JP2008004557A - Nonaqueous electrolyte for lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte for a lithium secondary battery suitable for manufacturing a secondary battery having high discharge capacity and good charge/discharge cycle characteristics. <P>SOLUTION: This nonaqueous electrolyte for a secondary battery contains cyclic carbonate, noncyclic carbonate, Li salt, and a boron compound at a rate of 0.0001-0.1 mole/l to a solvent, and the boron compound is represented by formula 1 or 2. In the formula, each of R<SP>31</SP>, R<SP>32</SP>, and R<SP>33</SP>is an aryl group, and each of R<SP>1</SP>, R<SP>2</SP>, and R<SP>3</SP>is an alkoxy group or the like. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte for a high-capacity non-aqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics, and a discharge in which a negative electrode material is mainly an amorphous chalcogen compound and / or an amorphous oxide. The present invention relates to improvement of charge / discharge characteristics such as charge / discharge cycle life of a non-aqueous electrolyte secondary battery having a large capacity.

In recent years, the development of portable electronic devices has been accelerated by the practical application of high voltage and high capacity lithium secondary batteries, and the demand for lithium secondary batteries is increasing. The high-voltage / high-capacity lithium secondary battery was realized by using a material capable of inserting and releasing lithium for the negative electrode and using a composite oxide of lithium and transition metal for the positive electrode. Improvements are still desired.
Attempts to improve cycle characteristics have been extensive for a long time, and the reaction involving the electrolyte is observed especially during the charge / discharge cycle, so the solvent composition of the electrolyte and the type of supporting salt have been studied. .
In addition, attempts have been made to prevent the decomposition of the electrolytic solution and extend the cycle life by adding a small amount of additive to the electrolytic solution. For example, Patent Document 1, Patent Document 2, Patent Document 3, etc. describe boric acid esters such as trimethyl borate, and Patent Document 4 describes silylated boric acid esters, which are used by adding them to the electrolyte. Are listed.
However, even if the above technique is used, it has not reached a level at which both high discharge capacity and excellent cycle characteristics can be achieved.

JP 59-3874 A JP 63-269461 A JP-A-8-321313 JP-A-3-236169

  The subject of this invention is providing the nonaqueous electrolyte for lithium secondary batteries suitable for manufacture of the secondary battery which has a large discharge capacity and has the charging / discharging cycling characteristics.

The above problems have been achieved by the following means.
(1) A non-aqueous electrolyte used in a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode containing a material capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte, and a separator. Contains a cyclic carbonate, an acyclic carbonate and a lithium salt, and further contains at least one organic boron compound in an amount of 0.0001 to 0.1 mol / l with respect to the electrolyte solvent. A non-aqueous electrolyte for a lithium secondary battery, which is a compound represented by the formula (1) or (2).
General formula (1)

(In the formula, R ³¹ , R ³² and R ³³ each represent an aryl group.)
General formula (2)

(Wherein R ¹ , R ² and R ³ may be the same or different from each other, and are an alkoxy group, an aryloxy group or —OB (R ¹¹ ) (R ¹² ), at least one of which is an alkoxy group or an aryloxy group. R ¹¹ and R ¹² may be the same or different from each other, and each represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a halogen atom, a cyano group, Nitro group, hydroxy group, formyl group, aryloxy group, alkylthio group, arylthio group, acyloxy group, sulfonyloxy group, amino group, alkylamino group, arylamino group, carbonamido group, sulfonamido group, oxycarbonylamino group, Oxysulfonylamino group, ureido group, acyl group, oxycarbonyl group, carbamoyl Represents a group, a sulfonyl group, a sulfinyl group, an oxysulfonyl group or a sulfamoyl group, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, or a heterocyclic group, wherein R ¹ , R ² , R ³ , R ¹¹ and R ¹² are They may be bonded to each other to form a ring, and at least ^one of R ¹ , R ² and R ³ may be bonded to each other to form a ring, and these rings may have a substituent. May be substituted by a substitutable group.)
(2) The nonaqueous electrolytic solution for a lithium secondary battery according to Item 1, wherein the organic boron compound is at least one selected from the following compounds.

(3) The lithium secondary battery according to Item 1 or 2, wherein the organoboron compound is at least one selected from the compounds B-1, B-6, C-14, and C-15. Non-aqueous electrolyte.
(4) The nonaqueous electrolytic solution for a lithium secondary battery according to any one of Items 1 to 3, wherein the lithium salt is at least LiBF ₄ and / or LiPF ₆ .
(5) The non-aqueous electrolyte for a lithium secondary battery according to any one of Items 1 to 4, wherein the cyclic carbonate is at least one of ethylene carbonate and propylene carbonate.
(6) The non-aqueous electrolysis for a lithium secondary battery according to any one of Items 1 to 5, wherein the acyclic carbonate is at least one of diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate. liquid.
(7) A lithium secondary battery using the nonaqueous electrolytic solution for a lithium secondary battery according to any one of items 1 to 6.

(8) In a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode containing a material capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and a separator, at least one organic substance is contained in the battery. A non-aqueous electrolyte secondary battery comprising a boron compound.
(9) The nonaqueous electrolyte secondary battery according to item 8, wherein the organic boron compound is a compound represented by the following general formula (3).
General formula (3)

In the formula, X ¹ , X ² and X ³ may be the same or different from each other, and represent a hetero atom (excluding an oxygen atom). R ²¹ , R ²² and R ²³ may be the same or different and each is a hydrogen atom, alkyl group, cycloalkyl group, alkoxy group, alkenyl group, alkynyl group, aralkyl group, aryl group, halogen atom, cyano group, hydroxy group , Formyl group, aryloxy group, alkylthio group, arylthio group, acyloxy group, sulfonyloxy group, amino group, alkylamino group, arylamino group, carbonamido group, sulfonamido group, oxycarbonylamino group, oxysulfonylamino group, It represents a ureido group, acyl group, oxycarbonyl group, carbamoyl group, sulfonyl group, sulfinyl group, oxysulfonyl group or sulfamoyl group, carboxylic acid group, sulfonic acid group, phosphonic acid group, and heterocyclic group. R ²¹ , R ²² and R ²³ may be bonded to each other to form a ring, and this ring may have a substituent. Each group may be substituted with a substitutable group. x, y, and z represent an integer of 1 to 5. When x, y and z are 2 or more, the plurality of R ²¹ , R ²² and R ²³ may be the same or different. k, m, and n represent 0 or an integer. However, at least one of k, m, and n is 1 or more.
(10) The nonaqueous electrolytic secondary battery according to item 8, wherein the organic boron compound is a compound represented by the following general formula (4).
General formula (4)

In the formula, R ⁴¹ , R ⁴² and R ⁴³ each represents an alkyl group or an alkoxy group.
(11) The nonaqueous electrolytic secondary battery according to item 8, wherein the organic boron compound is a compound represented by the following general formula (5).
General formula (5)

In the formula, Ar ¹ , Ar ² and Ar ³ each represents an aryl group.
(12) The nonaqueous electrolyte secondary battery according to any one of Items 8 to 11, wherein the organic boron compound is a nonaqueous electrolyte containing a lithium salt.
(13) The content of at least one organoboron compound contained in the nonaqueous electrolytic solution is 0.001 wt% to 10 wt% with respect to the supporting salt contained in the electrolytic solution. A nonaqueous electrolyte secondary battery according to 1.
(14) A nonaqueous electrolyte secondary battery, wherein the supporting salt according to item 13 is at least LiBF ₄ and / or LiPF ₆ .
(15) The nonaqueous electrolyte secondary battery according to any one of Items 8 to 14, wherein the solvent of the nonaqueous electrolytic solution is composed of at least one cyclic carbonate and at least one chain carbonate.
(16) The nonaqueous electrolyte secondary battery according to any one of Items 8 to 15, wherein the negative electrode is a carbonaceous material capable of occluding and releasing lithium.
(17) The negative electrode is composed of a negative electrode material mainly composed of an amorphous chalcogen compound and / or an amorphous oxide, containing three or more atoms selected from Group 1, 2, 13, 14, and 15 group atoms. Item 16. The nonaqueous electrolyte secondary battery according to any one of Items 8 to 15.
(18) The nonaqueous electrolyte secondary battery according to item 17, wherein at least one of the negative electrode materials is represented by the general formula (6).
M ¹ M ² pM ⁴ qM ⁶ r General formula (6)
(In the formula, M ¹ and M ² are different and are at least one selected from Si, Ge, Sn, Pb, P, B, Al, and Sb, and M ⁴ is Li, Na, K, Rb, Cs, Mg, Ca, (At least one selected from Sr and Ba, M ⁶ represents at least one selected from O, S, and Te, p and q each represent a number of 0.001 to 10, and r represents a number of 1.00 to 50.)

  By using the non-aqueous electrolyte for a lithium secondary battery of the present invention, a non-aqueous electrolyte secondary battery having excellent charge / discharge characteristics and little deterioration in discharge capacity due to repeated charge / discharge can be obtained.

Although the preferable form of this invention is raised below, this invention is not limited to these.
Examples of the organic boron compound used in the present invention include H.I. Examples include compounds described by Steinberg, “Organoboron Chemistry, Vol. 1-3, Wiley & Sons Inc., New York (1964)”.

The compound represented by the general formula (1) will be described in more detail.
In the general formula (1), R ³¹ , R ³² and R ^{33 each} represent a substituted or unsubstituted aryl group (preferably having 6 to 16 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group). Of these, a substituted or unsubstituted phenyl group is preferred. Examples of substituents include alkyl groups (eg, methyl, ethyl, butyl, dodecyl, cyclohexyl, trifluoromethyl, etc.), aryl groups (eg, phenyl, naphthyl, anthryl, etc.), alkoxy groups (eg, methoxy, ethoxy, dodecyloxy, benzyl). Oxy, phenoxy, etc.), halogen atoms (eg, chlorine atom, bromine atom, fluorine atom), cyano group, nitro group and the like.

Hereinafter, the compound of the general formula (2) will be described in detail.
In the general formula (2), R ¹ , R ² , and R ³ may be the same as or different from each other, and each is an alkoxy group (preferably having 1 to 16 carbon atoms. For example, methoxy, ethoxy, 2-methoxyethoxy) Represents an aryloxy group (preferably having 6 to 16 carbon atoms, such as phenoxy), or —OB (R ¹¹ ) (R ¹² ) [R ¹¹ and R ¹² may be the same as or different from each other; Atoms, alkyl groups (preferably having 1 to 16 carbon atoms), cycloalkyl groups (preferably having 3 to 9 carbon atoms), alkoxy groups (preferably having 1 to 16 carbon atoms), alkenyl groups (preferably Having 2 to 16 carbon atoms), an alkynyl group (preferably having 2 to 16 carbon atoms), an aralkyl group (preferably having 7 to 16 carbon atoms), an aryl group (preferably having 6 to 16 carbon atoms). ), Halogen atom, cyano group, nitro group, hydroxy group, formyl group, aryloxy group (preferably having 6 to 16 carbon atoms), alkylthio group (preferably having 1 to 16 carbon atoms), arylthio group (Preferably having 6 to 16 carbon atoms), acyloxy group (preferably having 1 to 12 carbon atoms), sulfonyloxy group (preferably having 1 to 12 carbon atoms), amino group, alkylamino group (preferably Having 1 to 32 carbon atoms), arylamino group (preferably having 6 to 32 carbon atoms), carbonamido group, sulfonamido group, oxycarbonylamino group, oxysulfonylamino group, ureido group, acyl group (preferably 1 to 12 carbon atoms), oxycarbonyl group, carbamoyl group, sulfonyl group, sulfinyl group, oxysulfonyl Or a sulfamoyl group, a carboxylic acid group, a sulfonic acid group, represents a phosphonic acid group, a Hajime Tamaki (preferably of 5 or 6 membered)]. R ¹ , R ² , R ³ , R ¹¹ and R ¹² may be bonded to each other to form a ring, and at least a pair of R ¹ , R ² and R ³ may be bonded to each other to form a ring. These rings may have a substituent. Unless otherwise specified, each group in the present specification may be substituted with a substituent if it can be substituted.

  Specific examples of the compounds used in the present invention are shown below, but the scope of the present invention is not limited to these.

Hereinafter, the compound of the general formula (3) will be described in detail.
In the general formula (3), X ¹ , X ² and X ³ may be the same or different from each other, and represent a hetero atom (excluding an oxygen atom). R ²¹ , R ²² and R ²³ may be the same or different and are each a hydrogen atom, an alkyl group (preferably having 1 to 16 carbon atoms, for example, methyl, ethyl, propyl, dodecyl) cycloalkyl group (preferably carbon Those having a number of 3 to 9. For example, cyclopropyl, cyclohexyl), alkoxy groups (preferably those having 1 to 16 carbon atoms, for example, methoxy, ethoxy, 2-methoxyethoxy), alkenyl groups (preferably having 2 to 16 carbon atoms). For example, vinyl, allyl, cyclohexenyl), alkynyl group (preferably having 2 to 16 carbon atoms, such as ethynyl, 2-propenyl, hexadecynyl), aralkyl group (preferably having 7 to 16 carbon atoms). For example, benzyl, diphenylmethyl, naphthylmethyl), an aryl group (preferably having 6 to 16 carbon atoms) For example, phenyl, naphthyl, anthryl), halogen atom (for example, chlorine atom, bromine atom, fluorine atom), cyano group, nitro group, hydroxy group, formyl group, aryloxy group (preferably having 6 to 16 carbon atoms) For example, phenoxy), an alkylthio group (preferably having 1 to 16 carbon atoms, such as methylthio, octylthio-2-phenoxyoctylthio), an arylthio group (preferably having 6 to 16 carbon atoms, such as phenylthio), Acyloxy group (preferably having 1 to 12 carbon atoms, for example, acetoxy), sulfonyloxy group (preferably having 1 to 12 carbon atoms, for example, methanesulfonyloxy, benzenesulfonyloxy), amino group, alkylamino group ( Preferably having 1 to 32 carbon atoms, such as methylamino, Tilamino), arylamino group (preferably having 6 to 32 carbon atoms, for example, phenylamino), carbonamido group (for example, acetylamino, propanoylamino), sulfonamide group (for example, methanesulfonamide, benzenesulfonamide) ), Oxycarbonylamino group (for example, methoxycarbonylamino), oxysulfonylamino group (for example, ethoxysulfonylamino), ureido group (for example, phenylureido, methylureido), acyl group (preferably having 1 to 12 carbon atoms) For example, acetyl, benzoyl, pivaloyl), oxycarbonyl group (for example, methoxycarbonyl), carbamoyl group (for example, N-ethylcarbamoyl, N-benzylcarbamoyl), sulfonyl group (for example, methanesulfonyl, benzoyl) Sulfonyl), sulfinyl group (eg methanesulfinyl), oxysulfonyl group (eg methoxysulfonyl) or sulfamoyl group (N-ethylsulfamoyl), carboxylic acid group or salt thereof, sulfonic acid group or salt thereof, phosphonic acid Represents a group, a salt thereof, or a heterocyclic group (preferably a 5- or 6-membered group). R ²¹ , R ²² and R ²³ may be bonded to each other to form a ring, and this ring may have a substituent. Each group may be substituted with a substitutable group. x, y, and z represent an integer of 1 to 5. When x, y and z are 2 or more, the plurality of R ²¹ , R ²² and R ²³ may be the same or different. k, m, and n represent 0 or an integer. However, at least one of k, m, and n is 1 or more.

Further, X ¹ , X ² and X ³ may be the same or different from each other, more preferably sulfur, nitrogen, phosphorus, silicon, tin or boron, and particularly preferably sulfur, nitrogen, phosphorus or boron. . R ²¹ , R ²² and R ²³ may be the same or different, and each is preferably an alkyl group or an aryl group. Most preferred is when X ¹ , X ² and X ³ are sulfur, nitrogen, phosphorus or boron, and R ²¹ , R ²² and R ²³ are an alkyl group or an aryl group.

The compound represented by formula (4) will be described in more detail. In the general formula (4), R ⁴¹ , R ⁴² and R ⁴³ are alkyl groups (preferably having 1 to 16 carbon atoms, such as methyl, ethyl, butyl, dodecyl, cyclohexyl, trifluoromethyl, etc.), alkoxy groups [preferably One having 1 to 16 carbon atoms. Methoxy, ethoxy, dodecyloxy, benzyloxy group, substituted or unsubstituted phenoxy, etc. Examples of substituents include alkyl groups (eg, methyl, ethyl, butyl, dodecyloxy, cyclohexyl, trifluoromethyl, etc.), aryl groups (eg, phenyl, naphthyl, anthryl, etc.), alkoxy groups (eg, methoxy, ethoxy, dodecyloxy). , Benzyloxy, phenoxy, etc.), halogen atoms (for example, chlorine atom, bromine atom, fluorine atom, etc.), cyano group, nitro group and the like. ].

The compound represented by the general formula (5) will be described in more detail. In the general formula (5), Ar ¹ , Ar ² and Ar ³ may be the same or different, and each is a substituted or unsubstituted aryl group (preferably having 6 to 16 carbon atoms. For example, phenyl group, naphthyl group, anthryl Group). Of these, a substituted or unsubstituted phenyl group is preferred. Examples of the substituent include an alkyl group (eg, methyl, ethyl, butyl, dodecyl, cyclohexyl, trifluoromethyl, etc.), an aryl group (eg, phenyl, naphthyl, anthryl, etc.), an alkoxy group (eg, methoxy, ethoxy, dodecyloxy, Benzyloxy, phenoxy, etc.), halogen atoms (eg chlorine atom, bromine atom, fluorine atom etc.), cyano group, nitro group and the like.

  Specific examples of the compound represented by any one of the general formulas (3) to (5) are shown below, but the scope of the present invention is not limited thereto.

The secondary battery using the non-aqueous electrolyte for a lithium secondary battery of the present invention will be described below.
The organoboron compound may be contained in any of the batteries. Preferably, it is in the electrode active material or the electrolytic solution. When contained in the electrode, the content is preferably 0.01% by mass to 5% by mass and more preferably 0.1% by mass to 2% by mass with respect to the active material of the electrode. This invention is a case where it contains in electrolyte solution, 0.0001-0.1 mol / l is preferable with respect to electrolyte solution solvent, and, as for content of a compound, 0.001-0.1 mol / l is further. preferable. As content of the compound with respect to the support salt contained in electrolyte solution, 0.001 mass%-10 mass% are preferable, and 0.01 mass%-5 mass% are still more preferable.

The electrolytic solution is generally composed of a solvent and a supporting salt dissolved in the solvent, and a lithium salt (anion and lithium cation) is preferable.
Examples of the electrolyte solution that can be used in the present invention include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, dioxane, acetonitrile, nitromethane, ethyl monoglyme, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2 -Non-propylated oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethyl ether, 1,3-propane sultone, etc. It can be exemplified ton organic solvent, mixed and used alone or in combination. Of these, carbonate solvents are preferred, and those containing cyclic carbonate and / or acyclic carbonate are preferred. As the cyclic carbonate, ethylene carbonate and propylene carbonate are preferable. Moreover, it is preferable to include diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate as the non-cyclic carbonate.
Examples of the lithium salt dissolved in those solvents that can be used in the present invention, for _{example, LiClO 4, LiBF 4, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower aliphatic Li salts such as lithium group carboxylates, LiAlCl ₄ , LiCl, LiBr, LiI, chloroborane lithium, and lithium tetraphenylborate can be raised, and these can be used alone or in combination. Of these, a solution in which LiBF ₄ and / or LiPF ₆ is dissolved is preferable.
The concentration of the supporting salt is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.
Examples of the electrolytic solution include an electrolytic solution containing LiCF ₃ SO ₃ , LiClO ₄ , LiBF ₄ and / or LiPF ₆ in an electrolytic solution in which ethylene carbonate, propylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate or diethyl carbonate is appropriately mixed. preferable. In particular, an electrolytic solution containing LiCF ₃ SO ₃ , LiClO ₄ , LiBF ₄ and / or LiPF ₆ in a mixed solvent of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate is preferable. And those containing LiPF ₆ are preferred.
The amount of the electrolytic solution added to the battery is not particularly limited, but a necessary amount can be used depending on the amount of the positive electrode active material and the negative electrode material and the size of the battery.

  Hereinafter, other materials and manufacturing methods for making the nonaqueous electrolyte secondary battery will be described in detail. The positive and negative electrodes used in the nonaqueous electrolyte secondary battery of the present invention can be prepared by coating a positive electrode mixture or a negative electrode mixture on a current collector. In addition to the positive electrode active material or the negative electrode material, the positive electrode or the negative electrode mixture can contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives, respectively.

  One of the negative electrode materials is a carbonaceous material capable of occluding and releasing lithium. The carbonaceous material is a material substantially composed of carbon, for example, petroleum pitch, natural graphite, artificial graphite, non-graphitizable carbon, mesocarbon microbead, PAN-based carbon fiber, cellulose-based carbon fiber, and pitch-based carbon fiber. , Vapor grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, and the like.

  Another negative electrode material is an oxide or chalcogen of a metal or semi-metal group element, and is preferably mainly amorphous when incorporated into a battery. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays that has a broad scattering band having a peak at 20 ° to 40 ° in terms of 2θ, and has crystalline diffraction lines. Also good. Preferably, the strongest intensity of the crystalline diffraction lines seen at 2θ values of 40 ° or more and 70 ° or less is 500 of diffraction line intensities at the apexes of broad scattering bands seen at 20 ° or more and 40 ° or less of 2θ values. It is preferably not more than twice, more preferably not more than 100 times, particularly preferably not more than 5 times, and most preferably not having a crystalline diffraction line.

The negative electrode material is preferably represented by the following general formula (6).
M ¹ M ² pM ⁴ qM ⁶ r General formula (6)
In the formula, M ¹ and M ² are at least one selected from Si, Ge, Sn, Pb, P, B, Al, and Sb, preferably Si, Ge, Sn, P, B, and Al, Particularly preferred are Si, Sn, P, B, and Al. M ⁴ is at least one selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba, preferably K, Cs, Mg, and Ca, and particularly preferably Cs and Mg. M ⁶ is at least one selected from O, S, and Te, preferably O and S, and particularly preferably O. p and q are each 0.001 to 10, preferably 0.01 to 5, and particularly preferably 0.01 to 2. r is 1.00-50, Preferably it is 1.00-26, Most preferably, it is 1.02-6. The valences of M ¹ and M ² are not particularly limited, and may be a single valence or a mixture of valences. The M ^1, M ^2, the ratio of M ⁴ can be continuously changed in a range M ² and M ⁴ are from 0.001 to 10 molar equivalents relative to M ^1, the amount of M ⁶ accordingly (typically In equation (1), the value of r) also changes continuously.

Among the compounds listed above, in the present invention, M ¹ is preferably Sn, and is represented by the general formula (7).
SnM ³ pM ⁵ qM ⁷ r General formula (7)
In the formula, M ³ is at least one selected from Si, Ge, Pb, P, B, and Al, preferably Si, Ge, P, B, and Al, particularly preferably Si, P, B, and Al. is there. M ⁵ is at least one selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba, preferably Cs and Mg, and particularly preferably Mg. M ⁷ is at least one selected from O and S, preferably O. p and q are each 0.001 to 10, preferably 0.01 to 5, more preferably 0.01 to 1.5, and particularly preferably 0.7 to 1.5. r is 1.00-50, Preferably it is 1.00-26, Most preferably, it is 1.02-6.

Although the example of said negative electrode material is shown below, this invention is not limited to these.
SnAl _0.4 B _0.5 P _0.5 K _0.1 O _3.65 , SnAl _0.4 B _0.5 P _0.5 Na _0.2 O _3.7 , SnAl _0.4 B _0.3 P _0.5 Rb _0.2 O _3.4 , SnAl _0.4 B _0.5 P _0.5 Cs _0.1 O _3.65 , SnAl _0.4 B _0.5 P _0.5 K _0.1 Ge _0.05 O _3.85 , SnAl _0.4 B _0.5 P _0.5 K _0.1 Mg _0.1 Ge _0.02 O _3.83 , SnAl _0.4 B _0.4 P _0.4 O _3.2 , SnAl _0.3 B _0.5 P _0.2 O _2.7 , SnAl _0.3 B _0.5 P _0.2 O _2.7 , SnAl _0.4 B _0.5 P _0.3 Ba _0.08 Mg _0.08 O _3.26 , SnAl _0.4 B _0.4 P _0.4 Ba _0.08 O _3.28 , SnAl _0.4 B _0.5 P _0.5 O _3.6 , SnAl _0.4 B _0.5 P _0.5 Mg _0.1 O _3.7 .

SnAl _0.5 B _0.4 P _0.5 Mg _0.1 F _0.2 O _3.65 , SnB _0.5 P _0.5 Li _0.1 Mg _0.1 F _0.2 O _3.05 , SnB _0.5 P _0.5 K _0.1 Mg _0.1 F _0.2 O _3.05 , SnB _0.5 P _0.5 K _0.05 Mg _0.05 F _0.1 O _3.03 , SnB _0.5 P _0.5 K _0.05 Mg _0.1 F _0.2 O _3.03 , SnAl _0.4 B _0.5 P _0.5 Cs _0.1 Mg _0.1 F _0.2 O _3.65 , SnB _0.5 P _0.5 Cs _0.05 Mg _0.05 F _0.1 O _3.03 , SnB _0.5 P _0.5 Mg _0.1 F _0.1 O _3.05 , SnB _0.5 P _0.5 Mg _0.1 F _0.2 O ₃ , SnB _0.5 P _0.5 Mg _0.1 F _0.06 O _3.07 , SnB _0.5 P _0.5 Mg _0.1 F _0.14 O _3.03 , SnPBa _0.08 O _3.58 , SnPK _0.1 O _3.55 , SnPK _0.05 Mg _{0.05 O 3.58, SnPCs 0.1 O 3.55} , SnPBa 0.08 F 0.08 O 3.54, SnPK 0.1 Mg 0.1 F 0.2 O 3.55, SnPK 0.05 Mg 0.05 F 0.1 O 3.53, SnPCs 0.1 Mg 0.1 F 0.2 O 3.55, Sn _{Cs 0.05 Mg 0.05 F 0.1 O 3.53} .

Sn _1.1 Al _0.4 B _0.2 P _0.6 Ba _0.08 F _0.08 O _3.54 , Sn _1.1 Al _0.4 B _0.2 P _0.6 Li _0.1 K _0.1 Ba _0.1 F _0.1 O _3.65 , Sn _1.1 Al _0.4 B _0.4 P _0.4 Ba _0.08 O _3.34 , Sn _1.1 Al _0.4 PCs _0.05 O _4.23 , Sn _1.1 Al _0.4 PK _0.05 O _4.23 , Sn _1.2 Al _0.5 B _0.3 P _0.4 Cs _0.2 O _3.5 , Sn _1.2 Al _0.4 B _0.2 P _0.6 Ba _0.08 O _3.68 , Sn _1.2 Al _0.4 B _0.2 P _0.6 Ba _0.08 F _0.08 O _3.64 , Sn _1.2 Al _0.4 B _0.2 P _0.6 Mg _0.04 Ba _0.04 O _3.68 , Sn _1.2 Al _0.4 B _0.3 P _0.5 Ba _0.08 O _3.58 , Sn _1.3 Al _0.3 B _0.3 P _0.4 Na _0.2 O _3.3 , Sn _1.3 Al _0.2 B _0.4 P _0.4 Ca _0.2 O _3.4 , Sn _1.3 Al _0.4 B _0.4 P _0.4 Ba _0.2 O _3.6 , Sn _1.4 Al _0.4 PK _0.2 O _4.6 , Sn _1.4 Al _0.2 Ba _0.1 PK _0.2 O _4.45 , Sn _1.4 Al _0.2 Ba _0.2 PK _0.2 O _4.6 , Sn _1.4 Al _{0. 4} Ba _0.2 PK _0.2 Ba _0.1 F _0.2 O _4.9 , Sn _1.4 Al _0.4 PK _0.3 O _4.65 , Sn _1.5 Al _0.2 PK _0.2 O _4.4 , Sn _1.5 Al _0.4 PK _0.1 O _4.65 , Sn _1.5 Al _0.4 PCs _0.05 O _4.63 , Sn _1.5 Al _0.4 PCs _0.05 Mg _0.1 F _0.2 O _4.63 .

SnSi _0.5 Al _0.1 B _0.2 P _0.1 Ca _0.4 O _3.1 , SnSi _0.4 Al _0.2 B _0.4 O _2.7 , SnSi _0.5 Al _0.2 B _0.1 P _0.1 Mg _0.1 O _2.8 , SnSi _0.6 Al _0.2 B _0.2 O _2.8 , SnSi _0.5 Al _0.3 B _0.4 P _0.2 O _3.55 , SnSi _0.5 Al _0.3 B _0.4 P _0.5 O _4.30 , SnSi _0.6 Al _0.1 B _0.1 P _0.3 O _3.25 , SnSi _0.6 Al _0.1 B _0.1 P _0.1 Ba _0.2 O _2.95 , SnSi _0.6 Al _0.1 B _0.1 P _0.1 Ca _0.2 O _2.95 , SnSi _0.6 Al _0.4 B _0.2 Mg _0.1 O _3.2 , SnSi _0.6 Al _0.1 B _0.3 P _0.1 O _3.05 , SnSi _0.6 Al _0.2 Mg _0.2 O _2.7 , SnSi _0.6 Al _0.2 Ca _0.2 O _2.7 , SnSi _0.6 Al _0.2 P _0.2 O _{3, SnSi 0.6 B 0.2 P 0.2} O 3, SnSi 0.8 Al 0.2 O 2.9, SnSi 0.8 Al 0.3 B 0.2 P 0.2 O 3.85, SnSi 0.8 B 0.2 O 2.9, SnSi 0.8 Ba 0.2 O 2.8, _{nSi 0.8 Mg 0.2 O 2.8, SnSi} 0.8 Ca 0.2 O 2.8, SnSi 0.8 P 0.2 O 3.1.

Sn _0.9 Mn _0.3 B _0.4 P _0.4 Ca _0.1 Rb _0.1 O _2.95 , Sn _0.9 Fe _0.3 B _0.4 P _0.4 Ca _0.1 Rb _0.1 O _2.95 , Sn _0.8 Pb _0.2 Ca _0.1 P _0.9 O _3.35 , Sn _0.3 Ge _0.7 Ba _0.1 P _0.9 O _{3.35, Sn 0.9 Mn 0.1 Mg 0.1} P 0.9 O 3.35, Sn 0.2 Mn 0.8 Mg 0.1 P 0.9 O 3.35, Sn 0.7 Pb 0.3 Ca 0.1 P 0.9 O 3.35, Sn 0.2 Ge 0.8 Ba 0.1 P 0.9 O 3.35.

  The chemical formula of the compound obtained by calcining can be calculated from the mass difference between the powders before and after calcining as an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measuring method.

  Lithium ions can be inserted into the negative electrode material before and / or after assembling the battery. The amount of insertion may be close to the deposition potential of lithium. For example, the amount is preferably 50 to 700 mol% per negative electrode material, and particularly preferably 100 to 600 mol%. It is preferable that the release amount be larger than the insertion amount. The light metal insertion method is preferably an electrochemical, chemical or thermal method. The electrochemical method is preferably a method in which a light metal contained in the positive electrode active material is inserted electrochemically or a method in which the light metal or an alloy thereof is directly inserted electrochemically. Chemical methods include mixing with light metals, contact, or reacting with organic metals such as butyllithium. Electrochemical methods and chemical methods are preferred.

By using the compounds represented by the general formulas (6) and (7) as the negative electrode material mainly as described above, the charge / discharge cycle characteristics are excellent, the discharge voltage is high, the capacity is high, and the safety is high. A nonaqueous electrolyte secondary battery having excellent current characteristics can be obtained. In the present invention, a particularly excellent effect can be obtained by using a compound containing Sn and having a valence of Sn of 2 as the negative electrode material. The valence of Sn can be determined by a chemical titration operation. For example, it can be analyzed by the method described on page 165 of Physics and Chemistry of Glasses Vol. 8 No. 4 (1967). It can also be determined from a night shift by Sn solid nuclear magnetic resonance (NMR) measurement. For example, in wide measurement, metal Sn (zero-valent Sn) has an extremely low magnetic field peak around 7000 ppm with respect to Sn (CH ₃ ) ₄ , whereas SnO (= 2 valence) has a peak near 100 ppm, SnO ₂ (= 4 valences) appears around -600 ppm. Thus, when it has the same ligand, since the night shift largely depends on the valence of Sn as the central metal, the valence can be determined at the peak position obtained by ¹¹⁹ Sn-NMR measurement.
Various compounds can be included in the negative electrode material. For example, transition metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, lanthanoid metals, Hf , Ta, W, Re, Os, Ir, Pt, Au, Hg) or a periodic table group 17 element (F, Cl). Further, it may contain dopants of various compounds (for example, Sb, In, and Nb compounds) that increase electron conductivity. The amount of the compound to be added is preferably 0 to 20 mol%.

As a method for synthesizing the composite oxide mainly composed of the oxides represented by the general formulas (6) and (7), either a firing method or a solution method can be employed. For example, the firing method will be described in detail. M ¹ compound, M ² compound and M ⁴ compound (M ¹ and M ² are different, Si, Ge, Sn, Pb, P, B, Al, Sb, M ⁴ are Mg, Ca , Sr, Ba) may be mixed and fired. Examples of Sn compounds include SnO, SnO ₂ , Sn ₂ O ₃ , Sn ₃ O ₄ , Sn ₇ O ₁₃ .H ₂ O, Sn ₈ O ₁₅ , stannous hydroxide, stannic oxyhydroxide, stannic acid , Stannous oxalate, stannous phosphate, orthostannic acid, metastannic acid, parastannic acid, stannous fluoride, stannous fluoride, stannous chloride, stannous chloride, stannous pyrophosphate , Tin phosphide, stannous sulfide, stannic sulfide, and the like.
Examples of the Si compound include organic silicon compounds such as SiO ₂ , SiO, tetramethylsilane and tetraethylsilane, alkoxysilane compounds such as tetramethoxysilane and tetraethoxysilane, and hydrosilane compounds such as trichlorohydrosilane.
Examples of the Ge compound include GeO ₂ , GeO, germanium tetramethoxide, germanium tetraethoxide, and other alkoxygermanium compounds.
Examples of Pb compounds include PbO ₂ , PbO, Pb ₂ O ₃ , Pb ₃ O ₄ , lead nitrate, lead carbonate, lead formate, lead acetate, lead tetraacetate, lead tartrate, lead diethoxide, lead di (isopropoxide), etc. Can be mentioned.
Examples of the P compound include phosphorus pentoxide, phosphorus oxychloride, phosphorus pentachloride, phosphorus trichloride, phosphorus tribromide, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, stannous pyrophosphate, boron phosphate and the like. Can be mentioned.
Examples of the B compound include boron trioxide, boron trichloride, boron tribromide, boron carbide, boric acid, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, boron phosphide, boron phosphate and the like.
Examples of the Al compound include aluminum oxide (α-alumina, β-alumina), aluminum silicate, aluminum tri-iso-propoxide, aluminum tellurite, aluminum chloride, aluminum boride, aluminum phosphide, aluminum phosphate, and lactic acid. Examples thereof include aluminum, aluminum borate, aluminum sulfide, aluminum sulfate, and aluminum boride.
Examples of the Sb compound include diantimony trioxide and triphenylantimony.

  Examples of the Mg, Ca, Sr, and Ba compounds include respective oxide salts, hydroxide salts, carbonates, phosphates, sulfates, nitrates, and aluminum compounds.

As firing conditions, the temperature rising rate is preferably 4 ° C. or more and 2000 ° C. or less, more preferably 6 ° C. or more and 2000 ° C. or less per minute. It is particularly preferably 10 ° C. or higher and 2000 ° C. or lower, and the firing temperature is preferably 250 ° C. or higher and 1500 ° C. or lower, more preferably 350 ° C. or higher and 1500 ° C. or lower, and particularly preferably 500 ° C. or higher and 1500 ° C. or lower. And the firing time is preferably 0.01 hours or more and 100 hours or less, more preferably 0.5 hours or more and 70 hours or less, and particularly preferably 1 hour or more and 20 hours or less, and the temperature is lowered. The rate is preferably 2 ° C. or higher and 107 ° C. or lower per minute, more preferably 4 ° C. or higher and 107 ° C. or lower, particularly preferably 6 ° C. or higher and 107 ° C. or lower, and particularly preferably 10 ° C. or higher and 10 7 ° C. or lower. It is.
In the present invention, the rate of temperature increase is an average rate of temperature rise from “50% of the firing temperature (° C.)” to “80% of the firing temperature (° C.)”. This is the average rate of temperature drop from reaching “80% of temperature (indicated in degrees Celsius)” to “50% of firing temperature (indicated in degrees Celsius)”.
The temperature lowering may be cooled in a firing furnace, or taken out of the firing furnace and cooled, for example, in water. In addition, a super rapid cooling method such as a gun method, a Hammer-Anvil method, a slap method, a gas atomizing method, a plasma spray method, a centrifugal quenching method, or a melt drag method described on page 217 of ceramic processing (Gihodo Publishing 1987) can also be used. Moreover, you may cool using the single-roller method and double roller method of New Glass Handbook (Maruzen 1991) p.172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.

  The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, and xenon.

  The average particle size of the compounds represented by the general formulas (6) and (7) is preferably 0.1 to 60 μm, particularly preferably 1.0 to 30 μm, and further preferably 2.0 to 20 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. There is no particular limitation on the classification method, and a sieve, an air classifier, a water tank, or the like can be used as necessary. Classification can be used both dry and wet.

More preferable lithium-containing transition metal oxide positive electrode material is a lithium compound / transition metal compound (where the transition metal is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is preferable to synthesize by mixing so that the total molar ratio of As a particularly preferable lithium-containing transition metal oxide positive electrode material used in the present invention, a lithium compound / transition metal compound (where the transition metal is at least one selected from V, Cr, Mn, Fe, Co, and Ni). It is preferable to synthesize by mixing so that the total molar ratio of is 0.3 to 2.2.
A particularly preferable lithium-containing transition metal oxide positive electrode material used in the present invention is Li _x QO _y (where Q is a transition metal mainly containing at least one of Co, Mn, Ni, V, and Fe), x = It is preferable that they are 0.2-1.2 and y = 1.4-3). As Q, in addition to the transition metal, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

More preferable lithium-containing metal oxide positive electrode materials include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _a Ni _1-a O ₂ , Li _x Co _b V _1-b O _z , Li _{x Co b Fe 1-b O} 2, Li x Mn 2 O 4, Li x Mn c Co 2-c O 4, Li x Mn c Ni 2-c O 4, Li x Mn c V 2-c O 4, Li _x Mn _c Fe _2-c O ₄ (where x = 0.7 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1 .96, z = 2.01 to 2.3).
The most preferable lithium-containing transition metal oxide positive electrode materials used in the present invention include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _a Ni _1-a O ₂ , and Li _x Mn ₂ O _4. Li _x Co _b V _1-b O _z (where x = 0.7 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.01 2.3).
Here, said x value is a value before the start of charging / discharging, and it increases / decreases by charging / discharging.

Any electrically conductive carbon compound may be used as long as it is an electron conductive material that does not cause a chemical change in the battery. Specific examples include natural graphite such as scaly graphite, scaly graphite and earthy graphite, high-temperature fired bodies such as petroleum coke, coal coke, celluloses, saccharides and mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. And carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black and thermal black, asphalt pitch, coal tar, activated carbon, mesofuse pitch, polyacene and the like. Of these, graphite and carbon black are preferred.
As conductive agents other than carbon, conductive fibers such as metal fibers, metal powders such as copper, nickel, aluminum and silver, conductive whiskers such as zinc oxide and potassium titanate, and conductive metals such as titanium oxide An oxide or the like can be contained alone or a mixture thereof as required.

  The addition amount of the conductive agent to the mixture layer is preferably 6 to 50% by mass, and particularly preferably 6 to 30% by mass with respect to the negative electrode material or the positive electrode material. In the case of carbon or graphite, the content is particularly preferably 6 to 20% by mass.

As the binder for holding the electrode mixture, one or a mixture of polysaccharides, thermoplastic resins and polymers having rubber elasticity can be used. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid, polyacrylic acid Na, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone. Water-soluble polymers such as polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene furo Ride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene (Meth) acrylic acid ester copolymer containing (meth) acrylic acid ester such as di-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, (meth) acrylic Acid ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, polyethylene oxide, polyester polyurethane Resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, phenol resin, epoxy resin emulsion (latex) or suspension It can be cited. In particular, polyacrylate ester latex, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride are preferable.
These binders can be used alone or in combination. If the amount of the binder added is small, the holding power / cohesive force of the electrode mixture is weak and the cycleability is poor, and if it is too large, the electrode volume increases and the electrode unit volume or the capacity per unit mass decreases. The conductivity decreases and the capacity decreases. Although the addition amount of a binder is not specifically limited, 1-30 mass% is preferable, and 2-10 mass% is especially preferable.

The adjustment of the negative electrode mixture or the positive electrode mixture paste is preferably performed in an aqueous system.
The mixture paste is prepared by first mixing the active material and the conductive agent, adding a binder (resin powder suspension or emulsion (latex)) and water, kneading and mixing, followed by a mixer, It can be carried out by dispersing with a stirring mixer or disperser such as a homogenizer, dissolver, planetary mixer, paint shaker or sand mill.
The prepared positive electrode active material and negative electrode active material mixture paste are mainly used after being applied (coated), dried and compressed on the current collector. Application can be performed by various methods, for example, reverse roll method, direct roll method, blade method, knife method, extrusion method, curtain method, gravure method, bar method, dipping method and squeeze method. I can do it. A blade method, a knife method and an extrusion method are preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the liquid physical property of a mixture paste, and drying property. The thickness, length, and width of the coating layer are determined by the size of the battery, and the thickness of the coating layer is particularly preferably 1 to 2000 μm in a compressed state after drying.

  As a drying or dehydration method for removing moisture from pellets and sheets, a generally adopted method can be used, and hot air, vacuum, infrared rays, far infrared rays, electron beams and low-humidity air are used alone or in combination. I can do it. The temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 250 ° C. The water content is preferably 2000 ppm or less for the entire battery, and preferably 500 ppm or less for each of the positive electrode mixture, the negative electrode mixture and the electrolyte from the viewpoint of charge / discharge cycle properties.

For the compression of the sheet-like electrode mixture, a generally adopted pressing method can be used, but a mold pressing method and a calendar pressing method are particularly preferable. The press pressure is not particularly limited, but is preferably 10 kg / cm ^{2 to 3} t / cm ² . The press speed of the calendar press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C.

  The positive electrode and negative electrode support, that is, the current collector is made of aluminum, stainless steel, nickel, titanium, or an alloy thereof for the positive electrode, and copper, stainless steel, nickel, titanium, or an alloy thereof for the negative electrode. As the form, foil, expanded metal, punching metal, and wire mesh are used. In particular, an aluminum foil is preferable for the positive electrode and a copper foil is preferable for the negative electrode.

  The separator has only to have a high ion permeability, a predetermined mechanical strength, and an insulating thin film. The material is olefin polymer, fluorine polymer, cellulose polymer, polyimide, nylon, glass fiber, alumina fiber. And non-woven fabric, woven fabric, and microporous film are used as forms. In particular, polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, and a mixture of polyethylene and Teflon are preferable as the material, and a microporous film is preferable as the form. In particular, a microporous film having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable.

  The shape of the battery can be applied to any of buttons, coins, sheets, cylinders, and corners. The battery is formed by inserting a pellet, a sheet or an electrode wound together with a separator into a battery can, electrically connecting the can and the electrode, injecting an electrolyte, and sealing. At this time, the safety valve can be used as a sealing plate. Furthermore, it is preferable to use a PTC element in order to guarantee the safety of the battery.

  The bottomed battery cans are made of nickel-plated steel plate, stainless steel plate (SUS304, SUS304L, SUS304N, SUS316, SUS316L, SUS430, SUS444, etc.), nickel-plated stainless steel plate (same as above), aluminum or an alloy thereof Nickel, titanium, and copper, and the shapes are a perfect circular cylinder, an elliptical cylinder, a square cylinder, and a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate and a nickel-plated steel plate are preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum, or an alloy thereof is preferable.

  The sheet-like mixture electrode is wound or folded and inserted into a can, the can and the sheet are electrically connected, an electrolyte is injected, and a battery can is formed using a sealing plate. At this time, the safety valve can be used as a sealing plate. In addition to the safety valve, various conventionally known safety elements may be provided. For example, a fuse, bimetal, PTC element, or the like is used as the overcurrent prevention element. In addition to the safety valve, a method of cutting the battery can, a method of cracking the gasket, or a method of cracking the sealing plate can be used as a countermeasure against an increase in the internal pressure of the battery can. Moreover, you may equip a charger with the circuit incorporating the countermeasure against overcharge or overdischarge.

  The electrolytic solution may be injected all at once, but is preferably performed in two or more stages. When the injection is divided into two or more stages, each liquid may have the same composition, but a different composition (for example, a nonaqueous solvent or a nonaqueous solvent having a viscosity higher than that of the solvent after injecting a solution in which a lithium salt is dissolved in the nonaqueous solvent). Or a solution in which a lithium salt is dissolved in a solvent or a non-aqueous solvent may be injected). In addition, the battery can can be decompressed (preferably 500 to 1 torr, more preferably 400 to 10 torr), or centrifugal force or ultrasonic waves can be applied to the battery can in order to shorten the electrolyte injection time. Good.

  For the can and the lead plate, a metal or an alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are used. A known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used for welding the cap, can, sheet, and lead plate. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

  Gaskets that can be used in the present invention are olefin polymers, fluoropolymers, cellulosic polymers, polyimides, and polyamides as materials. Olefin polymers are preferred from the viewpoint of organic solvent resistance and low moisture permeability, and are mainly composed of propylene. Polymers are preferred. Furthermore, a block copolymer of propylene and ethylene is preferable.

The battery to which the present invention is applied is covered with an exterior material as necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, and a plastic case. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be known.
A plurality of batteries are assembled in series and / or in parallel as required, and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, temperature fuses, fuses and / or current interrupting elements, the battery pack also requires safety circuits (monitoring the voltage, temperature, current, etc. of each battery and / or the entire battery pack) In this case, a circuit having a function of interrupting current may be provided. In addition to the positive and negative terminals of the entire assembled battery, the battery pack should be provided with the positive and negative terminals of each battery, the entire assembled battery, the temperature detection terminal of each battery, the current detection terminal of the entire assembled battery, etc. as external terminals. You can also. The battery pack may incorporate a voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed so that it can be easily attached and detached with a socket or the like. Further, the battery pack may be provided with display functions such as the remaining battery capacity, the presence / absence of charging, and the number of uses.

  The battery to which the present invention is applied is used in various devices. In particular, video movies, portable video decks with built-in monitors, movie cameras with built-in monitors, compact cameras, single-lens reflex cameras, film with lenses, notebook computers, notebook word processors, electronic notebooks, mobile phones, cordless phones, shavings, power tools, It is preferably used for electric mixers, automobiles and the like.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.

Example-1
[Example of making positive electrode mixture paste]
Cathode active material: LiCoO ₂ (mixed with a molar ratio of lithium carbonate and tricobalt tetroxide in a ratio of 3: 2 was placed in an alumina crucible, heated to 750 ° C. at 2 ° C./min in the air, and calcined for 4 hours. After that, the temperature was further raised to 900 ° C. at a rate of 2 ° C. per minute, baked and pulverized at that temperature for 8 hours. 2-ethylhexyl 0.6 mS / m, pH 10.1, specific surface area measured by the nitrogen adsorption method to 0.42 m ² / g) and 200g of acetylene black 10 g, were mixed in a homogenizer, as subsequently binder 8 g of an aqueous dispersion of a copolymer of acrylate, acrylic acid and acrylonitrile (solid concentration 50% by mass), 60 g of a 2% by mass carboxymethylcellulose aqueous solution were added, kneaded and mixed, and water was added. 0g was added and mixed with stirring with a homogenizer to prepare a positive electrode mixture paste.
[Example of making negative electrode mixture paste]
Negative electrode active material: SnGe _0.1 B _0.5 P _0.58 Mg _0.1 K _0.1 O _3.35 (6.7 g of tin monoxide, 10.3 g of tin pyrophosphate, 1.7 g of diboron trioxide, 0.7 g of potassium carbonate, 0.4 g of magnesium oxide Then, 1.0 g of germanium dioxide was dry-mixed, placed in an alumina crucible, heated to 1000 ° C. at 15 ° C./min in an argon atmosphere, baked at 1100 ° C. for 12 hours, and then cooled to room temperature at 10 ° C./min. Collected from the firing furnace, pulverized with a jet mill, an average particle size of 4.5 μm, and having a broad peak with a peak at around 28 ° in the 2θ value in an X-ray diffraction method using CuKα rays In the 2θ value, no crystalline diffraction line was observed between 40 ° and 70 °.) 200 g and a conductive agent (artificial graphite) 30 g were mixed with a homogenizer, and further concentrated as a binder. A mixture of 50 g of a 2% by mass aqueous carboxymethyl cellulose solution and 10 g of polyvinylidene fluoride and 30 g of water and further kneaded and mixed to prepare a negative electrode mixture paste.
[Creation of positive and negative electrode sheets]
After applying the positive electrode mixture paste prepared above on both sides of an aluminum foil current collector having a thickness of 30 μm with a blade coater so that the coating amount is 400 g / m ² and the thickness of the compressed sheet is 280 μm, and drying. Then, it was compression-molded with a roller press and cut into a predetermined size to produce a belt-like positive electrode sheet. Furthermore, it was sufficiently dehydrated and dried with a far-infrared heater in a dry box (dew point: dry air of −50 ° C. or lower) to prepare a positive electrode sheet.
Similarly, a negative electrode mixture paste was applied to a 20 μm copper foil current collector, and a negative electrode sheet having a coating amount of 70 g / m ² and a compressed sheet thickness of 90 μm was prepared in the same manner as the above positive electrode sheet. did.
[Example of electrolyte adjustment]
In an argon atmosphere, 65.3 g of diethyl carbonate was placed in a 200 cc narrow-necked polypropylene container, and 22.2 g of ethylene carbonate was dissolved little by little while taking care not to exceed a liquid temperature of 30 ° C. Next, 0.4 g of LiBF ₄ and 12.1 g of LiPF ₆ were dissolved in a small amount in the polypropylene container in order, while paying attention not to exceed 30 ° C. The obtained electrolyte was a colorless and transparent liquid with a specific gravity of 1.135. Moisture was 18ppm (measured by Kyoto Electronics, trade name MKC-210 type Karl Fischer moisture measuring device), free acid content was 24ppm (measured by neutralization titration with 0.1N NaOH aqueous solution using bromthymol blue as an indicator) )Met. Furthermore, each of the compounds of the present invention described in Table 1 was dissolved in this electrolytic solution to a predetermined concentration to prepare an electrolytic solution.
[Cylinder battery creation example]
A positive electrode sheet, a microporous polypropylene film separator, a negative electrode sheet and a separator were laminated in this order, and this was wound in a spiral shape. The wound body was housed in an iron-bottomed cylindrical battery can with nickel plating that also serves as a negative electrode terminal. Further, an electrolytic solution to which the additives listed in Table 1 were added as an electrolytic solution was poured into the battery can. A cylindrical battery was prepared by caulking the battery lid having the positive electrode terminal through a gasket.

  In this way, sample batteries 101 to 115 were prepared.

Comparative Example 1
In the same manner as in Example 1, a cylindrical battery was prepared using an electrolyte solution to which no additive was added.
Comparative Example 2
Instead of the oxide-based negative electrode active material, a carbon-based active material (graphite powder) is used to prepare a negative electrode sheet in the same manner as the above-described negative electrode sheet, and a cylindrical battery is formed using an electrolyte solution to which no additive is added. Created. Further, sample batteries 116 and 117 were made using an electrolytic solution to which the compound of the present invention was added.
Comparative Examples 3 and 4
A cylindrical battery was prepared in the same manner as in Example 1 using the electrolyte added by changing the amount of the additive significantly.

The battery prepared by the above method was charged and discharged under the conditions of a current density of 5 mA / cm ² , a charge end voltage of 4.1 V, and a discharge end voltage of 2.8 V, and the discharge capacity and cycle life were determined.
Table 1 shows the ratio of the capacity (Wh) of each battery and the cycle performance (ratio of the 300th capacity to the first charge / discharge). In addition, as a storage stability test, the capacity retention rate after charging at 4.1 V and storing at 60 ° C. for 1 month was measured in the same manner. The results are also shown in Table 1.

上記試料１０１、１０２、１１０〜１１５及び１１７は参考例であり、各参考例で用いた化合物は次のとおりである。

Samples 101, 102, 110-115 and 117 are reference examples, and the compounds used in each reference example are as follows.

Reference Example-1
Example 1 was repeated and similar results were obtained except that the addition of the additive was changed from the electrolytic solution to the positive electrode active material.

Reference example-2
Example-1 except that 120 mg of lithium metal foil per 1 g of the negative electrode material was applied in a strip shape on the negative electrode mixture and brought into electrical contact, and the coating amount of the positive electrode mixture was 240 g / m ² on one side. And Reference Example-1 were repeated and similar results were obtained.

A battery using the electrolytic solution of the present invention has greatly improved cycle performance.
Batteries using a carbonaceous material for the negative electrode are improved in capacity and cycleability, but the improvement rate is smaller than that of the oxide negative electrode.

Sectional drawing of the cylinder type battery used for the Example is shown.

Explanation of symbols

1 Polypropylene gasket 2 Negative electrode can also serves as negative electrode terminal (battery can)
3 Separator 4 Negative electrode sheet 5 Positive electrode sheet 6 Non-aqueous electrolyte 7 Explosion-proof valve body 8 Positive electrode cap also serving as a positive electrode terminal 9 PTC element 10 Internal lid body 11 Ring

Claims (7)

In a non-aqueous electrolyte used in a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode containing a material capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte, and a separator, the non-aqueous electrolyte is cyclic. A carbonate, an acyclic carbonate, and a lithium salt, and further containing at least one organic boron compound in an amount of 0.0001 to 0.1 mol / l with respect to the electrolyte solvent. ) Or a compound represented by (2), a non-aqueous electrolyte for a lithium secondary battery.
General formula (1)

(In the formula, R ³¹ , R ³² and R ³³ each represent an aryl group.)
General formula (2)

(Wherein R ¹ , R ² and R ³ may be the same or different from each other, and are an alkoxy group, an aryloxy group or —OB (R ¹¹ ) (R ¹² ), at least one of which is an alkoxy group or an aryloxy group. R ¹¹ and R ¹² may be the same or different from each other, and each represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a halogen atom, a cyano group, Nitro group, hydroxy group, formyl group, aryloxy group, alkylthio group, arylthio group, acyloxy group, sulfonyloxy group, amino group, alkylamino group, arylamino group, carbonamido group, sulfonamido group, oxycarbonylamino group, Oxysulfonylamino group, ureido group, acyl group, oxycarbonyl group, carbamoyl Represents a group, a sulfonyl group, a sulfinyl group, an oxysulfonyl group or a sulfamoyl group, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, or a heterocyclic group, wherein R ¹ , R ² , R ³ , R ¹¹ and R ¹² are They may be bonded to each other to form a ring, and at least ^one of R ¹ , R ² and R ³ may be bonded to each other to form a ring, and these rings may have a substituent. May be substituted by a substitutable group.) The non-aqueous electrolyte for a lithium secondary battery according to claim 1, wherein the organic boron compound is at least one selected from the following compounds.

  3. The nonaqueous lithium secondary battery according to claim 1, wherein the organoboron compound is at least one selected from the compounds B-1, B-6, C-14, and C-15. Electrolytic solution. The non-aqueous electrolyte for a lithium secondary battery according to claim 1, wherein the lithium salt is at least LiBF ₄ and / or LiPF ₆ .   The non-aqueous electrolyte for a lithium secondary battery according to any one of claims 1 to 4, wherein the cyclic carbonate is at least one of ethylene carbonate and propylene carbonate.   The non-aqueous electrolyte for a lithium secondary battery according to any one of claims 1 to 5, wherein the acyclic carbonate is at least one of diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.   The lithium secondary battery using the nonaqueous electrolyte for lithium secondary batteries of any one of Claims 1-6.

Images