li ⁺ ) or more can be used singly or in combination of two or more. Also, as the positive electrode active material, 4.4V (vsLi / Li ⁺⁾ and the positive electrode active material having a 10 mAh / g or more discharge capacity than the potential, 4.4V (vsLi / Li ⁺⁾ or more potential 10 mAh / g 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 of 4.4 V (vsLi / Li ⁺ ) or more is not particularly limited, and examples thereof include LiFePO ₄ .

  The number average particle diameter (primary particle diameter) of the positive electrode active material is preferably 0.050 μm to 100 μm, more preferably 1.0 μm to 10 μm. This number average particle diameter is obtained by randomly extracting 100 particles observed with a transmission electron microscope, analyzing them with image analysis software, and calculating the arithmetic average thereof. In this case, when the number average particle diameter differs between measurement methods for the same sample, a calibration curve created for the standard sample may be used.

(Lithium standard positive electrode potential at full charge)
The lithium-based positive electrode potential when the lithium ion secondary battery according to the present embodiment is fully charged is preferably 4.1 V (vsLi / Li ⁺ ) or more, more preferably 4.2 V (vsLi / Li ⁺ ) or more. More preferably, it is 4.3 V (vsLi / Li ⁺ ) or more, and particularly preferably 4.35 V (vsLi / Li ⁺ ) or more. The upper limit of the lithium-based positive electrode potential when the lithium ion secondary battery is fully charged is not particularly limited, but is preferably 5.0 V (vsLi / Li ⁺ ) or less. Even if the lithium-based positive electrode potential at the time of full charge is 4.1 V (vsLi / Li ⁺ ) or more at the time of full charge, the lithium-ion secondary battery of the present embodiment can be charged. It tends to be able to suppress decomposition of the non-aqueous electrolyte during discharge or storage. Thereby, stable charge and discharge can be performed over a long period of time, and a battery excellent in reliability and safety can be formed. Therefore, the charge / discharge capacity of the positive electrode active material of the lithium ion secondary battery can be more efficiently utilized, and the energy density of the lithium ion secondary battery tends to be further improved. The lithium-based positive electrode potential 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.

(Method for producing positive electrode active material)
Although it does not specifically limit as a positive electrode active material, For example, it can manufacture with the method similar to the manufacturing method of a general inorganic oxide. Specifically, a method of obtaining a positive electrode active material containing an inorganic oxide by firing a mixture in which metal salts (for example, sulfate and / or nitrate) are mixed at a predetermined ratio in an atmosphere environment containing oxygen. It is done. In addition, a carbonate and / or hydroxide salt is allowed to act on a solution in which the metal salt is dissolved to precipitate a hardly soluble metal salt, which is extracted and separated into a lithium source and lithium carbonate and / or hydroxide as a lithium source. After lithium is mixed, a method of obtaining a positive electrode active material containing an inorganic oxide by 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, dried to form a positive electrode mixture layer, and the positive electrode mixture layer is pressurized as necessary to adjust the thickness, whereby a positive electrode can be produced. .

  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.

[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 can be used. The negative electrode preferably contains at least one material selected from the group consisting of a material capable of inserting and extracting lithium ions as a negative electrode active material and metallic lithium. Such a negative electrode active material is not particularly limited, but for example, one type 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. The above is mentioned. Among these, one or more materials selected from the group consisting of metallic lithium, carbon materials, silicon materials, and materials containing an element capable of forming an alloy with lithium are more preferable. 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, fired body of organic polymer compound, mesocarbon microbead, carbon Examples thereof include fibers, activated carbon, graphite, carbon colloid, and carbon black. Although it does not specifically limit as coke, For example, pitch coke, needle coke, and petroleum coke are mentioned. 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 a silicon material, For example, a crystalline silicon compound, an amorphous silicon compound, an organic silicon compound, an alloy of silicon and a metal, etc. are 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, and examples thereof include a metal or a semimetal simple substance or an alloy. Moreover, the compound which has these 1 type, or 2 or more types of phases in at least one part can also be used.

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

  Although it does not specifically limit as a metal element and a metalloid element, For example, titanium (Ti), tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony ( Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr) and yttrium (Y). Among these, metal elements and metalloid elements of Group 4 or Group 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 one having at least one element selected from the group consisting of chromium.

  Although it does not specifically limit as an alloy of tin, For example, as a 2nd structural element other than tin, silicon, magnesium (Mg), nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti) And one having at least one element selected from the group consisting of germanium, bismuth, antimony, and 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 to adjust the thickness, whereby a negative electrode can be produced. .

  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 foil, such as copper foil, nickel foil, or stainless steel foil, is mentioned.

[Conductive aid or binder used to produce positive and negative electrodes]
Although it does not specifically limit as a conductive support agent used as needed at the time of preparation of a positive electrode and a negative electrode, For example, carbon black represented by graphite, acetylene black, and ketjen black; and carbon fiber are mentioned. The number average particle diameter (primary particle diameter) of the conductive assistant is preferably 0.1 μm to 100 μm, more preferably 1 μm to 10 μm. The number average particle size of the conductive additive is measured in the same manner as the number average particle size of the positive electrode active material.

  The binder is not particularly limited, and examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, styrene butadiene rubber, and fluorine rubber.

<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.

  In the manufacturing method of the lithium ion secondary battery in this embodiment, the process of pressurizing or depressurizing the inside of the battery may be included. 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 non-aqueous 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 non-aqueous electrolyte and the battery structure, and expresses various performances of the non-aqueous electrolyte in the present embodiment to a higher degree. Manufacture is also relatively 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. The method of initial charge in the present embodiment is not particularly limited, but the initial charge is preferably performed at 0.001 C to 0.5 C, more preferably 0.002 C to 0.3 C, and 0 More preferably, it is performed at 0.003C to 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 lithium ion secondary battery of this embodiment can also be connected and used 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 lithium ion secondary battery were measured and evaluated as follows.

(1) Preparation of non-aqueous electrolyte (preparation of non-aqueous electrolyte (A))
In a mixed solvent obtained by mixing ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3: 7, LiPF ₆ was dissolved so as to be 1 mol%, and a non-aqueous electrolyte (A ) These preparations were performed in an argon atmosphere.

(Preparation of non-aqueous electrolyte (B))
1% by weight of tris (trimethylsilyl) phosphate was added to the nonaqueous electrolyte (A) to obtain a nonaqueous electrolyte (B). These preparations were performed in an argon atmosphere.

(2) Manufacture of separator (Manufacture of separator (C))
47.5 parts by weight of polyethylene having a weight average molecular weight of 700,000, 47.5 parts by weight of polyethylene having a weight average molecular weight of 250,000, and 5 parts by weight of polypropylene having a homopolymer having a weight average molecular weight of 400,000 And 1 part by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] were dry blended to obtain a mixture. This mixture was put into an extruder under a nitrogen atmosphere and melt kneaded. At this time, liquid paraffin was added as a plasticizer. It adjusted so that the liquid paraffin amount which occupies in an extrusion composition might be 65 mass%.

  This melt-kneaded product was guided to a simultaneous biaxial tenter stretching machine, and subjected to simultaneous biaxial stretching of 7 times in the MD direction and 6.4 times in the TD direction. The stretched membrane was put into a methyl ethyl ketone bath, liquid paraffin was extracted and removed, and methyl ethyl ketone was dried. Then, heat setting was performed with a 122 ° C. heat fixing machine to obtain a separator base film. The film thickness of the base film was 16 μm.

  Subsequently, 96.0 parts by mass of calcined kaolin having an average particle diameter of 2 μm, 4.0 parts by mass of acrylic latex (average particle diameter 140 nm, solid content concentration 40%), and an aqueous ammonium polyacrylate solution (SN Dispersant 5468 manufactured by San Nopco) 0.5 parts by mass was uniformly dispersed in 180 parts by mass of water to prepare a coating solution. The obtained coating solution was applied to both surfaces of the base film using a gravure coater. The coating solution was dried at 60 ° C. to obtain a separator (C) having a fired kaolin layer having a thickness of 5 μm on the base film.

(Manufacture of separator (D))
A separator base film having a thickness of 20 μm was produced in the same manner as described above. This base film was used as a separator (D).

(3) Manufacture of positive electrode Composite oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) of lithium, nickel, cobalt and manganese, which are positive electrode active materials, and SuperP Li (TIMCAL, Inc.), which is an auxiliary agent Product), PVDF (made by Kuraray, polyvinylidene fluoride) as a binder, and N-methyl-pyrrolidone were mixed to obtain a positive electrode slurry. This positive electrode slurry was applied onto an aluminum current collector so that the positive electrode active material weight per unit area was 18 mg / cm ² and the electrode density was 2.7 g / cm ³ to obtain a positive electrode (E).

(4) Production of negative electrode Carbon (OMAC) as a negative electrode active material, styrene-butadiene rubber as a binder, carboxymethyl cellulose as a thickener, and water were mixed to obtain a negative electrode slurry. This negative electrode slurry was applied on a copper current collector so that the negative electrode active material weight per unit area was 10 mg / cm ² and the electrode density was 1.5 g / cm ³ to obtain a negative electrode (F).

(5) Production of battery An electrode-separator laminate was produced so that a separator was present between the positive electrode (E) and the negative electrode (F), and was introduced into the outer package of a laminated cell in which aluminum and a resin were laminated. did. Three directions of the cell were sealed with a dedicated laminator. Thereafter, a non-aqueous electrolyte was poured into the exterior body, defoamed, the electrode-separator laminate was impregnated with the non-aqueous electrolyte, and the remaining one direction was sealed. The battery was manufactured so that 1C = 1 Ah.

(6) Battery evaluation After the obtained battery was held in a thermostatic bath set at 25 ° C. (constant bath PLM-63S (trade name) manufactured by Futaba Kagaku Co., Ltd.) for 24 hours, a charge / discharge device (manufactured by Asuka Electronics Co., Ltd.) Product name “ACD-01”). Then, the battery was charged to 4.35 V at 0.05 C (constant current-constant voltage charging / charging time 3 hours), and was discharged at a constant current to 3.0 V at 0.2 C for initial conditioning. In addition, the environmental temperature at this time is 25 degreeC.

  Subsequently, in an environment of 50 ° C., the battery was charged to 4.35 V at 1 C (constant current-constant voltage charging / charging time 1 hour), and constant current discharge was performed to 3.0 V at 1 C. This charge / discharge was repeated 100 cycles. The discharge capacity at the 100th cycle relative to the discharge capacity at the first cycle was calculated as a discharge capacity retention rate (%).

[Example 1]
A battery was manufactured using the non-aqueous electrolyte (B) and the separator (C), and the battery was evaluated. The discharge capacity retention rate was 95%. The potential of the positive electrode based on lithium at the time of full charge was 4.4 V (vsLi / Li ⁺ ). The positive electrode had a discharge capacity exceeding 20 mAh / g at a potential of 4.4 V (vsLi / Li ⁺ ).

[Comparative Example 1]
A battery was manufactured using the non-aqueous electrolyte (A) and the separator (D), and the battery was evaluated. The discharge capacity retention rate was 10%.

[Comparative Example 2]
A battery was manufactured using the non-aqueous electrolyte (A) and the separator (C), and the battery was evaluated. The discharge capacity retention rate was 40%.

[Comparative Example 3]
A battery was manufactured using the non-aqueous electrolyte (B) and the separator (D), and the battery was evaluated. The discharge capacity retention rate was 55%.

  Both the non-aqueous electrolyte containing the silicon-containing compound and the separator containing the inorganic substance improve the discharge capacity retention rate in the high-voltage charge / discharge cycle, but it has been found that when they are used in combination, extremely high performance is exhibited. This is presumably because the inorganic compound contained in the silicon-containing compound and the separator has a common function and a different function in the effect of improving battery characteristics under high voltage. In particular, the use of an inorganic substance that improves the function of the separator and the silicon-containing compound that improves the function of the electrode suppresses short-circuiting and micro-short-circuiting, which are related to long-term charge and discharge characteristics retention and reliability. It is thought that there is.

  The present invention has industrial applicability in the technical field of lithium ion secondary batteries.

Claims (10)

A non-aqueous electrolyte, a separator having a layer containing an inorganic substance in a part or the whole of the base film, a positive electrode, and a negative electrode,
The non-aqueous electrolyte includes a silicon-containing compound, a lithium salt, and a non-aqueous solvent,
The silicon-containing compound includes a 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. Lithium ion secondary battery.   In the silicon-containing compound, one or more hydrogen atoms of one or more compounds selected from the group consisting of inorganic acids containing boron or phosphorus, carboxylic acids, sulfonic acids, and phosphoric acid amides are substituted with silicon-containing functional groups. The lithium ion secondary battery of Claim 1 containing the compound currently made.   The silicon-containing compound is a compound in which one or more hydrogen atoms of one or more compounds selected from the group consisting of an inorganic acid containing phosphorus, a carboxylic acid, and a phosphoric acid amide are substituted with a silicon-containing functional group. The lithium ion secondary battery of Claim 1 or 2 containing.   The lithium ion secondary battery according to any one of claims 1 to 3, wherein the silicon-containing compound further includes a compound having a Si-F bond.   The lithium ion secondary battery according to any one of claims 1 to 4, wherein the layer containing the inorganic substance is present on one side or both sides of the base film.   The lithium ion secondary battery according to any one of claims 1 to 5, wherein the inorganic substance includes one or more selected from the group consisting of metal oxides, metal hydroxides, carbonates, and clay minerals.   The lithium ion secondary battery according to any one of claims 1 to 6, wherein the layer containing an inorganic substance further contains an organic substance. The lithium ion secondary battery according to any one of claims 1 to 7, wherein a potential of the positive electrode based on lithium at a full charge is 4.1 V (vsLi / Li ⁺ ) or more. The positive electrode is
Following formula (1):
_{LiMn 2-x Ma x O 4} (1)
(In formula (1), Ma represents one or more selected from the group consisting of transition metals, and x satisfies 0.2 ≦ x ≦ 0.7.)
An oxide represented by
Following formula (2):
LiMn _1-u Me _u O ₂ (2)
(In formula (2), Me represents one or more selected from the group consisting of transition metals excluding Mn, and u satisfies 0.1 ≦ u ≦ 0.9.)
An oxide represented by
Following formula (3):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (3)
(In Formula (3), Mc and Md each independently represent one or more selected from the group consisting of transition metals, and z satisfies 0.1 ≦ z ≦ 0.9.)
A composite oxide represented by
Following formula (4):
LiMb _1-y Fe _y PO ₄ (4)
(In the formula (4), Mb represents one or more selected from the group consisting of Mn and Co, and y satisfies 0 ≦ y ≦ 0.9.)
And a compound represented by the following formula (5):
Li ₂ MfPO ₄ F (5)
(In formula (5), Mf represents one or more selected from the group consisting of transition metals.)
A compound represented by
The lithium ion secondary battery as described in any one of Claims 1-8 containing the 1 or more types of positive electrode active material chosen from the group which consists of. The lithium ion secondary battery according to any one of claims 1 to 9, wherein the positive electrode includes a positive electrode active material having a discharge capacity of 10 mAh / g or more at a potential of 4.3 V (vsLi / Li ⁺ ) or more. .