JP3236122B2 - Organic 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 an organic electrolyte battery, and more particularly, to an improvement in the electrolyte.

[0002]

2. Description of the Related Art Organic electrolyte batteries typified by lithium-manganese dioxide batteries using lithium as a negative electrode active material, manganese dioxide as a positive electrode active material and an organic solvent-based electrolyte as an electrolyte have high energy densities. And lightweight,
In addition, the demand tends to increase due to the long life.

In recent years, attention has been paid to the use of lithium batteries as secondary batteries, and lithium-ion storage batteries are already on the market as specific products. This lithium ion storage battery uses LiCoO ₂ as a positive electrode active material and a carbon compound as a negative electrode active material, and is characterized in that a high voltage can be obtained.

However, in order to maintain a high voltage, it is necessary to increase the oxidation resistance of the electrolytic solution. As a solvent for the electrolytic solution, carbonates such as propylene carbonate and esters such as γ-butyrolactone are generally used. However, the use of a solvent with excellent oxidation resistance increases the viscosity of the electrolyte, or worsens compatibility with electrodes and separators, and it takes a longer time to inject the electrolyte into the battery. In some cases, there were portions where the electrolyte could not be injected.

It has been proposed to use additives to improve this. For example, as described in JP-A-63-48762, a polyethylene glycol-type surfactant or the like is added to the electrolytic solution.
No. 267, coating an electrolyte such as LiCl on the positive electrode.

However, these have little effect and require addition of several percent, lower the discharge voltage of the battery,
There were problems such as poor stability to the positive electrode and decomposition at high temperatures.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional organic electrolyte battery at the time of injecting the electrolyte, and provides an organic electrolyte battery capable of injecting the electrolyte uniformly in a shorter time. An object of the present invention is to provide an electrolyte battery.

[0008]

The present invention SUMMARY OF], as the electrolyte second electrolyte of organic electrolyte battery, -SO ₂ - alkali metal having an alkyl group bond or -CO- bond and 2 to 15 carbon atoms Or a salt of an alkaline earth metal with —SO ₂
-Bond or -CO- bond, and from the second electrolyte
Low molecular weight alkali metal, alkaline earth metal or
By using the first electrolyte made of a quaternary ammonium salt, it is possible to shorten the time for injecting the electrolyte into the battery and to uniformly inject the electrolyte. In addition,
Akira described carbon dioxide as a solvent for the electrolyte of organic electrolyte batteries.
Solvents selected from salts, esters and sulfolane
90% by volume of the total solvent
Used above, as the electrolyte of the electrolytic solution, -SO ₂ - bond also
Has a -CO- bond and an alkyl group having 2 to 15 carbon atoms.
Of alkali metal or alkaline earth metal salts
Two electrolytes and a first electrolyte having a smaller molecular weight than the second electrolyte
The quality of the electrolyte used in the battery
This makes it possible to reduce the time between
You.

In the present invention, the second electrolyte is used to enhance the permeability of the electrolyte, and the second electrolyte may be, for example, LiC _n F _{2n + 1} SO ₃ , (C _n F
_{2n + 1} SO ₂ ) ₂ N · Li, (C _n F _{2n + 1} SO ₂ ) ₃ C ·
_{Li, LiC n F 2n + 1} CO 2, Li 2 C n F 2n (S
O ₃ ) _{2 and the} like are used.

[0010] In addition to the above Li salt,
Salts of alkali metals such as K and Na, and alkaline earth metals such as Ca and Mg can also be used. Above all, -S
Salts having an O ₂ -bond have better conductivity than those having a -CO- bond.

The reason why the second electrolyte needs to have a -SO ₂ -bond or a -CO- bond is to improve the solubility and conductivity when dissolved in an organic solvent. In the present invention, the conductivity refers to ionic conductivity.

The second electrolyte is an alkyl having 2 or more carbon atoms.
The reason for the necessity of the hydroxyl group is that the greater the carbon number, the more the osmotic action of the electrolytic solution can be promoted.

Since the oxidation resistance of the salt is improved as the hydrogen in the carbon chain is replaced with fluorine,
It is desirable for a battery to obtain the above high voltage.

Therefore, the alkyl group in the second electrolyte is preferably a fluoroalkyl group, particularly a perfluoroalkyl group.

On the other hand, even if the number of carbon atoms is too large, the permeability of the electrolytic solution is reduced. Therefore, it is necessary that the alkyl group in the second electrolyte has 15 or less carbon atoms.
In particular, those having 4 to 12, especially 6 to 10 are preferable.

Particularly preferred examples of the second electrolyte include, for example, LiC ₆ F ₁₃ SO ₃ and LiC ₇ F ₁₅
SO ₃ , LiC ₈ F ₁₇ SO ₃ , (C ₈ F ₁₇ SO ₂ ) ₂ N
Li, (C ₈ F ₁₇ SO ₂ ) ₃ CLi, LiC ₇ F ₁₅ CO
₂ and so on.

In the present invention, the above-mentioned second electrolyte is used to promote the penetration of the electrolyte solution. However, as described in the prior art, the second electrolyte is disclosed in JP-A-63-48762. There is also a method of improving by adding a polyethylene glycol type surfactant. However, such a method has little effect and has problems such as the necessity of addition of several percent, lowering of the discharge voltage of the battery, poor stability to the electrode, and decomposition at a high temperature.

On the other hand, in the case of the second electrolyte of the present invention, the effect is obtained not only with a smaller amount, but also as a good electrolyte, so that the battery performance is not impaired and the electrode is stable. In particular, it has excellent characteristics such as exhibiting excellent stability even for a high-voltage electrode.

The amount of the second electrolyte used is 0.01 to 0.5 mol / l, particularly 0.05 to 0.5 mol / l in the electrolytic solution.
It is preferable that the concentration be 2 mol / l. That is, when the amount of the second electrolyte is less than 0.01 mol / l, the effect of enhancing the permeation of the electrolyte is reduced. The amount of the second electrolyte may be more than 0.5 mol / l, but if the amount is more than 0.5 mol / l, the effect is not increased and there is no advantage of increasing the amount.

Next, LiClO is used as the first electrolyte.
₄ , LiPF ₆ , LiBF ₄ , LiAsF _6, etc., but when importance is placed on the permeability of the electrolytic solution, an alkali metal, an alkaline earth metal or a fourth metal having a —SO ₂ — bond or a —CO— bond and a fluoroalkyl group may be used. It is preferably a salt of quaternary ammonium, and in order to obtain high conductivity, an alkali metal or alkaline earth having a fluoroalkyl group containing 8 or less carbon atoms, particularly a fluoroalkyl group having 2 to 6 carbon atoms, in order to obtain high conductivity. Preference is given to salts of metals or quaternary ammoniums. However, it is necessary to use the first electrolyte having a smaller molecular weight than the second electrolyte.

Particularly preferred examples of the first electrolyte include, for example, LiC ₂ F ₅ SO ₃ and LiC ₃ F ₇
SO ₃ , LiC ₄ F ₉ SO ₃ , (CF ₃ SO ₂ ) ₂ NL
i, (CF ₃ SO ₂ ) ₃ CLi and the like.

In the present invention, examples of the organic solvent for the electrolytic solution include carbonates such as propylene carbonate, ethylene carbonate and butylene carbonate;
Esters such as γ-butyrolactone and γ-valerolactone, sulfur-containing compounds such as sulfolane and dimethyl sulfoxide, 1,2-dimethoxyethane, dimethoxymethane, dimethoxypropane, 1,3-dioxolan, tetrahydrofuran, and 2-methyltetrahydrofuran Organic solvents such as ethers are used alone or in combination of two or more.

Among them, carbonates, esters,
90 vol% or more, especially 100 vol% of sulfolane
When used, the effect of the present invention is particularly remarkably exhibited when the kinematic viscosity of the electrolytic solution is 1 cst or more, particularly 1.5 cst or more, especially 2 cst or more.

The above-mentioned second electrolyte, together with the first electrolyte,
The electrolyte may be dissolved in the electrolyte before being injected into the battery, or only the second electrolyte may be permeated by the electrolyte such as a separator or an electrode before the electrolyte containing the first electrolyte is injected into the battery. The second electrolyte may be dissolved in the electrolyte by contacting the electrolyte with the electrolyte containing the first electrolyte, and the desired effect may be obtained even with a smaller amount of use in the latter. Is preferred.

For the negative electrode, for example, an alkali metal, an alkaline earth metal or a compound containing these metals, for example, L
An alloy such as i-Al or Li-In or a carbon compound such as graphite in which lithium is intercalated can be used.

For the positive electrode, for example, an active material such as a manganese oxide, a vanadium oxide, a chromium oxide, a lithium-cobalt oxide, and a lithium-nickel oxide, a conductive assistant, and a binder are appropriately mixed. Then, a molded product together with a current collecting material such as stainless steel can be used.

[0027]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those examples.

Example 1 A heat-treated manganese dioxide mixture comprising a mixture of manganese dioxide, carbon black and polytetrafluoroethylene was applied to a stainless steel mesh as a core material with a thickness of 0.4 m.
m, formed into a 30 mm wide sheet into a strip-shaped positive electrode,
After attaching a current collector made of stainless steel to this belt-shaped positive electrode, it was dried at 250 ° C., dried, and then cooled to room temperature in a dry atmosphere.

The above-mentioned strip-shaped positive electrode is wrapped with a separator made of a microporous polypropylene film having a thickness of 25 μm, and a strip-shaped negative electrode made of lithium having a thickness of 0.18 mm and a width of 30 mm is superimposed thereon. After the body
The battery was filled in a bottomed cylindrical battery case having an outer diameter of 15 mm, and spot welding of the positive and negative electrode leads was performed.

Then, 1.5 ml of a solution prepared by dissolving LiC ₈ F ₁₇ SO ₃ in 1,2-dimethoxyethane at 0.1 mol / l was poured into the battery, and this was vacuum-dried to obtain 1,2-dimethoxyethane. Dimethoxyethane was removed. Then, (C
F ₃ SO ₂ ) ₂ NLi in propylene carbonate with 0.1%
1.5 ml of the electrolyte dissolved at 6 mol / l was injected into the battery.

To explain the electrolyte in the electrolyte, (CF ₃ SO ₂ ) ₂ NLi is the first electrolyte, and the concentration of the (CF ₃ SO ₂ ) ₂ NLi in the electrolyte is 0.6 m
ol / l, and LiC ₈ F ₁₇ SO ₃ is the second electrolyte,
The concentration of this LiC ₈ F ₁₇ SO _{3 in} the electrolyte is 0.1 mol
1 / l. The solvent of this electrolytic solution was propylene carbonate, and the kinematic viscosity at the time when the first electrolyte was dissolved was 3.0 cst.

Next, the opening of the battery case was sealed in a conventional manner to produce a cylindrical organic electrolyte battery having the structure shown in FIG.

Referring to the battery shown in FIG. 1, reference numeral 1 denotes a positive electrode formed by molding the above-mentioned manganese dioxide mixture, and a stainless steel mesh is used as a core material in the formation. Reference numeral 2 denotes a negative electrode made of lithium, and this negative electrode 2 is produced by press-bonding to a stainless steel net.

However, in FIG. 1, in order to avoid complication,
The stainless steel mesh used for producing the positive electrode 1 and the negative electrode 2 and the attached current collector are not shown. Reference numeral 3 denotes a separator, and reference numeral 4 denotes the above electrolyte.

5 is a battery case made of stainless steel,
This battery case 5 also serves as a negative electrode terminal. An insulator 6 made of a polytetrafluoroethylene sheet is provided at the bottom of the battery case 5, and an insulator 7 made of a polytetrafluoroethylene sheet is also provided at the inner periphery of the battery case 5. The spiral electrode body including the negative electrode 2 and the separator 3, the electrolyte 4, and the like are accommodated in the battery case 5.

Reference numeral 8 denotes a sealing plate made of stainless steel, and a gas ventilation hole 8a is provided in the center of the sealing plate 8. 9 is an annular packing made of polypropylene, 10 is a flexible thin plate made of titanium, and 11 is a thermally deformable member made of an annular polypropylene.

The above-mentioned heat-deformable member 11 functions to change the breaking pressure of the flexible thin plate 10 by being deformed by the temperature.

Reference numeral 12 denotes a nickel-plated rolled steel terminal plate. The terminal plate 12 is provided with a cutting edge 12a and a gas discharge hole 12b. When the internal pressure increases and the flexible thin plate 10 is deformed due to the increase in the internal pressure, the flexible thin plate 10 is broken by the cutting blade 12a, and gas inside the battery is discharged from the gas discharge hole 12b to the outside of the battery. Designed to be able to.

Reference numeral 13 denotes an insulating packing, 14 denotes a lead body, and the lead body 14 electrically connects the positive electrode 1 to the sealing plate 8, and the terminal plate 12 contacts the sealing plate 8 to form a positive terminal. Act as Reference numeral 15 denotes a lead body for electrically connecting the negative electrode 2 and the electric case 5.

Example 2 As the second electrolyte, LiC ₈ F ₁₇ SO ₃ was replaced with Li
A cylindrical organic electrolyte battery was manufactured in the same manner as in Example 1 except that C ₇ F ₁₅ CO ₂ was used.

To explain the electrolyte of the battery of Example 2, the solvent is propylene carbonate, the first electrolyte is (CF ₃ SO ₂ ) ₂ NLi, and the concentration is 0.6.
mol / l. And the second electrolyte is LiC ₇ F ₁₅
It is believed that the concentration of CO ₂ in the electrolyte is 0.1 mol / l.

Comparative Example 1 A manganese dioxide mixture comprising a mixture of heat-treated manganese dioxide, carbon black and polytetrafluoroethylene was used, and LiC ₈ F ₁₇ SO 2 was used as a second electrolyte.
_A cylindrical organic electrolyte battery was manufactured in the same manner as in Example 1 except that ₃ was not used.

The electrolytic solution of the battery of Comparative Example 1 will be described. (CF ₃ of the first electrolyte in the battery of Example 1)
Only SO ₂ ) ₂ NLi was dissolved in a propylene carbonate solvent at a concentration of 0.6 mol / l, and the concentration of the first electrolyte was the same as that in Example 1. Where L
Since no iC ₈ F ₁₇ SO ₃ was used, no second electrolyte was present.

Comparative Example 2 A manganese dioxide mixture comprising a mixture of heat-treated manganese dioxide, carbon black and polytetrafluoroethylene was used, and instead of LiC ₈ F ₁₇ SO ₃ as the second electrolyte, a polyethylene glycol type surfactant was used. A cylindrical organic electrolyte battery was manufactured in the same manner as in Example 1, except that the agent was added to the electrolyte.

Comparative Example 3 A cylindrical organic electrolyte battery was prepared in the same manner as in Comparative Example 1 except that LiPF ₆ dissolved in propylene carbonate at 0.6 mol / l was used as the electrolyte. However, the separator and the positive electrode repel the electrolyte,
Not much electrolyte could be injected.

The electrolyte of the battery of Comparative Example 3 will be described. (CF ₃ of the first electrolyte in the battery of Comparative Example 1)
Instead of SO ₂ ) ₂ NLi, LiPF ₆ was dissolved in propylene carbonate at 0.6 mol / l,
The concentration of the first electrolyte in the electrolyte was the same as that in Example 1, but the second electrolyte as in Example 1 was not used.

The batteries of Examples 1 and 2 and Comparative Examples 1 and 2
The time required for injecting the electrolytic solution during the fabrication of Battery No. 3 (hereinafter, injection time) was compared.

Here, the injection time was defined as the time until the electrolyte was absorbed into the spirally wound body of the sealing portion of the cylindrical organic electrolyte battery. The results are shown in Table 1 as the injection time ratio of each battery when the injection time of the battery of Example 1 is set to 100.

The batteries of Examples 1 and 2 and the batteries of Comparative Examples 1 to 3 were charged at 0.3 A for 10 msec. The closed circuit voltage (CCV) at the time of discharging was measured. The results are shown along with their open circuit voltage (OCV).

[0050]

[Table 1]

As shown in Table 1, the batteries of Examples 1 and 2 using the second electrolyte had a shorter electrolyte injection time than the batteries of Comparative Example 1 using no second electrolyte. The injection time of the electrolyte was shorter than that of the battery of Comparative Example 2 to which the glycol type surfactant was added.

The batteries of Examples 1 and 2 also have excellent battery performance, as is clear from the comparison with the battery of Comparative Example 1 in which the second electrolyte is not used. No decrease in battery performance as in the battery of Comparative Example 2 was observed.

[0053]

As described in the foregoing, in the present invention, without lowering the batteries performance, it was possible to shorten the injection time of the electrolyte into the battery.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of an organic electrolyte battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Electrolyte

Continuation of front page (56) References JP-A-4-47677 (JP, A) JP-A-5-47417 (JP, A) JP-A-5-74491 (JP, A) JP-A-5-326016 (JP) , A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 6/16

Claims (3)

(57) [Claims] 1. An organic electrolyte battery comprising a negative electrode, a positive electrode and an electrolyte, wherein -SO _2-
A second electrolyte comprising a bond or -CO- bond and an alkali metal or alkaline earth metal salt having an alkyl group of 2 to 15 carbon atoms, -SO ₂ - bond or -CO- binding
Alkali having a lower molecular weight than the second electrolyte
Metal, alkaline earth metal or quaternary ammonium salts
An organic electrolyte battery using a first electrolyte comprising: 2. An organic electrode comprising a negative electrode, a positive electrode and an electrolyte.
In the electrolyte battery, carbonate is used as a solvent for the electrolytic solution.
, Esters and sulfolane
90% by volume or more of all solvents alone or as a mixture of two or more
Used, as an electrolyte of the electrolytic solution, -SO ₂ - bond, or -
A having a CO-bond and an alkyl group having 2 to 15 carbon atoms;
A second electrode comprising a salt of a alkali metal or alkaline earth metal
A first electrolyte having a molecular weight smaller than that of the second electrolyte;
An organic electrolyte battery using: 3. A first electrolyte of the electrolytic solution, A alkali metal,
3. The organic electrolyte battery according to claim 2, comprising a salt of an alkaline earth metal or a quaternary ammonium.