JPH04206471A - Nonaqueous electrolyte and battery containing it - Google Patents

Abstract

PURPOSE:To improve the high-duty discharge characteristic and cycle characteristic by dissolving an electrolyte in a specific organic solvent or a mixed organic solvent containing it for use as a nonaqueous electrolytic solution. CONSTITUTION:An electrolyte is dissolved in at least one kind of sulfur- containing organic solvent selected among low-grade alkylene trithiocarbonate and 4-low-grade alkyl-1,3-oxathiolane-2-thion or a mixed organic solvent containing it. Ethylene trithiocarbonate, propylene trithiocarbonate, or butylenetrithiocarbonate is used as a practical example for the low-grade alkylenetrithiocarbonate, and propylene carbonate, ethylene carbonate, or 2- methoxytetrahydrofuran is used for the organic solvent, for example. The high- duty discharge characteristic and the cycle characteristic for use in a secondary battery are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a novel non-aqueous electrolyte and a battery containing the same.

(Prior art and its problems) In order to obtain a battery with high battery performance, it is necessary to develop a high-performance electrolyte. In non-aqueous electrolytes, battery performance is affected by the organic solvent in which the electrolyte is dissolved, so it is important to develop organic solvents that provide high battery performance.

Conventionally proposed organic solvents for non-aqueous electrolytes include:
For example, propylene carbonate, methyl aptatate,
2-Methyltetrahydrofuran (U.S. Pat. No. 4+185)
No. 59), ethylene glycol dialkyl ether (JP-A No. 59-205161), mixed solvent of propylene carbonate and ethylene carbonate (JP-A No. 57-1)
70463), a mixed solvent of propylene carbonate, ethylene carbonate, and tetrahydrofuran (Japanese Patent Publication No. 1-21712), a mixed solvent of propylene carbonate, dimethoxyethane, and γ-butyrolactone (Japanese Patent Publication No.
0-121676), thiophene (JP-A-58-75
778) etc.

However, the electrolytes containing these organic solvents that have been proposed so far are not yet satisfactory in terms of high rate discharge characteristics, and are not yet satisfactory in terms of cycle characteristics when used in secondary batteries. There wasn't.

(Problem of the Invention) An object of the present invention is to provide a non-aqueous electrolyte having excellent high-rate discharge characteristics and cycle characteristics when used in a secondary battery, and a battery containing the same.

(Means for Solving the Problems) The present inventors have conducted extensive research to solve the above problems, and as a result, have completed the present invention.

That is, according to the present invention, in at least one sulfur-containing organic solvent selected from lower alkylene trithiocarbonate and 4-lower alkyl-1,3-oxathiolane-2-thione, or a mixed organic solvent containing the same, Provided are a non-aqueous electrolytic solution formed by dissolving an electrolyte in a non-aqueous electrolyte, and a battery containing the same.

In the present invention, in the lower alkylene trithiocarbonate used as the organic solvent for the electrolytic solution, the number of carbon atoms in the lower alkylene group is usually 6 or less. Specific examples of such lower alkylene trithiocarbonates include ethylene trithiocarbonate, propylene trithiocarbonate, butylene trithiocarbonate, and the like. In the 4-lower alkyl-1,3-oxythiola/-2-thousand used as the organic solvent for the electrolyte in the present invention, the number of carbon atoms in the lower alkyl group is usually 6.
It is as follows. Specific examples of such 4-lower argyru-1,3-oxathiolane-2-thione include, for example,
4-Methyl-1,3-oxa-1-2-thi, 4
-ethyl-1,3-oxathiolane-2-thione and the like.

The organic solvent used in the present invention (hereinafter also simply referred to as the organic solvent of the present invention) does not need to be used alone, but can be used in the form of a mixed solvent mixed with various conventionally known organic solvents. Examples of such organic solvents include propylene carbonate, ethylene carbonate, 2-methyltetrahydrofuran, tetrahydrofuran, dioxolane, 2-methyldioxolane, 4-methyldioxolane, 1.2-dimethoxyethane, ethoxymethoxyethane, jetoxyethane, y- Examples include butyrolactone, dimethylsulfoxide, acetonitrile, formamide, dimethylformamide, nitromethane, and the like. When the organic solvent of the present invention is used in the form of a mixed solvent with other organic solvents, the mixing volume ratio is 19 to 91, more preferably),
] It is better to specify before and after.

Among the organic solvents of the present invention, propylene trithiocarbonate, especially when used as a mixed solvent with an ether solvent, exhibits relatively low viscosity and high conductivity, and can be used as an electrolytic solution with outstanding high rate discharge characteristics and cycle characteristics. give. Examples of suitable ether organic solvents to be mixed with this propylene trithiocarbonate include 2
-Methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, 1,3-dioquinrane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-dimethoxyethane,
Examples include 1,2-jethoxyethane, 1-methoxy-2-ethoxyethane, and tetrahydrobilane.

The electrolytic solution of the present invention can be obtained by dissolving an electrolyte in the above-described organic solvent of the present invention or a mixed organic solvent containing the same. The electrolyte is not particularly limited as long as it is used in normal non-aqueous electrolyte batteries. As such, for example, LiCIO4,
LiBF4, LiA+F6, LiPF6, LISbF6
, LiAQCQ4, LiCj+SO3, LiCF3CO
01N11cI04, NaBF4, Na5CN, KBF
a, (C4H9) 4NBF4, (C2Hs) 4NB
F4, (C4H9)4NCI04] Seeds or 2 harvests are mentioned above.

The battery of the present invention is a conventionally known battery equipped with a power generation element consisting of a negative electrode, a positive electrode, and a non-aqueous electrolyte. It can be obtained by using an electrolyte dissolved therein. In this case, the negative electrode active material and the positive electrode active material constituting the negative electrode and the positive electrode, respectively, can be conventionally known materials used in non-aqueous electrolyte batteries, and are not fundamentally limited. As the negative electrode active material,
For example, light metals such as aluminum, lithium, sodium, calcium, potassium, magnesium, or
Alloys thereof, and conductive polymers such as polyparaphenylene and polyacetylene doped with cations can be used. Further, as the positive electrode active material, for example, MI'102, V'205, MoO3, CrO2, V
Metal oxides such as 60+s, MoS2, TiS2, V2O
5. Metal chalcogen compounds such as metal sulfides such as Mo53, CuS, Cro, 5Vo, and 5S2, metal selenides such as VSe2 and NbSe3, and their composite oxides, composite sulfides, etc., or salts such as Li and K. Composites, etc., and conductive polymers such as polyaniline, polyvaraphenylene, polyacetylene, etc. can be used.

(Effects of the Invention) By using the electrolytic solution of the present invention, a battery with excellent high rate discharge characteristics and cycle characteristics can be obtained.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

EXAMPLE Using various electrolytes, a Teflon Bolt-Nand type battery for battery performance evaluation as shown in FIG. 1 was constructed.

In FIG. 1, 1 is a positive electrode plate, which contains heat-treated electrolytic manganese dioxide as an active material, GraT7ite as a conductive agent, and 60% Teflon Tishersion as a binder, thoroughly kneaded in a weight ratio of 8:]:l. diameter 2
It was press-molded into a disc shape of 0 mm and had a dry weight of 0.5 g. 2 is a negative electrode plate with a thickness of 0.5
+l1II+ metal lithium rolled plate was punched out into a disc shape with a diameter of 20 mm. These electrodes were laminated with a polypropylene separator 3 in between to form a bolt-nand type cell for performance evaluation.
is Teflon gap, 5 is Teflon exterior, 6 is SU
The positive electrode terminal is made by S, and 7 is the negative electrode terminal made by 5LIS.

For each battery constructed as described above, at room temperature, 50
The discharge characteristics when discharged with a constant resistance of 0Ω were tested.

The results are shown in FIG. The symbols shown in FIG. 2 correspond to battery numbers to be described later, and in FIG. 2, the battery (2) and the battery (2) of the present invention are shown as representative examples. Battery (1) and Battery (2) of the present invention showed almost the same results as Battery I of the present invention, and Battery V showed almost the same results as Battery H of the present invention.

As can be seen from Figure 2, the battery of the present invention has a higher battery voltage during high rate discharge and a higher power utilization rate than batteries A, B, C, and D configured using conventional electrolytes. It is excellent in

The electrolyte solution used in each battery is as follows.

Battery I LiCQ 04 in propylene trithiocarbonate
Uses an electrolyte dissolved in the ratio mo Q / Q.

Battery■ LICQ04 was added to a mixed solvent of propylene trithiocarbonate and dimethoxyethane at a volume ratio of 11 to 1fflOQ/
Uses an electrolyte dissolved in the proportion of Q.

Battery ■: LiCQO4 was added to Imo Q/in a mixed solvent of ethylene trithiocarbonate and dimethoxyethane at a volume ratio of 1.1.
Uses an electrolyte dissolved in the proportion of Q.

Battery ■.

L to 4-methyl-1,3-oxathiolane-2-thione
Uses an electrolyte solution in which iCQ04 is dissolved in a ratio of Imo Q/Q.

Battery ■.

4-methyl-1,3-oxathiolane-2 with a volume ratio of 11
- LiC (10
Use a solution in which 4 is dissolved at a ratio of Imon/R.

Battery A LiCQO4 in propylene carbonate Imo Q
/ Uses electrolyte solution dissolved in the ratio of Q.

Battery B: Uses an electrolyte solution in which L+CQ 04 is dissolved in thiophene at a ratio of Imo Q/Q.

Battery C: Uses an electrolytic solution in which LiCQOa is dissolved in a mixed solvent of propylene carbonate and dimethoxyethane at a volume ratio of 1:1 at a ratio of Imo Q/Q.

An electrolytic solution in which LiCQ 04 is dissolved in a ratio of Imo Q/Q in a mixed solvent of ethylene carbonate and dimethoxyethane with a volume ratio of 1:1 is used.

Example 2 In the battery shown in Example 1, titanium disulfide was used instead of manganese dioxide as the positive electrode active material, and LiBF4 was used instead of LiCQO, + as the electrolyte dissolved in the electrolyte.
A Bolt-Nand type battery (secondary battery) for performance evaluation was constructed in the same manner except that .

These batteries were repeatedly charged and discharged at room temperature, at a constant current of 2 mA, at an end-of-discharge voltage of 1.2 V, and at an end-of-charge voltage of 2.8 ■, and the number of cycles was determined when the discharge capacity decreased to 50% of the initial value. The results are shown in Table 1.

The electrolyte solution used for each battery was as follows.

Battery 1 (2): Im LiBF4 in propylene trithiocarbonate.

Uses an electrolyte solution dissolved at a ratio of p/Ω.

Battery II (2): An electrolytic solution was used in which [,1BF4 was dissolved in a mixed solvent of propylene trithiocarbonate and dimethoxyethane with a volume ratio of 1] at a ratio of 10ε/Q.

Battery m(2) LiBF4 was added to Imo Q/in a mixed solvent of ethylene trithiocarbonate and dimethoxyethane at a volume ratio of 1:1.
Uses an electrolyte dissolved in the proportion of Q.

Battery TV (2): 4-Methyl-1,3-oxathiolane-2-1,000 ions: An electrolytic solution in which LiBF4 was dissolved in a ratio of Imo Q/Q was used.

Battery V (2) LiBF4 in a mixed solvent of 4-methyl-1,3-oxo → Honmasu oran-2-thione and dimethoxyethane with a volume ratio of 11
Use an electrolyte solution in which 1rnoQ/Q is dissolved.

Battery A (2): - LiBF4 in propylene carbonate Imo Q/
Uses an electrolyte dissolved in the proportion of Q.

Battery B (2) Uses an electrolyte solution in which LiBF4 is dissolved in thiophene at a ratio of Imo Q/Q.

Battery C (2): An electrolytic solution in which LiBF< was dissolved in a mixed solvent of propylene carbonate and dimethoxyethane with a volume ratio of 1.1 at a ratio of Imo Q/Q was used.

Battery D (2) An electrolytic solution in which LiBF4 was dissolved in a mixed solvent of ethylene carbonate and dimethoxyethane at a volume ratio of 1°1 at a ratio of Imo Q/Q was used.

Table 1 As can be seen from Table 1, the batteries obtained using the electrolyte of the present invention have significantly improved cycle characteristics compared to those using conventional electrolytes.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional configuration diagram of a Bolt-Nand type cell for battery performance evaluation. FIG. 2 is a graph showing the test results of the discharge characteristics of each battery shown in Example 1. Orchid 1

Claims (3)

[Claims] (1) An electrolyte is dissolved in at least one sulfur-containing organic solvent selected from lower alkylene trithiocarbonate and 4-lower alkyl-1,3-oxathiolane-2-thione, or a mixed organic solvent containing the same. A non-aqueous electrolyte. (2) A non-aqueous electrolyte in which an electrolyte is dissolved in a mixed organic solvent of propylene trithiocarbonate and an ether solvent. (3) A battery comprising the non-aqueous electrolyte according to claim 1 or 2.