JP2001057238A - Non-aqueous electrolyte and secondary battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery with superior charging and discharging efficiency, load characteristic and low temperature characteristic by using an electrolyte solution composed of a non-aqueous solvent including a phenylene dicarbonate derivative and an electrolyte. SOLUTION: A non-aqueous solvent is preferably prepared by adding 0.01-15 wt.% of a phenylene dicarbonate derivative represented by a formula (R1 and R2 are 1-11C hydrocarbon group, R3 is 1-11C hydrocarbon group, alkyloxy group, aryloxy group or 1-9C alkylsilyloxy group, and (n) is an integer of 0-4), to the total non-aqueous solvent, and mixing the same with at least one kind of cyclic carbonic ester and/or chained carbonic ester represented by a formula II and a formula III (R4-R7 are each H or 1-6C alkyl group). A lithin ion secondary battery consists of non-aqueous electrolytic solution composed of lithium salt and the non-aqueous solvent, a negative electrode active material such as a carbon material or the like capable of doping and dedoping a lithium ion, and a positive electrode active material such as a compound oxide of lithium and transition metal or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte having excellent charge / discharge characteristics and a secondary battery using the same. More specifically, the present invention relates to a non-aqueous electrolyte suitable for a lithium secondary battery containing a phenylenedicarbonate derivative, and a secondary battery using the same.

[0002]

BACKGROUND OF THE INVENTION A battery using a non-aqueous electrolyte has a high voltage, a high energy density, and a high reliability such as storability, so that it is widely used as a power source for consumer electronic devices. Have been.

As such a battery, there is a non-aqueous electrolyte secondary battery, a typical example of which is a lithium ion secondary battery. Carbonate compounds having a high dielectric constant are known as non-aqueous solvents used for such a purpose, and the use of various carbonate compounds has been proposed. As an electrolytic solution, LiBF ₄ , LiPF ₆ , LiPF ₆ , a mixed solvent of the high dielectric constant carbonate compound solvent such as propylene carbonate and ethylene carbonate, and a low viscosity solvent such as diethyl carbonate.
A solution in which an electrolyte such as LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , or Li ₂ SiF ₆ is mixed is used.

[0004] On the other hand, research on electrodes has been promoted with the aim of increasing the capacity of batteries, and carbon materials capable of occluding and releasing lithium are used as negative electrodes of lithium ion secondary batteries. In particular, highly crystalline carbon such as graphite has characteristics such as a flat discharge potential, and is therefore used as most negative electrodes of currently commercially available lithium ion secondary batteries.

However, when highly crystalline carbon such as graphite is used for the negative electrode, propylene carbonate or 1,2-butylene carbonate, which is a high dielectric constant solvent having a low freezing point, is used as a non-aqueous solvent for the electrolytic solution. Occasionally, a reductive decomposition reaction of the solvent occurs, and the insertion reaction of lithium ions, which is an active material, into graphite hardly progresses, so that the function of the electrolytic solution is reduced. As a result, the initial charge / discharge efficiency is extremely reduced.

For this reason, as a non-aqueous solvent having a high dielectric constant used as an electrolyte, ethylene carbonate, which is solid at room temperature but hardly undergoes reductive decomposition reaction continuously, is mixed with propylene carbonate to form a non-aqueous solvent. Attempts have been made to suppress the reductive decomposition reaction of the solvent. Furthermore, in order to improve the viscosity characteristics of the non-aqueous solvent in addition to suppressing the reductive decomposition reaction, devising a combination with a low-viscosity solvent, adding various additives, and reducing the content of propylene carbonate in the electrolytic solution. Restrictions have been proposed. These measures have improved the charge-discharge characteristics and low-temperature characteristics of the battery.However, furthermore, for example, when the high-temperature storage and charge-discharge cycles are repeated, the battery life caused by minute reductive decomposition reaction is reduced. There is a need for an electrolyte solution that can be improved and further improved low-temperature characteristics.

[0007]

SUMMARY OF THE INVENTION In order to meet the above demand, the present invention suppresses the reductive decomposition reaction of a solvent even when a highly crystalline carbon such as graphite is used for a negative electrode, thereby shortening the battery life. It is an object of the present invention to provide a non-aqueous electrolyte which improves the charge and discharge efficiency, load characteristics and low-temperature characteristics of a battery. Another object is to provide a secondary battery including the non-aqueous electrolyte.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a non-aqueous electrolyte comprising a non-aqueous solvent containing a phenylenedicarbonate derivative and an electrolyte, and a secondary battery using the same. It is. (1) A non-aqueous electrolytic solution comprising a non-aqueous solvent containing a phenylenedicarbonate derivative represented by the general formula [1] and an electrolyte.

Embedded image (R ¹ and R ² may be the same or different and represent a hydrocarbon group having 1 to 11 carbon atoms, and R ³ has 1 to 1 carbon atoms.
1 hydrocarbon group, alkyloxy group having 1 to 11 carbon atoms,
An aryloxy group having 1 to 11 carbon atoms or 1 to 9 carbon atoms
Wherein n is an integer of 0-4. (2) The phenylene carbonate derivative represented by the general formula [1] is phenylene-1,4-di (methyl carbonate) or phenylene-1,4-di (ethyl carbonate). The non-aqueous electrolyte according to (1). (3) The non-aqueous solvent is a compound represented by the general formula [1], at least one of cyclic carbonates represented by the general formula [2a] or [2b] and / or chain carbonic acid (1) (2) characterized by containing an ester.
The non-aqueous electrolyte according to the above.

Embedded image (In the formula [2a] or [2b], R ^{4 to} R ⁷ may be the same or different from each other, and are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.) (3) The cyclic carbonate represented by the general formula [2a] or [2b] is any one of ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate.
The non-aqueous electrolyte according to the above. (5) The non-aqueous electrolyte according to (3), wherein the chain carbonate is one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. (6) The non-aqueous solution according to (1) to (5), wherein the compound represented by the general formula [1] is contained in an amount of 0.1 to 15% by weight based on the whole non-aqueous solvent. Electrolyte. (7) The weight ratio of at least one of the cyclic carbonates represented by the general formula [2a] or [2b] and the chain carbonate in the non-aqueous solvent is 15:85 to 55:45. The non-aqueous electrolyte according to any one of (4) to (6). (8) The non-aqueous electrolyte according to any one of (1) to (7), wherein the electrolyte is a lithium salt. (9) A secondary battery comprising the nonaqueous electrolyte according to any one of (1) to (8). (10) Metallic lithium, lithium-containing alloy, or carbon material capable of doping and undoping lithium ions, tin oxide capable of doping and undoping lithium ions, and doping and undoping of lithium ions as a negative electrode active material A negative electrode including any of titanium oxide, niobium oxide, silicon capable of doping and undoping of vanadium oxide or lithium ion, and a transition metal oxide as a positive electrode active material,
A positive electrode containing any one of a transition metal sulfide, a composite oxide of lithium and a transition metal, a conductive polymer material, a carbon material, and a mixture thereof; and a nonaqueous electrolyte according to any one of (1) to (8) And a lithium ion secondary battery comprising: (11) The carbon material capable of doping / dedoping lithium ions has a plane distance (d002) on the (002) plane measured by X-ray analysis of 0.340 nm or less. The lithium ion secondary battery according to the above (1).

Next, the non-aqueous electrolyte according to the present invention and a non-aqueous electrolyte secondary battery using this non-aqueous electrolyte will be described in detail. The non-aqueous electrolyte according to the present invention comprises a non-aqueous solvent containing a carboxylic anhydride having a carbon-carbon unsaturated bond in a molecule, and an electrolyte, and each will be described in detail.

Phenylenedicarbonate Derivatives As the phenylenedicarbonate derivatives contained in the non-aqueous solvent in the present invention, those represented by the following general formula [1] are used.

Embedded image (R ¹ and R ² may be the same or different and represent a hydrocarbon group having 1 to 11 carbon atoms, and R ³ has 1 to 1 carbon atoms.
1 hydrocarbon group, alkyloxy group having 1 to 11 carbon atoms,
An aryloxy group having 1 to 11 carbon atoms or 1 to 9 carbon atoms
Wherein n is an integer of 0-4. Specific examples of R ¹ and R ² include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group and a t-
C1-C6 alkyl groups such as butyl group, pentyl group and hexyl group; C6-C1 groups such as phenyl group, methylphenyl group, ethylphenyl group and tetramethylphenyl group.
1 to 2 carbon atoms such as aryl group, vinyl group, allyl group
And the like. Specific examples of R ³ include an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a t-butyl group, a pentyl group, and a hexyl group; An aryl group having 6 to 11 carbon atoms, such as a methyl group, a methylphenyl group, an ethylphenyl group, and a tetramethylphenyl group; an alkenyl group having 2 to 6 carbon atoms such as a vinyl group and an allyl group; a methoxy group, an ethoxy group, and a propoxy group An alkyloxy group having 1 to 6 carbon atoms such as an isopropoxy group, a butoxy group, a pentoxy group, and a hexyloxy group; an aryloxy group having 6 to 11 carbon atoms such as a phenoxy group; and a carbon atom having 1 to 1 carbon atom such as a trimethylsilyloxy group. And 9 alkylsilyloxy groups. From the viewpoint of the solubility of the additive in the electrolytic solution, the substituent preferably has 3 or less carbon atoms. In the above general formula, n is particularly preferably 0 to 2.

Specific examples of the compound include the following compounds. Phenylene-1,4-di (methyl carbonate), phenylene-1,3-di (methyl carbonate), phenylene-1,2-di (methyl carbonate), phenylene-1,4-di (ethyl carbonate), phenylene- 1,3-di (ethyl carbonate), phenylene-1,2-di (ethyl carbonate), phenylene-1,4-di (propyl carbonate), phenylene-1,4-di (butyl carbonate), phenylene-1, 4-di (phenyl carbonate), phenylene-2-methyl-1,4-di (methyl carbonate), phenylene-2-methoxy-1,4-di (methyl carbonate), phenylene-2-ethyl-
1,4-di (methyl carbonate), phenylene-2-
Ethoxy-1,4-di (methyl carbonate), phenylene-2-methyl-1,4-di (ethyl carbonate), phenylene-2-methoxy-1,4-di (ethyl carbonate), phenylene-2-ethyl- 1,4-di (ethyl carbonate), phenylene-2-ethoxy-
1,4-di (ethyl carbonate)

Such a phenylenedicarbonate derivative has an effect of suppressing the reductive decomposition reaction of the non-aqueous solvent during charging.

Non- aqueous solvent In the non-aqueous electrolyte according to the present invention, a non-aqueous solvent containing a phenylenedicarbonate derivative is used. This phenylenedicarbonate derivative can be used as an additive to commonly used non-aqueous solvents. In the non-aqueous electrolyte according to the present invention, the content of the phenylenedicarbonate derivative in the non-aqueous solvent is based on the non-aqueous solvent containing the phenylenedicarbonate derivative (total amount of the phenylenedicarbonate derivative and other non-aqueous solvents). 0.001% by weight or more, preferably 0.01 to 1%
It is desirable to be in the range of 5% by weight, more preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight. When the phenylenedicarbonate derivative is contained in the nonaqueous solvent containing the phenylenedicarbonate derivative in such a mixing ratio, the reductive decomposition reaction of the solvent that occurs at the time of charging can be suppressed low,
Battery life such as high-temperature storage characteristics and cycle characteristics can be improved. In the present invention, in particular, at least one of a phenylenedicarbonate derivative and a cyclic carbonate represented by the following general formula [2a] or [2b] from the viewpoint of improving battery characteristics (particularly, high-temperature storage characteristics, load characteristics, and low-temperature characteristics). It is desirable to use a non-aqueous solvent containing the seed and / or chain carbonate.

In the present invention, a non-aqueous solvent containing a phenylenedicarbonate derivative and at least one cyclic carbonate represented by the following general formula [2a] or [2b] and / or a chain carbonate is used. It is desirable to do.

Examples of the non-aqueous solvent that can be used include at least one cyclic carbonate represented by the following general formula [2a] or [2b] and / or a chain carbonate.

Embedded image (In the formula [2a] or [2b], R ^{4 to} R ⁷ may be the same or different and each is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.) The group is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples include a methyl group, an ethyl group, and an n-propyl group.

Specific examples of the cyclic carbonate represented by the general formula [2a] or [2b] include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate,
Examples thereof include 2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. In particular, ethylene carbonate and propylene carbonate having a high dielectric constant are preferably used. When the improvement of the battery life is particularly intended, ethylene carbonate is particularly preferable. These cyclic carbonates may be used as a mixture of two or more kinds.

Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, and ethyl propyl carbonate. In particular, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate having low viscosity are preferably used. These chain carbonates may be used as a mixture of two or more.

Specific examples of the combination of the cyclic carbonate and the chain carbonate of the non-aqueous solvent include ethylene carbonate and dimethyl carbonate, ethylene carbonate and methyl ethyl carbonate, ethylene carbonate and diethyl carbonate, propylene carbonate and dimethyl carbonate, and propylene carbonate. And methyl ethyl carbonate, propylene carbonate and diethyl carbonate, ethylene carbonate and propylene carbonate and dimethyl carbonate, ethylene carbonate and propylene carbonate and methyl ethyl carbonate,
Ethylene carbonate and propylene carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and propylene carbonate and dimethyl carbonate and methyl ethyl carbonate, ethylene carbonate and propylene carbonate and dimethyl carbonate Diethyl carbonate and the like.

When such a chain carbonate is contained in a non-aqueous solvent, the viscosity of the non-aqueous electrolyte can be reduced, the solubility of the electrolyte can be further increased, and the electric conductivity at normal temperature or low temperature can be improved. It is possible to obtain an electrolytic solution having excellent properties.
Therefore, low-temperature characteristics such as load characteristics at low temperatures of the battery can be improved.

In the present invention, when a non-aqueous solvent comprising a phenylenedicarbonate derivative and at least one of the cyclic carbonates represented by the general formula [2a] or [2b] and / or a chain carbonate is used. The content of the phenylenedicarbonate derivative represented by the general formula [1] in the nonaqueous solvent is determined based on the total amount of the nonaqueous solvent containing the phenylenedicarbonate derivative (the phenylenedicarbonate derivative and the general formula [2]
a] or at least one of the cyclic carbonates represented by [2b] and / or the total amount of the cyclic carbonates) and 0.001% by weight or more, preferably 0.1% by weight or more.
Desirably, it is contained in an amount of from 0.01 to 15% by weight, more preferably from 0.1 to 10% by weight, most preferably from 0.2 to 5% by weight.

When the phenylenedicarbonate derivative is contained in the entire non-aqueous solvent containing the phenylenedicarbonate derivative in such a mixing ratio, the reductive decomposition reaction of the solvent which occurs at the time of charging can be suppressed to a low level, and high-temperature storage characteristics, cycle characteristics, etc. Battery life can be improved.

In a non-aqueous solvent, the compound represented by the general formula [2a]
Alternatively, the mixing ratio of at least one of the cyclic carbonates represented by [2b] and the chain carbonate is represented by a weight ratio, and the cyclic carbonate represented by the above general formula [2a] or [2b] At least one of the following: a chain carbonate is 0: 100 to 100: 0, preferably 5: 9
5 to 80:20, more preferably 10:90 to 70:
30, particularly preferably 15:85 to 55:45.
With such a ratio, the increase in the viscosity of the electrolyte can be suppressed, and the degree of dissociation of the electrolyte can be increased. Therefore, the conductivity of the electrolyte relating to the charge / discharge characteristics of the battery can be increased.

Accordingly, a preferred non-aqueous solvent according to the present invention is a phenylenedicarbonate derivative, at least one of the cyclic carbonates represented by the general formula [2a] or [2b] and / or the chain carbonate. It contains esters.

When the phenylenedicarbonate derivative is used in combination with the non-aqueous electrolyte according to the present invention or the non-aqueous electrolyte according to the present invention, the other non-aqueous solvent is used. In addition to the above-mentioned solvent (cyclic and / or chain carbonate), or in addition to the above-mentioned solvent (cyclic and / or chain carbonate), other solvents widely used as non-aqueous solvents for batteries in general May be used,
Specific examples of other solvents include chain esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and methyl valerate; Phosphate esters such as trimethyl acid; 1,2-dimethoxyethane;
Chain ethers such as 1,2-diethoxyethane, diethyl ether, dimethyl ether, methyl ethyl ether and dipropyl ether; 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyl-1 Cyclic ethers such as 2,3-dioxolan and 2-methyl-1,3-dioxolan; amides such as dimethylformamide; linear carbamates such as methyl-N, N-dimethylcarbamate; γ-butyrolactone, γ-valerolactone, 3- Cyclic esters such as methyl-γ-butyrolactone and 2-methyl-γ-butyrolactone; cyclic sulfones such as sulfolane; cyclic carbamates such as N-methyloxazolidinone; cyclic amides such as N-methylpyrrolidone;
Cyclic ureas such as -dimethylimidazolidinone; 4,4-dimethyl-5-methyleneethylene carbonate, 4-methyl-4-
Ethyl-5-methylene ethylene carbonate, 4-methyl-4-
Propyl-5-methyleneethylene carbonate, 4-methyl
-4-butyl-5-methyleneethylene carbonate, 4,4-diethyl-5-methyleneethylene carbonate, 4-ethyl-4-propyl-5-methyleneethylene carbonate, 4-ethyl-4-
Butyl-5-methyleneethylene carbonate, 4,4-dipropyl-5-methyleneethylene carbonate, 4-propyl-4-
Butyl-5-methyleneethylene carbonate, 4,4-dibutyl-5-methyleneethylene carbonate, 4,4-dimethyl-5-
Ethylidene ethylene carbonate, 4-methyl-4-ethyl-
5-ethylidene ethylene carbonate, 4-methyl-4-propyl-5-ethylidene ethylene carbonate, 4-methyl-4
-Butyl-5-ethylidene ethylene carbonate, 4,4-diethyl-5-ethylidene ethylene carbonate, 4-ethyl-4-
Propyl-5-ethylidene ethylene carbonate, 4-ethyl-4-butyl-5-ethylidene ethylene carbonate, 4,4-
Dipropyl-5-ethylidene ethylene carbonate, 4-propyl-4-butyl-5-ethylidene ethylene carbonate,
4,4-dibutyl-5-ethylidene ethylene carbonate, 4-
Methyl-4-vinyl-5-methyleneethylene carbonate, 4-
Methyl-4-allyl-5-methyleneethylene carbonate, 4-
Methyl-4-methoxymethyl-5-methyleneethylene carbonate, 4-methyl-4-acryloxymethyl-5-methyleneethylene carbonate, 4-methyl-4-allyloxymethyl-
Cyclic carbonates such as 5-methyleneethylene carbonate; vinylethylene carbonate derivatives such as 4-vinylethylene carbonate, 4,4-divinylethylene carbonate, and 4,5-divinylethylene carbonate; 4-vinyl-4
-Methylethylene carbonate, 4-vinyl-5-methylethylene carbonate, 4-vinyl-4,5-dimethylethylene carbonate, 4-vinyl-5,5-dimethylethylene carbonate, 4-vinyl-4,5,5-trimethyl Alkyl-substituted vinyl ethylene carbonate derivatives such as ethylene carbonate; 4-allyloxymethyl ethylene carbonate, 4,5-
Allyloxymethylethylene carbonate derivatives such as diallyloxymethylethylene carbonate; 4-methyl
Alkyl-substituted allyloxymethylethylene carbonate derivatives such as -4-allyloxymethylethylene carbonate and 4-methyl-5-allyloxymethylethylene carbonate; 4-acryloxymethylethylene carbonate, 4,5-acryloxymethylethylene carbonate and the like Acryloxymethylethylene carbonate derivatives; alkyl-substituted acryloxymethylethylene carbonate derivatives such as 4-methyl-4-acryloxymethylethylene carbonate and 4-methyl-5-acryloxymethylethylene carbonate; and derivatives such as sulfolane and dimethyl sulfate Sulfur compounds; phosphorus-containing compounds such as trimethylphosphoric acid and triethylphosphoric acid; and compounds represented by the following general formula. HO (C
H ₂ CH ₂ O) aH, HO ｛CH ₂ CH (CH ₃ ) O｝ b
H, CH ₃ O (CH ₂ CH ₂ O) c H, CH ₃ O ｛CH ₂ C
H (CH ₃ ) O｝ d H, CH ₃ O (CH ₂ CH ₂ O) e CH
₃ , CH ₃ O ｛CH ₂ CH (CH ₃ ) O｝ f CH ₃ , C ₉ H ₁₉
PhO (CH ₂ CH ₂ O) g {CH (CH ₃ ) O} h CH ₃
(Ph is a phenyl group), CH ₃ O ｛CH ₂ CH (CH ₃ )
O｝ iCO ｛O (CH ₃ ) CHCH ₂ ｝ jOCH ₃ (where a to f are integers of 5 to 250, and g to j are 2 to 249
5 ≦ g + h ≦ 250 and 5 ≦ i + j ≦ 250. )

The non-aqueous electrolytic solution The non-aqueous electrolyte solution of the present invention is formed of a non-aqueous solvent containing a phenylene carbonate derivative in the molecule as described above and an electrolyte, a nonaqueous containing, for example, phenylene carbonate derivatives It is obtained by dissolving an electrolyte in a solvent.
As the electrolyte to be used, any electrolyte which is usually used as an electrolyte for a non-aqueous electrolyte can be used.

As a specific example of the electrolyte, LiPF₆, Li
BF_Four, LiClO_Four, LiAsF₆, Li _TwoSiF₆, LiC_FourF
₉SO_Three, LiC₈F₁₇SO_ThreeLithium salts such as
You. In addition, a lithium salt represented by the following general formula is also used.
be able to. LiOSO_TwoR⁸, Lin (SO_TwoR⁹) (S
O_TwoR^Ten), LiC (SO_TwoR¹¹) (SO_TwoR¹²) (SO_Two
R¹³), LiN (SO_TwoOR¹⁴) (SO_TwoOR^Fifteen)(here
And R⁸~ R^FifteenAre the same but different
And a perfluoroalkyl group having 1 to 6 carbon atoms.
). These lithium salts may be used alone or
Or two or more of them may be used in combination.

Among these, in particular, LiPF ₆ and LiB
F ₄ , LiOSO ₂ R ⁸ , LiN (SO ₂ R ⁹ ) (SO
^{_{2 R 10), LiC (SO}} 2 R 11) (SO 2 R 12) (SO 2 R
¹³ ), and LiN (SO ₂ OR ¹⁴ ) (SO ₂ OR ¹⁵ ) are preferred.

It is desirable that such an electrolyte is usually contained in the non-aqueous electrolyte at a concentration of 0.1 to 3 mol / l, preferably 0.5 to 2 mol / l.

The non-aqueous electrolyte in the present invention contains a non-aqueous solvent containing a phenylenedicarbonate derivative and an electrolyte as essential components, but may further contain other additives if necessary.

The non-aqueous electrolyte according to the present invention as described above comprises:
Not only is it suitable as a non-aqueous electrolyte for lithium ion secondary batteries, but it can also be used as a non-aqueous electrolyte for primary batteries.

The non-aqueous electrolyte secondary battery according to the secondary batteries present invention, a negative electrode, a positive electrode,
The non-aqueous electrolyte is basically configured to include,
Usually, a separator is provided between the negative electrode and the positive electrode.

As the negative electrode active material constituting the negative electrode, metallic lithium, a lithium alloy, a carbon material capable of doping and undoping lithium ions, tin oxide capable of doping and undoping lithium ions, and oxides Any of niobium, vanadium oxide, titanium oxide capable of doping and undoping lithium ions, and silicon capable of doping and undoping lithium ions can be used. Among these, a carbon material capable of doving / de-doping lithium ions is preferable. Such a carbon material may be graphite or amorphous carbon, and activated carbon, carbon fiber, carbon black, mesocarbon microbeads, natural graphite and the like are used.

As the negative electrode active material, the (002) plane spacing (d002) measured by X-ray analysis was 0.340 nm.
The following carbon materials are preferable, and the density is 1.70 g / cm ³
The graphite described above or a highly crystalline carbon material having properties similar thereto is desirable. When such a carbon material is used, the energy density of the battery can be increased.

As the positive electrode active material constituting the positive electrode, Mo is used.
Transition metal oxides or sulfides such as S ₂ , TiS ₂ , MnO ₂ , V ₂ O ₅ , LiCoO ₂ , LiMnO ₂ , LiMn ₂
Complex oxides composed of lithium and transition metals such as O ₄ , LiNiO ₂ , and LiNiXCo (1-X) O ₂ , conductive polymers such as polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene, and dimercaptothiadiazole / polyaniline composite Materials and the like. Among these, a composite oxide composed of lithium and a transition metal is particularly preferable. When the negative electrode is a lithium metal or lithium alloy, a carbon material can be used as the positive electrode.
Further, as the positive electrode, a mixture of a composite oxide of lithium and a transition metal and a carbon material can be used.

The separator is a porous membrane, and usually a microporous polymer film is suitably used. In particular, a porous polyolefin film is preferable, and specific examples thereof include a porous polyethylene film, a porous polypropylene film, and a multilayer film of a porous polyethylene film and polypropylene.

Such a non-aqueous electrolyte secondary battery can be formed in a cylindrical shape, a coin shape, a square shape, or any other shape. However, the basic structure of the battery is the same regardless of the shape, and the design can be changed according to the purpose. Next, the structures of the cylindrical and coin type batteries will be described. The negative electrode active material, the positive electrode active material, and the separator constituting each battery are commonly used.

For example, in the case of a cylindrical non-aqueous electrolyte secondary battery, a negative electrode obtained by applying a negative electrode active material to a negative electrode current collector,
A positive electrode obtained by applying a positive electrode active material to a positive electrode current collector is wound through a separator into which a non-aqueous electrolyte is injected, and is housed in a battery can with an insulating plate placed above and below the wound body. ing.

The non-aqueous electrolyte secondary battery according to the present invention can be applied to a coin-type non-aqueous electrolyte secondary battery. In a coin-type battery, a disc-shaped negative electrode, a separator, a disc-shaped positive electrode, and a stainless steel or aluminum plate are housed in a coin-shaped battery can in a state of being stacked in this order.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0039]

Example 1 <Preparation of non-aqueous electrolyte> Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed with E
After mixing at a ratio of C: DMC = 40: 60 (weight ratio), phenylene-1,4-di (methyl carbonate) was added as an additive to 99.5 parts by weight of the mixed solvent.
0.5 part by weight was added to prepare a non-aqueous solvent. Next, LiPF6 as an electrolyte is dissolved in a non-aqueous solvent, and the electrolyte concentration is set to 1.
A non-aqueous electrolyte was prepared so as to be 0 mol / liter.
The leakage current of a battery using this non-aqueous electrolyte was measured by the following method. The results are shown in Table 1.

<Preparation of Negative Electrode> Natural graphite (LF made of Chuetsu graphite)
-18A) 87 parts by weight and 13 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed and dispersed in N-methylpyrrolidinone as a solvent to prepare a natural graphite mixture slurry. Next, this negative electrode mixture slurry was applied to a 18-μm-thick negative electrode current collector made of strip-shaped copper foil, dried, compression-molded, and punched out into a 14 mm disk shape to form a coin-shaped natural graphite. An electrode was obtained. The thickness of this natural graphite electrode mixture is 1
10 microns, weight was 20 mg / Φ14 mm.

<Production of Battery> A coin-type battery shown in FIG. 1 was produced. 14mm diameter natural graphite electrode 14, diameter 16
A metal lithium foil 13 having a thickness of 0.3 mm and a separator 15 made of a microporous polypropylene film having a thickness of 25 μm and a diameter of 19 mm were made of stainless steel 20.
The lithium metal foil 13, the separator 15, and the natural graphite electrode 14 were stacked in the order of 32 in a 32-size battery can 16.
Thereafter, 0.05 ml of the non-aqueous electrolyte was poured into the separator, and a stainless steel plate 17 (thickness 1.2 mm, diameter 1
5.5 mm and the spring 20 were stored. Finally, a battery can lid 19 is inserted through a gasket 18 made of polypropylene.
By caulking, a coin-type Li-natural graphite battery having a diameter of 20 mm and a height of 3.2 mm was produced while maintaining the airtightness in the battery.

<Measurement of Amount of Electrolysis on Natural Graphite Electrode (Measurement of Leakage Current)> The amount of electrolysis of the electrolytic solution on the natural graphite electrode was measured by measuring a leakage current described below. First, the coin-type Li-natural graphite battery is 1 m
Discharge for a total of 10 hours under the condition of A constant current 0V constant voltage,
Next, charging was performed for 10 hours under the conditions of a constant current of 1 mA and a constant voltage of 1.2 V. Subsequently, a discharge was performed for a total of 5 hours under the condition of a constant current of 2 mA and a constant voltage of 0 V.
Assuming that charging for a total of 5 hours under the condition of V constant voltage was one cycle, two cycles of discharging and charging were performed. Further, discharge was performed for 10 hours under the condition of a constant current of 2 mA and a constant voltage of 0.01 V. Thereafter, the temperature of the battery was raised to 60 ° C., and a total of 2
The discharge was continued for 5 hours, and the change in the current flowing at this time was tracked. This current value rapidly attenuates immediately after the start of discharge at 60 ° C., and becomes substantially constant after 15 hours or more. The current that continues to flow by this fixed amount corresponds to the amount of electrolysis of the electrolytic solution on the natural graphite electrode, and the current value measured at 25 hours was defined as “leakage current”. The value of the leakage current was normalized by the weight of the natural graphite used for the measurement. Comparative Example 1 As an electrolytic solution, ethylene carbonate (E
C) and dimethyl carbonate (DMC) by EC: D
After mixing at a ratio of MC = 40: 60 (weight ratio), LiPF6 as an electrolyte was added to the mixed solvent at an electrolyte concentration of 1.
Leakage current was measured in the same manner as in Example 1 using a solution dissolved to 0 mol / liter.
The results are shown in Table 1.

[Table 1] As described above, in the electrolytic solution of the present invention, the leakage current representing the amount of electrolysis of the electrolytic solution on the natural graphite electrode is small, indicating that the electrolytic solution of the electrolytic solution is suppressed.

[0043]

The non-aqueous electrolyte of the present invention can suppress the reductive decomposition reaction of the solvent which occurs when highly crystalline carbon such as graphite is used for the negative electrode. As a result, a secondary battery using this non-aqueous electrolyte is excellent in battery life such as high-temperature storage characteristics and cycle characteristics, charge / discharge characteristics, load characteristics, and battery characteristics at low temperatures. Therefore, this non-aqueous electrolyte is particularly suitable as a non-aqueous electrolyte for a lithium ion secondary battery.

Claims (11)

[Claims] 1. A non-aqueous electrolyte comprising a non-aqueous solvent containing a phenylenedicarbonate derivative represented by the general formula [1] and an electrolyte. Embedded image (R ¹ and R ² may be the same or different and represent a hydrocarbon group having 1 to 11 carbon atoms, and R ³ has 1 to 1 carbon atoms.
1 hydrocarbon group, alkyloxy group having 1 to 11 carbon atoms,
An aryloxy group having 1 to 11 carbon atoms or 1 to 9 carbon atoms
Wherein n is an integer of 0-4. ) 2. The phenylenedicarbonate derivative represented by the general formula [1] is phenylene-1,4-di (methyl carbonate) or phenylene-1,4-di (ethyl carbonate). The non-aqueous electrolyte according to claim 1, wherein 3. The non-aqueous solvent according to the above general formula [1]
The compound represented by the formula (1) and at least one cyclic carbonate represented by the general formula [2a] or [2b] and / or a linear carbonate. Non-aqueous electrolyte. Embedded image (In the formula [2a] or [2b], R ^{4 to} R ⁷ may be the same or different from each other, and are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.) 4. The cyclic carbonate represented by the general formula [2a] or [2b] is ethylene carbonate,
The non-aqueous electrolyte according to claim 3, wherein the non-aqueous electrolyte is one of propylene carbonate, butylene carbonate, and vinylene carbonate. 5. The non-aqueous electrolyte according to claim 3, wherein the chain carbonate is one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. 6. The non-aqueous solution according to claim 1, wherein the compound represented by the general formula [1] is contained in an amount of 0.01 to 15% by weight based on the whole non-aqueous solvent. Electrolyte. 7. The weight ratio of at least one cyclic carbonate represented by the general formula [2a] or [2b] to a chain carbonate in a non-aqueous solvent is 15: 85-5.
The non-aqueous electrolyte according to claim 4, wherein the ratio is 5:45. 8. The non-aqueous electrolyte according to claim 1, wherein the electrolyte is a lithium salt. 9. A secondary battery comprising the non-aqueous electrolyte according to claim 1. 10. A negative electrode active material such as metallic lithium, a lithium-containing alloy, a carbon material capable of doping and undoping lithium ions, a tin oxide capable of doping and undoping lithium ions, and a doping and undoping of lithium ions A negative electrode containing any of titanium oxide, niobium oxide, vanadium oxide or silicon capable of doping and undoping lithium ions, and a transition metal oxide, a transition metal sulfide, and a mixture of lithium and a transition metal as a positive electrode active material. A lithium ion secondary comprising: a positive electrode containing any of a composite oxide, a conductive polymer material, a carbon material, or a mixture thereof; and a nonaqueous electrolyte according to any one of claims 1 to 8. battery. 11. The carbon material capable of doping / dedoping lithium ions is measured by X-ray analysis.
2) The plane distance (d002) on the plane is 0.340
11. The lithium ion secondary battery according to claim 10, wherein the thickness is not more than nm.