JPH08321313A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE: To make a nonaqueous electrolyte battery excellent in preservation characteristics. CONSTITUTION: One - twenty wt.% of specified additive is added to the nonaqueous electrolyte being constituted by dissolving lithium trifluoromethane sulfonate or lithium hexafluorophosphate in at least one kind of high permittivity solvent selected from among the group consisting of ethylene carbonate, propylene carbonate, and butylene carbonate. Hereby, the additive reacts upon lithium, etc., and a film is made on the surface of a negative electrode, and this film makes the reaction between the negative electrode and the nonaqueous solution hard to occur, so even in case that it is preserved for a long period, self discharge is hard to occur.

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 particularly to an improvement in a non-aqueous electrolyte solution for the purpose of improving the storage characteristics of the non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years,
A non-aqueous electrolyte battery including a negative electrode using lithium as an active material is drawing attention because it can have a high capacity by appropriately selecting the positive electrode active material.

By the way, as a negative electrode using lithium as an active material, metallic lithium, lithium alloys, carbon materials, etc. have been proposed.

However, these negative electrode materials generally easily react with the non-aqueous electrolyte solution during storage, and therefore a non-aqueous electrolyte battery using lithium as an active material of the negative electrode will have a discharge capacity due to self-discharge when stored for a long period of time. Is significantly reduced.

The present invention has been made to solve this problem, and an object thereof is to suppress self-discharge caused by a reaction between a negative electrode and a non-aqueous electrolyte, thereby achieving excellent preservation. A non-aqueous electrolyte battery having characteristics is provided.

[0006]

A non-aqueous electrolyte battery according to the present invention (a battery according to the present invention) for achieving the above object comprises a positive electrode, a negative electrode using lithium as an active material, ethylene carbonate, propylene carbonate and Non-aqueous electrolytic solution comprising lithium trifluoromethanesulfonate or lithium hexafluorophosphate dissolved in a solvent containing at least one high dielectric constant solvent selected from the group consisting of butylene carbonate, and a non-aqueous electrolytic solution comprising a separator In the battery, the non-aqueous electrolyte is trimethyl borate, triethyl borate, dimethyl ethyl boronate, methyl ethyl borinate, trimethyl phosphine, trimethyl phosphite, triethyl phosphite, trimethyl phosphate, triethyl phosphate. , Tetramethyl orthotitanate, tetraethyl orthotitane , Aluminum methoxide, aluminum ethoxide, carbon tetrachloride, 1,2-dichloroethane, difluorobenzene, chloromethyl ethyl ether,
1,2-dichloroethyl ethyl ether, β-methoxyethoxymethyl chloride, 1,2-bis (2-chloroethoxy) ethane, 3-bromofuran, cetyltrimethylammonium chloride, 4-chloro-1,3-dioxolane-2- On, magnesium nitrate, ferric nitrate,
Ferric iodide, zinc nitrate, zinc carbonate, indium nitrate,
1 to 20% by weight of at least one additive selected from the group consisting of gallium nitrate and hydrofluoric acid.

The non-aqueous electrolyte of the battery of the present invention contains 1 to 20% by weight of a specific additive. If the additive content is out of this range, it becomes difficult to improve the storage characteristics.

If a mixed solvent obtained by adding 1,2-dimethoxyethane to the above high dielectric constant solvent is used as the solvent for the non-aqueous electrolyte, the storage characteristics can be further improved. In that case, the preferable content ratio of the high dielectric constant solvent and 1,2-dimethoxyethane is in the range of 3: 7 to 7: 3 by weight.

Specific examples of the negative electrode using lithium as an active material include lithium alloys (lithium-aluminum alloys, lithium-lead alloys, lithium-tin alloys, etc.), metal oxides (LiNb ₂ O _5, etc.) or carbon materials (eg, Examples of the negative electrode material include graphite, coke, and a fired organic material.

The present invention aims to improve the storage characteristics of a non-aqueous electrolyte battery comprising a specific negative electrode and a specific non-aqueous electrolyte.
The characteristic is that a non-aqueous electrolyte containing a specific additive in a predetermined amount was used. Therefore, as the other members constituting the battery such as the positive electrode and the separator, various members conventionally proposed or put to practical use for the non-aqueous electrolyte battery can be used. Further, the present invention is applicable to both primary batteries and secondary batteries.

[0011]

The specific additive contained in the non-aqueous electrolytic solution reacts with the solvent / solute in the non-aqueous electrolytic solution and lithium in the negative electrode to form a film on the surface of the negative electrode. This coating makes it difficult for the reaction between the negative electrode and the non-aqueous electrolyte to occur, so that self-discharge is suppressed. As a result, the discharge capacity is less likely to decrease even after long-term storage (improvement of storage characteristics). Since the coating has good electron conductivity, the coating reaction on the negative electrode does not hinder the electrode reaction at the negative electrode.

[0012]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications may be made without departing from the scope of the invention. Is possible.

[Production of Positive Electrode] Manganese dioxide (manganese dioxide heat-treated at 375 ° C.) as an active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a weight ratio of 80:10. : 10 to prepare a positive electrode mixture, and the positive electrode mixture was mixed with N-methyl-
A slurry is prepared by dispersing in 2-pyrrolidone, and the slurry is applied onto an aluminum foil and rolled to obtain a diameter of 20.
After punching out into a disk shape of mm, it was heat treated at 150 ° C. for 2 hours to produce a positive electrode.

[Production of Negative Electrode] A rolled metal lithium plate was punched into a disk shape having a diameter of 20 mm to produce a negative electrode.

[Preparation of Non-Aqueous Electrolyte Solution] Lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) or lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a solvent having a composition shown in Tables 1 to 1 mol / liter. To prepare a non-aqueous electrolyte.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[Battery Assembly] Various flat type non-aqueous electrolyte batteries were assembled using the above positive electrode, negative electrode and non-aqueous electrolyte solution (battery size: diameter 20.0 mm, thickness 2.5 m).
m). As the separator, a polypropylene microporous film was used, which was impregnated with the above non-aqueous electrolyte solution.

[Self-Discharge Rate of Each Battery] The discharge capacity C1 of each battery immediately after assembling the battery at 25 ° C. and the discharge capacity C2 at 25 ° C. after storing at 80 ° C. for two months were obtained, and The self-discharge rate after storage of the battery was calculated by the following formula. The discharge capacities C1 and C2 are all obtained by discharging with a constant resistance of 1 kΩ. The results are shown in Tables 1 to 5 above. In the table, EC represents ethylene carbonate, PC represents propylene carbonate, BC represents butylene carbonate, and DME represents 1,2-dimethoxyethane.

Self-discharge rate (%) = (1−C2 / C1) × 100

As shown in Tables 1 to 4, the battery of the present invention using the non-aqueous electrolyte containing the specific additive (additive content is 5% by weight) is a solvent containing no additive. In addition, the self-discharge rate is lower than that of the comparative battery using the non-aqueous electrolyte solution having the same solute. From this, it can be seen that by adding a specific additive to the non-aqueous electrolyte, a non-aqueous electrolyte battery having excellent storage characteristics can be obtained.

Further, since the battery X of the present invention in Table 1 has a lower self-discharge rate than the battery Y of the present invention in Table 2, a mixed solvent of a high rate discharge solvent and 1,2-dimethoxyethane was used. It can be seen that a non-aqueous electrolyte battery having more excellent storage characteristics can be obtained by using it.

Further, as shown in Table 5, when the additive content is 1 to 20% by weight, the self-discharge rate is as low as 5%, whereas the additive content is out of this range. And the self-discharge rate becomes high. From this, it is understood that it is necessary to regulate the additive content of the non-aqueous electrolytic solution within the range of 1 to 20% by weight.

[0027]

The additive reacts with lithium or the like to form a film on the surface of the negative electrode, and this film makes it difficult for the reaction between the negative electrode and the non-aqueous electrolyte to occur, so that self-discharge occurs even when stored for a long period of time. Hateful. Therefore, the battery of the present invention has excellent storage characteristics.

Front page continuation (72) Inventor Koji Nishio 2-5-5 Keihan Hon-dori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toshihiko Saito 2-5-5 Keihan-hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A positive electrode, a negative electrode using lithium as an active material,
Ethylene carbonate, propylene carbonate and a non-aqueous electrolytic solution obtained by dissolving lithium trifluoromethanesulfonate or lithium hexafluorophosphate in a solvent containing at least one high dielectric constant solvent selected from the group consisting of butylene carbonate, and a separator. A non-aqueous electrolyte battery comprising, wherein the non-aqueous electrolyte is trimethyl borate, triethyl borate, dimethyl ethyl boronate, methyl ethyl borinate, trimethyl phosphine,
Trimethyl phosphite, triethyl phosphite, trimethyl phosphate, triethyl phosphate, tetramethyl orthotitanate, tetraethyl orthotitanate, aluminum methoxide, aluminum ethoxide, carbon tetrachloride, 1,
2-dichloroethane, fluorobenzene, chloromethyl ethyl ether, 1,2-dichloroethyl ethyl ether, β-methoxyethoxymethyl chloride, 1,2-
Bis (2-chloroethoxy) ethane, 3-bromofuran, cetyltrimethylammonium chloride, 4-chloro-1,3-dioxolan-2-one, magnesium nitrate, ferric nitrate, ferric iodide, zinc nitrate, carbonic acid A non-aqueous electrolyte battery containing 1 to 20% by weight of at least one additive selected from the group consisting of zinc, indium nitrate, gallium nitrate and hydrofluoric acid. 2. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte further contains 1,2-dimethoxyethane.