JP2015072867A - Method of manufacturing lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a lithium ion secondary battery which has a high cycle life even in the case of having a positive electrode including a positive electrode active material and operated with a high voltage.SOLUTION: A method of manufacturing a lithium ion secondary battery comprises: a step for enclosing, in a case, an electrolytic solution containing a compound (A), a positive electrode having a discharge capacity of 10 mAh/g or larger at a potential of 4.4 V(vsLi/Li) or higher and a negative electrode and then, tentatively sealing the case; a formation step after the tentatively sealing step; and a degassing step to be performed after the formation step. In the method, the compound (A) consists of an oxo acid selected from a proton acid having phosphorus and boron, a sulfonic acid and a carboxylic acid, provided that a hydrogen atom of the oxo acid is substituted with a substituent group expressed by the formula (1) below. (In the formula (1), R1, R2 and R3 independently represent an organic group having 1-10 carbon atoms.)

Description

  The present invention relates to a method for manufacturing a lithium ion secondary battery.

  With the recent development of electronic technology and increasing interest in environmental technology, various electrochemical devices are used. In particular, as the demand for energy savings increases, expectations for electrochemical devices that can contribute to this increase. Conventionally, lithium ion secondary batteries, which are representative examples of power storage devices, have been mainly used as rechargeable batteries for portable devices, but in recent years, they are also expected to be used as batteries for hybrid vehicles and electric vehicles.

In such a trend, a higher energy density is required for the lithium ion secondary battery, and in order to achieve the higher energy density, higher voltage of the battery is also being studied. In order to achieve a higher voltage of the battery, it is necessary to use a positive electrode that operates at a high voltage. Specifically, various positive electrode active materials that operate at 4.4 V (vsLi / Li ⁺ ) or higher have been proposed. (For example, refer to Patent Document 1).

  In a conventional lithium ion secondary battery that operates at a voltage of about 4 V, a nonaqueous electrolytic solution in which a lithium salt is dissolved in a nonaqueous solvent mainly composed of a carbonate-based solvent is widely used (for example, Patent Document 2). reference). The electrolytic solution containing such a carbonate-based solvent is excellent in the balance between oxidation resistance and reduction resistance and excellent in lithium ion conductivity under a voltage of about 4V.

  In addition, various methods for manufacturing a power storage element have been proposed, and a method for manufacturing a power storage element in which gas generated in the storage case during the manufacturing process is discharged to the outside of the storage case by a degassing process has been proposed. (For example, refer to Patent Document 3).

JP 2000-515672 A JP-A-7-006786 JP 2007-141774 A

However, in a high voltage lithium ion secondary battery including a positive electrode containing a positive electrode active material that operates at a high voltage of 4.4 V (vs Li / Li ⁺ ) or higher, a carbonate-based solvent contained in the electrolyte is a positive electrode. There arises a problem that the cycle life of the battery is reduced due to oxidative decomposition on the surface. In Patent Document 3, a degassing step is performed after the conditioning step or the aging step, but a high-voltage lithium ion secondary having a positive electrode containing a positive electrode active material that operates at 4.4 V (vsLi / Li ⁺ ) or higher. The battery is not mentioned, and the countermeasure against the oxidative decomposition that occurs on the positive electrode surface is unknown. No solution for cycle life reduction due to oxidative decomposition is shown, and an electrolyte that improves the cycle life of the high-voltage lithium ion secondary battery and a lithium ion secondary battery including the same are desired. .

The present invention has been made in view of the above problems, and a lithium ion secondary battery having a high cycle life even when a positive electrode containing a positive electrode active material operating at 4.4 V (vsLi / Li ⁺ ) or higher is provided. It aims at providing the manufacturing method of.

  As a result of intensive studies to achieve the above object, the present inventors made a battery using a non-aqueous solvent and an electrolytic solution containing a silicon-containing phosphate compound having a specific structure, and after charging that satisfies a certain condition By degassing, it was found that a lithium ion secondary battery having a high cycle life can be achieved, and the present invention has been completed.

That is, the present invention is as follows.
[1]
A positive electrode containing a positive electrode active material;
A negative electrode containing a negative electrode active material;
An electrolyte containing a non-aqueous solvent and a lithium salt;
A method for producing a lithium ion secondary battery comprising:
In the electrolytic solution, at least one hydrogen atom of an oxo acid selected from a proton acid, a sulfonic acid, and a carboxylic acid having a phosphorus atom and / or a boron atom is substituted with a substituent represented by the following formula (1) An electrolytic solution containing the prepared compound (A), the positive electrode having a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vs Li / Li ⁺ ) or more, and the negative electrode in a housing case. Storing and temporarily sealing the storage case;
(In formula (1), R1, R2 and R3 each independently represents an organic group having 1 to 10 carbon atoms.)
A formation process performed after the temporary sealing process;
A degassing step performed after the formation step;
A method for producing a lithium ion secondary battery, comprising:
[2]
The manufacturing method of the lithium ion secondary battery as described in [1] whose content of the said compound (A) is 0.01 mass% or more and 10 mass% or less with respect to the said electrolyte solution.
[3]
The method for producing a lithium ion secondary battery according to [1], wherein the compound (A) includes a compound represented by the following formula (2).
(In the formula (2), n represents an integer of 0 or 1, and R4 and R5 each independently represents an OH group, an OLi group, an optionally substituted alkyl group having 1 to 10 carbon atoms, or a substituted group. A good 1 to 10 alkoxy group and a siloxy group having 3 to 10 carbon atoms.)
[4]
The method for producing a lithium ion secondary battery according to [1] or [2], wherein the compound represented by the formula (2) contains tris (trimethylsilyl) phosphate.
[5]
The aging step is a step of charging 50% or more of the full charge capacity at a current value of 0.3 C or less, and then storing it at 35 to 60 ° C. for 5 to 10 days, [1] The manufacturing method of the lithium ion secondary battery of description.
[6]
The method for producing a lithium ion secondary battery according to [1], wherein the degassing step is a step of evacuating the storage space to −100 kPa or more and −30 kPa or less by evacuation through the opened sealing portion to seal the opening. .
[7]
The positive electrode active material has the following general formula (1):
_{LiMn 2-x Ma x O 4} (1)
(In the formula, Ma represents one or more selected from the group consisting of transition metals, and 0.2 ≦ x ≦ 0.7.)
A compound represented by the following general formula (6):
LiMO ₂ (6)
(In the formula, M represents one or more selected from transition metals and Al.)
A compound represented by the following general formula (2A):
Li ₂ McO ₃ (2A)
(In the formula, Mc represents one or more selected from the group consisting of transition metals.)
And the following general formula (2B):
LiMdO ₂ (2B)
(In the formula, Md represents one or more selected from the group consisting of transition metals.)
A composite oxide with an oxide represented by the following general formula (2):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (2)
(In the formula, Mc and Md are synonymous with Mc and Md in the general formulas (2A) and (2B), respectively, and 0.1 ≦ z ≦ 0.9.)
A compound represented by the following general formula (3):
LiMb _1-y Fe _y PO ₄ (3)
(In the formula, Mb represents one or more selected from the group consisting of Mn and Co, and 0 ≦ y ≦ 0.9.)
And the following general formula (4):
Li ₂ MePO ₄ F (4)
(In the formula, Me represents one or more selected from the group consisting of transition metals.)
The manufacturing method of the lithium ion secondary battery in any one of [1]-[3] containing 1 or more types chosen from the group which consists of a compound represented by these.

  According to the method for manufacturing a lithium ion secondary battery according to the present invention, it is possible to manufacture a lithium ion secondary battery that can operate even at a high voltage and has a high cycle life.

It is sectional drawing which shows roughly an example of the lithium ion secondary battery in this embodiment.

  Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof. The positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

A method for manufacturing a lithium ion secondary battery according to the present embodiment includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and an electrolyte containing a nonaqueous solvent and a lithium salt. This is a method for manufacturing a secondary battery. Furthermore, the method for producing a lithium ion secondary battery according to the present embodiment is the electrolytic solution, wherein at least one hydrogen atom of an oxo acid selected from a proton acid, a sulfonic acid, and a carboxylic acid having a phosphorus atom and a boron atom. An electrolyte containing the compound (A) substituted with a substituent represented by the following formula (1), and the positive electrode, and a discharge of 10 mAh / g or more at a potential of 4.4 V (vs Li / Li ⁺ ) or more Storing a positive electrode having a capacity and the negative electrode in a storage case, and temporarily sealing the storage case;
(In formula (1), R1, R2, and R3 each independently represents an organic group having 1 to 10 carbon atoms.) Performed after the temporary sealing step and after the formation step. And a degassing step. Since it is comprised in this way, according to the manufacturing method of the lithium ion secondary battery of this embodiment, the lithium ion secondary battery which can be operated even at a high voltage and has a high cycle life can be manufactured.

  In this embodiment, a lithium ion secondary battery (hereinafter also simply referred to as “battery”) contains a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a nonaqueous solvent, and a lithium salt. An electrolyte solution. Hereafter, each said material used for the manufacturing method of the lithium ion secondary battery of this embodiment is demonstrated in detail.

  The nonaqueous solvent used in the electrolytic solution in the present embodiment is not particularly limited, and various solvents can be used. For example, an aprotic polar solvent is preferable. Specific examples thereof include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, trifluoromethylethylene carbonate, fluoroethylene. Cyclic carbonates such as carbonate and 4,5-difluoroethylene carbonate; lactones such as γ-butyrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl Propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate, Chain carbonates such as tilpropyl carbonate and methyl trifluoroethyl carbonate; Nitriles such as acetonitrile; Chain ethers such as dimethyl ether; Chain carboxylic acid esters such as methyl propionate; Chain ether carbonate compounds such as dimethoxyethane . These can be used individually by 1 type or in combination of 2 or more types.

  As the non-aqueous solvent in the present embodiment, it is more preferable to use a carbonate-based solvent such as a cyclic carbonate or a chain carbonate from the viewpoint of ion conductivity. Further, it is more preferable to use a combination of a cyclic carbonate and a chain carbonate as the carbonate solvent. Although it does not specifically limit as a cyclic carbonate and various things can be used, For example, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate are preferable, and ethylene carbonate and propylene carbonate are more preferable. The chain carbonate is not particularly limited, and various types can be used. For example, ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate are preferable.

  When the carbonate-based solvent in the present embodiment includes a combination of a cyclic carbonate and a chain carbonate, the mixing ratio of the cyclic carbonate and the chain carbonate is 1:10 to 5: 1 in terms of volume ratio from the viewpoint of ion conductivity. It is preferable that the ratio is 1: 5 to 3: 1.

  In the case of using the carbonate-based solvent in the present embodiment, another nonaqueous solvent such as acetonitrile or sulfolane can be further added as necessary from the viewpoint of improving the physical properties of the battery.

The electrolytic solution in the present embodiment contains a lithium salt. The electrolyte solution content of the lithium salt is preferably 1% by mass or more from the viewpoint of ion conductivity, and preferably 40% by mass or less from the viewpoint of solubility at low temperatures. The lithium salt content is more preferably 5% by mass or more and 35% by mass or less, and further preferably 7% by mass or more and 30% by mass or less. Note that the content of the lithium salt in the electrolyte solution included in the lithium ion secondary battery according to the present embodiment is based on the elements included in the lithium salt, such as ¹⁹ F-NMR, ³¹ P-NMR, etc. This can be confirmed by performing NMR measurement.

The structure of the lithium salt in the present embodiment is not particularly limited, but from the viewpoint of ionic conductivity, LiPF ₆ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{2k + 1} (k Is an integer of 1 to 8), LiN (SO ₂ C _k F _{2k + 1} ) ₂ [k is an integer of 1 to 8], LiPF _n (C _k F _{2k + 1} ) _6-n [n is 1 to 5 Integer, k is an integer of 1 to 8], LiPF ₄ (C ₂ O ₂ ) ₂ , LiPF ₂ (C ₂ O ₂ ) ₂ , and more preferably LiPF ₆ . These electrolytes can be used singly or in combination of two or more.

  In the electrolytic solution in the present embodiment, at least one hydrogen atom of an oxo acid selected from proton acid, sulfonic acid, and carboxylic acid having a phosphorus atom and / or a boron atom is substituted with a structure represented by the following formula (3). Containing the compound (A).

(In Formula (3), R1, R2, and R3 each independently represents an organic group having 1 to 10 carbon atoms.)

  In the electrolytic solution in the present embodiment, the protonic acid having a phosphorus atom may be a compound having a phosphorus atom in the molecule and a hydrogen atom that can be dissociated as a proton. In addition to halogen atoms such as atoms, organic groups such as alkoxy groups and alkyl groups, hetero atoms such as Si, B, O, and N may be contained. Further, a plurality of phosphorus atoms may be contained in the molecule like polyphosphoric acid. Preferred examples of the protonic acid having a phosphorus atom include phosphoric acid, phosphorous acid, pyrophosphoric acid, polyphosphoric acid, and phosphonic acid. Among these, phosphoric acid, phosphorous acid, and phosphonic acid are more preferable from the viewpoint of the stability of the compound (A). These protonic acids may be substituted.

  In the electrolytic solution in the present embodiment, the proton acid having a boron atom may be a compound having a boron atom in the molecule and a hydrogen atom that can be dissociated as a proton. In addition to halogen atoms such as atoms, organic groups such as alkoxy groups and alkyl groups, hetero atoms such as Si, P, O, and N may be contained. Further, a plurality of boron atoms may be contained in the molecule. Preferred examples of the protonic acid having a boron atom include boric acid, boronic acid, and borinic acid. These protonic acids may be substituted.

In the electrolytic solution in the present embodiment, the sulfonic acid is a compound having a —SO ₃ H group (sulfonic acid group) in the molecule, and may have a plurality of sulfonic acid groups in the molecule. In the present embodiment, sulfuric acid (HOSO ₃ H) may be included. Although not particularly limited, preferred examples include methylsulfonic acid, ethylsulfonic acid, propylsulfonic acid, 1,2 ethanedisulfonic acid, trifluoromethylsulfonic acid, phenylsulfonic acid, benzylsulfonic acid, and sulfuric acid. .

In the electrolytic solution in the present embodiment, the carboxylic acid is a compound having a CO ₂ H group (carboxylic acid group) in the molecule, and may have a plurality of carboxylic acid groups in the molecule. Although it does not specifically limit as carboxylic acid, For example, acetic acid, trifluoroacetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, methacrylic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, phthalic acid, isophthalic acid, Examples include terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, and itaconic acid. From the viewpoint of improving battery performance, preferred are dicarboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, malonic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, itaconic acid, and more preferred. Adipic acid, itaconic acid, succinic acid, isophthalic acid, terephthalic acid.

The electrolytic solution in the present embodiment contains a compound (A) in which at least one hydrogen atom of the oxo acid is substituted with a structure represented by the formula (3). Here, in the structure represented by the formula (3), R1, R2, and R3 each independently represents an organic group (hydrocarbon group) having 1 to 10 carbon atoms. In addition to hydrogen groups, aromatic hydrocarbon groups such as phenyl groups are also included. Further, a fluorine-substituted hydrocarbon group such as a trifluoromethyl group in which all hydrogen atoms in the hydrocarbon group are substituted with fluorine atoms is also included. Further, if necessary, halogen atoms such as fluorine atom, chlorine atom, bromine atom, nitrile group (—CN), ether group (—O—), carbonate group (—OCO ₂ —), ester group (—CO _2- ), carbonyl group (—CO—) sulfide group (—S—), sulfoxide group (—SO—), sulfone group (—SO ₂ —), urethane group (—NHCO ₂ —) are introduced. be able to.

  Preferable examples of R1, R2, and R3 in the present embodiment include aliphatic hydrocarbon groups such as methyl group, ethyl group, vinyl group, 1-methylvinyl group, propyl group, butyl group, and fluoromethyl group; benzyl group, Aromatic hydrocarbon groups such as a phenyl group, a nitrile-substituted phenyl group, and a fluorinated phenyl group can be mentioned. Among these, a methyl group, an ethyl group, a vinyl group, a 1-methylvinyl group, and a fluoromethyl group are more preferable from the viewpoint of chemical stability. Two Rs may be bonded to form a ring. Although it does not specifically limit, In order to form a ring, the example substituted by the substituted or unsubstituted saturated or unsaturated alkylene group is mentioned, for example.

  In the present embodiment, R1, R2, and R3 each independently represent an organic group (hydrocarbon group) having 1 to 10 carbon atoms. From the viewpoint of miscibility with a non-aqueous solvent, carbons R1, R2, and R3 The number is preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms.

From the viewpoint of chemical durability in the lithium ion secondary battery, the structure represented by the formula (3) includes —Si (CH ₃ ) ₃ , —Si (C ₂ H ₅ ) ₃ , —Si (CHCH). ₂ ) ₃ , —Si (CH ₂ CHCH ₂ ) ₃ , —Si (CF ₃ ) ₃ are more preferable, and —Si (CH ₃ ) ₃ is most preferable.

  The electrolytic solution in the present embodiment is characterized by containing a compound (A) in which at least one hydrogen atom of an oxo acid is substituted with a structure represented by the formula (3). Here, when the oxo acid has a plurality of hydrogen atoms, it is sufficient that at least one hydrogen atom is substituted with the structure represented by the formula (3). Further, the remaining hydrogen atoms not substituted by the formula (3) may exist as they are, or may be substituted by a functional group other than the structure represented by the formula (3). As such a functional group, a halogen-substituted or unsubstituted saturated or unsaturated C1-C20 hydrocarbon group can be mentioned preferably, for example. The halogen-substituted or unsubstituted saturated or unsaturated hydrocarbon group is not particularly limited, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, an allyl group, and a vinyl group. Two hydrogen atom substituents may be bonded to form a ring. Although it does not specifically limit, In order to form a ring, the example substituted by a substituted or unsubstituted saturated or unsaturated alkylene group is mentioned, for example.

  With respect to the electrolytic solution in the present embodiment, as a compound (A) in which at least one hydrogen atom of the oxo acid is substituted with a structure represented by the formula (3), the following formula (4) and / or the following formula (5): It is preferable that it is a compound represented.

(In Formula (4), M represents a P atom or a B atom. When M is a B atom, n is 0, and when M is a P atom, n represents an integer of 0 or 1. R1, R2, R3 Each independently represents an organic group having 1 to 10 carbon atoms, R4 and R5 each independently represents an OH group, an OLi group, an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted carbon group. An alkoxy group having 1 to 10 carbon atoms and a siloxy group having 3 to 10 carbon atoms;

(In Formula (5), R1, R2, and R3 each independently represents an organic group having 1 to 10 carbon atoms. R6 represents an optionally substituted organic group having 1 to 20 carbon atoms.)

  As described above, in the compound (A) represented by the formula (4), M represents a P atom or a B atom, n is 0 when M is a B atom, and n is 0 or M when M is a P atom. An integer of 1 is shown. That is, in Formula (4), when M is a B atom and n is 0, the compound (A) has a boric acid structure, and when M is a P atom and n is 0, the compound (A) has a phosphorous acid structure. When M is a P atom and n is 1, the compound (A) has a phosphoric acid structure. From the viewpoint of the stability of the electrolytic solution containing the compound (A), a structure of the following formula (6) in which M is a P atom is more preferable.

(In Formula (6), R1, R2, and R3 each independently represent an organic group having 1 to 10 carbon atoms. R4 and R5 each independently represent an OH group, an OLi group, or an optionally substituted carbon number of 1). To an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms that may be substituted, and a siloxy group having 3 to 10 carbon atoms.)

Regarding the compound (A) represented by the formula (4), the alkyl group has a structure in which a carbon atom is directly bonded to an M atom, and is not particularly limited, but the alkyl group is not limited to an aliphatic group. Further, a structure having an aromatic ring such as a phenyl group or a benzyl group may be used. Further, fluorine-substituted hydrocarbon groups such as a trifluoromethyl group in which all hydrogen atoms in the alkyl group are substituted with fluorine atoms are also included. The alkyl group may be substituted with various functional groups. If necessary, a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom, a nitrile group (—CN), an ether group (—O—) , Carbonate group (—OCO ₂ —), ester group (—CO ₂ —), carbonyl group (—CO—) sulfide group (—S—), sulfoxide group (—SO—), sulfone group (—SO ₂ —) And a functional group such as a urethane group (—NHCO ₂ —) can be introduced.

  Preferred examples of the alkyl group represented by R4 and R5 in the formula (4) include a methyl group, an ethyl group, a vinyl group, an allyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and a fluorohexyl group. Aromatic alkyl groups such as aliphatic alkyl groups, benzyl groups, phenyl groups, nitrile-substituted phenyl groups, fluorinated phenyl groups and the like can be mentioned. Of these, methyl, ethyl, allyl, propyl, butyl, pentyl, hexyl, and fluorohexyl are more preferred from the viewpoint of chemical stability. The carbon number of the alkyl group is 1 to 10, 1 or more from the viewpoint of improving battery performance, and 10 or less from the viewpoint of affinity with the electrolytic solution. The carbon number of the alkyl group is preferably 2 or more and 10 or less, more preferably 3 or more and 8 or less.

Regarding the compound (A) represented by the formula (4), the alkoxy group shows a structure in which a carbon atom is bonded to an M atom via an oxygen atom, and is not particularly limited. A structure having an aromatic ring such as a phenoxy group and a benzylalkoxy group as well as a group may be used. Further, fluorine-substituted alkoxy groups such as a trifluoroethyl group or a hexafluoroisopropyl group in which a hydrogen atom in the alkoxy group is fluorine-substituted are also included. The alkoxy group may be substituted with various functional groups. If necessary, a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, a nitrile group (—CN), an ether group (—O—) , Carbonate group (—OCO ₂ —), ester group (—CO ₂ —), carbonyl group (—CO—) sulfide group (—S—), sulfoxide group (—SO—), sulfone group (—SO ₂ —) And a functional group such as a urethane group (—NHCO ₂ —) can be introduced.

  Preferred examples of the alkoxy group represented by R4 and R5 in the formula (4) include a methoxy group, an ethoxy group, a vinyloxy group, an allyloxy group, a propoxy group, a butoxy group, a cyanohydroxy group, a fluoroethoxy group, and a fluoropropoxy group. And an aromatic alkoxy group such as an aliphatic alkoxy group such as phenoxy group, benzylalkoxy group, nitrile substituted phenoxy group, and fluorinated phenoxy group. Of these, from the viewpoint of chemical stability, a methoxy group, an ethoxy group, a vinyloxy group, an allyloxy group, a propoxy group, a butoxy group, a cyanohydroxy group, a fluoroethoxy group, and a fluoropropoxy group are more preferable. The alkoxy group has 1 to 10 carbon atoms, 1 or more from the viewpoint of improving battery performance, and 10 or less from the viewpoint of affinity with the electrolytic solution. The number of carbon atoms of the alkoxy group is preferably 1 or more and 8 or less, more preferably 2 or more and 8 or less.

  Regarding the compound (A) represented by the formula (4), the siloxy group shows a structure in which a silicon atom is bonded to an M atom through an oxygen atom, and is not particularly limited. A siloxane structure such as —O—Si— may be included. Preferred examples of the siloxy group include trimethylsiloxy group, triethylsiloxy group, dimethylethylsiloxy group, and diethylmethylsiloxy group from the viewpoint of chemical stability. More preferably, it is a trimethylsiloxy group. The siloxy group has 3 to 10 carbon atoms, 1 or more from the viewpoint of improving battery performance, and 10 or less from the viewpoint of chemical stability. The siloxy group preferably has 3 to 8 carbon atoms, more preferably 3 to 6 carbon atoms. Further, the number of silicon in the siloxy group is not particularly limited, but from the viewpoint of improving chemical stability and battery performance, the number of silicon atoms in the siloxy group is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less. Particularly preferably, it is 1 or more and 2 or less, and most preferably 1.

  In the compound (A) represented by the formula (4), R4 and R5 are each independently a hydroxyl group, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted carbon group having 1 to 10 carbon atoms. An alkoxy group and a siloxy group having 3 to 10 carbon atoms are shown. From the viewpoint of solubility in an electrolytic solution, preferably an alkyl group having 1 to 10 carbon atoms which may be substituted, and 1 carbon atom which may be substituted. To an alkoxy group having 3 to 10 carbon atoms and a siloxy group having 3 to 10 carbon atoms. More preferably, at least one of R4 and R5 has a functional group selected from an optionally substituted alkoxy group having 1 to 10 carbon atoms and a siloxy group having 3 to 10 carbon atoms.

  In the compound (A) represented by the formula (4), R1, R2, and R3 each independently represent a hydrocarbon group having 1 to 10 carbon atoms, and preferred structures of R1, R2, and R3 are those described above. This is the same as the preferred structure of R1, R2, and R3 in the structure represented by (3).

In the compound (A) represented by the formula (5), R6 represents an optionally substituted hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbon group includes not only an aliphatic hydrocarbon group. An aromatic hydrocarbon group such as a phenyl group is also included. Further, a fluorine-substituted hydrocarbon group such as a trifluoromethyl group in which all hydrogen atoms in the hydrocarbon group are substituted with fluorine atoms is also included. Further, if necessary, halogen atoms such as fluorine atom, chlorine atom, bromine atom, nitrile group (—CN), ether group (—O—), carbonate group (—OCO ₂ —), ester group (—CO _2- ), carbonyl group (—CO—) sulfide group (—S—), sulfoxide group (—SO—), sulfone group (—SO ₂ —), urethane group (—NHCO ₂ —) are introduced. be able to. Here, the carbon number of R6 is 1 to 20, but is preferably 1 or more and 16 or less, more preferably 1 or more and 14 or less, from the viewpoint of miscibility with the nonaqueous solvent.

  Further, R6 can preferably have a structure represented by the following formula (7). In this case, the basic skeleton of the compound (A) has a dicarboxylic acid derivative structure.

(In the formula (7), R7 represents an optionally substituted hydrocarbon group having 1 to 13 carbon atoms, and R8 represents an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, or may be substituted. (It represents a trialkylsilyl group having 3 to 6 carbon atoms.)

  In the formula (7), R7 is preferably a methylene group, an ethylene group, a propylene group, a butylene group, a phenyl group, a fluoromethylene group, a fluoroethylene group, a fluoropropylene group, from the viewpoint of the chemical stability of the compound (A). And a fluorobutylene group. In the formula (7), R8 is preferably a trialkylsilyl group such as a methyl group, an ethyl group, a vinyl group, an allyl group, a trimethylsilyl group, or a triethylsilyl group from the viewpoint of the chemical stability of the compound (A). Is mentioned. More preferred are trialkylsilyl groups such as trimethylsilyl group and triethylsilyl group. In particular, when R8 is a trialkylsilyl group, the compound (A) has a structure represented by the following formula (8).

(In Formula (8), R1, R2, and R3 each independently represents an organic group having 1 to 10 carbon atoms.)

  Preferable specific examples of the compound (A) contained in the electrolytic solution of this embodiment include tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, tris (triethylsilyl) phosphate, tetrakis pyrophosphate (trimethylsilyl) , Trimethylsilyl polyphosphate, di (trimethylsilyl) butylphosphonate, di (trimethylsilyl) propylphosphonate, di (trimethylsilyl) ethylphosphonate, di (trimethylsilyl) methylphosphonate, monomethyldi (trimethylsilyl) phosphate, monoethyldi (trimethylsilyl) phosphate, Mono (trifluoroethyl) diphosphate (trimethylsilyl) phosphate, mono (hexafluoroisopropyl) di (trimethylsilyl) phosphate, tris (trimethylsilyl) borate, di (trimethylsilyl sulfate) , Trimethylsilyl acetate, di (trimethylsilyl) oxalate, di (trimethylsilyl) malonate, di (trimethylsilyl) succinate, di (trimethylsilyl) itaconate, di (trimethylsilyl) adipate, di (trimethylsilyl) phthalate, di (trimethylsilyl) phthalate Trimethylsilyl) and di (trimethylsilyl) terephthalate. Among them, from the viewpoint of cycle life and gas generation suppression, tris phosphate (trimethylsilyl), tris phosphite (trimethylsilyl), tetrakis pyrophosphate (trimethylsilyl), trimethylsilyl polyphosphate, dibutyl phosphonate (trimethylsilyl), dipropyl phosphophosphonate (Trimethylsilyl), ethylphosphonic acid di (trimethylsilyl), methylphosphonic acid di (trimethylsilyl), phosphoric acid monomethyldi (trimethylsilyl), phosphoric acid monoethyldi (trimethylsilyl), phosphoric acid mono (trifluoroethyl) di (trimethylsilyl), phosphoric acid mono ( More preferred are hexafluoroisopropyl) di (trimethylsilyl), di (trimethylsilyl) succinate, di (trimethylsilyl) itaconate, and di (trimethylsilyl) adipate. However, the compound (A) is not limited to the above.

It is preferable that the electrolyte solution in this embodiment contains 0.01 mass% or more and 10 mass% or less of compound (A) with respect to the electrolyte solution. From the viewpoint of obtaining a good cycle life in the lithium ion secondary battery, the content of the compound (A) is preferably 0.01% by mass or more, and preferably 10% by mass or less from the viewpoint of battery output. From the same viewpoint, the content of the compound (A) is more preferably 0.05% by mass to 10% by mass, further preferably 0.1% by mass to 8% by mass, and still more preferably 0.2% by mass. % To 5% by mass, particularly preferably 0.3% to 4% by mass. In addition, content of the said compound (A) in the electrolyte solution contained in the lithium ion secondary battery which concerns on this embodiment is based on the element contained in the said compound (A), for example, ¹ H-NMR, ¹¹ It can confirm by performing NMR measurement, such as B-NMR, < ¹³ > C-NMR, < ²⁹ > Si-NMR, < ³¹ > P-NMR.

  The positive electrode containing the positive electrode active material in the present embodiment is not particularly limited as long as it can reversibly occlude / release lithium ions as a positive electrode active material and acts as a positive electrode of a lithium ion secondary battery, and is a known one. Can be used. The positive electrode preferably contains at least one selected from the group consisting of materials capable of reversibly occluding and releasing lithium ions as a positive electrode active material.

In the present embodiment, a positive electrode containing a positive electrode active material having a discharge capacity of 10 mAh / g or higher at a potential of 4.4 V (vsLi / Li ⁺ ) or higher is employed from the viewpoint of obtaining a battery that develops a higher voltage. Even in the case where such a positive electrode is provided, according to the present embodiment, it is possible to obtain a battery that can not only speak a high voltage but also has excellent cycle life. Here, 4.4 V and a positive electrode active material having a 10 mAh / g or more discharge capacity (vsLi / Li ⁺⁾ or more potential, 4.4V (vsLi / Li ⁺⁾ of the lithium ion secondary battery or a potential It is a positive electrode active material capable of causing charge and discharge reactions as a positive electrode, and has a discharge capacity at a constant current discharge of 0.1 C of 10 mAh or more with respect to 1 g of mass of the active material. Thus, may be the positive electrode active material is only to have a 10 mAh / g or more discharge capacity 4.4V (vsLi / Li ⁺⁾ or more potential, 4.4V (vsLi / Li ⁺⁾ expression in the following potential It does not matter whether the discharge capacity is large or small.

The positive electrode active material having a discharge capacity of 10 mAh / g or higher at a potential of 4.4 V (vs Li / Li ⁺ ) or higher is not particularly limited, but from the viewpoint of the structural stability of the positive electrode active material, the following general formula is preferable. (1):
_{LiMn 2-x Ma x O 4} (1)
A spinel oxide which is a compound represented by the following general formula (6):
LiMO ₂ (6)
(In the formula, M represents one or more selected from transition metals and Al.)
A compound represented by the following general formula (2A):
Li ₂ McO ₃ (2A)
And a compound represented by the following general formula (2B):
LiMdO ₂ (2B)
A compound oxide represented by the following general formula (2):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (2)
Li-excess layered oxide positive electrode active material which is a compound represented by the following general formula (3):
LiMb _1-y Fe _y PO ₄ (3)
An olivine-type positive electrode active material that is a compound represented by the following general formula (4):
Li ₂ MePO ₄ F (4)
One or more positive electrode active materials selected from the group consisting of fluorinated olivine-type positive electrode active materials, which are compounds represented by:

  Here, in each of the above formulas, Ma represents one or more selected from the group consisting of transition metals, 0.2 ≦ x ≦ 0.7, and Mc and Md are each independently a group consisting of transition metals. One or more selected from the group consisting of 0.1 ≦ z ≦ 0.9, Mb represents one or more selected from the group consisting of Mn and Co, 0 ≦ y ≦ 0.9, and Me is 1 or more types chosen from the group which consists of transition metals are shown.

Although it does not specifically limit as a spinel type oxide which is a compound represented by the said General formula (1), From a viewpoint of stability, following General formula (1a):
LiMn _2-x Ni _x O ₄ (1a)
It is preferable that it is a compound represented by these. Here, 0.2 ≦ x ≦ 0.7. The compound represented by the general formula (1) is more preferably the following general formula (1b):
LiMn _2-x Ni _x O ₄ (1b)
(Where 0.3 ≦ x ≦ 0.6), and more preferably LiMn _1.5 Ni _0.5 O ₄ and LiMn _1.6 Ni _0.4 O ₄ . Here, the spinel oxide represented by the general formula (1) is within a range of 10 mol% or less with respect to the number of moles of Mn atoms from the viewpoint of stability of the positive electrode active material, electronic conductivity, and the like. In addition to the above structure, it may further contain a transition metal or a transition metal oxide. The compound represented by the general formula (1) can be used alone or in combination of two or more.

Although it does not specifically limit as an olivine type positive electrode active material which is a compound represented by the said General formula (3), From a viewpoint of stability and electronic conductivity, following General formula (3a):
LiMn _1-y Fe _y PO ₄ (3a)
And the following general formula (3b):
LiCo _1-y Fe _y PO ₄ (3b)
It is preferable that it is a compound represented by these. Here, in the formulas (3a) and (3b), 0.05 ≦ y ≦ 0.8, respectively. The compounds represented by the general formula (3) can be used singly or in combination of two or more.

The fluoride olivine-type positive electrode active material is a compound represented by the general formula (4) is not particularly limited, from the viewpoint of _{stability, Li 2 FePO 4 F, Li} 2 MnPO 4 F and Li ₂ CoPO ₄ F is preferred. The compound represented by the general formula (4) can be used alone or in combination of two or more.

Although it does not specifically limit as Li excess layered oxide positive electrode active material which is a compound represented by the said General formula (2), From a stability viewpoint, following General formula (2a):
_{zLi 2 MnO 3 - (1-} z) LiNi a Mn b Co c O 2 (2a)
It is preferable that it is a compound represented by these. Here, in the formula, 0.3 ≦ z ≦ 0.7, a + b + c = 1, 0.2 ≦ a ≦ 0.6, 0.2 ≦ b ≦ 0.6, 0.05 ≦ c ≦ 0.4 is there. Among them, in the above formula (2a), 0.4 ≦ z ≦ 0.6, a + b + c = 1, 0.3 ≦ a ≦ 0.4, 0.3 ≦ b ≦ 0.4, 0.2 ≦ c ≦ 0 More preferably, the compound is .3. The said positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

  The positive electrode active material in the present embodiment can be synthesized by the same method as a general inorganic oxide synthesis method, and the method is not particularly limited. For example, a positive electrode active material containing an inorganic oxide is obtained by firing a mixture in which a metal salt (for example, but not limited to, sulfate and / or nitrate) is mixed in a predetermined ratio in an atmosphere environment containing oxygen. be able to. Alternatively, a carbonate and / or hydroxide salt is allowed to act on a solution in which the metal salt is dissolved to precipitate a hardly soluble metal salt, which is extracted and separated into lithium carbonate and / or hydroxide as a lithium source. After mixing lithium, the positive electrode active material containing an inorganic oxide can be obtained by baking in an atmosphere environment containing oxygen.

The positive electrode active materials having a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vsLi / Li ⁺ ) or more can be used singly or in combination of two or more. Also, as the positive electrode active material, 4.4V (vsLi / Li ⁺⁾ and the positive electrode active material having a 10 mAh / g or more discharge capacity than the potential, 4.4V (vsLi / Li ⁺⁾ or more potential 10 mAh / g A positive electrode active material having no discharge capacity as described above can also be used in combination. The positive electrode active material that does not have a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vsLi / Li ⁺ ) or more is not particularly limited, and examples thereof include LiFePO ₄ .

A lithium ion secondary battery including a positive electrode containing a positive electrode active material having a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vsLi / Li ⁺ ) or more as described above has a positive electrode potential when fully charged. It is preferably 4.4 V (vsLi / Li ⁺ ) or higher. By setting the potential of the positive electrode at full charge to 4.4 V (vsLi / Li ⁺ ) or higher, the charge / discharge capacity of the positive electrode active material included in the lithium ion secondary battery of this embodiment can be efficiently utilized. Potential of full charge when the positive electrode from the viewpoint of improving the energy density of the lithium ion secondary battery, more preferably 4.45V (vsLi / Li ⁺⁾ or higher, more preferably 4.5V (vsLi / Li ⁺⁾ or more. The potential of the positive electrode when fully charged can be easily measured by disassembling a fully charged lithium ion secondary battery in an Ar glove box, taking out the positive electrode, reassembling the battery using metallic lithium as the counter electrode, and measuring the voltage. Can be measured. When a carbon negative electrode active material is used for the negative electrode, the potential of the carbon negative electrode active material at full charge is 0.05 V (vsLi / Li ⁺ ). ) Plus 0.05 V, the potential of the positive electrode at full charge can be easily calculated. For example, in a lithium ion secondary battery using a carbon negative electrode active material for the negative electrode, when the voltage (Va) of the lithium ion secondary battery at full charge is 4.4 V, the potential of the positive electrode at full charge is It can be calculated as 4.4V + 0.05V = 4.45V.

  Here, an example of a method for manufacturing the positive electrode is described below. First, a paste containing a positive electrode mixture is prepared by dispersing, in a solvent, a positive electrode mixture obtained by adding a conductive additive or a binder to the positive electrode active material, if necessary. Next, this paste is applied to a positive electrode current collector and dried to form a positive electrode mixture layer, which is pressurized as necessary to adjust the thickness, whereby a positive electrode can be produced. Although it does not specifically limit as said positive electrode electrical power collector, For example, it comprises metal foil, such as aluminum foil or stainless steel foil.

  The lithium ion secondary battery obtained in the present embodiment includes a negative electrode. The negative electrode is not particularly limited as long as it reversibly occludes / releases lithium ions as a negative electrode active material and functions as a negative electrode of a lithium ion secondary battery, and a known one can be used. It is preferable that a negative electrode contains 1 or more types chosen from the group which consists of a material which can occlude and discharge | release lithium ion as a negative electrode active material. That is, the negative electrode includes, as a negative electrode active material, a negative electrode active material including an element capable of forming an alloy with lithium, such as a carbon negative electrode active material, a silicon alloy negative electrode active material, and a tin alloy negative electrode active material; It is preferable to contain one or more negative electrode active materials selected from the group consisting of: a tin oxide negative electrode active material; and a lithium-containing compound typified by a lithium titanate negative electrode active material. These negative electrode active materials can be used individually by 1 type or in combination of 2 or more types.

  The carbon negative electrode active material is not particularly limited. For example, hard carbon, soft carbon, artificial graphite, natural graphite, graphite, pyrolytic carbon, coke, glassy carbon, organic polymer compound fired body, mesocarbon micro Examples include beads, carbon fiber, activated carbon, graphite, carbon colloid, and carbon black. Examples of the coke include pitch coke, needle coke, and petroleum coke. Moreover, the fired body of an organic polymer compound is obtained by firing and carbonizing a polymer material such as a phenol resin or a furan resin at an appropriate temperature.

  The negative electrode active material containing an element capable of forming an alloy with lithium is not particularly limited, and may be, for example, a metal or a semimetal alone, an alloy or a compound, and one of these. Or what has two or more types of phases in at least one part may be sufficient. The “alloy” includes an alloy having one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Further, the alloy may contain a nonmetallic element as long as it has metal properties as a whole.

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

  The negative electrode is obtained as follows, for example. First, a negative electrode mixture containing a negative electrode mixture is prepared by dispersing, in a solvent, a negative electrode mixture prepared by adding a conductive additive or a binder to the negative electrode active material, if necessary. Next, this paste is applied to a negative electrode current collector and dried to form a negative electrode mixture layer, which is pressurized as necessary to adjust the thickness, whereby a negative electrode can be produced. Although it does not specifically limit as said negative electrode collector, For example, it comprises metal foil, such as copper foil, nickel foil, or stainless steel foil.

  In the production of the positive electrode and the negative electrode, the conductive aid used as necessary is not particularly limited, and examples thereof include carbon black such as graphite, acetylene black, and ketjen black, and carbon fiber. The binder is not particularly limited, and examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, styrene butadiene rubber, and fluororubber.

  The lithium ion secondary battery obtained in the present embodiment preferably includes a separator between the positive electrode and the negative electrode from the viewpoint of providing safety such as prevention of short circuit between the positive and negative electrodes and shutdown. As the separator, those similar to those provided in known lithium ion secondary batteries can be used, and among them, an insulating thin film having high ion permeability and excellent mechanical strength is preferable. Although it does not specifically limit as said separator, For example, a woven fabric, a nonwoven fabric, a synthetic resin microporous film etc. are mentioned, Among these, a synthetic resin microporous film is preferable. The microporous membrane made of synthetic resin is not particularly limited. For example, a polyolefin microporous membrane such as a microporous membrane containing polyethylene or polypropylene as a main component or a microporous membrane containing both of these polyolefins is suitable. Used. As the non-woven fabric, a porous film made of a heat-resistant resin such as ceramic, polyolefin, polyester, polyamide, liquid crystal polyester, or aramid is used. The separator may be a single microporous membrane or a laminate of a plurality of microporous membranes, or may be a laminate of two or more microporous membranes.

  In addition, in order to ensure the safety and functionality of the separator, separators using a method in which heat-resistant fine particles are immersed and dispersed in a resin solution and dried to coat the heat-resistant fine particles with a resin, heat resistance of polyamideimide, etc. It is also preferable to use a separator in which a porous layer made of resin is formed by resin coating.

  The lithium ion secondary battery obtained in the present embodiment includes, for example, a separator, a positive electrode and a negative electrode that sandwich the separator from both sides, a positive electrode current collector (positioned outside the positive electrode) that sandwiches the laminate, and a negative electrode A current collector (arranged outside the negative electrode) and a battery exterior housing them can be provided. The laminate in which the positive electrode, the separator, and the negative electrode are laminated is preferably impregnated with the electrolytic solution in the present embodiment.

  FIG. 1 is a schematic cross-sectional view showing an example of a lithium ion secondary battery in the present embodiment. A lithium ion secondary battery 100 shown in FIG. 1 includes a separator 110, a positive electrode 120 and a negative electrode 130 that sandwich the separator 110 from both sides, and a positive electrode current collector 140 that sandwiches a laminate thereof (arranged outside the positive electrode). And a negative electrode current collector 150 (arranged outside the negative electrode) and a battery outer case 160 for housing them. The laminate in which the positive electrode 120, the separator 110, and the negative electrode 130 are laminated is impregnated with the electrolytic solution of this embodiment.

  The lithium ion secondary battery obtained in the present embodiment is manufactured by using the above-described electrolytic solution, positive electrode, and negative electrode through the following steps.

  The manufacturing method of the lithium ion secondary battery of this embodiment has the process of accommodating the above-mentioned desired electrolyte solution, a positive electrode, and a negative electrode in an accommodation case, and temporarily sealing the said accommodation case. According to the manufacturing method of the lithium ion secondary battery of this embodiment having such steps, a lithium ion secondary battery that operates at a high voltage can be obtained. In addition, although it does not specifically limit as a storage case, For example, although metal cans, such as an aluminum can and an iron can, are used, an aluminum laminated bag can be used from a viewpoint of thin weight reduction. Further, the temporary sealing described above is not particularly limited, but for example, the aluminum laminated bag may be temporarily sealed after the electrolyte solution is poured, and formation described later may be performed. Here, the sealing means is not particularly limited, and for example, the devices described in the examples described later can be used. After performing such temporary sealing, it can be opened again to remove the gas generated inside the battery and perform the main sealing.

  In the manufacturing method of the lithium ion secondary battery of this embodiment, a formation process is performed before a degassing process. By this formation step, a stable film is formed on the electrode surface, and an effect of improving battery performance is obtained. The formation process may include an aging process described later. In addition, a degassing process (referred to as a first degassing process) can be performed before the aging process, and a degassing process (referred to as a second degassing process) can be performed after the aging process. From the viewpoint of preventing the film formation from becoming insufficient due to the generated gas, it is preferable that the housing case is temporarily sealed again after the first degassing step.

  The formation step is not particularly limited as long as it is a step for performing a process for stabilizing the initial performance of the electric storage element. Specifically, for example, a step for performing a process such as repeated initial charging or charging / discharging is performed. Can be mentioned. The aging process is not particularly limited as long as the battery is placed in a high temperature atmosphere for a predetermined period, and can be various processes.

  In the present embodiment, the aging step is performed at a current value of 0.3 C or less and a charge state of 50% or more with respect to the full charge amount, and at a temperature of 35 ° C. or more and 60 ° C. or less for 2 days or more and 10 days or less. It is preferable that it is a process to preserve | save. Here, 0.3 C of the charging current is a ratio with respect to the current value when the current value that can discharge the discharge capacity in 1 hour from the state where the battery is fully charged (SOC 100%) is 1 C. In the lithium ion secondary battery in the present embodiment, the charging current is preferably 0.2 C or less, more preferably 0.1 C, and even more preferably 0.05 C. About the temperature of aging, the temperature range of 40 to 50 degreeC is preferable. The aging time (storage time) is preferably 4 days or more and 10 days or less, and more preferably 6 days or more and 10 days or less. By providing the charging and aging time, the cycle life of the obtained lithium ion secondary battery can be greatly improved. The reason for this is not clear, but the compound (A) can act on the positive electrode, the negative electrode, or both during aging to produce a coating, and suppress the oxidative decomposition of the electrolyte in the lithium ion secondary battery. This is probably because of this.

In general, it is known that secondary batteries tend to generate various gases such as hydrogen gas due to a chemical reaction between an electrode and an electrolyte during initial charging. In particular, when the positive electrode potential is 4.4 V (vsLi / Li ⁺ ) or more, gas generation due to oxidative decomposition of the electrolytic solution tends to be remarkable. When the gas is present between the electrodes, a phenomenon such as an increase in the internal resistance of the battery occurs, resulting in a decrease in battery capacity and a decrease in battery characteristics such as cycle characteristics. If the gas generated after the formation continues to remain in the battery, there is a problem that the battery swells or the battery characteristics deteriorate. Such a problem is particularly prominent in a laminate type battery that swells more easily than a metal can. On the other hand, according to the manufacturing method of the lithium ion secondary battery of the present embodiment, since the degassing process performed after the formation process is passed, the residual gas as described above is eliminated, and the battery expansion and battery characteristics are eliminated. Is suppressed. As a result, a lithium ion secondary battery that not only exhibits an excellent high voltage but also has excellent cycle characteristics can be obtained.

  The degassing step in the present embodiment is not particularly limited as long as it is a step of discharging gas to the outside. For example, a method of sealing the opening after injecting a nonaqueous electrolyte with the opening of the exterior body facing upward, performing initial charging and discharging the gas to the outside, or all or part of the sealing portion of the exterior material A method of resealing after the gas generated by opening the gas is discharged to the outside.

  The degassing step is preferably a step of sealing the opening by reducing the storage space to −100 kPa or more and −30 kPa or less by vacuuming through the opened sealing portion from the viewpoint of sufficiently excluding the generated gas. The storage space refers to the internal space of the exterior body. The method for reducing the pressure is not particularly limited, and can be performed by using a general vacuum pump and a pressure gauge.

  In addition to the steps described above, various known steps can be added to the method of manufacturing the lithium ion secondary battery of the present embodiment. For example, a plurality of positive electrodes in which a positive electrode and a negative electrode are wound in a laminated state with a separator interposed therebetween to be formed into a laminate having a wound structure, or they are alternately laminated by bending or laminating a plurality of layers. Then, the laminate is formed in a battery case (exterior), and the electrolytic solution of the present embodiment is injected into the case. Is immersed in the electrolytic solution and sealed, a lithium ion secondary battery can be produced. In addition, the shape of the lithium ion secondary battery obtained in the present embodiment is not particularly limited. For example, a cylindrical shape, an elliptical shape, a rectangular tube shape, a button shape, a coin shape, a flat shape, a laminate shape, and the like are preferable. Adopted.

  Next, the present embodiment will be described with reference to examples and comparative examples. The following examples are given to illustrate this embodiment and do not limit the scope of this embodiment in any way.

[Example 1]
<Synthesis of positive electrode active material>
(Synthesis of LiNi _0.5 Mn _1.5 O ₄ )
Nickel sulfate and manganese sulfate in an amount of 1: 3 as the molar ratio of the transition metal element were dissolved in water to prepare a nickel-manganese mixed aqueous solution so that the total metal ion concentration was 2 mol / L. Subsequently, this nickel-manganese mixed aqueous solution was dropped into 1650 mL of a 2 mol / L sodium carbonate aqueous solution heated to 70 ° C. at an addition rate of 12.5 mL / min for 120 minutes. During dropping, air with a flow rate of 200 mL / min was bubbled into the aqueous solution while stirring. Thereby, a precipitated substance was generated, and the obtained precipitated substance was sufficiently washed with distilled water and dried to obtain a nickel manganese compound. The obtained nickel-manganese compound and lithium carbonate having a particle size of 2 μm were weighed so that the molar ratio of lithium: nickel: manganese was 1: 0.5: 1.5, and obtained after dry-mixing for 1 hour. The obtained mixture was fired at 1000 ° C. for 5 hours in an oxygen atmosphere to obtain a positive electrode active material represented by LiNi _0.5 Mn _1.5 O ₄ .

<Preparation of positive electrode>
The positive electrode active material obtained as described above, an acetylene black powder (manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive auxiliary agent, and a polyvinylidene fluoride solution (manufactured by Kureha Co., Ltd.) as a binder are 90: 6: 4 Mixing was performed at a solid content mass ratio, and N-methyl-2-pyrrolidone was added as a dispersion solvent so as to have a solid content of 40% by mass and further mixed to prepare a slurry solution. This slurry-like solution was applied to one side of an aluminum foil having a thickness of 20 μm, and the solvent was removed by drying, followed by rolling with a roll press to obtain a positive electrode. The rolled product was punched into a 30 mm × 50 mm rectangular shape excluding the tab portion to obtain a positive electrode.

<Production of negative electrode>
Graphite powder (made by Osaka Gas Chemical Co., trade name “OMAC1.2H / SS”) and another graphite powder (made by TIMCAL, trade name “SFG6”) as a negative electrode active material, and styrene butadiene rubber (SBR) as a binder and The aqueous solution of carboxymethyl cellulose was mixed at a solid mass ratio of 90: 10: 1.5: 1.8. The obtained mixture was added to water as a dispersion solvent so that the solid content concentration was 45% by mass to prepare a slurry-like solution. This slurry-like solution was applied to one side of a copper foil having a thickness of 18 μm, and the solvent was removed by drying, followed by rolling with a roll press. The rolled product was punched into a rectangular shape of 32 mm × 52 mm excluding the tab portion to obtain a negative electrode.

<Preparation of electrolyte>
1 mol / L of LiPF ₆ salt is contained in a mixed solvent in which ethylene carbonate (also expressed as “EC” in the table) and ethyl methyl carbonate (also expressed as “MEC” in the table) are mixed at a volume ratio of 1: 2. Then, 0.2 g of tris (trimethylsilyl) phosphate (manufactured by Aldrich) as an additive was mixed with 9.8 g of the above solution (manufactured by Kishida Chemical Co., Ltd., LBG00069) to obtain an electrolytic solution A.

<Production of battery>
A laminate in which the positive electrode and the negative electrode produced as described above are laminated on both sides of a separator (thickness 25 μm, porosity 50%, pore diameter 0.1 μm to 1 μm) made of a polypropylene microporous film is made of aluminum. After inserting the positive and negative terminals into a bag made of a laminate film in which both surfaces of a foil (thickness 40 μm) are coated with a resin layer, the electrolyte solution described in the following example is injected into a 0.5 mL bag. Then, after reducing the pressure to -90 kPa and then returning to -30 kPa twice, the operation was held at -95 kPa for 5 minutes. After returning to normal pressure, the pressure was reduced to -85 kPa, and then temporary sealing was performed to produce a sheet-like lithium ion secondary battery. For decompression and temporary sealing, a decompression seal device (model: M-3295) manufactured by Techny Co., Ltd. was used.

<Formation>
The obtained lithium ion secondary battery before formation is accommodated in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) set at 25 ° C., and a charge / discharge device (manufactured by Asuka Electronics Co., Ltd., product) Name “ACD-01”) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. The full charge amount is a charge amount when charging is performed at a constant current up to 4.8V and subsequently charging at a constant voltage of 4.8V for 2 hours. Then, as aging, the battery was left for 7 days in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 45 ° C.

<Degassing process>
The formed battery was unsealed under an argon atmosphere, depressurized to -85 kPa, and then vacuum-sealed to degas the generated gas. The decompression was performed in the same manner as described above. Moreover, the vacuum sealing was performed using a reduced pressure sealing device (model: M-3295) manufactured by Techny Co., Ltd.

<Battery performance evaluation>
Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After connecting for 2 hours and charging at a constant current of 4.8 V with a maximum current value of 0.3 C, the battery was discharged at a constant current of 3 C with a current value of 0.2 C.

  The lithium ion secondary battery obtained by forming as described above is housed in a thermostatic chamber (product name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.) set to 50 ° C., and a charge / discharge device (Asuka Electronics Co., Ltd.). ), Product name “ACD-01”). The battery was then charged to 4.8 V with a constant current of 1.0 C, discharged for 6 minutes at a constant current of 1.0 C, rested for 5 minutes, and then discharged to 3.0 V. The value (V1−V0) / I obtained by dividing the difference between the final voltage (V0) of 6 minutes of discharge and the voltage (V1) of 5 minutes after the rest by the discharge current (I) is the resistance (R1) of the battery. It was. Next, the following charge / discharge cycle evaluation was performed. The battery was charged to 4.8 V at a constant current of 1.0 C, subsequently charged at a constant voltage of 4.8 V for 1 hour, and discharged to 3.0 V at a constant current of 1.0 C. Furthermore, this series of charging / discharging was made into 1 cycle, 49 cycles charging / discharging was repeated, and 50 cycles of cycle charging / discharging was performed in total. Subsequently, the discharge capacity per mass of the positive electrode active material in the first cycle and the 50th cycle was confirmed in the same manner as described above. After 50 cycles of charge / discharge, R1 was measured by the same method as described above. As a result, the resistance R1 of the battery is 18.3Ω initially and 60.2Ω after 50 cycles. The discharge capacity at the first cycle is as high as 120 mAh / g, the discharge capacity at the 50th cycle is as high as 100 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is The value was as high as 83%.

<Evaluation of gas generation>
After 50 cycles, the battery was cooled to room temperature and then immersed in a water bath to measure the volume. From the volume change of the battery before and after continuous charge and discharge, the amount of gas generated (mL) after battery operation was determined. It was as low as 0.082 mL.

[Example 2]
With the method described in Example 1, formation was performed under the following conditions on a lithium ion secondary battery before formation produced by injecting electrolytic solution A. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and was left to stand for 20 hours. Next, 50% of the full charge was charged at a constant current of 0.2C. Thereafter, the battery was left in a thermostat set at 45 ° C. for 7 days. Next, it is housed in a constant temperature bath set at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then a current value of 0.2 C. At a constant current of 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 19.0Ω at the initial stage and 61.0Ω after 50 cycles. The discharge capacity in the first cycle is as high as 128 mAh / g, the discharge capacity in the 50th cycle is as high as 98 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity in the 50th cycle by the discharge capacity in the first cycle is The value was as high as 84%. The gas generation amount (mL) after battery operation was as low as 0.088 mL.

[Example 3]
To 9.9 g of a solution containing 1 mol / L of LiPF ₆ salt in a mixed solvent of ethylene carbonate and ethyl methyl carbonate mixed at a volume ratio of 1: 2 (LBG00069, manufactured by Kishida Chemical Co., Ltd.), phosphorus as an additive described above was added. An electrolytic solution B was obtained by mixing and dissolving 0.1 g of tris (trimethylsilyl) acid.

  With the method described in Example 1, the formation was performed on the pre-formation lithium ion secondary battery produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left in a thermostatic bath operating at 45 ° C. for 7 days to degas. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is initially 16.2Ω, and after 50 cycles, 59Ω. The discharge capacity at the first cycle is as high as 121 mAh / g, the discharge capacity at the 50th cycle is as high as 102 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is The value was as high as 84%. The gas generation amount (mL) after battery operation was as low as 0.134 mL.

[Example 4]
To 9.95 g of a mixed solvent of ethylene carbonate and ethyl methyl carbonate mixed at a volume ratio of 1: 2 containing 1 mol / L of LiPF ₆ salt (LBG00069, manufactured by Kishida Chemical Co., Ltd.), phosphorus as an additive described above was added. An electrolytic solution C was obtained by mixing and dissolving 0.05 g of acid tris (trimethylsilyl).

  With the method described in Example 1, formation was performed under the following conditions on a lithium ion secondary battery before formation produced by injecting electrolyte C. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left for 7 days in a thermostatic chamber operating at 45 ° C. to degas. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 15Ω initially and 65Ω after 50 cycles. The discharge capacity at the first cycle is as high as 118 mAh / g, the discharge capacity at the 50th cycle is as high as 95 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is The value was as high as 81%. The gas generation amount (mL) after battery operation was as low as 0.155 mL.

[Example 5]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left for 7 days in a thermostatic chamber operating at 60 ° C., and degassing was performed. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 22Ω in the initial stage and 68Ω after 50 cycles. The discharge capacity at the first cycle is 113 mAh / g, the discharge capacity at the 50th cycle is 90 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is 80%. It was. The gas generation amount (mL) after battery operation was as low as 0.124 mL.

[Example 6]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left in a thermostatic bath operating at 60 ° C. for 3 days, and degassing after formation was performed. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 18.3Ω initially and 63Ω after 50 cycles. The discharge capacity at the first cycle is as high as 115 mAh / g, the discharge capacity at the 50th cycle is as high as 92 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is The value was as high as 80%. The gas generation amount (mL) after battery operation was as low as 0.153 mL.

[Example 7]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left in a thermostatic bath operating at 60 ° C. for 10 days, and degassing after formation was performed. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 24Ω initially and 63Ω after 50 cycles. The discharge capacity at the first cycle is 110 mAh / g, the discharge capacity at the 50th cycle is 90 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is as high as 82%. The value is shown. The gas generation amount (mL) after battery operation was as low as 0.146 mL.

[Comparative Example 1]
A solution (LBG00069, manufactured by Kishida Chemical Co., Ltd.) containing 1 mol / L of LiPF ₆ salt in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 2 was used as an electrolytic solution D.

  With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution D under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. Next, the battery was charged to 4.8 V at a constant current of 0.2 C, subsequently charged at a constant voltage of 4.8 V for 2 hours, and then discharged at a constant current of 0.2 C to 3 V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the battery resistance R1 was 24.6Ω at the initial stage, 70.5Ω after 50 cycles, the discharge capacity at the first cycle was 120 mAh / g, the discharge capacity at the 50th cycle was as low as 69 mAh / g, and 50 cycles. The discharge capacity retention ratio obtained by dividing the discharge capacity of the eye by the discharge capacity of the first cycle showed a low value of 58%. The gas generation amount (mL) after battery operation was as high as 0.303 mL.

[Comparative Example 2]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution D under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left for 7 days in a thermostatic bath operating at 60 ° C. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the battery resistance R1 was 24Ω initially, 71Ω after 50 cycles, the discharge capacity at the first cycle was as high as 122 mAh / g, the discharge capacity at the 50th cycle was as high as 75 mAh / g, and the discharge capacity at the 50th cycle. The discharge capacity retention rate obtained by dividing by the discharge capacity at the first cycle was as low as 61%. The gas generation amount (mL) after battery operation was as high as 0.298 mL.

[Comparative Example 3]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged at 30% of full charge with a constant current of 0.2C. Thereafter, the battery was left for 7 days in a thermostatic chamber operating at 45 ° C. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 22Ω initially, and 69Ω after 50 cycles. The discharge capacity at the first cycle is as low as 120 mAh / g, the discharge capacity at the 50th cycle is as low as 70 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is 58%. And showed a low value. The gas generation amount (mL) after battery operation was as high as 0.275 mL.

[Comparative Example 4]
With the method described in Example 1, the formation was performed on the lithium ion secondary battery before the formation produced by injecting the electrolytic solution B under the following conditions. It accommodated in the thermostat set to 25 degreeC, connected to the charging / discharging apparatus, and left still for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Thereafter, the battery was left for 7 days in a thermostatic bath operating at 25 ° C. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  The obtained lithium ion secondary battery was subjected to battery performance evaluation by the method described in Example 1. As a result, the resistance R1 of the battery is 21Ω at the initial stage and 70Ω after 50 cycles. The discharge capacity at the first cycle is 115 mAh / g, the discharge capacity at the 50th cycle is 72 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is as low as 63%. The value is shown. The gas generation amount (mL) after battery operation was as high as 0.270 mL.

[Comparative Example 5]
The lithium ion battery obtained by injecting the electrolytic solution B was accommodated in a thermostatic bath set at 25 ° C., connected to a charge / discharge device, and allowed to stand for 20 hours. The battery was then charged at 80% of full charge with a constant current of 0.5C. Thereafter, the battery was left for 7 days in a thermostatic chamber operating at 45 ° C. Next, it is housed in a constant temperature bath operating at 25 ° C., connected to a charging / discharging device, left to stand for 2 hours, charged with a constant current of 4.8 V at a maximum current value of 0.3 C, and then charged with 0.2 C. Was discharged at a constant current up to 3V.

  Battery performance evaluation was performed on the obtained lithium ion secondary battery in the same manner as in Example 1. As a result, the resistance R1 of the battery was 24.3Ω initially and 71Ω after 50 cycles. The discharge capacity at the first cycle is as high as 120 mAh / g, the discharge capacity at the 50th cycle is as high as 82 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is 68%. And showed a low value. The gas generation amount (mL) after battery operation was as high as 0.280 mL.

  The specifications of Examples 1 to 7 and Comparative Examples 1 to 5 described above and the results obtained for these are shown in Table 1.

[Example 8]
<Preparation of positive electrode>
LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (manufactured by Nippon Kagaku Kogyo Co., Ltd.) as a positive electrode active material, acetylene black powder (manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive additive, and a polyvinylidene fluoride solution as a binder (Manufactured by Kureha Co., Ltd.) at a solid content mass ratio of 90: 6: 4, N-methyl-2-pyrrolidone as a dispersion solvent is added to a solid content of 40% by mass, and further mixed. A slurry solution was prepared. This slurry-like solution was applied to one side of an aluminum foil having a thickness of 20 μm, and the solvent was removed by drying, followed by rolling with a roll press to obtain a positive electrode. The rolled product was punched into a 30 mm × 50 mm rectangular shape excluding the tab portion to obtain a positive electrode.

<Production of negative electrode>
Graphite powder (made by Osaka Gas Chemical Co., trade name “OMAC1.2H / SS”) and another graphite powder (made by TIMCAL, trade name “SFG6”) as a negative electrode active material, and styrene butadiene rubber (SBR) as a binder and The aqueous solution of carboxymethyl cellulose was mixed at a solid mass ratio of 90: 10: 1.5: 1.8. The obtained mixture was added to water as a dispersion solvent so that the solid content concentration was 45% by mass to prepare a slurry-like solution. This slurry-like solution was applied to one side of a copper foil having a thickness of 18 μm, and the solvent was removed by drying, followed by rolling with a roll press. The rolled product was punched into a rectangular shape of 32 mm × 52 mm excluding the tab portion to obtain a negative electrode.

<Production of battery>
A laminate in which the positive electrode and the negative electrode produced as described above are laminated on both sides of a separator (thickness 25 μm, porosity 50%, pore diameter 0.1 μm to 1 μm) made of a polypropylene microporous film is made of aluminum. After inserting the positive and negative terminals into a bag made of a laminate film in which both surfaces of a foil (thickness 40 μm) are coated with a resin layer, the electrolyte solution described below is injected into a 0.5 mL bag, Vacuum sealing was performed to produce a sheet-like lithium ion secondary battery.

<Formation>
The lithium ion secondary battery obtained by injecting the electrolytic solution C as described above is accommodated in a thermostatic bath (trade name “PLM-73S”, manufactured by Futaba Kagaku Co., Ltd.) set at 25 ° C., and charged. It was connected to a discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. The full charge amount is a charge amount when charging with a constant current up to 4.35V and subsequently charging with a constant voltage of 4.35V for 2 hours. Next, the battery was left for 7 days in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 45 ° C. Next, degassing after formation was performed in the same manner as in Example 1.

<Battery performance evaluation>
Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The obtained battery was charged to 4.35 V with a constant current of 1.0 C, subsequently charged with a constant voltage of 4.35 V for 1 hour, and discharged to 3.0 V with a constant current of 1.0 C. This series of charging / discharging was made into 1 cycle, and 49 cycles charging / discharging was repeated, and the cycle charging / discharging of 50 cycles was performed in total. The discharge capacity per mass of the positive electrode active material at the first cycle and the 50th cycle was confirmed. Further, a value (ΔV / I) obtained by dividing the difference (ΔV = V3−V4) of the voltage (V4) 10 seconds after the discharge start from the voltage (V2) before the discharge by the discharge current value is set as a DC resistance value R2 for one cycle. The DC resistance value of the eye and the DC resistance at the 50th cycle were confirmed. As a result, the discharge capacity at the first cycle is as high as 160 mAh / g, the discharge capacity at the 50th cycle is as high as 144 mAh / g, and the discharge capacity retention rate obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle. Showed a high value of 90%. The DC resistance R2 showed a low value of 7Ω at the first cycle and 10Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as low as 0.078 mL.

[Example 9]
The lithium ion secondary battery obtained by injecting the electrolytic solution C in the same manner as in Example 8 is housed in a thermostatic bath (trade name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.) set at 25 ° C., and a charge / discharge device It was connected to (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged at 50% of full charge with a constant current of 0.2C. Next, the battery was allowed to stand for 7 days in a constant temperature bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 45 ° C., and degassing was performed after formation. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The battery performance was evaluated in the same manner as in Example 8 for the obtained battery. As a result, the discharge capacity at the first cycle is as high as 161 mAh / g, the discharge capacity at the 50th cycle is as high as 141 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle. Showed a high value of 88%. The DC resistance R2 was a low value of 7Ω at the first cycle and 13Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as low as 0.072 mL.

[Example 10]
The lithium ion secondary battery obtained by injecting the electrolytic solution C in the same manner as in Example 8 is housed in a thermostatic bath set to 25 ° C. (trade name “PLM-73S”, manufactured by Futaba Kagaku Co., Ltd.) The battery was connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Next, the battery was allowed to stand for 10 days in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 45 ° C., and degassing was performed after formation. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The battery performance was evaluated in the same manner as in Example 8 for the obtained battery. As a result, the discharge capacity at the first cycle is as high as 158 mAh / g, the discharge capacity at the 50th cycle is as high as 138 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle. Showed a high value of 87%. The DC resistance R2 was a low value of 9Ω at the first cycle and 13Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as low as 0.070 mL.

[Example 11]
The lithium ion secondary battery obtained by injecting the electrolytic solution B in the same manner as in Example 8 is housed in a thermostatic bath set to 25 ° C. (trade name “PLM-73S”, manufactured by Futaba Kagaku Co., Ltd.) The battery was connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. The battery was allowed to stand for 7 days in a constant temperature bath (manufactured by Futaba Kagaku Co., Ltd., trade name “PLM-73S”) operating at 45 ° C., and degassing was performed after formation. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The battery performance was evaluated in the same manner as in Example 8 for the obtained battery. As a result, the discharge capacity at the first cycle is as high as 160 mAh / g, the discharge capacity at the 50th cycle is as high as 139 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle. Showed a high value of 87%. The DC resistance R2 was a low value of 7Ω at the first cycle and 10Ω at the 30th cycle. The gas generation amount (mL) after battery operation was as low as 0.066 mL.

[Example 12]
The lithium ion secondary battery obtained by injecting the electrolytic solution C in the same manner as in Example 8 is housed in a thermostatic bath set to 25 ° C. (trade name “PLM-73S”, manufactured by Futaba Kagaku Co., Ltd.), and charged and discharged. It was connected to an apparatus (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Next, the battery was allowed to stand for 7 days in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 35 ° C., and degassing was performed after formation. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The battery performance was evaluated in the same manner as in Example 8 for the obtained battery. As a result, the discharge capacity at the first cycle is as high as 159 mAh / g, the discharge capacity at the 50th cycle is as high as 137 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle. Showed a high value of 86%. The DC resistance R2 was a low value of 8Ω at the first cycle and 11Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as low as 0.080 mL.

[Comparative Example 6]
In the same manner as in Example 8, a lithium ion secondary battery was prepared using the electrolytic solution C, and stored in a thermostatic bath set to 25 ° C. (trade name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.). It was connected to an apparatus (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. Next, a lithium ion secondary battery obtained by charging the battery at a constant current constant voltage of 4.35 V at a maximum current value of 0.2 C and then discharging at a constant current of 3 C at a current value of 0.2 C was found to be Example 8. The battery performance was evaluated in the same manner as above. As a result, the discharge capacity at the first cycle is as high as 160 mAh / g, the discharge capacity at the 50th cycle is 135 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is The value was as high as 84%. The DC resistance was 9Ω at the first cycle and 17Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as high as 0.145 mL.

[Comparative Example 7]
In the same manner as in Example 8, a battery in which a lithium ion secondary battery was prepared using the electrolytic solution C was accommodated in a thermostatic bath set to 25 ° C. (trade name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.) The battery was connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) and allowed to stand for 20 hours. The battery was then charged with 80% of the full charge at a constant current of 0.2C. The battery was then left for 7 days in a thermostatic bath (Futaba Kagaku, trade name “PLM-73S”) operating at 25 ° C. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged with a constant current of 4.35 V at a maximum current value of 0.3 C, and then discharged at a constant current of 3 C at a current value of 0.2 C.

  The obtained lithium ion secondary battery was evaluated for battery performance in the same manner as in Example 8. As a result, the discharge capacity at the first cycle is 159 mAh / g, the discharge capacity at the 50th cycle is 128 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is 81%. Indicated. The DC resistance was 11Ω at the first cycle and 18Ω at the 30th cycle. The gas generation amount (mL) after battery operation was as high as 0.156 mL.

[Comparative Example 8]
To 9.5 g of a solution (LBG00069, manufactured by Kishida Chemical Co., Ltd.) containing 1 mol / L of LiPF ₆ salt in a mixed solvent obtained by mixing ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 2, phosphorus as an additive described above was added. An electrolytic solution E was obtained by mixing 0.5 g of tris (trimethylsilyl) acid. Further, in the same manner as in Example 8, the electrolytic solution E was injected to produce a lithium ion secondary battery, and the following formation was performed.

  It is accommodated in a thermostatic bath set at 25 ° C. (trade name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.) and connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) for 20 hours. Left to stand. The battery was then charged with 80% of the full charge at a constant current of 0.2C. The battery was allowed to stand for 7 days in a thermostatic bath (trade name “PLM-73S”, manufactured by Futaba Kagaku) operating at 45 ° C. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged at a constant current of 4.35 V with a maximum current value of 0.3 C, and then discharged at a constant current of 0.2 C to 3 V.

  The battery performance evaluation similar to Example 8 was performed about the obtained lithium ion secondary battery. As a result, the discharge capacity at the first cycle was 140 mAh / g, the discharge capacity at the 50th cycle was 90 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle was 64 % And a low value. The direct current resistance was 20Ω at the first cycle and 60Ω at the 50th cycle, which were high values. The gas generation amount (mL) after battery operation was as high as 0.150 mL.

[Comparative Example 9]
In the same manner as in Example 8, the electrolytic solution D was injected to produce a lithium ion secondary battery, and the following formation was performed.

  It is accommodated in a thermostatic bath set at 25 ° C. (trade name “PLM-73S” manufactured by Futaba Kagaku Co., Ltd.) and connected to a charge / discharge device (trade name “ACD-01” manufactured by Asuka Electronics Co., Ltd.) for 20 hours. Left to stand. The battery was then charged with 80% of the full charge at a constant current of 0.2C. Next, the battery was left for 7 days in a thermostatic bath (manufactured by Futaba Kagaku, trade name “PLM-73S”) operating at 45 ° C. Next, it is housed in a thermostatic bath (manufactured by Futaba Kagaku Co., trade name “PLM-73S”) operating at 25 ° C., and charged / discharged (made by Asuka Electronics Co., Ltd., trade name “ACD-01”). After being connected and allowed to stand for 2 hours, the battery was charged at a constant current of 4.35 V with a maximum current value of 0.3 C, and then discharged at a constant current of 0.2 C to 3 V.

  The battery performance evaluation similar to Example 8 was performed about the obtained lithium ion secondary battery. As a result, the discharge capacity at the first cycle is as high as 159 mAh / g, the discharge capacity at the 50th cycle is 125 mAh / g, and the discharge capacity maintenance ratio obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the first cycle is 79%. The DC resistance was 7.7Ω at the first cycle and 15Ω at the 50th cycle. The gas generation amount (mL) after battery operation was as high as 0.177 mL.

  The specifications of Examples 8 to 12 and Comparative Examples 6 to 9 described above and the results obtained for these are shown in Table 2.

  The electrolyte solution for non-aqueous electricity storage devices of the present invention and the lithium ion secondary battery using the same have industrial applicability to various consumer equipment power supplies, automobile power supplies, and the like.

DESCRIPTION OF SYMBOLS 100 Lithium ion secondary battery 110 Separator 120 Positive electrode 130 Negative electrode 140 Positive electrode collector 150 Negative electrode collector 160 Battery exterior

Claims (7)

A positive electrode containing a positive electrode active material;
A negative electrode containing a negative electrode active material;
An electrolyte containing a non-aqueous solvent and a lithium salt;
A method for producing a lithium ion secondary battery comprising:
In the electrolytic solution, at least one hydrogen atom of an oxo acid selected from a proton acid, a sulfonic acid, and a carboxylic acid having a phosphorus atom and / or a boron atom is substituted with a substituent represented by the following formula (1) An electrolytic solution containing the prepared compound (A), the positive electrode having a discharge capacity of 10 mAh / g or more at a potential of 4.4 V (vs Li / Li ⁺ ) or more, and the negative electrode in a housing case. Storing and temporarily sealing the storage case;
(In formula (1), R1, R2 and R3 each independently represents an organic group having 1 to 10 carbon atoms.)
A formation process performed after the temporary sealing process;
A degassing step performed after the formation step;
A method for producing a lithium ion secondary battery, comprising:   The manufacturing method of the lithium ion secondary battery of Claim 1 whose content of the said compound (A) is 0.01 mass% or more and 10 mass% or less with respect to the said electrolyte solution. The manufacturing method of the lithium ion secondary battery of Claim 1 in which the said compound (A) contains the compound represented by following formula (2).
(In the formula (2), n represents an integer of 0 or 1, and R4 and R5 each independently represents an OH group, an OLi group, an optionally substituted alkyl group having 1 to 10 carbon atoms, or a substituted group. A good 1 to 10 alkoxy group and a siloxy group having 3 to 10 carbon atoms.)   The method for producing a lithium ion secondary battery according to claim 1, wherein the compound represented by the formula (2) contains tris (trimethylsilyl) phosphate.   The formation process includes an aging process in which 50% or more of the full charge capacity is charged at a current value of 0.3 C or less and then stored at 35 to 60 ° C. for 5 to 10 days. The manufacturing method of the lithium ion secondary battery as described in 2 ..   2. The method for producing a lithium ion secondary battery according to claim 1, wherein the degassing step is a step of depressurizing the storage space to −100 kPa to −30 kPa by vacuuming through the opened sealing portion and sealing the opening. 3. . The positive electrode active material has the following general formula (1):
_{LiMn 2-x Ma x O 4} (1)
(In the formula, Ma represents one or more selected from the group consisting of transition metals, and 0.2 ≦ x ≦ 0.7.)
A compound represented by the following general formula (6):
LiMO ₂ (6)
(In the formula, M represents one or more selected from transition metals and Al.)
A compound represented by the following general formula (2A):
Li ₂ McO ₃ (2A)
(In the formula, Mc represents one or more selected from the group consisting of transition metals.)
And the following general formula (2B):
LiMdO ₂ (2B)
(In the formula, Md represents one or more selected from the group consisting of transition metals.)
A composite oxide with an oxide represented by the following general formula (2):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 (2)
(In the formula, Mc and Md are synonymous with Mc and Md in the general formulas (2A) and (2B), respectively, and 0.1 ≦ z ≦ 0.9.)
A compound represented by the following general formula (3):
LiMb _1-y Fe _y PO ₄ (3)
(In the formula, Mb represents one or more selected from the group consisting of Mn and Co, and 0 ≦ y ≦ 0.9.)
And the following general formula (4):
Li ₂ MePO ₄ F (4)
(In the formula, Me represents one or more selected from the group consisting of transition metals.)
The manufacturing method of the lithium ion secondary battery as described in any one of Claims 1-3 containing 1 or more types chosen from the group which consists of a compound represented by these.