JP3306121B2 - 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 of a non-aqueous electrolyte for the purpose of improving storage characteristics.

[0002]

2. Description of the Related Art
Organic solvents such as propylene carbonate and dimethyl carbonate are generally used as electrolyte solvents for non-aqueous electrolyte batteries.

However, in the conventional non-aqueous electrolyte battery, the solvent molecules in the non-aqueous electrolyte are liable to react with the positive electrode active material and electrochemically oxidatively decompose on the positive electrode side, which has a particularly high potential during charging. However, there has been a problem that the storage characteristics and the charge / discharge cycle characteristics of the battery are generally not good.

The present invention has been made to solve such a problem, and an object of the present invention is to suppress storage reaction and charge / discharge by suppressing a side reaction between a nonaqueous electrolyte and a positive electrode active material. An object of the present invention is to provide a non-aqueous electrolyte battery having excellent cycle characteristics (in the case of a secondary battery) .

[0005]

Nonaqueous electrolyte battery according to the present invention for achieving the above object, according to the solution to (hereinafter, referred to as "the present cell".) Is, in the non-aqueous electrolyte, the following formula of 2
(Hereinafter referred to as “specific compound”) in an amount of 0.01 to 0.5 mol / L.

[0006]

Embedded image

However, n in Chemical formula 2 is 1, 2 or 3 .

As described above, in the battery of the present invention, since the specific compound is added as a stabilizer for the non-aqueous electrolyte, the non-aqueous electrolyte, which has been a problem in the conventional non-aqueous electrolyte, can be used. The problem that storage characteristics and charge / discharge cycle characteristics deteriorate due to side reactions with the positive electrode active material is solved.

The inventors of the present invention do not necessarily know why the specific compound functions as a stabilizer for the non-aqueous electrolyte, but it is considered to be due to the following reasons.

That is, the specific compound is liable to be radicalized by releasing one electron from each electron pair of two N during charging, and this radical forming reaction occurs preferentially to the oxidative decomposition reaction of the solvent molecule. Isn't the degradation of non-aqueous electrolyte solution suppressed? Here, it is presumed that the specific compound is easily radicalized because each of the two generated radical portions is stabilized by the resonance effect. The radicals generated during charging in this way are reduced at the time of discharging and return to the original specific compound.

The specific compound according to the present invention is obtained by converting two N, N-dimethylanilines into a methylene group, an ethylene group or
Has a structure linked via a trimethylene group . Among them , 4,4 ^'
- methylenebis (N, N-dimethylaniline) (formula 2 in
Is most preferably 1) .

In the present invention, the addition ratio of the specific compound to the non-aqueous electrolyte is 0.01 to 0.01 to the non-aqueous electrolyte.
It is in the range of 0.5 mol / l (M), more preferably in the range of 0.05 to 0.1 mol / l. When the addition ratio of the specific compound is less than 0.01 mol / liter, the effect intended by the present invention of stabilizing the non-aqueous electrolyte solution is not sufficiently exhibited because the amount is too small. If the value exceeds / l decrease rather storage characteristics and charge-discharge cycle characteristics.

[0013] The solvent of the non-aqueous electrolyte in the present invention includes propylene carbonate, ethylene carbonate,
Organic solvents such as 1,2-butylene carbonate, and dimethyl carbonate, diethyl carbonate,
Examples thereof include a mixed solvent with a low boiling point solvent such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and ethoxymethoxyethane, and examples of the solute include LiPF ₆ , LiCl
O ₄ and LiCF ₃ SO ₃ are exemplified. The non-aqueous electrolyte in the present invention can be oxidized and decomposed by reacting with a positive electrode active material at the time of charging, and the present invention can be achieved by adding a specific compound. It is not limited to these solvents and solutes because the intended effect is achieved.

As described in detail above, the present invention is characterized in that the oxidative decomposition of a non-aqueous electrolyte during charging is prevented by adding a specific compound thereto.
Therefore, for other members constituting the battery, such as the positive electrode, the negative electrode, and the separator, it is possible to use various materials that have been conventionally used or proposed for non-aqueous batteries.

For example, as the positive electrode active material in the present invention, metal oxides (MnO ₂ , modified MnO ₂ , heavy M
nO ₂ , MoO ₂ , CuO, Cr ₂ O ₃ , CrO ₃ , V
₂ O ₅ , NiOOH, etc.); metal sulfides (FeS, Ti
S ₂ or MoS ₂ ); metal selenide (TiSe)
₂ etc.); at least one metal selected from the group consisting of chromium, manganese, iron, cobalt and nickel and Li
Various materials can be used, such as a composite oxide with

Further, as the negative electrode material in the present invention,
Examples thereof include lithium metal or a substance capable of inserting and extracting lithium. Examples of the substance capable of inserting and extracting lithium include a lithium alloy, an oxide, and a carbon material. In addition,
A powder material such as a carbon material is kneaded with a binder such as polytetrafluoroethylene and used as a mixture.

[0017]

In the battery of the present invention, since the specific compound is added to the non-aqueous electrolyte, the oxidative decomposition of the electrolyte solvent due to the reaction between the positive electrode active material and the electrolyte solvent during charging is suppressed.

[0018]

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 85: 1.
The mixture was mixed at 0: 5 to obtain a positive electrode mixture. This positive electrode mixture was molded into a mold to produce a disk-shaped positive electrode. Note that a stainless steel plate (SUS304) was used as the positive electrode current collector.

[Preparation of Negative Electrode] A disk-shaped negative electrode made of lithium metal was prepared by rolling and punching. Note that a stainless steel plate (SUS304) was used as the negative electrode current collector.

[Preparation of non-aqueous electrolyte] Propylene carbonate (PC) and 1,2-dimethoxyethane (DME)
And a solution prepared by dissolving LiClO ₄ (lithium perchlorate) at 1 mol / liter in an equal volume mixed solvent of
^' -Methylenebis (N, N-dimethylaniline)
A non-aqueous electrolyte was prepared by adding and mixing at a rate of 05 mol / liter.

[Preparation of Primary Battery] A flat type battery BA1 of the present invention (battery size: diameter 20 mm, thickness: 2.5 mm) was prepared using the above positive and negative electrodes and a non-aqueous electrolyte. As the separator, a polypropylene microporous membrane was used, which was impregnated with the above-mentioned non-aqueous electrolyte.

FIG. 1 is a cross-sectional view schematically showing a fabricated battery BA1 of the present invention. The battery BA1 of the present invention shown in FIG.
Positive electrode 1, negative electrode 2, separator 3 separating these electrodes, positive electrode can 4, negative electrode can 5, positive electrode current collector 6, negative electrode current collector 7
And an insulating packing 8 made of polypropylene. The positive electrode 1 and the negative electrode 2 face each other via a separator 3 impregnated with a non-aqueous electrolyte and are accommodated in a battery case formed by positive and negative bipolar cans 4 and 5.
And the negative electrode 2 is connected to the negative electrode can 5 via the negative electrode current collector 7, and the chemical energy generated inside the battery 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.

[0025] 4,4 ^'in the preparation of (Comparative Example 1) Non-aqueous electrolyte - methylenebis (N, N-dimethylaniline)
Comparative Battery BC1 was produced in the same manner as in Example 1, except that was not added.

(Initial Discharge Characteristics) The room temperature (25 ° C.) was measured for each of the five cells of the battery BA1 of the present invention and the comparative battery BC1.
Below, constant resistance discharge was performed at 300 ohms, and the initial discharge characteristics were examined. The results are shown in FIG.

FIG. 2 is a graph showing the discharge characteristics, in which the vertical axis represents the battery voltage (V) and the horizontal axis represents the discharge time (h). It can be seen that there is no difference between the inventive battery BA1 and the comparative battery BC1.

(Discharge characteristics after storage)
Battery BA1 of the present invention and comparative battery BC1 after storage for months
For each of the five cells, constant-resistance discharge was performed at 300 ohms, and discharge characteristics were examined. The results are shown in FIG. 3 in a coordinate system similar to FIG.

FIG. 3 shows that the battery BA1 of the present invention is a comparative battery B
It can be seen that the discharge capacity is larger than that of C1 and the storage characteristics are clearly superior.

Example 2 A flat nonaqueous electrolyte secondary battery (battery of the present invention) was manufactured.

[Preparation of Positive Electrode] Lithium-containing 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 85: 10: 5. A positive electrode mixture was obtained. This positive electrode mixture was molded into a mold to produce a disk-shaped positive electrode. In addition, as a positive electrode current collector, a stainless steel plate (SUS30
4) was used.

[Preparation of Negative Electrode] A disk-shaped negative electrode made of lithium metal was prepared by rolling and punching. Note that a stainless steel plate (SUS304) was used as the negative electrode current collector.

[Preparation of Nonaqueous Electrolyte] Ethylene carbonate (EC), propylene carbonate (PC) and 1,
3: 3: 4 volume ratio with 2-dimethoxyethane (DME)
In a mixed solvent of LiPF ₆ in 1 mole / liter of dissolved solution for further 4,4 ^'- methylenebis (N, N-dimethylaniline) was added and mixed at a ratio of 0.01 mol / liter non-aqueous electrolyte solution Prepared.

[Preparation of Secondary Battery] A flat type battery BA2 of the present invention (battery size: diameter 24 mm, thickness: 3.0 mm) was prepared using the positive and negative electrodes and the non-aqueous electrolyte described above. As the separator, a polypropylene microporous membrane was used, which was impregnated with the above-mentioned non-aqueous electrolyte.

[0035] 4,4 ^'in the preparation of Example 3 Non-aqueous electrolyte - methylenebis (N, N-dimethylaniline)
Was prepared in the same manner as in Example 2 except that was added and mixed at a ratio of 0.05 mol / liter.

[0036] 4,4 ^'in the preparation of Example 4 Non-aqueous electrolyte - methylenebis (N, N-dimethylaniline)
Was prepared in the same manner as in Example 2 except that 0.1 mol / liter was added and mixed.

[0037] 4,4 ^'in the preparation of Example 5 nonaqueous electrolyte - methylenebis (N, N-dimethylaniline)
Was added and mixed at a ratio of 0.5 mol / liter to prepare a battery BA5 of the present invention in the same manner as in Example 2.

[0038] 4,4 ^'in the preparation of (Comparative Example 2) Non-aqueous electrolyte - methylenebis (N, N-dimethylaniline)
Comparative Battery BC2 was produced in the same manner as in Example 2 except that was not added.

Example 6 As a non-aqueous electrolyte, a solution prepared by dissolving LiClO ₄ at 1 mol / L in an equal volume mixed solvent of propylene carbonate (PC) and 1,2-dimethoxyethane (DME) was added. , 4 ^'- methylene bis (N, N-dimethylaniline) except for using a non-aqueous electrolytic solution prepared by adding and mixing in a ratio of 0.05 moles / liter in the same manner as in example 2, the present invention battery B
A6 was produced.

[0040] 4,4 ^'in the preparation of (Comparative Example 3) non-aqueous electrolyte solution - methylenebis (N, N-dimethylaniline)
Comparative Battery BC3 was produced in the same manner as in Example 6, except that was not added.

(Charge / Discharge Cycle Characteristics) Battery BA2 of the Present Invention
For each of the five cells of ~ BA6 and comparative batteries BC2 and BC3, a cycle test was performed in which a cycle of charging at 1 mA for 3 hours and then discharging at 1 mA for 3 hours was one cycle, and the battery life of each battery was examined. The battery life was evaluated by the number of cycles (times) until the battery voltage reached 1.8 V within 3 hours of discharge time. Table 1 shows the results.

[0042]

[Table 1]

[0043] From Table 1, each present batteries BA2~BA5 and BA6 are in a non-aqueous electrolyte solution of 4,4 ^'- compared methylenebis (N, N-dimethylaniline) in comparison cell BC2 and BC3 were not added It can be seen that the number of cycles is large and the charge / discharge cycle characteristics are excellent.

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.

[0045]

According to the battery of the present invention, the positive electrode active material and the electrolyte solution solvent do not easily react during charging. Therefore, the present invention is excellent in storage characteristics, and in particular, in the secondary battery, has excellent charge / discharge cycle characteristics. It has a special effect.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a flat type battery BA1 of the present invention.

FIG. 2 is an initial discharge characteristic diagram of a battery BA1 of the present invention and a comparative battery BC1.

FIG. 3 is a discharge characteristic diagram after storage of a battery BA1 of the present invention and a comparative battery BC1.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-43960 (JP, A) JP-A-6-84523 (JP, A) JP-A-2-260374 (JP, A) JP-A-5-260 29019 (JP, A) JP-A-6-36797 (JP, A) JP-A-1-186564 (JP, A) JP-A-58-87777 (JP, A) JP-A-56-84881 (JP, A) JP-A-56-84880 (JP, A) JP-A-54-22520 (JP, A) JP-A-60-17872 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 6/16 H01M 10/40

Claims (2)

(57) [Claims] 1. A non-aqueous electrolyte battery characterized in that a compound represented by the following general formula 1 is added to the non-aqueous electrolyte solution in an amount of 0.01 to 0.5 mol / L. Embedded image However, n in Chemical formula 1 is 1, 2 or 3 . Wherein said compound is 4,4 ^'- methylenebis
(N, N-dimethylaniline).
Aqueous electrolyte battery.