JP3011529B2 - Non-aqueous electrolyte battery - Google Patents

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 improving the storage characteristics and cycle characteristics of the non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art
As an electrolyte for a non-aqueous electrolyte battery, a non-aqueous electrolyte obtained by dissolving an electrolyte solute such as LiPF ₆ or LiClO _{4 in} a solvent such as propylene carbonate or dimethyl carbonate is generally used.

However, such conventional non-aqueous electrolytes have poor storage characteristics because the solvent molecules are easily decomposed by lithium ions (Li ⁺ ). In particular, in the case of secondary batteries, only batteries having a short cycle life are used. There was a problem that it was difficult to obtain.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a non-aqueous electrolyte battery having excellent storage characteristics and charge / discharge cycle characteristics.

[0005]

A non-aqueous electrolyte battery according to the present invention (hereinafter referred to as "battery of the present invention") for achieving the above object is capable of inserting and extracting a positive electrode and lithium metal or lithium. A non-aqueous electrolyte battery comprising a non-aqueous electrolyte battery comprising: a negative electrode mainly composed of a non-aqueous substance; a separator separating the two electrodes; and a non-aqueous electrolyte solution.
It is characterized by containing at least one unsaturated nitrogen-containing heterocyclic compound represented by the following chemical formula (3) or (4).

[0006]

Embedded image

[0007]

Embedded image However, in Chemical Formulas 3 and 4, R ^{1 to} R ⁸ are each independently a hydrogen atom, an alkyl group, or an amino group.

As the unsaturated nitrogen-containing heterocyclic compound represented by the above formula (3) or (4), pyrazole, 3-amino-4
-Methylpyrazole, 5-amino-1-ethylpyrazole, 3-amino-5-methylpyrazole, 3-amino-
1-methylpyrazole, 3-methyl-1-ethylpyrazole, 5-amino-3-ethylpyrazole, pyridazine, 3-amino-5-ethylpyridazine, 3-amino-
4,5-dimethylpyridazine, 3,5-dimethylpyridazine, 6-ethyl-3-methylpyridazine, 6-amino-3-methylpyridazine, or 6-amino-3,4-
Dimethylpyridazine is exemplified.

As described above, in the battery of the present invention, a non-aqueous electrolyte to which a specific unsaturated nitrogen-containing heterocyclic compound is added is used, which causes a problem in the conventional non-aqueous electrolyte battery. Thus, the deterioration of the non-aqueous electrolyte due to the decomposition of the solvent described above is suppressed.

In other words, the battery of the present invention comprises the step of solvating a specific unsaturated nitrogen-containing heterocyclic compound with lithium ions (Li ⁺ ) to inactivate the lithium ions with respect to other solvent molecules. Thus, stabilization of the solvent and prevention of deterioration of the non-aqueous electrolyte are realized.

FIG. 1 is an explanatory diagram schematically showing the state of solvation by taking pyridazine as an example. A plurality (three in the figure) of pyridazine molecules are formed around a lithium ion by a ring member carbon atom. FIG. 3 also shows a state in which the -N = N-bonded portion having a high electronegativity is solvated in a state of facing the lithium ion. As described above, when the non-aqueous electrolyte solution according to the present invention is used, a specific unsaturated nitrogen-containing heterocyclic compound is solvated with lithium ions, so that decomposition of other solvent molecules by lithium ions is suppressed. is there.

The preferred addition amount of the specific unsaturated nitrogen-containing heterocyclic compound in the present invention to the non-aqueous electrolyte is 0.5
In the range of 10 to 10% by weight. If the amount is less than 0.5% by weight, the effect of suppressing decomposition is not sufficiently exhibited because the amount is too small. , The cycle characteristics tend to worsen.

[0013] The solvent of the non-aqueous electrolyte in the present invention includes propylene carbonate, ethylene carbonate,
Examples thereof include organic solvents such as 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate, and mixed solvents of these with low-boiling solvents, and examples of solutes include LiPF ₆ , LiClO ₄ , and LiCF ₃ SO _3. The non-aqueous electrolytic solution of the present invention, as long as it contains a solvent that is easily decomposed by lithium ions, the effect intended by the present invention is achieved by adding an unsaturated nitrogen-containing heterocyclic compound. Not limited.

The other members of the battery of the present invention other than the non-aqueous electrolyte are not particularly limited, and various materials conventionally used for non-aqueous electrolyte batteries can be used.

That is, as the positive electrode material (active material),
Metal oxide (MnO ₂ , modified MnO ₂ , heavy Mn
O ₂ , MoO ₂ , CuO, Cr ₂ O ₃ , CrO ₃ , V ₂
O ₅ , LiCoO ₂ , LiNiO ₂ , NiOOH, etc .; metal sulfides (eg, FeS, TiS ₂ , or MoS ₂ ); metal selenides (eg, TiSe ₂ ); from the group consisting of chromium, manganese, iron, cobalt and nickel Such as a composite oxide of at least one selected metal and Li,
Various materials can be used.

For the positive electrode of the battery of the present invention, for example, the above positive electrode material is kneaded with a conductive agent such as acetylene black or carbon black and a binder such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVdF). After forming the positive electrode mixture, the positive electrode mixture is rolled into an aluminum or stainless steel foil or lath plate as a current collector, and heat-treated under a vacuum at a temperature of about 50 to 250 ° C. for about 2 hours. It is produced by

Examples of the negative electrode material include lithium metal, lithium alloy, carbon material, and other substances capable of inserting and extracting lithium. The carbon material is kneaded with a binder such as polytetrafluoroethylene and used as a negative electrode mixture.

[0018]

In the battery of the present invention, the non-aqueous electrolyte contains a specific unsaturated nitrogen-containing heterocyclic compound, and the unsaturated nitrogen-containing heterocyclic compound is coordinated around lithium ions by solvation. I do. As a result, the contact between the lithium ion and the other solvent molecules in the non-aqueous electrolyte solution is cut off, and the degradation of the solvent molecules is suppressed.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples, and may be carried out by appropriately changing the scope of the present invention. Is possible.

Example 1 A flat non-aqueous electrolyte primary battery (battery of the present invention) was manufactured.

[Preparation of Positive Electrode] Manganese dioxide as an active material, acetylene black as a conductive agent, and a fluororesin as a binder for both of them were mixed at a weight ratio of 80: 1.
The mixture was mixed at 0:10 to obtain a positive electrode mixture. This positive electrode mixture was molded into a mold to produce a disk-shaped positive electrode.

[Preparation of Negative Electrode] A disk-shaped negative electrode made of lithium metal was prepared by rolling and punching.

[Preparation of Non-Aqueous Electrolyte] Ethylene carbonate (EC) and 1,2-butylene carbonate (BC)
And a volume ratio of 1,2-dimethoxyethane (DME) 1:
To a solution in which lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) was added at 1 mol / l to a 1: 3 mixed solvent, 5-amino-1-ethylpyrazole was further added based on the total weight of the non-aqueous electrolyte. A non-aqueous electrolyte solution was prepared by adding and mixing so as to be 5% by weight.

[Fabrication of Battery] A flat primary battery (battery size: diameter 24) was prepared using the positive and negative electrodes and the non-aqueous electrolyte described above.
mm, thickness: 3.0 mm). A microporous thin film made of polypropylene was used as a separator, which was impregnated with the nonaqueous electrolyte described above.

FIG. 2 shows the prepared flat battery BA1 of the present invention.
FIG. 1 is a cross-sectional view schematically showing a battery B of the present invention shown in FIG.
A1 includes a positive electrode 1, a negative electrode 2, a separator 3 separating these electrodes, a positive electrode can 4, a negative electrode can 5, a positive electrode current collector 6, a negative electrode current collector 7, an insulating packing 8 made of polypropylene, and the like. The positive electrode 1 and the negative electrode 2 face each other via a separator 3 impregnated with a non-aqueous electrolyte and are housed in a battery case formed by positive and negative bipolar cans 4 and 5. The positive electrode can 4 and the negative electrode 2 are connected to the negative electrode can 5 via the negative electrode current collector 7, and the chemical energy generated inside the battery BA 1 of the present invention is externally converted into electric energy from both terminals of the positive electrode can 4 and the negative electrode can 5. To be taken out.

Comparative Example 1 A comparative battery BC1 was prepared in the same manner as in Example 1 except that 5-amino-1-ethylpyrazole was not added in the preparation of the non-aqueous electrolyte.

(Initial Discharge Characteristics Test) For each of the battery BA1 of the present invention and the comparative battery BC1 immediately after fabrication, 3
A constant resistance discharge of 00 ohms was performed to examine the initial discharge characteristics. The results are shown in FIG.

FIG. 3 is a graph showing the discharge characteristics of each battery, the battery voltage (V) on the ordinate, and the discharge time (h) on the abscissa. It can be seen that there is no significant difference in the discharge characteristics between the battery BA1 of the present invention and the comparative battery BC1.

(Discharge characteristic test after storage) 60 ° C. after production
Battery BA1 and comparative battery B after storage for 3 months at
For each of C1, a 300 ohm constant resistance discharge was performed and the discharge characteristics were examined. The results are shown in FIG.

FIG. 4 shows the discharge characteristics of each battery after storage in a graph similar to the graph shown in FIG. 3. From FIG. 4, the battery BA1 of the present invention was compared after storage for 3 months. It can be seen that the discharge characteristics are clearly superior to the battery BC1.

Examples 2 to 14 Flat nonaqueous electrolyte secondary batteries (batteries of the present invention) were produced.

[Preparation of Positive Electrode] Lithium-containing manganese dioxide as an active material (a lithium salt and manganese dioxide
Heat-treated at 75 ° C. to occlude lithium in the pores of manganese dioxide), acetylene black as a conductive agent, and a fluororesin as a binder for both of them.
The mixture was mixed at a weight ratio of 80:10:10 to obtain a positive electrode mixture. This positive electrode mixture was molded into a mold to produce a disk-shaped positive electrode.

[Preparation of Negative Electrode] A disk-shaped negative electrode made of lithium metal was prepared by rolling and punching.

[Preparation of Nonaqueous Electrolyte] A mixed solvent of ethylene carbonate, propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 2: 2: 1 (Examples 2 to 8)
Alternatively, Li was added to an equal volume mixed solvent of ethylene carbonate and propylene carbonate (PC) (Examples 9 to 14).
Each of the unsaturated nitrogen-containing heterocyclic compounds shown in Table 1 (additives) was added to a solution in which PF ₆ was added at 1 mol / L and dissolved.
Was added and mixed so as to be 5% by weight with respect to the total weight of the non-aqueous electrolyte to prepare a non-aqueous electrolyte.

[Preparation of Battery] Using the positive and negative electrodes and the nonaqueous electrolyte described above, a flat battery of the present invention (secondary battery) BA2 of the same shape and size as the battery BA1 of the present invention obtained in Example 1 was used. BA
14 was produced. As a separator, a microporous thin film made of polypropylene was used, which was impregnated with the above-mentioned non-aqueous electrolyte.

Comparative Example 2 A comparative battery BC2 was produced in the same manner as in Examples 2 to 8, except that the unsaturated nitrogen-containing heterocyclic compound was not added.

Comparative Example 3 A comparative battery BC3 was produced in the same manner as in Examples 9 to 14, except that the unsaturated nitrogen-containing heterocyclic compound was not added.

(Charge / Discharge Cycle Test) Battery BA2 of the Present Invention
A charge / discharge cycle test was performed for each of the batteries BA2 to BA14 and the comparative batteries BC2 and BC3. Table 1 shows the results. In the charge / discharge cycle test, charge and discharge were each performed at 2 mA for 4 hours, and this was defined as one cycle.
The number of cycles (times) until the battery voltage dropped to 1.8 V during discharging was defined as the cycle life.

[0039]

[Table 1]

From Table 1, it can be seen that the batteries BA2 to BA14 of the present invention were obtained.
Indicates that the cycle life is generally longer than those of the comparative batteries BC2 and BC3.

Examples 15 to 18 LiPF ₆ was added to a mixed solvent of ethylene carbonate, 1,2-butylene carbonate and 1,2-dimethoxyethane in a volume ratio of 2: 2: 1.
Was added to 1 mol / liter and dissolved in the solution.
Amino-1-ethylpyrazole was added and mixed at 0.5, 1, 5, 10% by weight with respect to the total weight of the non-aqueous electrolyte to prepare four kinds of non-aqueous electrolytes. Next, Example 2 was repeated except that these non-aqueous electrolytes were used.
In the same manner as in Nos. To 14, Batteries BA15 to 18 of the present invention were produced.

Comparative Example 4 A comparative battery BC4 was prepared in the same manner as in Examples 15 to 19 except that 5-amino-1-ethylpyrazole was not added.

(Charge / Discharge Cycle Test) Battery BA1 of the Present Invention
A charge / discharge cycle test was performed on each of the cells Nos. 5 to BA18 and the comparative battery BC4. Table 2 shows the results. The charge / discharge cycle test was performed under the same conditions as those described in Examples 2 to 14 above.

[0044]

[Table 2]

From Table 2, it is found that the batteries BA15 to BA18 of the present invention were obtained.
Indicates that the cycle life is generally longer than that of the comparative battery BC4.

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

[0047]

In the battery of the present invention, a non-aqueous electrolyte containing a specific unsaturated nitrogen-containing heterocyclic compound is used, so that other solvent molecules in the non-aqueous electrolyte are decomposed by lithium ions. The present invention has excellent unique effects such as excellent storage characteristics and charge / discharge cycle characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a schematic sectional view of a flat type battery of the present invention.

FIG. 3 is an initial discharge characteristic diagram of a battery of the present invention and a comparative battery.

FIG. 4 is a graph showing discharge characteristics of a battery of the present invention and a comparative battery after storage for 3 months.

[Explanation of symbols]

 BA1 Battery of the present invention 1 Positive electrode 2 Negative electrode 3 Separator

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryuji Oshita 2--18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Atsushi Suemori 2--18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Nobuhiro Furukawa 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 6/14 -6/16 H01M 10/40

Claims (4)

(57) [Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode mainly composed of lithium metal or a substance capable of inserting and extracting lithium metal, a separator for separating these two electrodes, and a non-aqueous electrolyte. Wherein the non-aqueous electrolyte is
Or a non-aqueous electrolyte battery comprising at least one unsaturated nitrogen-containing heterocyclic compound represented by Chemical Formula 2. Embedded image Embedded image [However, in Chemical Formula 1 and Chemical Formula 2, R ^{1 to} R ⁸ are each independently a hydrogen atom, an alkyl group, or an amino group. ] 2. The unsaturated nitrogen-containing heterocyclic compound is pyrazole, 3-amino-4-methylpyrazole, 5-amino-1-ethylpyrazole, 3-amino-5-methylpyrazole, 3-amino-1. -Methylpyrazole, 3-methyl-1-ethylpyrazole, 5-amino-3-ethylpyrazole, pyridazine, 3-amino-5-ethylpyridazine, 3-amino-4,5-dimethylpyridazine,
The non-aqueous electrolyte battery according to claim 1, which is 3,5-dimethylpyridazine, 6-ethyl-3-methylpyridazine, 6-amino-3-methylpyridazine, or 6-amino-3,4-dimethylpyridazine. 3. The method according to claim 1, wherein the non-aqueous electrolyte contains at least one unsaturated nitrogen-containing heterocyclic compound represented by the formula (1) or (2) in an amount of 0.5 to 10% by weight. Non-aqueous electrolyte battery. 4. The positive electrode according to claim 1, wherein the positive electrode is a metal oxide, a metal sulfide, a metal selenide, or a composite oxide of lithium and at least one metal selected from the group consisting of chromium, manganese, iron, cobalt, and nickel. The non-aqueous electrolyte battery according to any one of claims 1 to 3, wherein the non-aqueous electrolyte battery is an active material.