WO2012039250A1

WO2012039250A1 - Nonaqueous electrolyte for secondary battery and lithium secondary battery

Info

Publication number: WO2012039250A1
Application number: PCT/JP2011/069828
Authority: WO
Inventors: 稔彦八幡; 小野　三千夫; 吉憲金澤
Original assignee: 富士フイルム株式会社
Priority date: 2010-09-22
Filing date: 2011-08-31
Publication date: 2012-03-29
Also published as: JP5680468B2; JP2012089468A

Abstract

This nonaqueous electrolyte for a secondary battery contains a salt of a metal ion from group 1 or group 2 of the periodic table, and a siloxane oligomer containing a partial structure represented by general formula (1) and having a number average molecular weight of 500 - 1500 for the styrene conversion. In general formula (1), R¹ represents a hydrocarbon or OR²; -OR² represents an alkoxy group or a substituent group represented by the general formula (2) -O-Q¹-COOR³; and the molar fraction of the group represented by the general formula (2) is 5 - 100 mol% of the total molar amount of R¹and -OR² in all partial structures represented by general formula (1). This constitution provides a nonaqueous electrolyte for a secondary battery that has flame resistance and superior lithium ion conductivity and is suitably used in a lithium secondary battery, and a high output lithium secondary battery containing this nonaqueous electrolyte for a secondary battery is provided.

Description

Non-aqueous secondary battery electrolyte and lithium secondary battery

TECHNICAL FIELD The present invention relates to an electrolyte for a non-aqueous secondary battery and a lithium secondary battery containing the electrolyte, and more specifically, a non-aqueous secondary battery suitably used for a lithium secondary battery containing a specific silicon oligomer. The present invention relates to an electrolytic solution for use and a lithium secondary battery using the same.

Lithium secondary batteries are used in personal computers, video cameras, mobile phones, and the like. As these electronic devices become more functional, batteries that serve as power sources are also required to have higher energy density. In recent years, against the background of global environmental issues such as reducing carbon dioxide emissions, the use of lithium secondary batteries has been studied in automotive power supply and natural energy storage applications, and cost, performance, and safety have been improved. There is a growing demand, and there is a need for improvements in electrolytes that enable them.

In conventional lithium secondary batteries, a flammable organic solvent is used in the electrolyte, and therefore there is a danger that the battery may ignite due to runaway or internal short circuit during overcharge. Therefore, various studies have been made to make the electrolyte used in the lithium secondary battery difficult to burn and to ensure safety.

For example, Japanese Patent Application Laid-Open No. 8-88023 discloses an electrolytic solution having a self-extinguishing property and a good charge / discharge performance, which contains a phosphate ester compound as an electrolyte in a conventional hydrocarbon solvent, and uses the same. Although a battery has been proposed, the flame retardancy is still not sufficient for practical use, and further improvement is necessary.
Further, a technique for forming the electrolyte itself with a polymer electrolyte such as crosslinked polyether, polyphosphazene, or polysiloxane, which is a material that is difficult to burn, is disclosed in, for example, JP-A-11-273733, JP-A-9-92331, Various techniques disclosed in Japanese Patent Laid-Open No. 3-146559, Japanese Patent No. 3648447, and the like, and techniques using a flame-retardant ionic liquid as an electrolyte are disclosed in, for example, Japanese Patent No. 4045252 and Japanese Patent Laid-Open No. 2007-106849. It has been proposed in Japanese Laid-Open Patent Publication No. 2008-239514. However, solid electrolytes such as polymer electrolytes and inorganic glasses have low ionic conductivity, and some ionic liquids have high ionic conductivity, but the lithium ion transport number is low, and when used in lithium secondary batteries High performance could not be obtained.
For example, Japanese Patent Laid-Open No. 2002-25203 proposes a method of using polysiloxane having a specific structure as an inflammable liquid in an electrolytic solution. According to the method described in the official gazette, the electrolytic solution is difficult. Although the flammability is good and the lithium ion transport number is improved, there is still room for improvement in the ion conductivity due to the high viscosity of the electrolyte.

Thus, there is a need for a non-aqueous secondary battery electrolyte that is flame retardant and has both ionic conductivity and lithium ion transport number.
An object of the present invention is an electrolyte solution for a non-aqueous secondary battery that is flame-retardant and excellent in lithium ion conductivity, and is suitably used for a lithium secondary battery, and contains the electrolyte solution for the non-aqueous secondary battery An object of the present invention is to provide a high-power lithium secondary battery.

As a result of examining the above problems, the inventors have obtained a low-viscosity, high ionic conductivity, and flame-retardant electrolyte solution by using a silicon oligomer having a specific structure. The inventors have found that a lithium secondary battery with high output and high safety can be obtained by using the electrolytic solution, and the present invention has been achieved.

That is, the first aspect of the present invention is a styrene conversion number average molecular weight of 500 or more including a salt of a metal ion belonging to Group 1 or Group 2 of the Periodic Table and a partial structure represented by the following general formula (1). An electrolyte solution for a battery containing a siloxane oligomer that is 1500 or less.

(In the general formula (1), R ¹ represents a hydrocarbon group or —OR ² , —OR ² represents an alkoxy group, a halogenated alkoxy group, or a substituent represented by the following general formula (2); When -OR ² represents an alkoxy group, R ² represents an alkyl group, and when -OR ² represents a halogenated alkoxy group, R ² represents a halogenated alkyl group, provided that the general formula contained in the siloxane oligomer is The molar fraction of the substituent represented by the following general formula (2) with respect to the total molar amount of R ¹ and —OR ² in the entire partial structure represented by (1) is 5 mol% or more and 100 mol% or less. .)

(In the general formula (2), Q ¹ represents an alkylene group, and R ³ represents an alkyl group.)
According to a second aspect of the present invention, the siloxane oligomer has the following general formula (1-a), general formula (1-b), general formula (1-c), general formula (1-d), and general formula: A partial structure selected from the group consisting of (1-e), and the following general formula (1-a), general formula (1-b), general formula (1-c), and general formula (1-d): ) And a partial structure represented by the general formula (1-e), where xa, xb, xc, xd and xe are respectively, relative to the total amount of all partial structures contained in the siloxane oligomer. , Xa + xb is an electrolyte solution for a non-aqueous secondary battery according to the first aspect of the present invention, which is a siloxane oligomer having a total amount of 70 mol% to 100 mol%.

(In the general formula (1-a) to the general formula (1-e), * and ** are linking sites with other partial structures, and the general formula (1-a) to the general formula (1-e When the partial structures represented by) are linked, they are linked at the position of ** and * .R ¹ and R ² are respectively synonymous with R ¹ and R ² in the general formula (1).
In a third aspect of the present invention, R ¹ in the partial structure represented by the general formula (1) is a methyl group or —OR ² , and —OR ² is an ethoxy group or the following general formula (3): It is electrolyte solution for non-aqueous secondary batteries as described in the said 1st aspect or 2nd aspect of this invention which is group represented.

(In the general formula (3), R ³ represents an alkyl group, R ⁴ and R ⁵ each independently represents an alkyl group or a hydrogen atom, and R ⁴ and R ⁵ are linked to each other to form a ring. You may do it.)
In the fourth aspect of the present invention, in the partial structure represented by the general formula (1) contained in the siloxane oligomer, —OR ² is a substituent represented by the general formula (2), and the siloxane The molar fraction of the substituent represented by the general formula (2) with respect to the total molar amount of R ¹ and —OR ² in the entire partial structure represented by the general formula (1) contained in the oligomer is 30 mol% or more and 75 The electrolyte solution for a non-aqueous secondary battery according to any one of the first to third aspects of the present invention, which is at most mol%.
In the fifth aspect of the present invention, R ¹ in the general formula (1) is a linear or branched hydrocarbon group, and —OR ² is a linear or branched alkoxy group, linear or branched. Or a substituent represented by the general formula (2), wherein Q ¹ in the general formula (2) represents a linear or branched alkylene group, and R ³ represents a linear or branched alkylene group. The electrolyte solution for nonaqueous secondary batteries according to any one of the first to fourth aspects of the present invention, which represents an alkyl group.
In the sixth aspect of the present invention, any one of the first to fifth aspects of the present invention, wherein the content of the siloxane oligomer with respect to the total electrolyte solution is 20% by mass or more and 80% by mass or less. It is electrolyte solution for non-aqueous secondary batteries as described in above.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, the salt of a metal ion belonging to Group 1 or Group 2 of the periodic table is a lithium salt. It is electrolyte solution for non-aqueous secondary batteries of description.
The eighth aspect of the present invention is the electrolyte solution for a non-aqueous secondary battery according to any one of the first to seventh aspects of the present invention, further comprising a non-aqueous organic solvent. .
In the ninth aspect of the present invention, the siloxane oligomer is synthesized using an alkoxysilane compound and a hydroxycarboxylic acid in the presence of a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table. The electrolyte solution for non-aqueous secondary batteries according to any one of the first to eighth aspects of the present invention obtained by the above.
The tenth aspect of the present invention is the electrolyte for a non-aqueous secondary battery according to any one of the first to ninth aspects of the present invention, further comprising a phosphorus compound.
In an eleventh aspect of the present invention, the phosphorus compound is at least one selected from the group consisting of a phosphate ester compound, a phosphazene compound, a phosphonate ester compound, and a phosphite compound. It is electrolyte solution for non-aqueous secondary batteries as described in 10 aspects.
The twelfth aspect of the present invention is the electrolyte solution for a non-aqueous secondary battery according to the eleventh aspect of the present invention, wherein the phosphate ester compound is a compound represented by the following general formula (p1). is there.

In the general formula (p1), Rp ¹¹ , Rp ¹² , and Rp ¹³ each independently represents an alkyl group or an aryl group.
The thirteenth aspect of the present invention is the electrolysis for a nonaqueous secondary battery according to the eleventh aspect of the present invention, wherein the phosphazene compound is a compound having a partial structure represented by the following general formula (p2). It is a liquid.

In the general formula (p2), Rp ²¹ and Rp ²² each independently represent a halogen atom, an alkoxy group, or an aryloxy group. n _p ² represents an integer of 1 or more.
The fourteenth aspect of the present invention is the electrolyte solution for a non-aqueous secondary battery according to the eleventh aspect of the present invention, wherein the phosphonate compound is a compound represented by the following general formula (p3). is there.

In the general formula (p3), Rp ³¹ , Rp ³² , and Rp ³³ each independently represents an alkyl group or an aryl group.
The fifteenth aspect of the present invention is the electrolyte solution for a non-aqueous secondary battery according to the eleventh aspect of the present invention, wherein the phosphite compound is a compound represented by the following general formula (p4). .

In the general formula (p4), Rp ⁴¹ , Rp ⁴² , and Rp ⁴³ each independently represents an alkyl group or an aryl group.
In a sixteenth aspect of the present invention, any one of the tenth to fifteenth aspects of the present invention, wherein the content of the phosphorus compound with respect to the total electrolyte is 5% by mass or more and 40% by mass or less. It is electrolyte solution for non-aqueous secondary batteries as described in above.
According to a seventeenth aspect of the present invention, there is provided a nonaqueous secondary battery electrolytic solution according to any one of the first to sixteenth aspects, and a positive electrode capable of inserting and releasing lithium ions. And a negative electrode capable of inserting and releasing lithium ions and dissolving and depositing lithium ions.

Since the present invention has the above-described configuration, an electrolyte for a non-aqueous secondary battery that has high ion conductivity, good lithium ion transport number, and is difficult to burn is provided. In addition, when the electrolyte is used, a lithium secondary battery with high safety and high output can be provided.
In the present specification, when a substituent (atomic group) is represented, the substituent may be unsubstituted or may further have a substituent unless otherwise specified. For example, when describing as an “alkyl group”, the alkyl group is used in a meaning including an unsubstituted alkyl group and an alkyl group further having a substituent. The same applies to other substituents (atomic groups).

According to the present invention, there is provided an electrolyte for a non-aqueous secondary battery that is suitable for use in a lithium secondary battery that is flame retardant and excellent in lithium ion conductivity. Moreover, according to this invention, a high output lithium secondary battery can be provided by using the electrolyte solution for non-aqueous secondary batteries of the said invention.

It is a schematic sectional drawing which shows the one aspect | mode of the lithium secondary battery of this invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents. Various modifications can be made within the scope of the gist.

[1] Non-aqueous secondary battery electrolyte The non-aqueous secondary battery electrolyte of the present invention is a metal ion salt belonging to Group 1 or Group 2 of the periodic table, and a general formula (1) described below. A siloxane oligomer having a number average molecular weight of 500 or more and 1500 or less (hereinafter, appropriately referred to as a specific siloxane oligomer) containing a partial structure represented.
The electrolyte solution for a non-aqueous secondary battery of the present invention is suitably used for a lithium ion battery.
Hereafter, each component contained in the electrolyte solution for non-aqueous secondary batteries of this invention is demonstrated sequentially.
[(A) Siloxane oligomer containing a partial structure represented by the general formula (1) and having a number average molecular weight of 500 to 1500 in terms of styrene]
The specific siloxane oligomer used in the present invention includes a partial structure represented by the following general formula (1), and the number average molecular weight in terms of styrene is required to be 500 or more and 1500 or less.

In the general formula (1), R ¹ represents a hydrocarbon group or —OR ² , —OR ² represents an alkoxy group, a halogenated alkoxy group, or a substituent represented by the following general formula (2): When OR ² represents an alkoxy group, R ² represents an alkyl group, and when —OR ² represents a halogenated alkoxy group, R ² represents a halogenated alkyl group. However, the molar fraction of the group represented by the following general formula (2) with respect to the total molar amount of R ¹ and —OR ^{2 in} the total partial structure represented by the general formula (1) contained in the siloxane oligomer is 5 It is mol% or more and 100 mol% or less.

In the general formula (2), Q ¹ represents an alkylene group, and R ³ represents an alkyl group.
Examples of the hydrocarbon group when R ¹ in the general formula (1) represents a hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group.
Here, when R ¹ represents an alkyl group, a preferable alkyl group is an alkyl group having 1 to 10 carbon atoms (such as methyl, ethyl, hexyl, or cyclohexyl), and is linear or branched having 1 to 6 carbon atoms. And a linear alkyl group having 1 to 3 carbon atoms is more preferable. A preferred alkenyl group when R ¹ represents an alkenyl group is an alkenyl group having 2 to 10 carbon atoms (such as vinyl, allyl, or -cyclohexenyl), and a linear or branched alkenyl group having 2 to 3 carbon atoms Is more preferable, and a preferable alkynyl group in the case of representing an alkynyl group is an alkynyl group having 1 to 10 carbon atoms (such as ethynyl or propynyl), more preferably a linear or branched alkynyl group having 2 to 3 carbon atoms. A preferable aryl group in the case of representing an aryl group is an aryl group having 6 to 20 carbon atoms (such as phenyl or naphthyl), and more preferably an aryl group having 6 to 10 carbon atoms.
From the viewpoint of improving the ionic conductivity, R ¹ preferably has no ring structure, and from such a viewpoint, it is preferably a linear or branched hydrocarbon group.
More specifically, R ¹ is preferably a hydrocarbon group selected from a linear or branched alkyl group, a linear or branched alkenyl group, and a linear or branched alkynyl group.
Formula (1) ^{R 1} represents -OR ² in the case -OR ² is an alkoxy group, the alkyl group represented by ^{R 2,} an alkyl group (methyl 1 to 10 carbon atoms, ethyl, or Butyl and the like), and a methyl group or an ethyl group is more preferable. That is, when —OR ² is an alkoxy group, it is preferably a methoxy group or an ethoxy group. Also -OR ^2, wherein R ¹ and similarly, from the viewpoint of ion conductivity improvement, preferably a structure having no cyclic structure, R ² in the -OR ² is a straight or branched alkyl group It is preferable.
When —OR ² is a halogenated alkoxy group, the halogenated alkyl group represented by R ² is preferably a linear or halogenated alkyl group having 1 to 10 carbon atoms, such as methyl, ethyl, butyl, etc. A halogenated alkyl group in which at least one of the hydrogen atoms in the alkyl group is replaced by a fluorine atom, an iodine atom, or a chlorine atom, particularly 2 to 6 hydrogen atoms among the hydrogen atoms in a linear alkyl group having 2 to 3 carbon atoms; Those substituted with fluorine atoms are preferred.

The hydrocarbon group represented by these alkyl groups may further have a substituent, and preferred substituents that can be introduced into the hydrocarbon group include a halogen atom, an alkyl group, an aryl group, and a heterocyclic group. , Cyano group, nitro group, alkoxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonyl Amino group, sulfamoylamino group, alkylsulfonylamino group, arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkylsulfinyl group, arylsulfinyl group, alkyls Honiru group, an arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, and the like silyl groups.
More preferred as a substituent is an alkyl group, an aryl group, a cyano group, an alkoxy group, a silyloxy group, an alkoxycarbonyloxy group, or a fluorine atom. Further, from the viewpoint that the physical properties of the electrolytic solution can be maintained hydrophobic, an embodiment in which at least one of R ¹ and —OR ² has a cyano group, an embodiment in which —OR ² has a fluoroalkyl group, and the like are more preferable.

In the specific siloxane oligomer, at least a part of the group represented by —OR ² in the general formula (1) is a substituent represented by the general formula (2).
The molar fraction of the substituent represented by the general formula (2) with respect to the total molar amount of R ¹ and —OR ² in the entire partial structure represented by the general formula (1) contained in the specific siloxane oligomer according to the present invention. The rate is required to be 5 mol% or more and 100 mol% or less.
In the general formula (2), examples of the alkylene group represented by Q ¹ include a linear or branched alkylene group such as a methylene group, an ethylene group, or a propylene group. These alkylene groups may have a substituent.
R ³ represents an alkyl group. Examples of the alkyl group include the same alkyl groups as those represented by R ² in the general formula (1), and preferred examples are also the same.
The substituent represented by the general formula (2) is preferably a substituent represented by the following general formula (3).

In the general formula (3), the alkyl group represented by R ^3, the general formula in (1) the same as the alkyl group represented by R ² are exemplified, and preferred examples are also the same.
R ⁴ and R ⁵ each independently represent an alkyl group or a hydrogen atom, preferably a methyl group or a hydrogen atom, and more preferably both R ⁴ and R ⁵ are hydrogen atoms.
R ⁴ and R ⁵ may be linked to each other to form a ring structure. Examples of the formed ring structure include a ring formed from a 5-membered ring to a 10-membered hydrocarbon (cyclopentane ring, Or a cyclohexane ring).
The substituents represented by the general formula (2) and the general formula (3) are one embodiment of —OR ² which is the above-described substituent, and thus the general formula (2) and the general formula ( As in the case of —OR ² , the substituent represented by 3) preferably has no ring structure in the structure of the substituent from the viewpoint of improving ionic conductivity. That is, in the substituent represented by the general formula (2), Q ¹ is a linear or branched alkylene group, and R ³ represents a linear or branched alkyl group, represented by the general formula (3). In a preferred substituent, R ³ is a linear or branched alkyl group, and both R ⁴ and R ⁵ are hydrogen atoms.

The specific siloxane oligomer according to one embodiment of the present invention includes the following general formula (1-a), general formula (1-b), general formula (1-c), general formula (1-d), and general formula (1- Comprising a partial structure selected from the group consisting of 1-e).

The formula (1-a) represents an example of an embodiment of the partial structure represented by the general formula (1) that exists at the end of the specific siloxane oligomer, and the formula (1-b) represents the formula (1-b) The aspect which comprises the chain structure in the partial structure represented by 1) is shown. The specific siloxane oligomer further has a branched structure containing at least one selected from the partial structures represented by the general formula (1-c), the general formula (1-d), and the general formula (1-e). The general formula (1-a), the general formula (1-b), the general formula (1-c), the general formula (1-d), and the general formula (1-e) may be used. And xa, xb, xc, xd, and xe, respectively, the total amount of xa + xb is 70 mol% or more with respect to the total amount of all partial structures contained in the siloxane oligomer. It is preferable that it is 100 mol% or less from a viewpoint that the viscosity of a specific siloxane oligomer is maintained appropriately, and it is more preferable that xa + xb is 80 mol% or more. In other words, the molar fraction of the branched partial structure is preferably 30 mol% or less, and more preferably 20 mol% or less. Moreover, from the viewpoint of suppressing an increase in viscosity due to having a branched structure or a crosslinked structure at a high density, xe is preferably 5 mol% or less.
The presence or absence of a branched structure or a crosslinked structure contained in the specific siloxane oligomer is confirmed by Si-NMR.

Specific examples [(Si-1) to (Si-8)] of the specific siloxane oligomer according to the present invention are confirmed by the content ratio of each substituent in the partial structure represented by the general formula (1) and Si-NMR measurement. Specific branched siloxane oligomers that can be used in the present invention are not limited to the following exemplified compounds, although the branched mole fractions and the number average molecular weights obtained by styrene conversion by GPC measurement are listed.

The molecular weight (number average molecular weight in terms of styrene by GPC) of the specific siloxane oligomer according to the present invention needs to be 500 or more and 1,500 or less, and preferably 500 or more and 1,000 or less.
The content of the specific siloxane oligomer in the electrolytic solution of the present invention is preferably in the range of 30% by mass to 80% by mass, and more preferably in the range of 60% by mass to 80% by mass with respect to the total amount of the electrolytic solution.

(2) Salt of metal ion belonging to Group 1 or Group 2 of periodic table Is appropriately selected. Specific examples of salts of metal ions belonging to Group 1 or Group 2 of the Periodic Table include, for example, lithium salts, potassium salts, sodium salts, calcium salts, magnesium salts, and the like. When used for a secondary battery or the like, a lithium salt is preferable from the viewpoint of high output of the secondary battery. When the electrolytic solution of the present invention is used as an electrolyte of a non-aqueous electrolytic solution for a lithium secondary battery, a lithium salt may be selected as a metal ion salt. The lithium salt is not particularly limited as long as it is a lithium salt usually used for an electrolyte of a non-aqueous electrolyte solution for a lithium secondary battery. For example, those described below are preferable.

(2-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBRO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(2-2) Fluorine-containing organic lithium salt: perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF ₃ _{_{_{_{)], Li [PF 4 (}}}} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(2-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.

Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) ₂ is preferred, and lithium imide salts such as LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) ₂ are further preferable. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.
In addition, the lithium salt used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.
The content of a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table in the electrolytic solution is added in an amount that provides a preferable salt concentration described below in the method for preparing the electrolytic solution. The salt concentration is selected according to the purpose of the electrolytic solution, but is generally 10% by mass to 50% by mass, and more preferably 15% by mass to 30% by mass in the total mass of the electrolytic solution.

(3) Method for Preparing Electrolytic Solution Next, a typical method for preparing the electrolytic solution of the present invention will be described by taking (2) a case where a lithium salt is used as a salt of metal ions as an example.
As shown in the following scheme 1, the electrolytic solution of the present invention first synthesizes a siloxane oligomer using (4) an alkoxysilane compound and (5) a hydroxycarboxylic acid, and then dissolves the lithium salt. By adding the method, an electrolyte solution is prepared and in the presence of a lithium salt, a siloxane oligomer is synthesized by synthesizing a siloxane oligomer using the above (4) alkoxysilane compound and (5) hydroxycarboxylic acid. Any method of preparing an electrolytic solution containing a salt in one step can be used.

In the condensation reaction of the above (4) alkoxysilane compound and (5) hydroxycarboxylic acid, the (5) hydroxycarboxylic acid used as the acid catalyst is esterified by transesterification with (4) alkoxysilane to form HOQ ¹ COOR. ^{2 is} further exchanged with an alkoxy group on the oligomer and introduced onto the oligomer. At this time, when (6) another alcohol [HO-Q ² -X] coexists, (6) the other alcohol is exchanged with the —OR ² group in the (4) alkoxysilane compound and introduced into the oligomer. (Scheme 1).
(6) The other alcohol [HO-Q ² -X] may be allowed to coexist in the reaction solution from the beginning, or may be added after the condensation has progressed.

Formula (4) and ^R 1, ^{R 2} and ^{Q 1} in the formula (5) is respectively ^R 1, ^{R 2} and ^{Q 1} synonymous in Formula (1) and the general formula (2), ^{Q 2} Is synonymous with Q ¹ and X represents the same substituent as described for R ² .
Hereinafter, various conditions of the electrolytic solution adjustment method will be described in detail.

(I) Condensation conditions (composition ratio, temperature, distillation conditions, solvent)
(1) Raw material charge ratio:
In the preparation of the electrolytic solution in the present invention, when the charged molar amount of the (4) alkoxysilane compound is a and the charged molar amount of the (5) hydroxycarboxylic acid is b, the charged molar ratio b / a of the reaction solution is A preferred range is from 0.1 to 2, more preferably from 0.2 to 1, more preferably from 0.3 to 0.8. (4) Alkoxysilane compounds and (5) hydroxycarboxylic acids may be used singly or as a mixture of compounds having different structures.

(2) Reaction temperature, reaction time, etc .:
In the siloxane oligomer of the present invention, the (4) alkoxysilane compound is condensed using the (5) hydroxycarboxylic acid as an acid catalyst, and then a volatile component derived from an unreacted raw material and a generated volatile component Obtained by distillation. The reaction temperature during the condensation reaction depends on the boiling point of the alcohol produced during the condensation, but is preferably in the range of room temperature to 200 ° C, more preferably in the range of 50 ° C to 170 ° C, and in the range of 80 ° C to 160 ° C. Is more preferable. The volatile matter after the condensation reaction is usually distilled off at normal pressure and then preferably after reduced pressure and then reduced pressure heating. The preferred heating temperature range during reduced pressure heating is from 60 ° C to 200 ° C. ° C, more preferably 100 ° C to 160 ° C. The degree of vacuum is preferably gradually increased in the range of 600 mmHg to 5 mmHg, and finally the volatile matter is preferably distilled off in the range of 100 mmHg to 5 mmHg and a temperature of 100 ° C to 160 ° C. . The temperature here is the temperature of the heat medium for heating the reactor.
(3) Solvent:
Preparation of the electrolytic solution of the present invention can be performed without a solvent, but may be performed using a solvent. In addition, when a solvent is used, the solvent may finally be completely distilled off, or it can be intentionally left as long as it does not adversely affect the characteristics of the lithium secondary battery.
Here, preferably used solvents are organic synthesis such as alcohols such as methanol, ethanol and propanol, aprotic solvents such as acetonitrile, ethyl acetate, dimethylformamide, dimethyl sulfoxide, terahydrofuran (THF), and sulfolane. Can be selected from a wide range of solvents. Moreover, it is also possible to select from the solvent used by the lithium secondary battery mentioned later, and to use as a solvent at the time of electrolyte solution adjustment.
When the solvent is used, the amount of the solvent to be added is preferably in the range of 0.1 to 10 and more preferably in the range of 0.1 to 1 by mass ratio with respect to the siloxane oligomer.

(Ii) Composition and Physical Properties of Electrolytic Solution The lithium salt concentration in the prepared electrolytic solution has an appropriate concentration range for exhibiting high ionic conductivity because the viscosity of the electrolytic solution increases as the concentration increases. . A preferable concentration range is 10% by mass to 50% by mass, and more preferably 15% by mass to 30% by mass, based on the total mass of the electrolytic solution.
When preparing an electrolyte by performing a condensation reaction in the presence of a lithium salt, the lithium salt concentration is controlled by the raw material charge ratio described in (1) above and the reaction conditions described in (2). What is necessary is just to adjust the preparation ratio of a raw material so that a final density | concentration may enter into said range.
The viscosity of the electrolytic solution of the present invention is controlled by the above (1) raw material charge ratio and (2) reaction conditions, and is preferably 100 mPa · s or less, but in order to achieve both low volatility and 5 mPa · s to 50 mPa · s. The range of is more preferable.

(Vii) Specific compound examples used for preparation of specific siloxane oligomer In the above synthesis method, specific compound examples of raw materials used for the synthesis of the specific siloxane oligomer according to the present invention are listed below, but are not limited thereto.
(4) Alkoxysilane compound (4-1) Si (OMe) ₄ , (4-2) Si (OEt) ₄ ,
(4-3) Si (OPr) ₄ , (4-4) Si (OBu) ₄ ,
(4-5) MeSi (OMe) ₃ , (4-6) MeSi (OEt) ₃ ,
(4-7) Me ₂ Si (OMe) ₂ etc.

(5) hydroxycarboxylic acid (5-1) HOCH ₂ COOH, (5-2) HOCH ₂ CH ₂ COOH,
(5-3) HOCH (Me) COOH, (5-4) HOC (Me) ₂ COOH,
(5-5) HOCH ₂ CH (Me) COOH,
(5-6) HOCH ₂ C (Me) ₂ COOH, etc.

(6) Substituent-containing alcohol (6-1) HOCH ₂ COOC ₂ H ₅ , (6-1) HOCH ₂ CH ₂ CN,
(6-2) HOCH ₂ CF ₂ CF ₂ H, (6-3) HOCH ₂ CF ₃ ,
(6-4) HOCH ₂ CH ₂ F, (6-5) HOCH ₂ CH ₂ Si (CH ₃ ) _3, etc. Here, Me represents a methyl group, OMe represents a methoxy group, OEt represents an ethoxy group, OPr represents a propoxy group, and OBu represents a butoxy group.

(7) Phosphorus compound The electrolytic solution of the present invention may further contain a phosphorus compound. By using a phosphorus compound in the electrolytic solution, the viscosity of the electrolytic solution is lowered, and thereby the ionic conductivity is improved and the flame retardancy is improved. Moreover, the improvement of charging / discharging characteristic was seen by using together the preferable phosphorus compound shown below. This is considered to be derived from the fact that the phosphorus compound forms a thin film (SEI) covering the negative electrode and the positive electrode during battery charging.
Phosphorus compounds used in the electrolytic solution of the present invention include (7-1) phosphate ester compound, (7-2) phosphazene compound, (7-3) phosphonate ester compound, and (7-4) phosphite. The compound etc. are mentioned, What is necessary is just to select 1 type (s) or 2 or more types from the group which consists of these compounds.
Hereinafter, preferable phosphorus compounds will be described.
(7-1) Phosphate Compound As the phosphate compound, a compound represented by the following general formula (p1) is preferable.

In the general formula (p1), Rp ¹¹ , Rp ¹² , and Rp ¹³ each independently represents an alkyl group or an aryl group. Preferably, two of Rp ¹¹ , Rp ¹² , and Rp ¹³ represent the same substituent, and more preferably, all three represent the same substituent.
When at least one of Rp ¹¹ , Rp ¹² , and Rp ¹³ represents an alkyl group, an alkyl group having 1 to 8 carbon atoms is preferable. In addition, when at least one of Rp ¹¹ , Rp ¹² , and Rp ¹³ represents an aryl group, an aryl group having 6 to 12 carbon atoms is preferable. Among ^them, Rp 11, ^{Rp 12,} and ^{Rp 13,} respectively, it is preferable that an alkyl group.
More specifically, the unsubstituted alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tert-butyl group, and more preferably a methyl group, Or it is an ethyl group.
The substituted alkyl group is preferably a halogenated alkyl group, particularly preferably a fluorinated alkyl group, and more preferably a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a trifluoroethyl group, or a tetrafluoro group. Propyl group.
Preferable specific embodiment of the phosphate ester compound is a case where Rp ¹¹ , R ¹² and R ¹³ are each independently any of a methyl group, an ethyl group, a trifluoromethyl group, and a trifluoroethyl group. More preferably, all of Rp ¹¹ , Rp ¹² and Rp ¹³ are methyl groups or trifluoroethyl groups.

(7-2) Phosphazene Compound As the phosphazene compound, a compound having a partial structure represented by the following general formula (p2) is preferable.

In the general formula (p2), Rp ²¹ and Rp ²² each independently represent a halogen atom, an alkoxy group, or an aryloxy group. n _p ² represents an integer of 1 or more, preferably an integer of 1 to 4, and particularly preferably 3 or 4.
When at least one of Rp ²¹ and Rp ²² represents a halogen atom, a chlorine atom or a fluorine atom is preferable, and a fluorine atom is more preferable. In addition, when at least one of Rp ²¹ and Rp ²² represents an alkoxy group, an alkoxy group having 1 to 8 carbon atoms is preferable. When at least one of Rp ²¹ and Rp ²² represents an aryloxy group, an aryloxy group having 6 to 12 carbon atoms is preferable. Among them, ^{Rp 21,} and ^{Rp 22} are each independently preferably represents a halogen atom or an alkoxy group.
The alkoxy group preferably includes a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, and a halogenated alkyloxy group, more preferably a methoxy group, An ethoxy group or a halogenated alkyloxy group. The halogenated alkyloxy group is more preferably a trifluoromethoxy group, a trifluoroethoxy group, or a tetrofluoropropyloxy group.
Rp ²¹ and Rp ²² may be the same or different, but an embodiment in which at least one of Rp ²¹ and Rp ²² is a fluorine atom is preferable.
As the phosphazene compound having a partial structure represented by the general formula (P2), one of Rp ²¹ and Rp ²² is a fluorine atom, the other is a methoxy group, and Np2 is 3 or 4. The compound which has the cyclic structure which the terminal has connected is mentioned.

(7-3) Phosphonate Compound As the phosphonate compound, a compound represented by the following general formula (p3) is preferable.

In the general formula (p3), Rp ³¹ , Rp ³² , and Rp ³³ each independently represents an alkyl group or an aryl group.
Rp ³¹ , Rp ³² , and Rp ³³ may be the same or different, but an embodiment in which Rp ³² and Rp ³³ are the same is preferable.
When at least one of Rp ³¹ , Rp ³² , and Rp ³³² represents an alkyl group, an alkyl group having 1 to 8 carbon atoms is preferable. Further, when at least one of Rp ³¹ , Rp ³² , and Rp ³³² represents an aryl group, an aryl group having 6 to 12 carbon atoms is preferable. Among ^them, Rp 31, ^{Rp 32,} and ^{Rp 33} are each independently preferably represents an alkyl group.
When at least one of Rp ³¹ , Rp ³² , and Rp ³³² represents an alkyl group, the unsubstituted alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and A tert-butyl group, more preferably a methyl group or an ethyl group. The substituted alkyl group is preferably a halogenated alkyl group, particularly preferably a fluorinated alkyl group, and more preferably a trifluoromethyl group, difluoromethyl group, monofluoromethyl group, trifluoroethyl group, or tetra It is a fluoropropyl group.
A preferred specific embodiment of the phosphonate compound is a case where Rp ³¹ is a methyl group, and Rp ³² and Rp ³³ are both trifluoroethyl groups.

(7-4) Phosphite Compound Examples of the phosphite compound include compounds represented by the following general formula (p4).

In the general formula (p4), Rp ⁴¹ , Rp ⁴² , and Rp ⁴³ each independently represents an alkyl group or a phenyl group.
Rp ⁴¹ , Rp ⁴² , and Rp ⁴³ may be the same or different, but an embodiment in which two of Rp ⁴¹ , Rp ⁴² , and Rp ⁴³ are the same is preferable, and an embodiment in which three are the same substituents Is more preferable.
When at least one of Rp ⁴¹ , Rp ⁴² , and Rp ⁴³² represents an alkyl group, an alkyl group having 1 to 8 carbon atoms is preferable. In addition, when at least one of Rp ⁴¹ , Rp ⁴² , and Rp ⁴³² represents an aryl group, an aryl group having 6 to 12 carbon atoms is preferable. Among ^them, Rp 41, ^{Rp 42,} and ^{Rp 43} are each independently a phenyl group, or preferably represents an alkyl group.
When at least one of Rp ³¹ , Rp ³² , and Rp ³³² represents an alkyl group, the unsubstituted alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and A tert-butyl group, more preferably a methyl group or an ethyl group. The substituted alkyl group is preferably a halogenated alkyl group, particularly preferably a fluorinated alkyl group, and more preferably a trifluoromethyl group, difluoromethyl group, monofluoromethyl group, trifluoroethyl group, or tetra It is a fluoropropyl group.
By way of preferred specific embodiments of the phosphite ^compound, a case Rp 41, ^{Rp 42,} and ^{Rp 43} is independently a methyl group, an ethyl group, or a phenyl group, more ^preferably, Rp 41, ^{Rp 42,} And Rp ⁴³ is all a methyl group.
Specific preferred examples of the phosphorus compound that can be used in the electrolytic solution of the present invention [Exemplary compounds (A1) to (A5)] are shown below, but the present invention is not limited thereto.

The said phosphorus compound may contain only 1 type in electrolyte solution, and may contain 2 or more types.
The phosphorus compound may be added at any timing in the process for preparing the electrolytic solution, but is preferably added simultaneously with the addition of the lithium salt.
The content of the phosphorus compound is desirably in the range of 5% by mass to 40% by mass with respect to the total electrolyte solution. Preferably, it is the range of 5 mass% or more and 30% mass% or less, Most preferably, it is the range of 10 mass% or more and 20 mass% or less.
When the addition amount is 5% by mass or more, the effect of improving the flame retardancy due to the addition of the phosphorus compound is sufficiently exhibited, and when it is 40% by mass or less, the battery characteristics, particularly the charge / discharge characteristics are maintained well. .

The electrolyte solution of the present invention containing the specific siloxane oligomer is prepared as described above. The electrolyte solution for a non-aqueous secondary battery of the present invention thus obtained is suitable for battery applications that require high ion conductivity because both the ion conductivity and the ion transport number are good. Among them, it is useful as an electrolytic solution for lithium secondary batteries.

[2] Lithium secondary battery The lithium secondary battery of the present invention comprises the electrolyte solution for a non-aqueous secondary battery of the present invention, a positive electrode capable of inserting and releasing lithium ions, and insertion and release or dissolution precipitation of lithium ions. Possible negative electrode.
In addition to these members, in consideration of the purpose for which the battery is used, the shape of the potential, and the like, the battery may be configured to include a separator, a current collecting terminal, and an outer case disposed between the positive electrode and the negative electrode. If necessary, a protective element may be attached to at least one of the inside of the battery and the outside of the battery.
Hereinafter, the configuration of the lithium secondary battery of the present invention will be described in detail.
(1) Battery shape There is no restriction | limiting in particular in the battery shape to which the lithium secondary battery of this invention is applied, For example, a bottomed cylindrical shape, a bottomed square shape, a thin shape, a sheet shape, and a paper shape Any of these may be used. Also, it may be an unusual battery shape such as a horseshoe shape or a comb shape considering the shape of the system or device to be incorporated.
In particular, from the viewpoint of efficiently releasing the heat inside the battery to the outside, a rectangular battery shape such as a bottomed square shape or a thin shape having at least one surface that is relatively flat and has a large area is preferable.

In the case of a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging or discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced.

In the bottomed square shape, the ratio of the area S of the largest surface (the product of the width and height of the outer dimensions excluding the terminal portion, unit cm ² ) to the thickness T (unit cm) of the battery outer shape The 2S / T value is preferably 100 or more, and more preferably 200 or more. By increasing the maximum surface, it is possible to improve characteristics such as cycle performance and high-temperature storage, even for high-power and large-capacity batteries, as well as increase the heat dissipation efficiency during abnormal heat generation. ”Can be suppressed.

(2) Members Constructing the Battery The lithium secondary battery of the present invention includes (a) an electrolytic solution, (b) a positive electrode / negative electrode electrode mixture, and (c) a separator basic member. Hereinafter, each of these members will be described. The lithium secondary battery of the present invention contains (a) the electrolyte solution for a non-aqueous battery of the present invention at least.
(A) Electrolytic Solution The electrolytic solution used for the lithium secondary battery of the present invention is the non-aqueous secondary battery of the present invention containing at least a specific siloxane oligomer and a lithium salt as an electrolyte salt, prepared by the method described above. Contains an electrolytic solution as a main component.
That is, (a) electrolyte solution is an electrolyte solution for non-aqueous secondary batteries containing the specific siloxane oligomer as a non-aqueous electrolyte solution and a lithium salt as an electrolyte salt.
The electrolyte salt used in the electrolyte for a non-aqueous secondary battery is a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table, and the electrolyte for a non-aqueous secondary battery of the present invention. Those described in detail in the embodiment can be used.
In addition, the (a) electrolyte used in the lithium secondary battery of the present invention is further improved in performance by adding the following solvent and other additives to the extent that the effects of the present invention are not impaired. Can be made.
(A-1) Solvent for Electrolyte Solution The electrolyte solution prepared by the method of the present invention can be used as it is as an electrolyte solution for a lithium secondary battery. Further, it is a non-aqueous solution generally used for lithium secondary batteries. An organic solvent may be added.
Examples of such solvents include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, and propylene glycol dialkyl ether. , Chain ethers such as polyethylene glycol dialkyl ether and polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether and polypropylene glycol monoalkyl ether, ethylene Glycol, propylene glycol, polyethylene glycol Polyhydric alcohols such as polypropylene glycol and glycerin, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile and benzonitrile, esters such as carboxylic acid esters, aprotic polar substances such as dimethyl sulfoxide and sulfolane And the like.
Among them, carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile, and esters are particularly preferred. preferable. These may be used alone or in combination of two or more.

The preferable solvent property is that the boiling point at normal pressure (1 atm) is preferably 200 ° C. or higher, more preferably 250 ° C. or higher, from the viewpoint of improving durability due to volatility resistance, and 270 ° C. More preferably, it is the above.
The addition amount when adding the organic solvent is preferably 1% by mass to 50% by mass, and more preferably 5% by mass to 40% by mass with respect to the electrolytic solution of the present invention.
Since the electrolyte solution of the present invention has a good lithium transport number, it does not contain an organic solvent as compared with the conventional case, or even if it is added in a small amount, both excellent ionic conductivity and lithium transport number are compatible.

(A-2) Functional Additive Various additives can be used in the electrolytic solution according to the present invention depending on the purpose so as to improve the performance of the battery as long as the effects of the present invention are not impaired.
As such an additive, a functional additive such as an overcharge inhibitor, a negative electrode film forming agent, a positive electrode protective agent; and the like may be used.
Examples of the compound used for the functional additive include, for example, biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran and the like. Aromatic compounds; partially fluorinated products of the aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; and 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6- Overcharge inhibitors such as fluorine-containing anisole compounds such as difluoroanisole and 3,5-difluoroanisole;
Negative electrode coatings such as vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, trifluoropropylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, and cyclohexanedicarboxylic anhydride Forming agent;
Ethylene sulfite, propylene sulfite, dimethyl sulfite, propane sultone, butane sultone, methyl methanesulfonate, busulfan, methyl toluene sulfonate, dimethyl sulfate, ethylene sulfate, sulfolane, dimethyl sulfone, diethyl sulfone, dimethyl sulfoxide, diethyl sulfoxide, tetramethylene sulfoxide, And positive electrode protecting agents such as diphenyl sulfide, thioanisole, diphenyl disulfide, and dipyridinium disulfide.

As the overcharge inhibitor, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable. Two or more of these may be used in combination. When two or more types are used in combination, it is particularly preferable to use cyclohexylbenzene or terphenyl (or a partially hydrogenated product thereof) together with t-butylbenzene or t-amylbenzene.

As the negative electrode film forming agent, vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, succinic anhydride, and maleic anhydride are preferable. Two or more of these may be used in combination. When using 2 or more types together, the combination of vinylene carbonate and vinyl ethylene carbonate, fluoroethylene carbonate, succinic anhydride, or maleic anhydride is preferable.

As the positive electrode protective agent, ethylene sulfite, propylene sulfite, propane sultone, butane sultone, methyl methanesulfonate, and busulfan are preferable. Two or more of these may be used in combination.

Also, the combined use of a negative electrode film forming agent and a positive electrode protective agent, and the combined use of an overcharge inhibitor, a negative electrode film forming agent, and a positive electrode protective agent are particularly preferable.

The content of the functional additive in the non-aqueous electrolyte solution is not particularly limited, but is preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more, based on the whole non-aqueous electrolyte solution. The upper limit is preferably 5% by mass or less, particularly preferably 3% by mass or less, and further preferably 2% by mass or less. By adding these compounds, it is possible to suppress rupture / ignition of the battery at the time of abnormality due to overcharge, and to improve the capacity maintenance characteristic and cycle characteristic after high-temperature storage.

(B) Electrode mixture The electrode mixture is obtained by applying a dispersion of an active material, a conductive agent, a binder, and a filler onto a current collector. In a lithium battery, the active material is a positive electrode active material. And a negative electrode mixture in which the active material is a negative electrode active material.
Next, the positive electrode active material, the negative electrode active material, the conductive agent, the binder, the filler, and the current collector that constitute the electrode mixture will be described.
(B-1) Cathode Active Material The electrolyte solution for a non-aqueous secondary battery of the present invention may contain a particulate cathode active material. As the positive electrode active material used in the present invention, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but a lithium-containing transition metal oxide is preferably used. In the present invention, the lithium-containing transition metal oxide preferably used as the positive electrode active material includes lithium-containing Ti, lithium-containing V, lithium-containing Cr, lithium-containing Mn, lithium-containing Fe, lithium-containing Co, lithium-containing Ni, and lithium-containing Preferable examples include an oxide containing one or more of Cu, lithium-containing Mo, and lithium-containing W. Alkali metals other than lithium (elements of Group 1 (Ia) and Group 2 (IIa) of the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P , B, etc. may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

Among the lithium-containing transition metal oxides preferably used as the positive electrode active material, a lithium compound / transition metal compound (wherein the transition metal is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) And a mixture synthesized so that the total molar ratio is 0.3 to 2.2 is more preferable.

Further, among the lithium compounds / transition metal compounds, Li _g M3O ₂ (M3 represents one or more elements selected from Co, Ni, Fe, and Mn. _G represents 0 to 1.2. ) Or a material having a spinel structure represented by Li _h M4 ₂ O (M4 represents Mn, h represents 0 to 2). As M3 and M4, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be mixed in addition to the transition metal. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

The _Li g M3O material containing _2, among the materials having the spinel structure represented by _{_{_{_{Li h M4 2 O, Li g}}}} CoO 2, Li g NiO 2, Li g MnO 2, Li g Co j Ni 1-j O _{_{_{_{2, Li h Mn 2 O 4}}}} , LiNi j Mn 1-j O 2, LiCo j Ni h Al 1-j-h O 2, LiCo j Ni h Mn 1-j-h O 2, LiMn h Al 2-h O ₄ , and LiMn _h Ni _2-h O ₄ (wherein g represents 0.02 to 1.2, j represents 0.1 to 0.9, and h represents 0 to 2) Is particularly preferred. Here, the g value and the h value are values before the start of charge / discharge, and are values that increase / decrease due to charge / discharge. In particular,
LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.01 Al _0.05 O ₂ ,
LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn _1.8 Al _0.2 O ₄ , or
LiMn _1.5 Ni _0.5 O ₄ and the like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like are preferable. Specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Examples thereof include those substituted with other metals such as Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, or Si.

The positive electrode active material can be synthesized by a method of mixing and baking a lithium compound and a transition metal compound or by a solution reaction, and a compound obtained by a baking method is particularly preferable.
In the firing method applied to the synthesis of the positive electrode active material in the present invention, the firing temperature may be any temperature at which a part of the mixed compound is decomposed and melted. For example, 250 ° C. to 2000 ° C. is preferable. 350 ° C. to 1500 ° C. is more preferable. In firing, it is preferably calcined at 250 ° C. to 900 ° C. In the firing method, the firing time is preferably 1 hour to 72 hours, more preferably 2 hours to 20 hours. The raw material mixing method may be dry or wet. Further, annealing may be performed at 200 ° C. to 900 ° C. after firing.

In addition, a material in which a substance having a composition different from that of the main constituent of the positive electrode active material is attached to the surface of the positive electrode active material can be used.
Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, sulfuric acid Examples thereof include sulfates such as calcium and aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.

These surface adhering substances are, for example, a method of dissolving or suspending in a solvent and impregnating and drying the positive electrode active material, and a method of dissolving or suspending a surface adhering substance precursor in a solvent and impregnating and adding to the positive electrode active material, followed by heating. It can be made to adhere to the positive electrode active material surface by the method of making it react by the method etc., the method of adding to a positive electrode active material precursor, and baking simultaneously.

In the firing method, the firing gas atmosphere is not particularly limited, and both an oxidizing atmosphere and a reducing atmosphere can be used. For example, air, gas adjusted to an arbitrary oxygen concentration, hydrogen, carbon monoxide, nitrogen, argon, helium, krypton, xenon, carbon dioxide, and the like can be given.

In the nonaqueous electrolyte secondary battery of the present invention, the average particle size of the positive electrode active material used is not particularly limited, but is preferably 0.1 μm to 50 μm. The specific surface area is not particularly limited, but is preferably 0.01 m ² / g to 50 m ² / g by the BET method. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

A well-known pulverizer or classifier is used to make the positive electrode active substance have a predetermined particle size. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

(B-2) Negative electrode active material The negative electrode active material used in the electrolyte for a non-aqueous secondary battery of the present invention is not particularly limited as long as it can reversibly insert and release lithium ions. Examples include materials, metal oxides such as tin oxide and silicon oxide, metal composite oxides, lithium alloys such as lithium alone and lithium aluminum alloys, and metals that can form alloys with lithium such as Sn and Si.
These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of safety.
Further, the metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. .

The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has a face spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not have to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

The metal oxide and metal composite oxide which are the negative electrode active materials used in the lithium secondary battery of the present invention need only contain at least one of them. As the metal oxide and metal complex oxide, amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used.
The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having a peak in the region of 20 ° to 40 ° in terms of 2θ, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, an amorphous oxide of a semimetal element and a chalcogenide are more preferable, and elements of Groups 13 (IIIB) to 15 (VB) of the periodic table are preferable. An oxide consisting of Al, Ga, Si, Sn, Ge, Pb, Sb and Bi alone or a combination of two or more thereof, and chalcogenide are particularly preferable.
Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , And SnSiS ₃ are preferred. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

Among the preferred amorphous oxides and chalcogenide compound groups that can be used as the negative electrode active material used in the lithium secondary battery of the present invention, amorphous oxides centered on Sn, Si, and Ge are more preferred. An amorphous oxide represented by the following general formula (12) is particularly preferable.
SnM ¹ dM ² eOf General formula (12)

In the general formula (12), M ¹ represents at least one element selected from Al, B, P, and Ge. M ² represents at least one element selected from Group 1 (Ia) group elements, Group 2 (IIa) elements, Group 3 (IIIa) elements, and halogen elements in the periodic table. d represents a number of 0.2 to 2, e represents a number of 0.01 to 1, and a relation of 0.2 <d + e <2. f represents a number from 1 to 6.

As a method for synthesizing a compound selected from the group consisting of an amorphous oxide and a chalcogenite suitable as a negative electrode active material in the present invention, either a firing method or a solution method can be adopted, but a firing method is more preferable. preferable.
When synthesizing a negative electrode active material by a firing method, it is preferable to obtain an amorphous oxide and a chalcogenite by thoroughly mixing oxides, chalcogenites or compounds of the corresponding elements and then firing them.
The firing temperature in the firing method is preferably 500 ° C. or more and 1500 ° C. or less, and the firing time is preferably 1 hour or more and 100 hours or less.

In the firing method, the temperature drop after firing may be cooled in a firing furnace, or may be taken out of the firing furnace and cooled, for example, in water. In addition, a super rapid cooling method such as the gun method, Hammer-Anvil method, slap method, gas atomization method, plasma spray method, centrifugal quenching method, or melt drag method described on page 217 of ceramics processing (Gihodo Publishing 1987) can also be used. Alternatively, cooling may be performed using the single roller method or the double roller method described in page 172 of the New Glass Handbook (Maruzen 1991). 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 in the firing method is preferably an atmosphere having an oxygen content of 5% by volume or less, more preferably an inert gas atmosphere. Preferable examples of the inert gas include nitrogen, argon, helium, krypton, and xenon. Among these, pure argon is particularly preferable.

In the nonaqueous electrolyte secondary battery of the present invention, the average particle size of the negative electrode active material used is preferably 0.1 μm to 60 μm. To make the negative electrode active material have a predetermined particle size, a well-known pulverizer or classifier is used. For example, pulverizers such as a mortar, ball mill, sand mill, vibration ball mill, satellite ball mill, and planetary ball mill, a pulverizer having a classification function such as a swirling airflow type jet mill, and a sieve as a classifier are preferably 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. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

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

In the present invention, a negative electrode active material that can be used in combination with an amorphous oxide negative electrode active material centered on Sn, Si, or Ge includes a carbon material capable of inserting and extracting lithium ions or lithium metal, lithium Preferable examples include lithium alloys and metals that can be alloyed with lithium.

(B-3) Conductive Material As the conductive material, any electronic conductive material that does not cause a chemical change in the configured secondary battery may be used, and any known conductive material may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63-63)) Or a conductive material such as a metal fiber or a polyphenylene derivative (described in JP-A-59-20971) as a single type or a mixture of two or more types thereof. it can. Among these, the combined use of graphite and acetylene black is particularly preferable.
The addition amount of the conductive agent is preferably 1% by mass to 50% by mass, and more preferably 2% by mass to 30% by mass. In the case of carbon or graphite, 2% by mass to 15% by mass is particularly preferable.

(B-3) Binder In the present invention, a binder for holding the electrode mixture is used.
Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Among them, for example, starch, carboxymethylcellulose, cellulose, diacetylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, sodium alginate, Water-soluble polymers such as polyacrylic acid, sodium polyacrylate, polyvinylphenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, and styrene-maleic acid copolymer, polyvinyl Chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylide (Meta) such as fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, and 2-ethylhexyl acrylate (Meth) acrylic acid ester copolymer containing acrylic acid ester, (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 Over preparative polyurethane resins, polyester resins, phenolic resins, and emulsion (latex) or a suspension such as an epoxy resin is preferable, a latex of polyacrylate, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride is more preferable.

A binder can be used individually by 1 type or in mixture of 2 or more types.
When the amount of the binder added is small, the holding power and cohesive force of the electrode mixture are weakened. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For these reasons, the amount of binder added is preferably 1% by mass to 30% by mass, and more preferably 2% by mass to 10% by mass.

(B-5) Filler The electrolytic solution of the present invention may contain a filler. As the material for forming the filler, any fibrous material that does not cause a chemical change in the secondary battery of the present invention can be used. Usually, fibrous fillers made of materials such as olefin polymers such as polypropylene and polyethylene, glass, and carbon are used.
The amount of filler added is not particularly limited, but is preferably 0 to 30% by mass.

(B-6) Current collector As the positive and negative electrode current collectors, an electron conductor that does not cause a chemical change in the nonaqueous electrolyte secondary battery of the present invention is used. As the positive electrode current collector, aluminum, stainless steel, nickel, titanium, and the like, and those obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver are preferable. Among them, aluminum and aluminum alloys are preferable. More preferred.

As the negative electrode current collector, copper, stainless steel, nickel, and titanium are preferable, and copper or a copper alloy is more preferable.

As the shape of the current collector, a film sheet shape is usually used, but a net shape, a film sheet having an opening formed by punching, a lath body, a porous body, a foam, and a fiber group are formed. The fiber sheet body obtained by doing in this way can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.
An electrode mixture for a lithium secondary battery is formed by a member appropriately selected from these materials.

(C) Separator The separator used in the lithium secondary battery of the present invention is a material that mechanically insulates the positive electrode and the negative electrode, has ion permeability, and has oxidation / reduction resistance on the contact surface between the positive electrode and the negative electrode. If there is no particular limitation.
As such a material, a porous polymer material, an inorganic material, an organic-inorganic hybrid material, glass fiber, or the like is used. These separators preferably have a shutdown function for ensuring safety, that is, a function of closing a gap at 80 ° C. or higher to increase resistance and interrupting current, and the closing temperature is 90 ° C. or higher and 180 ° C. or lower. It is preferable.

The shape of the holes of the separator is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

The polymer material may be a single material such as polyethylene or polypropylene, or two or more composite materials. What laminated | stacked the 2 or more types of microporous film which changed the hole diameter, the porosity, the obstruction | occlusion temperature of a hole, etc. is preferable.

As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. As the thin film shape, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle diameter of less than 1 μm are formed on both surfaces of the positive electrode as a porous layer using a fluororesin binder.

(4) Production of Nonaqueous Electrolyte Secondary Battery Here, a production method of the nonaqueous electrolyte lithium secondary battery of the present invention will be described.
As described above, the lithium secondary battery of the present invention can be applied to any shape such as a sheet shape, a square shape, and a cylinder shape. A positive electrode active material or a mixture of negative electrode active materials is mainly used after being applied (coated), dried and compressed on a current collector.

Hereinafter, with reference to FIG. 1, a configuration and a manufacturing method thereof will be described using a bottomed cylindrical lithium secondary battery 10 as an example. FIG. 1 is a schematic cross-sectional view showing an example of a bottomed cylindrical lithium secondary battery 10 in which a positive electrode sheet 14 and a negative electrode sheet 16 stacked with a separator 12 interposed therebetween are wound and stored in an outer can 18.

First, a negative electrode active material is mixed with a binder or filler used as desired in an organic solvent to prepare a slurry or paste negative electrode mixture. The obtained negative electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a negative electrode mixture layer. Further, the laminate of the current collector and the negative electrode mixture layer is rolled with a roll press or the like to prepare a predetermined thickness to obtain a negative electrode sheet (electrode sheet) 16.

Preferred examples of the method for applying the negative electrode mixture include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. . Among these, the blade method, the knife method, and the extrusion method are preferable as the method for applying the negative electrode mixture.
The coating is preferably performed at a speed of 0.1 m / min to 100 m / min. Under the present circumstances, the surface state of a favorable application layer can be obtained by selecting the said application | coating method according to the solution physical property and dryability of a mixture. Application may be performed one side at a time or both sides simultaneously.

Further, in the application, the negative electrode mixture may be applied in a continuous layer, may be applied intermittently (discontinuously with respect to the application direction), or applied in stripes parallel to the application direction. May be. The thickness, length and width of the negative electrode mixture coating layer are determined by the shape and size of the battery, but the thickness of the coating layer on one side is preferably 1 μm to 2000 μm in a compressed state after drying. .

As a method for drying and dehydrating a negative electrode mixture coated product for obtaining an electrode sheet obtained by rolling a laminate of the current collector and the negative electrode mixture layer, hot air, vacuum, infrared rays, far infrared rays, electron beams and Examples thereof include a method in which low-humidity air is used alone or in combination. The drying temperature is preferably 80 ° C to 350 ° C, more preferably 100 ° C to 250 ° C.
The water content is preferably 2000 ppm or less for the entire battery, and the water content of each of the positive electrode mixture, the negative electrode mixture and the electrolyte is preferably 500 ppm or less.
As the sheet pressing method when rolling the laminate of the current collector and the negative electrode mixture layer, a generally adopted method can be used, and the calendar pressing method is particularly preferable. The pressing pressure is not particularly limited, but is preferably 0.2 t / cm ² to 3 t / cm ² .
The press speed of the calendar press method is preferably 0.1 m / min to 50 m / min, and the press temperature is preferably room temperature (25 ° C.) to 200 ° C.

Next, a positive electrode active material and a carbon-based conductive agent, a binder or the like used as desired are mixed in an organic solvent to prepare a slurry-like or paste-like positive electrode mixture. The obtained positive electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a positive electrode mixture layer on the current collector surface. Furthermore, the laminated body of a collector and a positive mix layer is rolled with a roll press etc., and it adjusts to predetermined thickness and obtains the positive electrode sheet 14. FIG.
The application method of the positive electrode mixture at the time of preparing the positive electrode sheet 16 and the drying method of the positive electrode mixture layer formed by the application may be the same as the conditions at the time of forming the negative electrode sheet 14.
The obtained positive electrode sheet 16 and negative electrode sheet 14 are laminated via the separator 12 and wound to obtain a spiral electrode body in a cylindrical shape.
When forming the spiral electrode body, the ratio of the width of the negative electrode sheet 14 to the positive electrode sheet 16 is preferably 0.9 to 1.1 when the width of the positive electrode sheet 16 is 1. 95 to 1.0 is particularly preferred. The content ratio of the positive electrode active material and the negative electrode active material in the spiral electrode body varies depending on the compound type and the mixture formulation.

After the insulating plates 20 are respectively arranged above and below the obtained spiral electrode body, the electrode body is attached to the outer can 18 from the opening of the outer can 18 that also serves as a negative electrode terminal formed into a cylindrical shape by pressing from a single plate. Insert inside. Thereafter, a negative electrode current collecting tab (not shown) extending from the negative electrode sheet 14 of the electrode body is welded and electrically connected to the inner bottom portion of the outer can 18, and a positive electrode extending from the positive electrode sheet 16 of the electrode body. The current collecting tab 24 is welded and electrically connected to the bottom of the bottom plate of the sealing plate 22.
Thereafter, the electrolytic solution of the present invention is injected into the outer can 18, covered with the sealing plate 22, and the opening of the outer can 18 is sealed using the gasket 26, so that the bottomed cylindrical lithium secondary battery 10 is sealed. Is formed. In the present embodiment, the sealing plate 22 is provided with a pressure sensitive valve body 28 as a safety valve and a current interruption element 30 as an overcurrent prevention element.

In the present embodiment, a cylindrical battery is taken as an example, but the shape of the lithium secondary battery of the present invention is not limited thereto. For example, a positive / negative electrode sheet manufactured by the above method is used as a separator. After being stacked, it is processed into a sheet-like battery as it is, or after being folded and inserted into a rectangular can, the can and the sheet are electrically connected, an electrolyte is injected, and a sealing plate is used. A square battery may be formed by sealing the opening.

In any of the embodiments, similarly to the present embodiment, the safety valve can be used as a sealing plate for sealing the opening. In addition to the safety valve, the sealing member represented by the sealing plate may be provided with various conventionally known safety elements. For example, as an overcurrent prevention element, a fuse, a bimetal, a PTC element, or the like is suitably used as a safety element attached to the sealing member.

Further, as a countermeasure against the increase in internal pressure of the battery can, in addition to the method of attaching the safety valve, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate is used. be able to. In addition, the lithium secondary battery is provided with a protection circuit in which an overcharge countermeasure member and an overdischarge countermeasure member are incorporated in a charger, or the protection circuit is provided independently of a thirium secondary battery. May be connected to each other.

For the production of cans and lead plates, electrically conductive metals and alloys can be used. As the material for the can and the lead plate, for example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are preferably used.

As a welding method for welding the cap, the can, the sheet, and the lead plate, a known method (for example, a DC or AC electric welding method, a laser welding method, an ultrasonic welding method, or the like) can be used. As the sealing agent used for sealing the lithium secondary battery, conventionally known compounds and mixtures such as asphalt can be used.

[3] Use of the lithium secondary battery of the present invention The lithium secondary battery of the present invention has high output while using a flame-retardant electrolyte, and can be applied to various applications.
Although the application mode of the lithium secondary battery of the present invention is not particularly limited, for example, when mounted on an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager , Handy Terminal, Mobile Fax, Mobile Copy, Mobile Printer, Headphone Stereo, Video Movie, LCD TV, Handy Cleaner, Portable CD, Mini Disc, Electric Shaver, Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Examples include backup power supplies and memory cards. Other consumer applications include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, and cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used as various munitions batteries and space batteries. In addition, the lithium secondary battery of the present invention can be combined with a solar battery.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
[Examples 1 to 21, Comparative Examples 1 to 4]
Preparation of electrolyte for non-aqueous secondary battery [1. Method of dissolving lithium salt after synthesizing siloxane oligomer]
(Preparation Example 1-1: Preparation of electrolytic solution E-1)
Methyltriethoxysilane (4-6) 50.0 g and glycolic acid (5-1) 7.65 g were mixed and heated to reflux at 150 ° C. for 1 hour. After the reaction, the temperature was maintained at 150 ° C., and the volatile components were distilled off while gradually decreasing the vacuum from normal pressure to 5 mmHg to obtain 16 g of a specific siloxane oligomer (Si-1) as a colorless liquid. The number average molecular weight in terms of styrene as measured by GPC was 1,200. Further, the content mole fraction of the substituent corresponding to —O—Q ¹ —COOR ³ with respect to all the substituents contained in the partial structure represented by the general formula (1), measured by H ¹ -NMR, was 32 The branched mole fraction (xc + xd + xe) in the total partial structure contained in the specific siloxane oligomer confirmed by Si-NMR measurement was 25 mol%.
In 3 g of the siloxane oligomer (Si-1) obtained above, 0.96 g of N-lithiotrifluoromethanesulfonimide (hereinafter appropriately referred to as LiTFSI) was dissolved to obtain an electrolytic solution E-1.
(Preparation Example 1-2: Preparation of electrolytic solution E-2)
Tetraethoxysilane (4-2) 50.0 g and glycolic acid (5-1) 18.6 g were mixed and heated to reflux at 150 ° C. for 1 hour. After the reaction, the temperature was maintained at 150 ° C., and the volatile component was distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 42.7 g of a specific siloxane oligomer (Si-3) as a colorless liquid. The number average molecular weight in terms of styrene by GPC measurement is 1,500, and the content of the substituent —OQ ¹ —COOR ³ contained in the partial structure represented by the general formula (1), measured by H ¹ -NMR. The fraction was 52 mol%, and the branched molar fraction (xc + xd + xe) confirmed by Si-NMR measurement was 20%.
In 3 g of the siloxane oligomer (Si-3) obtained above, 0.96 g of LiTFSI was dissolved to obtain an electrolytic solution E-2.

(Preparation Example 1-3: Preparation of electrolytic solution E-3)
50 g of methyltetraethylsilane (4-2), 7.65 g of glycolic acid (5-1) and 24.2 g of ethyl glycolate (6-1) were mixed and heated to reflux at 150 ° C. for 1 hour. After the reaction, the temperature was maintained at 150 ° C., and the volatile components were distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 16 g of a specific siloxane oligomer (Si-2) as a colorless liquid. The number average molecular weight in terms of styrene as measured by GPC is 1,450, and the content of the substituent —OQ ¹ —COOR ³ contained in the partial structure represented by the general formula (1) as measured by H ¹ -NMR The fraction was 41 mol%, and the branched molar fraction (xc + xd + xe) confirmed by Si-NMR measurement was 23%.
In 3 g of the siloxane oligomer (Si-2) obtained above, 0.96 g of LiTFSI was dissolved to obtain an electrolytic solution E-3.

[2. Method of synthesizing oligomer in the presence of lithium salt and preparing electrolyte in one step]
(Preparation Example 2-1: Preparation of electrolyte E-4)
100.0 g of methyltriethoxysilane (4-5), 13.1 g of glycolic acid (5-1) and 14.0 g of LiTFSI were mixed and heated to reflux at 150 ° C. for 1 hour. After the reaction, the temperature was maintained at 150 ° C., and the volatile components were distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 54 g of colorless liquid (E-4).
The number average molecular weight in terms of styrene by GPC measurement of the specific siloxane oligomer (Si-8) contained in the colorless liquid is 650, and is contained in the partial structure represented by the general formula (1) measured by H ¹ -NMR. The content mole fraction of the substituent —O—Q ¹ —COOR ³ was 21 mole%, and the branched mole fraction (xc + x + xe) confirmed by Si-NMR measurement was 5%.
(Preparation Example 2-2: Preparation of electrolytic solution E-5)
Tetraethoxysilane (4-2) 50.0 g, glycolic acid (5-1) 5.25 g, and LiTFSI 9.5 g were mixed and heated to reflux at 150 ° C. for 1 hour. After the reaction, the temperature was kept at 150 ° C., and the volatile components were distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 37 g of colorless liquid (E-5).
The specific siloxane oligomer (Si-9) contained in the colorless liquid has a styrene-equivalent number average molecular weight of 800 by PC measurement and is contained in the partial structure represented by the general formula (1) measured by H ¹ -NMR. The mole fraction of the substituent —O—Q ¹ —COOR ^{3 to be obtained} is. The branched mole fraction (xc + xd + xe) confirmed by Si-NMR measurement was 3%.

(Preparation Example 2-3: Preparation of electrolyte E-6)
50 g of tetramethoxysilane (4-1), 36.6 g of tetraethoxysilane (4-2), 13.1 g of glycolic acid (5-1) and 13.1 g of LiTFSI were mixed and heated to reflux at 150 ° C. for 1 hour. It was. After the reaction, the temperature was maintained at 150 ° C., and the volatile components were distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 58.9 g of colorless liquid (E-6).
The specific siloxane oligomer (Si-4) contained in the colorless liquid has a styrene-equivalent number average molecular weight of 620 by PC measurement and is contained in the partial structure represented by the general formula (1) measured by H ¹ -NMR. The contained mole fraction of the substituent —O—Q ¹ —COOR ³ was 37 mole%, and the branched mole fraction (xc + xd + xe) confirmed by Si-NMR measurement was 8%.
(Preparation Example 2-4: Preparation of electrolytic solution E-7)
40 g of tetraethoxysilane (4-2), 10.4 g of 2-cyanoethyltriethoxysilane (6-1), 6.57 g of glycolic acid (5-1), and 13.1 g of LiTFSI were mixed, and the mixture was stirred at 150 ° C. for 1 hour. Heated to reflux. After the reaction, the temperature was maintained at 150 ° C., and the volatile components were distilled off while gradually decreasing the degree of vacuum from normal pressure to 5 mmHg to obtain 29.0 g of colorless liquid (E-7).
The specific siloxane oligomer (Si-7) contained in the colorless liquid has a styrene-equivalent number average molecular weight of 750 by PC measurement, and is contained in the partial structure represented by the general formula (1) measured by H ¹ -NMR. The contained mole fraction of the substituent —O—Q ¹ —COOR ³ was 34 mole%, and the branched mole fraction (xc + xd + xe) confirmed by Si-NMR measurement was 11%.

[3. Preparation of electrolyte containing additive]
(Preparation Example 3-1: Preparation of Electrolytic Solution E-8)
Electrolytic solution E-8 was prepared by adding 5 wt% vinyl carbonate (VC) to the electrolytic solution E-6 obtained in the above (Preparation Example 2-1).
(Preparation Example 3-2: Preparation of electrolytic solution E-9)
To the electrolytic solution E-6 obtained in (Preparation Example 2-1), 5 wt% ethylene sulfite (ES) was added to the electrolytic solution to prepare an electrolytic solution E-9.
(Preparation Example 3-3: Preparation of electrolytic solution E-10)
10% by weight of ethyl phosphate (PE) was added to the electrolytic solution E-6 obtained in the above (Preparation Example 2-1) to prepare an electrolytic solution E-10.
(Preparation Example 3-4: Preparation of electrolytic solution E-12)
Electrolytic solution E-12 was prepared by adding 20 wt% trimethyl phosphate to electrolytic solution E-1 obtained in Preparation Example 1-1 above.
(Preparation Example 3-5: Preparation of electrolytic solution E-13)
To electrolyte solution E-1 obtained in (Preparation Example 1-1), 20 wt% of tris (2,2,2-trifluoroethyl) phosphate (A1) was added to the electrolyte solution to prepare electrolyte solution E-13. did.
(Preparation Example 3-6: Preparation of Electrolytic Solution E-14)
Electrolytic solution E-14 was prepared by adding 20 wt% of the phosphazene compound (A2) to electrolytic solution E-1 obtained in (Preparation Example 1-1) above.
(Preparation Example 3-7: Preparation of Electrolytic Solution E-15)
20% by weight of the phosphazene compound (A3) was added to the electrolytic solution E-1 obtained in the above (Preparation Example 1-1) to prepare an electrolytic solution E-15.
(Preparation Example 3-8: Preparation of electrolytic solution E-16)
20% by weight of the phosphonic acid ester compound (A4) was added to the electrolytic solution E-1 obtained in the above (Preparation Example 1-1) to prepare an electrolytic solution E-16.
(Preparation Example 3-9: Preparation of Electrolytic Solution E-17)
Electrolytic solution E-17 was prepared by adding 20 wt% of the phosphite compound (A5) to the electrolytic solution E-1 obtained in the above (Preparation Example 1-1).
(Adjustment Example 3-10: Adjustment of Electrolyte E-18)
An electrolytic solution E-18 was prepared in the same manner as the electrolytic solution E-1, except that (Si-8) was used as the specific silicon compound.
(Preparation Example 3-11: Preparation of electrolytic solution E-19)
To the electrolytic solution E-1 obtained in the above (Preparation Example 1-1), 50 wt% trimethyl phosphate was added to the electrolytic solution to prepare an electrolytic solution E-19.
(Preparation Example 3-12: Preparation of electrolytic solution E-20)
40% by weight of trimethyl phosphate was added to the electrolytic solution E-1 obtained in the above (Preparation Example 1-1) to prepare an electrolytic solution E-19.
(Preparation Example 3-13: Preparation of electrolytic solution E-20)
1% by weight of trimethyl phosphate was added to the electrolytic solution E-1 obtained in the above (Preparation Example 1-1) to prepare an electrolytic solution E-21.

[4. Preparation of mixed electrolyte with organic solvent]
(Preparation Example: 4-1 Preparation of Electrolytic Solution E-11)
3 g of the oligomer (Si-1) synthesized in (Preparation Example 1-1) above and a solution obtained by dissolving 0.32 g of LiPF _{6 in} 0.6 g of propylene carbonate were mixed to prepare an electrolytic solution E-11. did.

[5. Preparation of comparative electrolyte
(Preparation Example 5-1: Preparation of Comparative Electrolyte RE-1)
Electrolyte composition (SiE-3) described in Example 3 of JP-A-2002-252030
The average molecular weight of the polysiloxane synthesized according to Example 1 of JP-A-2002-252030 was 5,300, and the branched mole fraction (xc + xd + xe) confirmed by Si-NMR measurement was 35%. Although the polysiloxane synthesized according to Example 1 of JP-A-2002-252030 contains the following partial structure (A-1), the number average molecular weight in terms of styrene by GPC measurement is outside the scope of the present invention.
The electrolytic solution prepared according to Example 3 of JP-A-2002-252030 was designated as RE-1.

(Preparation Example 5-2: Preparation of comparative electrolytic solution RE-2)
JP, 2002-252030, A polysiloxane synthesized according to Example 1 and 0.6 g of propylene carbonate were mixed with 0.32 g of LiPF ₆ to prepare an electrolytic solution RE-2. The polysiloxane used in the comparative electrolyte RE-2 is the same compound as that used in the comparative electrolyte RE-1, and is a compound whose styrene-equivalent number average molecular weight by GPC measurement is outside the scope of the present invention.
(Preparation Example 5-3: Preparation of comparative electrolyte RE-3)
0.96 g of LiTFSI was dissolved in 3 g of siloxane compound (15) described in JP-A-2005-154697 (the following structure, molecular weight: 630.96) to prepare a comparative electrolyte RE-3. The following siloxane compound (15) is a monomer as apparent from the structure, and is not included in the siloxane oligomer used in the present invention.

(Preparation Example 5-4: Preparation of Comparative Electrolyte RE-4)
A comparative electrolyte RE-4 was prepared by mixing 3 g of the siloxane compound (15) described in JP-A-2005-154697, 0.6 g of propylene carbonate, and 0.32 g of LiPF ₆ . The siloxane compound used in the comparative electrolytic solution RE-4 is the same compound as that used in the comparative electrolytic solution RE-3 and is out of the scope of the present invention.

[Characteristic evaluation of electrolyte]
The ionic conductivity and transport number of the electrolyte solutions of Examples 1 to 21 and Comparative Examples 1 to 4 were measured.
(Ion conductivity measurement)
Using a cell in which a Teflon (registered trademark) spacer (6 mmφ hole) with a thickness of 250 μm was sandwiched between two stainless steel plates, it was determined by an AC impedance method at 30 ° C.
(Transport rate measurement)
It was determined by the method described in the literature (James Evans, Colin A. Vincent, Peter G. Bruce, Polymer, Volume 28, Issue 13, 1987, Pages 2324-2328).
(Flame retardancy test)
The evaluation of the flame resistance of the electrolyte was performed by a method based on the UL94HB method of the UL (Underwriting Laboratory) standard, which is a polymer flame retardancy test standard.
Specifically, a nonflammable glass fiber filter paper is cut into a size of 13 mm × 125 mm, 1.5 mL of an electrolytic solution to be evaluated is soaked, a test sample (test piece) is adjusted, and 25 mm and 100 mm from the end. A marked line was drawn and ignited with a gas burner having a test flame height of 20 mm from the end on the 25 mm surface side. The state of combustion was observed visually, and flame retardancy was evaluated according to the following criteria.
(Evaluation criteria)
AA: When the combustion is stopped without reaching the 25 mm mark A: When the test flame is stopped at 25 mm to 100 mm or when the combustion time of 25 mm to 100 mm is 50 seconds or more B: The combustion time of 25 mm to 100 mm When it is 30 seconds or more and less than 50 seconds C: When the burning time of 25 mm to 100 mm is less than 30 seconds Ion conductivity, transport number measurement result, “Transport number × ion conductivity” which is an index of Li ion conductivity Table 1 below shows the results of evaluation of flame retardancy.

As is apparent from Table 1, the electrolytes E-1 to E-21 of Examples 1 to 21 are more lithium ion conductive (compared to the electrolytes RE-1 to RE-4 of Comparative Examples 1 to 4). (Ion conductivity x transport number) is high.
Compared with the siloxane oligomer electrolyte solution RE-1 having a similar structure, electrolyte solutions E-1 to E-7 containing a siloxane oligomer having a lower molecular weight and fewer branched chains have a slightly lower transport number, but have a lower ion conductivity. Since the improvement is great, the lithium ion conductivity that is the product is high. Also in the comparison between the electrolytic solution RE-2 (comparative example) and E-11 (the present invention) mixed with the PC solvent, the electrolytic solution E-11 of the present invention is the same as the electrolytic solution RE-2 (comparative example). On the other hand, although the transport number is a little low, the lithium ion conductivity tends to be high. Electrolyte solution RE-3 (Comparative Example) using a siloxane compound whose main component is an ethyleneoxy group has good ionic conductivity, but has a low transport number, and therefore its product lithium ion conductivity is low. I understand that.
In comparison between the electrolytic solution E-1 and the electrolytic solution E-18, it can be seen that higher ionic conductivity can be obtained when the specific siloxane oligomer does not have a ring structure in the molecule.
In addition, the electrolytic solutions E-1 to E-7 and the electrolytic solution E-11 (PC mixed system) of the present invention include electrolytic solutions RE-3 and RE-4 (polyethylene oxide-containing siloxane compounds linked with polyethyleneoxy groups). Compared with the PC mixed system), the ionic conductivity is equal to or less than that, but since the lithium ion transport number is high, it is understood that the lithium ion conductivity which is the product is high.
Furthermore, in the electrolytic solutions E-10 and E-12 to E-21 of the present invention, excellent flame retardancy is achieved by adding a phosphorus compound, and when the content of the phosphorus compound is large, flame retardancy is achieved. Although improved, the conductivity tends to decrease slightly, and if the amount added is small, the effect of flame retardancy is also small. Therefore, when the content of the total electrolyte is 5% to 40% by mass, the flame retardancy and conductivity It can be seen that the degree balance is particularly good.

[Examples 22 to 30, Comparative Examples 5 and 6]
[Lithium secondary battery]
Lithium cobaltate mixture sheet (electrode capacity 1.5 mAh / cm ² : aluminum foil base, 16 mmΦ) on the positive electrode, natural spherical graphite electrode sheet (electrode capacity 1.6 mAh / cm2: Cu foil base, 16 mmΦ) on the negative electrode, and separator Using a polypropylene porous film (thickness 25 μm, 24 mmΦ), a lithium secondary battery for evaluation using an electrolytic solution shown in Table 2 below was produced.
The battery was charged at a constant current of 3.02 mA until the battery voltage reached 4.2 V, and then charged at a constant voltage of 4.2 V until the current value reached 0.1 mA.
The lithium secondary battery cell was placed in a constant temperature bath at 60 ° C., and discharged at 0.6 mA corresponding to 0.2 C until the battery voltage dropped to 2.5V.
The above charge / discharge was repeated twice, and the second discharge efficiency (discharged electricity / charged electricity × 100%) was evaluated. The results are shown in Table 2.

As is apparent from Table 2, Cell-1 to Cell-9 using the electrolytic solution of the present invention having high lithium ion conductivity are compared with Cell-10 and Cell-11 using the electrolytic solution of the comparative example. The charge / discharge efficiency of the battery is high.
Further, as is clear from the above results, the electrolyte solution using the specific siloxane oligomer according to the present invention exhibits good battery characteristics without using a large amount of highly flammable organic solvent electrolyte solution. Even so, it is flame retardant and has an advantage that, for example, ignition to the electrolyte during battery runaway is suppressed.

The disclosures of Japanese application 2010-212519 and Japanese application 2011-086244 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

Contains a salt of a metal ion belonging to Group 1 or Group 2 of the Periodic Table, and a siloxane oligomer having a partial structure represented by the following general formula (1) and having a number average molecular weight of 500 to 1500 in terms of styrene. Electrolyte for non-aqueous secondary battery.

(In the general formula (1), R 1 represents a hydrocarbon group or —OR 2 , —OR 2 represents an alkoxy group, a halogenated alkoxy group, or a substituent represented by the following general formula (2); When -OR 2 represents an alkoxy group, R 2 represents an alkyl group, and when -OR 2 represents a halogenated alkoxy group, R 2 represents a halogenated alkyl group, provided that the general formula contained in the siloxane oligomer is The molar fraction of the substituent represented by the following general formula (2) with respect to the total molar amount of R 1 and —OR 2 in the entire partial structure represented by (1) is 5 mol% or more and 100 mol% or less. .)

(In the general formula (2), Q 1 represents an alkylene group, and R 3 represents an alkyl group.)
The siloxane oligomer is selected from the group consisting of the following general formula (1-a), general formula (1-b), general formula (1-c), general formula (1-d), and general formula (1-e). Including a selected partial structure, and the following general formula (1-a), general formula (1-b), general formula (1-c), general formula (1-d), and general formula (1-e) ), The total amount of xa + xb is 70 mol% with respect to the total amount of all the partial structures contained in the siloxane oligomer, where xa, xb, xc, xd and xe are the mole fractions of the partial structures represented by The electrolyte solution for a non-aqueous secondary battery according to claim 1, which is a siloxane oligomer having a content of 100 mol% or less.

(In the general formula (1-a) to the general formula (1-e), * and ** are linking sites with other partial structures, and the general formula (1-a) to the general formula (1-e When the partial structures represented by) are linked, they are linked at the position of ** and * .R 1 and R 2 are respectively synonymous with R 1 and R 2 in the general formula (1).
2. The R 1 in the partial structure represented by the general formula (1) is a methyl group or —OR 2 , and —OR 2 is an ethoxy group or a group represented by the following general formula (3). Or the electrolyte solution for non-aqueous secondary batteries of Claim 2.

(In the general formula (3), R 3 represents an alkyl group, R 4 and R 5 each independently represents an alkyl group or a hydrogen atom, and R 4 and R 5 are linked to each other to form a ring. May be.)
In the partial structure represented by the general formula (1) contained in the siloxane oligomer, —OR 2 is a substituent represented by the general formula (2), and in the general formula (1) contained in the siloxane oligomer, The mole fraction of the substituent represented by the general formula (2) with respect to the total molar amount of R 1 and —OR 2 in the entire partial structure represented is from 30 mol% to 75 mol%. Item 4. The electrolyte solution for a non-aqueous secondary battery according to any one of Items 3.
In the general formula (1), R 1 is a linear or branched hydrocarbon group, and —OR 2 is a linear or branched alkoxy group, a linear or branched halogenated alkoxy group, or the general formula The substituent represented by (2), wherein Q 1 in the general formula (2) represents a linear or branched alkylene group, and R 3 represents a linear or branched alkyl group. 5. The electrolyte solution for a non-aqueous secondary battery according to any one of 4.
The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 5, wherein a content of the siloxane oligomer with respect to the total electrolyte solution is 20% by mass or more and 80% by mass or less.
The electrolyte for a non-aqueous secondary battery according to any one of claims 1 to 6, wherein the salt of a metal ion belonging to Group 1 or Group 2 of the periodic table is a lithium salt.
The electrolyte solution for a non-aqueous secondary battery according to any one of claims 1 to 7, further comprising a non-aqueous organic solvent.
The siloxane oligomer is obtained by synthesizing the siloxane oligomer using an alkoxysilane compound and a hydroxycarboxylic acid in the presence of a salt of a metal ion belonging to Group 1 or Group 2 of the Periodic Table. The electrolyte solution for nonaqueous secondary batteries of any one of 8.
Furthermore, the electrolyte solution for non-aqueous secondary batteries of any one of Claim 1 to 9 containing a phosphorus compound.
The electrolyte solution for a non-aqueous secondary battery according to claim 10, wherein the phosphorus compound is at least one selected from the group consisting of a phosphate ester compound, a phosphazene compound, a phosphonate ester compound, and a phosphite compound.
The electrolyte solution for a non-aqueous secondary battery according to claim 11, wherein the phosphate ester compound is a compound represented by the following general formula (p1).

In the general formula (p1), Rp 11 , Rp 12 , and Rp 13 each independently represents an alkyl group or an aryl group.
The electrolyte solution for a non-aqueous secondary battery according to claim 11, wherein the phosphazene compound is a compound having a partial structure represented by the following general formula (p2).

In the general formula (p2), Rp 21 and Rp 22 each independently represent a halogen atom, an alkoxy group, or an aryloxy group. n p 2 represents an integer of 1 or more.
The electrolyte solution for a non-aqueous secondary battery according to claim 11, wherein the phosphonic acid ester compound is a compound represented by the following general formula (p3).

In the general formula (p3), Rp 31 , Rp 32 , and Rp 33 each independently represents an alkyl group or an aryl group.
The electrolyte solution for a non-aqueous secondary battery according to claim 11, wherein the phosphite compound is a compound represented by the following general formula (p4).

In the general formula (p4), Rp 41 , Rp 42 , and Rp 43 each independently represents an alkyl group or an aryl group.
The electrolyte solution for a non-aqueous secondary battery according to any one of claims 10 to 15, wherein a content of the phosphorus compound with respect to the total electrolyte solution is 5 mass% or more and 40 mass% or less.
The electrolyte for a non-aqueous secondary battery according to any one of claims 1 to 16, a positive electrode capable of inserting and releasing lithium ions, and a negative electrode capable of inserting and releasing lithium ions and dissolution and precipitation. A lithium secondary battery provided.