JPH07282849A - Nonaqueous electrolytic battery - Google Patents

Abstract

PURPOSE:To increase high rate discharge performance both in the initial stage and after storage by using a solvent containing at least one of specified alkylene biscarbonate compounds. CONSTITUTION:A specified alkylene biscarbonate compound is used as a solvent of a nonaqueous electrolyte. A positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte comprising a solute and a solvent are arranged, and at least one of alkylene biscarbonate compounds represented by a specified general formula is contained in the solvent. The alkylene biscarbonate compound represented by a specified general formula is used alone as the solvent, or by mixing with a cyclic carbonate compound such as ethylene carbonate and propylene carbonate to increase dielectric constant of the solvent. High rate discharge performance in the initial stage and after storage is increased and cycle performance is increased when the battery is used as a secondary battery.

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 battery, and more specifically, a non-aqueous electrolyte solution using a solvent containing at least one specific alkylene biscarbonate compound as a solvent constituting the non-aqueous electrolyte solution. It concerns batteries.

[0002]

2. Description of the Related Art In recent years,
A non-aqueous electrolyte battery using a lithium metal or a lithium alloy or a substance capable of inserting and extracting lithium ions as a negative electrode active material is attracting attention because it has characteristics such as high energy density and low self-discharge. .

However, in the above non-aqueous electrolyte battery,
On the negative electrode side, a reaction occurs with a negative electrode using lithium as an active material, and since the positive electrode side is kept at a high potential, the electrolytic solution is easily decomposed on both the positive and negative electrodes, and storage stability is poor.

Therefore, the development of a non-aqueous electrolyte having excellent storage characteristics or cycle characteristics has been the most important issue in putting the non-aqueous electrolyte battery into practical use.

The above-mentioned non-aqueous electrolyte is a solution of an electrolyte which is a solute dissolved in an organic solvent. The properties required for this solvent are that it has a large dielectric constant and can dissolve a large amount of the electrolyte that is a solute, and that it has a low viscosity. It is stable against oxidation-reduction and does not decompose, has low volatility, and is highly safe in use.

Conventionally, low boiling point solvents such as 1,2-dimethoxyethane and 1,3-dioxolane have been used as a solvent for a non-aqueous electrolyte battery, but these low boiling point solvents have a dielectric constant. In addition to being small, when used alone, lithium, which is the material of the negative electrode, reacts with the solvent and elutes in the electrolyte to reduce the storage characteristics, and the ionic conductivity of the lithium oxide film formed by the reaction is low. Since it is not good, there is a drawback that the internal resistance of the battery increases and the high rate discharge characteristic deteriorates.

Therefore, a mixed solvent of cyclic carbonate having a large dielectric constant such as ethylene carbonate and propylene carbonate and a low boiling point solvent such as 1,2-dimethoxyethane and tetrahydrofuran has been used. This type of solvent is intended to reduce the viscosity of the electrolytic solution by using a solvent having a low boiling point as well as forming a lithium carbonate coating film having excellent ionic conductivity on the surface of the negative electrode by reacting the cyclic carbonic acid ester with lithium. The purpose of this is to prevent the deterioration of the ionic conductivity of the electrolytic solution and to improve the high rate discharge characteristics.

However, low-boiling solvents such as 1,2-dimethoxyethane and tetrahydrofuran are easily decomposed at the contact interface with the high-potential positive electrode because of their low redox potential, and when stored at high temperature for a long time. The lithium carbonate coating formed on the negative electrode surface is gradually decomposed,
Although the initial high rate discharge characteristics could be improved to some extent by changing to an insulating lithium oxide coating, the high rate discharge characteristics after storage were not sufficiently satisfactory.

Therefore, there is a strong demand for improvement in the electrolyte solvent, and for example, JP-A-2-172162, JP-A-2-172163, and JP-A-4-171 are known.
No. 674 and JP-A-5-13088,
It has been proposed to use a mixed solvent of a cyclic carbonate compound such as ethylene carbonate and propylene carbonate and a chain carbonate compound such as dimethyl carbonate, diethyl carbonate and dipropyl carbonate.

By using chain carbonate compounds in place of 1,2-dimethoxyethane and tetrahydrofuran, the high rate discharge characteristics at the initial stage and after storage are improved to some extent, but these chain carbonate compounds are solutes. However, the problem that the electrolyte is difficult to dissolve and that the compound is a low molecular weight compound and easily volatilizes cannot be solved. Therefore, it has been strongly desired to find a solvent that is stable in an oxidation-reduction reaction, is hard to decompose, has excellent electrolyte solubility, and has low volatility.

Therefore, an object of the present invention is to provide a non-aqueous electrolyte battery which is excellent in high rate discharge characteristics at the initial stage and after storage, and is also excellent in cycle characteristics when used as a secondary battery. .

[0012]

Means for Solving the Problems As a result of various studies, the present inventors have found that a specific alkylene biscarbonate compound is a solvent that can meet the above-mentioned demand, and that this solvent is used as a solvent for a non-aqueous electrolyte. It was found that the above-mentioned non-aqueous electrolyte battery can achieve the above object.

The present invention has been made based on the above findings, and in a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution comprising a solute and a solvent, the solvent is ] A non-aqueous electrolyte battery containing at least one alkylenebiscarbonate compound represented by the general formula (I) (same as the above [Chemical Formula 1]).

[0014]

[Chemical 2]

The non-aqueous electrolyte battery of the present invention will be described in detail below.

The non-aqueous electrolyte battery of the present invention comprises a positive electrode, a negative electrode,
It is composed of a separator and a non-aqueous electrolytic solution containing a solute and a solvent, and the solvent contains at least one alkylene biscarbonate compound represented by the general formula (I) which is a non-aqueous solvent. .

In the above alkylenebiscarbonate compound, examples of the linear or branched alkyl group having 1 to 18 carbon atoms represented by R ₁ , R ₂ and R ₃ in the general formula (I) include , Methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, pentyl, isopentyl, sec-pentyl, hexyl, heptyl, octyl, isooctyl, sec-octyl, 2-ethylhexyl, nonyl, isononyl, decyl, isodecyl, dodecyl. , Tetradecyl, hexadecyl, octadecyl, and the like. As the compound represented by the general formula (I), R ₁ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₂ and R ₃ has 1 carbon atom
Compounds that are alkyl groups of ~ 6 are preferred.

Therefore, examples of the alkylenebiscarbonate compound represented by the above general formula (I) used as a solvent in the present invention include 1,2-bis (methoxycarbonyloxy) ethane and 1,2-bis (ethoxy). Carbonyloxy) ethane, 1,2-bis (isopropoxycarbonyloxy) ethane, 1,2-bis (butoxycarbonyloxy) ethane, 1,2-bis (isobutoxycarbonyloxy) ethane, 1,2-bis (hexyl) Siloxycarbonyloxy) ethane, 1,2-bis (methoxycarbonyloxy) propane, 1,2-bis (ethoxycarbonyloxy) propane, 1,2-bis (isopropoxycarbonyloxy) propane, 1,2-bis (butoxy) Carbonyloxy) propane, 1,2-bis (isobutoxyca) Boniruokishi) propane, 1,2
Bis (hexyloxycarbonyloxy) propane, 1,
2-bis (methoxycarbonyloxy) butane, 1,2
-Bis (methoxycarbonyloxy) hexane, 1,2
-Bis (methoxycarbonyloxy) octane and the like.

The alkylenebiscarbonate compound represented by the general formula (I) can be used alone as a solvent, but in order to increase the dielectric constant of the solvent,
It is preferably used as a mixed solvent with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate. The ratio of the alkylene bis carbonate compound to the cyclic carbonate compound according to the present invention is not particularly limited, and may be 5:95 to 100: depending on the purpose.
It is appropriately selected from the range of 0 (capacity ratio).

Further, in the non-aqueous electrolyte battery of the present invention, another non-aqueous solvent may be used together with the above alkylene bis carbonate compound for the purpose of reducing the viscosity. The other non-aqueous solvent is not particularly limited and includes, for example, γ-butyrolactone, diethyl ether, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, 1,3-dioxolane. , 4-methyl-1,3-dioxolane, dimethyl sulfoxide, dimethylformamide, sulfolane, methyl acetate, toluene and the like which have been used as conventional solvents for non-aqueous electrolytes.

When used as a mixed solvent of the alkylene bis carbonate compound and the other non-aqueous solvent, the content of the alkylene bis carbonate compound in the mixed solvent is 5% by volume or more, particularly 10% by volume or more. It is preferable. When the content is less than 5% by volume, the effect of using the alkylenebiscarbonate compound is poor, and the effect as a non-aqueous electrolyte battery cannot be sufficiently exhibited.

The positive electrode, the negative electrode and the separator in the present invention are not particularly limited, but conventionally,
Various materials used for the non-aqueous electrolyte battery can be used as they are.

Examples of the positive electrode material include LiCoO ₂ ,
Inorganic lithium compounds such as LiMn ₂ O ₄ and LiNiO ₂ , titanium disulfide, iron disulfide, ferrous sulfide, iron sulfide such as ferric sulfide, manganese dioxide, cobalt monoxide, dicobalt trioxide, cobalt dioxide, Niobium disulfide, V ₆ O ₁₃ , Cu ₅ V
₂ O ₁₀ , organic conductive polymer substances such as aniline, polyacetylene, polypyrrole, and polythiophene can be cited.Examples of the negative electrode material include a lithium or lithium alloy rolled plate and a carbon material capable of absorbing and desorbing lithium ions. Examples of the separator include
For example, a polypropylene microporous film or a non-woven fabric may be used.

Further, the non-aqueous electrolyte used in the non-aqueous electrolyte battery of the present invention is a non-aqueous solvent in which an electrolyte is dissolved as a solute, and any conventionally known one can be used as the electrolyte. , For example, LiClO ₄ , LiBF ₄ , LiAsF ₆ , Li
SbF ₆ , LiPF ₆ , LiAlCl ₄ , LiB ₁₀ Cl ₁₀ , LiB ₁₂ Cl ₁₂ , Li
B (C ₆ H ₅ ) ₄ , LiB (p-FC ₆ H ₄ ) ₄ , LiB (p-FC ₆ H ₄ ) ₃ CH ₃ , LiI, C
_{F 3 SO 3 Li, NaClO 4} , NaBF 4, such as NaI and the like.

The non-aqueous electrolyte battery of the present invention having the above structure is useful as a primary battery and a secondary battery, and is particularly useful when used as a lithium secondary battery,
Not only the high rate discharge characteristics at the initial stage and after storage but also the cycle characteristics are excellent.

Although it is not clear why the non-aqueous electrolyte battery of the present invention exerts an excellent effect as compared with the case of using another non-aqueous electrolyte solution, a compound having two carbonate bonds in one molecule. By using a solvent containing, it is possible to solvate lithium ions and become electrochemically stable and less likely to decompose, and the solubility of the electrolyte as a solute is high and the conductivity of the electrolytic solution is increased. Conceivable.

[0027]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples, and can be appropriately modified and implemented within the scope of the invention.

The alkylene biscarbonate compound represented by the general formula (I) is obtained by reacting 1,2-alkylene glycol and alkyl chlorocarbonate in the presence of an acid acceptor such as an organic amine compound. However, the manufacturing method is not limited at all. A specific synthesis example of the alkylene bis carbonate compound is shown below.

Synthesis Example [Synthesis of 1,2-bis (methoxycarbonyloxy) propane] 1500 g of toluene, 152 g of 1,2-propanediol and Taking 586 g of 4-dimethylaminopyridine, a solution prepared by dissolving 567 g of methyl chlorocarbonate in 500 g of toluene was added dropwise while maintaining the temperature at 20 to 25 ° C. After the completion of dropping, the mixture was stirred at room temperature for 30 minutes and then at 60 ° C. for 5 hours.

It was confirmed by gas chromatography that the residual ratio of the methyl chlorocarbonate was 5% or less, 1000 g of toluene and 1000 g of water were added, and the mixture was left standing after stirring. After separating the oil and water, the organic layer was further washed with water, water was added, and hydrochloric acid was added until the aqueous layer became acidic. After taking the organic layer, washing with water and drying, trace amounts of insoluble matter are removed by filtration, the solvent is distilled off under reduced pressure, and 280 g of a colorless liquid product is obtained.
Got

The product analysis results are as follows:
It was confirmed to be the target compound represented by CH ₃ -O-CO-0-CH ₂ CH (CH ₃ ) -O-CO-O-CH ₃ .

Analysis results IR: 2960 cm ^-1 (alkyl), 1750 cm ^-1 (carbonyl) NMR: 1.17-1.27 ppm (3H), 3.70 ppm (6H), 4.03
-4.15 ppm (2H), 4.67-5.17 ppm (1H) Boiling point: 85 ° C / 0.5 mmHg

Example 1 (Non-Aqueous Electrolyte Secondary Battery) FIG. 1 is a cross-sectional view of a flat type non-aqueous electrolyte battery (battery A) which is an embodiment of the non-aqueous electrolyte battery of the present invention.

The negative electrode 1 is made of a lithium-aluminum alloy and is pressure-bonded to the negative electrode current collector 3 fixed to the inner bottom surface of the negative electrode can 2.

The positive electrode 4 was formed by mixing 85% by weight of manganese dioxide, which is a rechargeable active material, with 10% by weight of acetylene black as a conductive agent and 5% by weight of a fluororesin as a binder, mixing them sufficiently, and then molding. It is attached to the positive electrode current collector 6 fixed to the inner bottom surface of the positive electrode can 5 by pressure.

The separator 7 is made of a polypropylene porous film, and the separator 7 has a 1: 1 ratio of 1,2-bis (methoxycarbonyloxy) propane and propylene carbonate obtained in the above synthesis example. (Volume) The mixture is impregnated with an electrolytic solution in which LiBF ₄ is dissolved at a rate of 1 mol / liter.

Reference numeral 8 is an insulating packing, and the size of this battery A is 24 mm in diameter and 3 mm in height.

Comparative Example 1 A comparative battery W was prepared in the same manner as in Example 1 except that a 1: 1 mixture of dimethyl carbonate and propylene carbonate was used as the non-aqueous solvent.

The above batteries A and W were stored in a charged state at 60 ° C. for 20 days, and the battery voltage when discharged at a discharge current of 2 mA was measured with time. Also, battery A after storage
Regarding the battery W, the cycle characteristics were compared under the conditions of discharge current 1.5 mA and discharge charge 3 hours, and the number of cycles until the discharge voltage decreased to 1.5 V within the discharge time was taken as the cycle life. The results are shown in [Table 1] below.

[0040]

[Table 1]

Example 2 (Nonaqueous Electrolyte Secondary Battery) 1,4-bis (methoxycarbonyloxy) propane and propylene carbonate were used as the nonaqueous solvent with which the separator 7 was impregnated with cobalt oxide which could be discharged and charged. And 1,2-dimethoxyethane 20:30:
A battery B similar to that of Example 1 was prepared except that the 50 (capacity) mixture was used.

Comparative Example 2 As the non-aqueous solvent with which the separator 7 is impregnated, dimethoxy carbonate, propylene carbonate and 1,2-
A battery X was prepared in the same manner as in Example 2 except that a 20:30:50 (capacity) mixture of dimethoxyethane was used.

The batteries B and X were stored in a charged state at 60 ° C. for 20 days, and the battery voltage when discharged at a discharge current of 2 mA was measured with time. In addition, changes in internal resistance of the batteries B and X during storage were measured with time. The results are shown in [Table 2] below.

[0044]

[Table 2]

Example 3 (Non-Aqueous Electrolyte Secondary Battery) 1,2-bis (methoxycarbonyloxy) was used as the non-aqueous solvent with which the separator 7 was impregnated, using carbon capable of absorbing and desorbing lithium ions. )propane,
Propylene carbonate and γ-butyrolactone 1
Example 1 except that a 0:30:60 (volume) mixture was used.
A battery C similar to the above was manufactured.

Comparative Example 3 A battery Y was prepared in the same manner as in Example 3 except that a 10:30:60 (volume) mixture of dimethoxycarbonate, propylene carbonate and γ-butyrolactone was used as the nonaqueous solvent with which the separator 7 was impregnated. .

Using the above batteries C and Y, they were stored in a charged state at 60 ° C. for 20 days, and the battery voltage when discharged at a discharge current of 2 mA was measured with time. The results are shown in [Table 3] below.

[0048]

[Table 3]

Example 4 (Nonaqueous Electrolyte Primary Battery) Lithium metal was used for the negative electrode 1 and 350 to 43 for the positive electrode 4.
Using manganese dioxide heat-treated at 0 ° C., 1,2-bis (methoxycarbonyloxy) propane, propylene carbonate and 1,2-dimethoxyethane as a non-aqueous solvent with which the separator 7 is impregnated 20:30:50.
Battery D as in Example 1 except that the (capacity) mixture was used.
Was produced.

Comparative Example 4 As the organic solvent with which the separator 7 is impregnated, dimethoxy carbonate, propylene carbonate and 1,2-
A battery Z was prepared in the same manner as in Example 4 except that a 20:30:50 (capacity) mixture of dimethoxyethane was used.

The batteries D and Z were stored in a charged state at 60 ° C. for 20 days, and the battery voltage when discharged at a discharge current of 2 mA and discharged at a discharge current of 2 mA with time was measured. Measured. The results are shown in [Table 4] below.

[0052]

[Table 4]

As is clear from the results of [Table 1] to [Table 4] above, the non-aqueous electrolytic solution of the present invention using the alkylene bis carbonate compound represented by the general formula (I) as a solvent for the electrolytic solution. The battery has a small decrease in battery voltage even when continuously discharged for a long time after being stored at a high temperature (Examples 1 to 1).
4) Also, it is clear that the increase in internal resistance is small (Example 2). It is also apparent that when the non-aqueous electrolyte battery of the present invention is used as a secondary battery, its cycle characteristics are excellent (Example 1) and the discharge life is remarkably extended.

In the above embodiment, a specific example in which the present invention is applied to a flat type non-aqueous electrolyte battery has been described.
The shape of the non-aqueous electrolyte battery of the present invention is not particularly limited, and it can be applied to various shapes of non-aqueous electrolyte batteries such as a cylindrical type and a rectangular type.

[0055]

INDUSTRIAL APPLICABILITY The non-aqueous electrolyte battery of the present invention is excellent in high rate discharge characteristics at the initial stage and after storage by using a specific alkylene bis carbonate compound as a solvent used in the non-aqueous electrolyte solution, and When used as a secondary battery, it also has excellent cycle characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a non-aqueous electrolyte battery according to the present invention.

[Explanation of symbols]

 1 Negative electrode 2 Negative electrode can 3 Negative electrode current collector 4 Positive electrode 5 Positive electrode can 6 Positive electrode current collector 7 Separator 8 Insulating packing

Claims (1)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution comprising a solute and a solvent, wherein the solvent is a compound represented by the following general formula (I):
A non-aqueous electrolyte battery containing at least one alkylene biscarbonate compound represented by: [Chemical 1]