JP2001155768A - Non-aqueous electrolyte and secondary cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the non-aqueous electrolyte which controls a resolution at a minimum, and the non-aqueous electrolytic secondary cell of a high energy density using the same which has excellent cycle property and maintenance property. SOLUTION: A non-aqueous electrolyte contains a solute and an organic solvent, wherein the organic solvent contains a carbonate compound, and the carbonate compound has a Mulliken population value (HP value) of at least one of carbon atom (this carbon atom is not a constituent atom of methyl group) bonded to the carbonate group of less then 0.17, in an optimum structure of an anion state calculated by non-experience molecule orbital method using 3-21G base function in non-limiting Hartree Fock method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte and a secondary battery using the same. More specifically, the present invention relates to a non-aqueous electrolyte containing a carbonate compound having specific parameters and a secondary battery using the same. The decomposition of the non-aqueous electrolyte of the present invention is minimized, and a secondary battery using the same has high capacity, high cycle characteristics, and excellent storage characteristics.
High performance can be achieved.

[0002]

2. Description of the Related Art With the recent reduction in the weight and size of electric products, attention has been paid to lithium secondary batteries having a high energy density, and various studies have been made. In addition, with the expansion of the application field of the lithium secondary battery, improvement in battery characteristics is also demanded. Non-aqueous organic solvents such as carbonates or esters such as ethylene carbonate, propylene carbonate, diethyl carbonate, and γ-butyrolactone have been used as a solvent for the electrolyte solution of such a lithium secondary battery.

[0003]

However, the lithium secondary battery has a working potential width of 3 V or more,
Due to the use of extremely active lithium, even when an electrolyte containing a relatively stable non-aqueous organic solvent as described above is used, decomposition of the electrolyte on the electrode surface during the charge / discharge process is inevitable. , Resulting in lower charge and discharge efficiency,
There were problems such as deterioration of cycle characteristics and storage characteristics. The present invention has been made in order to solve such problems, and an electrolytic solution with its decomposition minimized, and a non-aqueous electrolyte secondary solution having a high energy density and excellent cycle characteristics using the electrolytic solution. A battery is provided.

[0004]

Means for Solving the Problems As a result of intensive studies in view of such circumstances, the present inventors have found that the decomposition of a non-aqueous electrolyte containing a carbonate compound having specific parameters can be minimized. In addition, the inventors have found that secondary batteries using the same have excellent cycle characteristics and storage characteristics, and have completed the present invention.

That is, the gist of the present invention is as follows. In a non-aqueous electrolyte containing a solute and an organic solvent, the organic solvent contains a carbonate compound (I), and the compound uses a 3-21G basis function by the unrestricted Hartree-Fock method. Value of at least one Mulliken population of carbon atoms bonded to the carbonate group (however, the carbon atoms are not constituent atoms of the methyl group) in the optimized structure of the anion state obtained by the ab initio molecular orbital method (MP value) is -0.17 or less, non-aqueous electrolyte solution characterized by the above-mentioned. In a non-aqueous electrolytic solution containing a solute and an organic solvent, the organic solvent is a carbonate compound (I ′)
And the compound binds to a carbonate group when its stable structure in the anion state determined by an ab initio molecular orbital method using a 3-21G basis function is determined by the unrestricted Hartree-Fock method. 2. A non-aqueous electrolyte solution in which at least one of carbon atoms (the carbon atom is not a constituent atom of a methyl group) and a terminal oxygen atom of a carbonate group are cleaved. A non-aqueous electrolyte secondary battery comprising at least a negative electrode, a positive electrode, and the non-aqueous electrolyte described in 1 or 2 containing a carbonaceous material capable of inserting and extracting lithium.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (Non-Aqueous Electrolyte) The non-aqueous electrolyte of the present invention has an organic solvent whose anionic state is determined by an ab initio molecular orbital method using a 3-21G basis function by an unrestricted Hartree-Fock method. In the optimized structure, a carbonate system in which the value (MP value) of at least one Mulliken population of a carbon atom bonded to a carbonate group (the carbon atom is not a constituent atom of a methyl group) is -0.17 or less. When the stable structure of the compound (I) or its anion state obtained by the ab initio molecular orbital method using the 3-21G basis function by the unrestricted Hartree-Fock method was obtained, the carbon atom bonded to the carbonate group ( However, at least one of the carbon atoms is not a constituent atom of a methyl group) and a terminal oxygen atom constituting a carbonate group is cleaved. Characterized in that it contains an object (I '). The structure of the carbonate compound (I) or (I ′) is not particularly limited, but a compound represented by the following general formula (I) is preferable.

[0007]

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(Wherein A and B independently represent a hydrogen atom and / or a carbon atom to which a substituent is bonded. A cross-linking bond may exist between A and B. )
Then, in this case, the carbon atoms A and / or B in the formula (1) are subjected to a non-empirical molecular orbital method and an unrestricted Hartree-Fock method to optimize the structure of the anion state using a 3-21G basis function. After that, the value of the Mulliken population is equal to or less than -0.17, or is expressed by equation (1) using a 3-21G basis function by the unrestricted Hartree-Fock method of the ab initio molecular orbital method. When a stable structure in the anion state of the compound is determined, the A—O bond or the B—O bond in the formula (1) is cleaved.

The MP of the carbonate compound (I)
The value is usually -0.17 or less, -1 or more, preferably -0.18 or less, -0.8 or more, more preferably-
0.19 or less and -0.8 or more. If the MP value is too small, it may become unstable. In the carbonate compounds (I) and (I ') used in the present invention, the carbon atom bonded to the carbonate group is not a constituent atom of the methyl group. That is, compounds such as dimethyl carbonate in which an oxygen atom constituting a carbonate group is bonded to a methyl group are not included in the carbonate compounds (I) and (I ′). In addition, the carbonate-based compound of the formula (1) used in the present invention includes formulas (2) to (2).
Compounds of the formula (9) are preferred, among which the compounds of the formula (4)
The compounds (8) and (9) are particularly preferred.

[0010]

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(In the formula, -F- is a structure bridging between D and E, and has a carbon chain of 1 to 5 carbon atoms which may have a single bond, a double bond or a triple bond, or a substituent. Represents D
And E each independently represent a hydrogen atom and / or a carbon atom to which a substituent is bonded. (A cross-linking structure between D, E, F and the above substituents may be present.)

[0012]

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(Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group,
Represents an acyl group, an ester group or an ether group, or a halogen atom. G represents a methylene group or a vinylene group which may have a substituent, -IJ- (wherein I and J
Each independently represents a methylene group or a vinylene group which may have a substituent) or

[0014]

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(Wherein R ⁵ and R ⁶ are each independently a hydrogen atom, an alkyl group which may have a substituent,
Alkenyl group, alkynyl group, phenyl group, acyl group,
(It represents an ester group or an ether group or a halogen atom.) A cross-linking structure between G and the above substituents may be present.)

In the formula (3), when R ¹ , R ² , R ³ and R ⁴ are an optionally substituted alkyl group, alkenyl group or alkynyl group, the number of carbon atoms is not particularly limited. However, it is preferably 1 to 6, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group, for example, a methyl group, an ethyl group,
In the case of an alkenyl group such as a propyl group and a butyl group, for example, an ethenyl group, a propenyl group, a butenyl group, and the like, and in the case of an alkynyl group, for example, an ethynyl group, a propynyl group, a butynyl group, and the like.

When R ¹ , R ² , R ³ and R ⁴ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably from 6 to 12, and more preferably from 6 to 12. Examples include, for example, phenyl, tolyl, xylyl and the like. Also, as a halogen atom,
A chlorine atom and a bromine atom are preferred. When R ⁵ and R ⁶ are an alkyl group, an alkenyl group or an alkynyl group which may have a substituent, the number of carbon atoms is not particularly limited, but 1 to 6 is preferable. Any of branched or cyclic may be used.Specific examples thereof include an alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc., and an alkenyl group, for example, an ethenyl group, a propenyl group, a butenyl group, etc. In the case of an alkynyl group, for example, an ethynyl group, a propynyl group, a butynyl group and the like can be mentioned. When R ⁵ and R ⁶ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably 6 to 12, and specific examples thereof include a phenyl group and a tolyl group. And xylyl groups. Further, as the halogen atom, a chlorine atom and a bromine atom are preferable.

[0018]

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(Wherein R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group,
Represents an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.)

In the formula (4), when R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are an alkyl group, alkenyl group or alkynyl group which may have a substituent, the number of carbon atoms is not particularly limited. Although not performed, preferably 1 to 6,
It may be linear, branched, or cyclic, and specific examples thereof include an alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, and an alkenyl group, for example, an ethenyl group, a propenyl group, In the case of an alkynyl group such as a butynyl group, for example, an ethynyl group, a propynyl group, a butynyl group and the like can be mentioned.

When R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably from 6 to 12, and more preferably from 6 to 12. Examples include, for example, phenyl, tolyl, xylyl and the like. Also, as a halogen atom,
A chlorine atom and a bromine atom are preferred. In addition, as a specific example of such a compound, phenylethylene carbonate can be given, for example.

[0022]

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(Wherein R ¹¹ and R ¹² are each independently a hydrogen atom, an alkyl group which may have a substituent,
Alkenyl group, alkynyl group, phenyl group, acyl group,
Represents an ester group or an ether group or a halogen atom. (A crosslinked structure between the above substituents may be present.)

In the formula (5), when R ¹¹ and R ¹² are an alkyl group, an alkenyl group or an alkynyl group which may have a substituent, the number of carbon atoms is not particularly limited. Is preferred, and may be linear, branched, or cyclic.Specific examples thereof include an alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, and an alkenyl group, for example, ethenyl. In the case of an alkynyl group such as a group, propenyl group and butenyl group, for example, an ethynyl group, a propynyl group, a butynyl group and the like can be mentioned. When R ¹¹ and R ¹² are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably 6 to 12, and specific examples thereof include a phenyl group and a tolyl group. And xylyl groups. Further, as the halogen atom, a chlorine atom and a bromine atom are preferable.

[0025]

Embedded image (In the formula, G represents a methylene group or a vinylene group which may have a substituent, n is 0 or 1, and R ¹³ , R ¹⁴ ,
R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.)

In the formula (6), when R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are an alkyl group, alkenyl group or alkynyl group which may have a substituent, the number of carbon atoms is not particularly limited. However, it is preferably 1 to 6, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group, for example, a methyl group, an ethyl group,
In the case of an alkenyl group such as a propyl group and a butyl group, for example, an ethenyl group, a propenyl group, a butenyl group, and the like, and in the case of an alkynyl group, for example, an ethynyl group, a propynyl group, a butynyl group, and the like. When R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably 6 to 12, and specific examples thereof include For example, a phenyl group, a tolyl group, a xylyl group and the like can be mentioned. Further, as the halogen atom, a chlorine atom and a bromine atom are preferable.

[0027]

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(Wherein, R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group,
Represents an acyl group, an ester group or an ether group, or a halogen atom. (In the formula (7), R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ may have a substituent.) Or when it is an alkynyl group, the number of carbon atoms is not particularly limited, but is preferably 1 to 6, and may be linear, branched, or cyclic, and specific examples thereof include, in the case of an alkyl group, For example, in the case of an alkenyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, for example, an ethenyl group, a propenyl group, and a butenyl group; and in the case of an alkynyl group, for example, an ethynyl group, a propynyl group, and a butynyl group.

When R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited, but is preferably from 6 to 12, and more preferably from 6 to 12. Examples include, for example, phenyl, tolyl, xylyl and the like. Also, as a halogen atom,
A chlorine atom and a bromine atom are preferred.

[0030]

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(Wherein, R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group ,
Represents a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom. (A cross-linking structure may exist between the above substituents.) In the formula (8), even if R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ have a substituent. When it is a good alkyl group, alkenyl group or alkynyl group, the number of carbon atoms is not particularly limited, but is preferably 1 to 6, and may be any of linear, branched, or cyclic. In the case of an alkyl group, for example, a methyl group, an ethyl group,
In the case of an alkenyl group such as a propyl group and a butyl group, for example, an ethenyl group, a propenyl group, a butenyl group, and the like, and in the case of an alkynyl group, for example, an ethynyl group, a propynyl group, a butynyl group, and the like.

When R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited. 12 is preferable, and specific examples thereof include a phenyl group, a tolyl group, and a xylyl group. Further, as the halogen atom, a chlorine atom and a bromine atom are preferable. Incidentally, specific examples of such a compound include, for example, vinyl ethylene carbonate.

[0033]

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(Wherein R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ ,
R ³² independently represents a hydrogen atom, an optionally substituted alkyl group, an alkenyl group, an alkynyl group, a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom. (In the formula (9), R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ and R ³² may have a substituent.) When it is a good alkyl group, alkenyl group or alkynyl group, the number of carbon atoms is not particularly limited, but is preferably 1 to 6, and may be any of linear, branched, or cyclic. In the case of an alkyl group, for example, a methyl group, an ethyl group,
In the case of an alkenyl group such as a propyl group and a butyl group, for example, an ethenyl group, a propenyl group, a butenyl group, and the like, and in the case of an alkynyl group, for example, an ethynyl group, a propynyl group, a butynyl group, and the like.

When R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ and R ³² are a phenyl group which may have a substituent, the number of carbon atoms is not particularly limited. 12 is preferable, and specific examples thereof include a phenyl group, a tolyl group, and a xylyl group. Further, as the halogen atom, a chlorine atom and a bromine atom are preferable.

Then, the formula (1), preferably the formulas (2) to
Specific examples of the compound (9) include, for example, phenylethylene carbonate (MP value: -0.185) and vinylethylene carbonate (MP value: -0.220). The carbonate compound (I)
And (I ′), the total content in the organic solvent is usually 0.001 to 20% by weight, preferably 0.01 to 20% by weight.
It is used so as to be in the range of 10 to 10% by weight, more preferably 0.1 to 5% by weight. If the content is less than 0.001% by weight, the effect cannot be sufficiently obtained, and if it exceeds 20% by weight, the viscosity of the electrolytic solution increases, the electric conductivity decreases, and the performance of the battery deteriorates. Is not preferred.

The organic solvent component has a relative dielectric constant of 20.
It is preferable to include at least the above solvents. Examples of the solvent having a relative dielectric constant of 20 or more include cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate, cyclic esters such as γ-butyrolactone and γ-valerolactone, sulfolane, 3-methylsulfolane and the like.

Examples of other organic solvent components include, but are not particularly limited to, chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; chain esters such as methyl acetate and methyl propionate; tetrahydrofuran; Cyclic ethers such as methyltetrahydrofuran and tetrahydropyran; chain ethers such as dimethoxyethane and dimethoxymethane; and phosphate esters such as trimethyl phosphate and triethyl phosphate. These may be used as a mixture of two or more.

As the solute, a lithium salt is usually used. The lithium salt is not particularly limited, and specific examples thereof include, for example, LiClO
_{4, LiPF 6, LiBF 4,} LiAsF 6, LiSb
F ₆ , LiI, LiBr, LiCl, LiAlCl, L
iHF ₂ , LiSCN, LiBPh _{4 and the} like. Examples of the organic salt include LiCF ₃ SO ₃ , LiN
(CF ₃ SO ₂ ), LiN (CF ₃ CF ₂ SO ₂ ) ₂ ,
LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC
(CF ₃ SO ₂ ) _{3 and} other fluorine-containing organic lithium salts. Among them, LiPF ₆ , LiBF ₄ , LiN
(CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂
Are preferred.

These solutes may be used as a mixture of two or more kinds. The concentration of the solute in the electrolyte is 0.5
To 2.0 mol / l, preferably 0.5 to 1.5 mol / l. If it is less than 0.5 mol / l or more than 2.0 mol / l, the electric conductivity of the electrolytic solution is undesirably reduced.

(Non-Aqueous Electrolyte Secondary Battery) The material of the negative electrode constituting the battery of the present invention is not particularly limited as long as it contains a carbonaceous material capable of occluding and releasing lithium. Examples thereof include thermal decomposition products of organic substances under various thermal decomposition conditions, artificial graphite, natural graphite, and the like. Preferably, artificial graphite and refined natural graphite produced by high-temperature heat treatment of easily-graphitizable pitch obtained from various raw materials, or materials obtained by subjecting these graphites to various surface treatments including pitch are mainly used. The graphite material having a lattice plane (002 plane) d value (interlayer distance) of 0.335 to 0.34 nm, more preferably 0.335 to 0.337 nm, determined by X-ray diffraction according to the Gakushin method. preferable. These graphite materials have an ash content of 1% by weight or less, more preferably 0.5% by weight or less, and most preferably 0.1% by weight.
It is preferable that the crystallite size (Lc) obtained by X-ray diffraction according to the Gakushin method is 30 nm or more.

Further, the crystallite size (Lc) is more preferably 50 nm or more, and most preferably 100 nm or more. The median diameter of the graphite material is 1 to 100 μm, preferably 3 to 50 μm, more preferably 5 to 40 μm, as measured by a laser diffraction / scattering method.
More preferably, it is 7 to 30 μm. BET of graphite material
The specific surface area is 0.5 to 25.0 m ² / g, preferably 0.7 to 20.0 m ² / g, more preferably 1.
0 to 15.0 m ² / g, more preferably 1.5 to 10.
0 m ² / g. In Raman spectrum analysis using argon ion laser light, 1580 to 162
0cm peak in the range of ^-1 P _A (peak intensity I _A) and 1
Intensity ratio R = I _B / I _A of 350～1370Cm ^-1 ranging peak P _B (peak intensity I _B) is 0～0.5,158
The half width of the peak in the range of ⁰ to 1620 cm ^-1 is 26 cm
^-1, the half width of the peak in the range of 1580～1620Cm ^-1 is 25 cm ^-1 or less is more preferable.

A negative electrode material capable of occluding and releasing lithium can be mixed with these carbonaceous materials and used.
Examples of the negative electrode material capable of occluding and releasing lithium other than the carbonaceous material include metal oxide materials such as tin oxide and silicon oxide, as well as lithium metal and various lithium alloys. These negative electrode materials may be used as a mixture of two or more.

The method for producing a negative electrode using these negative electrode materials is not particularly limited. For example, a negative electrode can be manufactured by adding a binder, a thickener, a conductive material, a solvent, and the like to a negative electrode material as needed to form a slurry, applying the slurry to a current collector substrate, and drying. Alternatively, the negative electrode material may be directly roll-formed into a sheet electrode,
A pellet electrode can be obtained by compression molding.

The binder used in the production of the electrode is not particularly limited as long as it is a material that is stable with respect to the solvent and electrolyte used in the production of the electrode. Specific examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, styrene / butadiene rubber, isoprene rubber, and butadiene rubber. As a thickener,
Examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and the like. Examples of the conductive material include metal materials such as copper and nickel, and carbon materials such as graphite and carbon black.

As the material of the current collector for the negative electrode, metals such as copper, nickel, and stainless steel are used, and among these, copper foil is preferable from the viewpoint of easy processing into a thin film and cost. As the material of the positive electrode constituting the battery of the present invention, a material capable of inserting and extracting lithium, such as a lithium transition metal composite oxide material such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide, is used. Can be.

The method for manufacturing the positive electrode is not particularly limited, and the positive electrode can be manufactured according to the above-described method for manufacturing the negative electrode. As for the shape, a binder, a conductive material, a solvent, and the like are added to the positive electrode material as necessary and mixed, and then applied to a current collector substrate to form a sheet electrode, or a pellet electrode formed by press molding. It can be. As a material of the current collector for the positive electrode, a metal such as aluminum, titanium, and tantalum or an alloy thereof is used. Among these, aluminum or its alloy is desirable in terms of energy density because it is lightweight.

The material and shape of the separator used in the battery of the present invention are not particularly limited. However, it is preferable to select from materials that are stable with respect to the electrolyte and have excellent liquid retention properties, and it is preferable to use a porous sheet or nonwoven fabric made of a polyolefin such as polyethylene or polypropylene as a raw material. The method for producing the battery of the present invention having at least the negative electrode, the positive electrode, and the nonaqueous electrolyte is not particularly limited, and can be appropriately selected from commonly employed methods. The shape of the battery is not particularly limited, and a cylinder type in which a sheet electrode and a separator are spirally formed, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, and a coin type in which a pellet electrode and a separator are stacked are used. It is possible.

[0049]

EXAMPLES The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these examples unless it exceeds the gist. (Example 1) As for an electrolytic solution, lithium hexafluorophosphate (Li) was sufficiently dried under a dry argon atmosphere.
Using PF ₆ ) as a solute, a mixture of propylene carbonate and diethyl carbonate (1: 1 by volume) is modified by the ab initio molecular orbital method using carbon atom A or B or both in formula (1) without restriction. 3-21 by law
After optimizing the structure of the anion state using the G basis function, the value of the Mulliken population is -0.220, and further, the 3-21G basis is obtained by the unrestricted Hartree-Fock method of the ab initio molecular orbital method. When a stable structure in the anion state is obtained using the function, the A—O bond or the B—
It was prepared by dissolving vinylethylene carbonate at which the O bond is cleaved at a ratio of 3% by weight, and further dissolving LiPF ₆ at a ratio of 1 mol / l.

D of lattice plane (002 plane) in X-ray diffraction
Value is 0.336 nm, crystallite size (Lc) is 100 n
m (264 nm), ash content: 0.04% by weight, median diameter by laser diffraction / scattering method: 17 μm, BET specific surface area: 8.9 m ² / g, Raman spectrum analysis using argon ion laser light: 1580 to 16
Intensity ratio R = I _B / I _A of the peak P _A in the range of 20 cm ^-1 (peak intensity I _A) and the peak P _B in the range of 1350 ^-1 (peak intensity I _B) is 0.15,158
The half width of the peak in the range of ⁰ to 1620 cm ^-1 is 22.2.
A styrene-butadiene rubber (SBR) dispersed in distilled water was added to 94 parts by weight of artificial graphite powder KS-44 (trade name, manufactured by Timcal Co., Ltd.) having a cm ^-1 of 6 parts by weight in a solid content to obtain a disperser. The slurry was uniformly mixed on a 18 μm-thick copper foil as a current collector, dried, and punched into a disk having a diameter of 12.5 mm to produce an electrode. A coin-type half cell having a lithium foil as a counter electrode via a separator impregnated with the liquid was produced.

Example 2 In a mixture of propylene carbonate and diethyl carbonate (1: 1 by volume), the carbon atom A or B or both in the formula (1) was subjected to the ab initio molecular orbital method by the unrestricted Hartree-Fock method. 3-21 by law
After optimizing the structure of the anion state using the G basis function, the value of the Mulliken population is -0.185, and furthermore, 3-21G by the unrestricted Hartree-Fock method of the ab initio molecular orbital method. When a stable structure in an anion state is obtained using a basis function, the A—O bond or B in formula (1) is obtained.
Phenylethylene carbonate in which the -O bond is cleaved
A coin-type battery was produced in the same manner as in Example 1 except that an electrolyte solution prepared by dissolving at a ratio of 1% by weight and further dissolving LiPF ₆ at a ratio of 1 mol / liter was used.

Comparative Example 1 Propylene carbonate and di
Formula for the mixture of ethyl carbonate (1: 1 volume ratio)
(1) Inexperienced carbon atoms A and / or B in both
3-21 Molecular orbital method using unrestricted Hartree-Fock method
Structure optimization of anion state was performed using G basis set
Later, the value of the Mulliken population was -0.044
Yes, unrestricted Hartree-Fock of ab initio molecular orbital method
Stability of anion state using 3-21G basis function
When the structure is obtained, the A—O bond or the B—O bond in the formula (1) is obtained.
3% by weight of phenylvinylene carbonate that does not cleave
% And dissolved in LiPF ₆1 mol / liter
Except that an electrolyte prepared by dissolving at a
A coin-type battery was produced in the same manner as in Example 1.

Comparative Example 2 In a mixture of propylene carbonate and diethyl carbonate (1: 1 by volume), the carbon atom A or B or both in the formula (1) was subjected to the ab initio molecular orbital method by the unrestricted Hartree-Fock method. 3-21 by law
After optimizing the structure of the anion state using the G basis function, the value of the Mulliken population is 0.050, and the 3-21G basis function is obtained by the unrestricted Hartree-Fock method of the ab initio molecular orbital method. When the stable structure in the anion state is determined, vinylene carbonate in which the A—O bond or the B—O bond in the formula (1) is not cleaved is dissolved at a ratio of 3% by weight, and LiPF ₆ is further dissolved at 1 mol / L. A coin-type battery was produced in the same manner as in Example 1, except that an electrolytic solution prepared by dissolving at a ratio was used.

Comparative Example 3 In a mixture of propylene carbonate and diethyl carbonate (1: 1 by volume), the carbon atom A or B or both in the formula (1) was subjected to the ab initio molecular orbital method by the unrestricted Hartley method. 3-21 by Fock method
After the structure optimization of the anion state was performed using the G basis function, the value of the Mulliken population was 0.291, and the 3-21G basis function was determined by the unrestricted Hartree-Fock method of the ab initio molecular orbital method. When the stable structure in the anion state is determined, diphenylvinylene carbonate in which the A—O bond or the B—O bond in the formula (1) is not cleaved is dissolved at a ratio of 3% by weight, and LiPF ₆ is further dissolved at 1 mol / liter. A coin-type battery was produced in the same manner as in Example 1, except that the electrolytic solution prepared by dissolving at a ratio of 1 was used.

Next, Examples 1 and 2 manufactured as described above were used.
And about coin-type half cells of Comparative Examples 1 to 3, 25
At 0 ° C. at a constant current of 0.2 mA and a discharge end voltage of 0 V,
A charge / discharge test was performed at a constant current of 0.4 mA and a charge end voltage of 1.5 V. Table 1 shows the undoped capacity (dedoped capacity of lithium from the working electrode) and the efficiency (dedoped capacity / doped capacity) in the first cycle of Examples 1 and 2 and Comparative Examples 1 to 3. Here, the capacity indicates a capacity per weight of graphite used as a working electrode. From Table 1, it is apparent that the capacity and efficiency are improved when an electrolyte containing a carbonate compound having specific parameters is used.

[0056]

[Table 1]

[0057]

According to the present invention, in a non-aqueous electrolyte secondary battery provided with a negative electrode containing a carbonaceous material, by using an organic solvent containing a carbonate compound having specific parameters, a considerably stable ion A permeable protective film is formed, minimizing decomposition of the electrolyte, obtaining high capacity, and producing a battery with excellent cycle characteristics and storage characteristics. It can contribute to downsizing and high performance.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akinori Murakami 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Institute (72) Inventor Hiroshi Suzuda 1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi Inside the Yokohama Research Laboratory, Chemical Co., Ltd. (72) Inventor, Shinichiro Nakamura 1000, Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Within the Yokohama Research Laboratory, Mitsubishi Chemical Co., Ltd. No. 1 Mitsubishi Chemical Corporation Tsukuba Research Laboratories (72) Inventor Hitoshi Suzuki 3-1, Chuo, Ami-cho, Inashiki-gun, Ibaraki Pref. Mitsubishi Chemical Corporation Tsukuba Research Laboratories F-term (reference) AL12 AL18 AM03 AM05 AM07 BJ03 BJ12 HJ00 HJ02 HJ10 HJ20

Claims (17)

[Claims] 1. A non-aqueous electrolytic solution containing a solute and an organic solvent, wherein the organic solvent contains a carbonate compound (I), and the compound is obtained by a non-restricted Hartree-Fock method. In the optimized structure of the anion state obtained by an ab initio molecular orbital method using a 21G basis function, at least one of carbon atoms bonded to a carbonate group (the carbon atom is not a constituent atom of a methyl group) The value of Mulliken population (MP value) is-
Non-aqueous electrolyte solution characterized by being 0.17 or less. 2. The method according to claim 1, wherein the MP value is -0.19 or less.
2. The non-aqueous electrolyte according to 1. 3. A non-aqueous electrolytic solution containing a solute and an organic solvent, wherein the organic solvent contains a carbonate compound (I ′), and the compound is obtained by a non-restricted Hartree-Fock method. When a stable structure in an anion state obtained by an ab initio molecular orbital method using a -21G basis function is obtained, a carbon atom bonded to a carbonate group (however, the carbon atom is not a constituent atom of a methyl group) Characterized in that at least one of the above and the terminal oxygen atom constituting the carbonate group are cleaved. 4. A method according to claim 1, wherein said carbonate compound (I) has a stable structure in an anion state obtained by an ab initio molecular orbital method using a 3-21G basis function by an unrestricted Hartree-Fock method. The carbonate compound according to claim 1, wherein at least one of the carbon atoms bonded to the carbonate group (the carbon atom is not a constituent atom of the methyl group) and the terminal oxygen atom of the carbonate group are cleaved. Non-aqueous electrolyte. 5. The carbonate compound (I) or (I ′) is a compound represented by the following general formula:
5. The non-aqueous electrolytic solution according to any one of items 1 to 4. Embedded image (Wherein A and B are each independently a hydrogen atom and / or
Or a carbon atom to which a substituent is bonded. (A cross-linking may exist between A and B.) 6. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (2). Embedded image (In the formula, -F- is a structure bridging between D and E, and represents a carbon chain having 1 to 5 carbon atoms which may have a single bond, a double bond or a triple bond, or a substituent. And E each independently represent a hydrogen atom and / or a carbon atom to which a substituent is bonded, wherein D, E, F, or a crosslinked structure between the above substituents may be present. ) 7. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (3). Embedded image (Wherein, R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group which may have a substituent,
Alkenyl group, alkynyl group, phenyl group, acyl group,
Represents an ester group or an ether group or a halogen atom. G represents a methylene group or a vinylene group which may have a substituent; -IJ- (wherein I and J each independently represent a methylene group or a vinylene group which may have a substituent; Represents) or (Wherein, R ⁵ and R ⁶ are each independently a hydrogen atom,
An alkyl group which may have a substituent, an alkenyl group,
Represents an alkynyl group, a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom). A cross-linking structure between G and the above substituents may be present. 8. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (4). Embedded image (Wherein, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group which may have a substituent,
Alkenyl group, alkynyl group, phenyl group, acyl group,
Represents an ester group or an ether group or a halogen atom. (A crosslinked structure between the above substituents may be present.) 9. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (5). Embedded image (Wherein, R ¹¹ and R ¹² are each independently a hydrogen atom,
An alkyl group which may have a substituent, an alkenyl group,
Represents an alkynyl group, a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.) 10. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (6). Embedded image (In the formula, G represents a methylene group or a vinylene group which may have a substituent, n is 0 or 1, and R ¹³ , R ¹⁴ ,
R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group, an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.) 11. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (7). Embedded image (Wherein, R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ each independently represent a hydrogen atom, an alkyl group which may have a substituent,
Alkenyl group, alkynyl group, phenyl group, acyl group,
Represents an ester group or an ether group or a halogen atom. (A crosslinked structure between the above substituents may be present.) 12. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (8). Embedded image (Wherein, R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group ,
Represents an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.) 13. The non-aqueous electrolyte according to claim 1, wherein the carbonate compound (I) or (I ′) is a compound represented by the following general formula (9). Embedded image (Wherein, R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, a phenyl group ,
Represents an acyl group, an ester group or an ether group, or a halogen atom. (A crosslinked structure between the above substituents may be present.) 14. The total content of the carbonate compounds (I) and (I ′) in the organic solvent is 0.001 to 2
The non-aqueous electrolyte according to any one of claims 1 to 13, which is 0% by weight. 15. The method according to claim 1, wherein the solute contains a lithium salt.
15. The non-aqueous electrolytic solution according to any one of items 14 to 14. 16. The non-aqueous electrolyte according to claim 1, wherein the organic solvent contains an organic solvent having a relative dielectric constant of 20 or more. 17. A negative electrode, a positive electrode, and a positive electrode containing a carbonaceous material capable of inserting and extracting lithium.
A non-aqueous electrolyte secondary battery comprising at least the non-aqueous electrolyte according to any one of the above.