JPH06215775A - Organic electrolytic liquid and organic electrolytic battery - Google Patents

Abstract

PURPOSE:To improve storage stability by using a metal salt as an electrolyte of an organic electrolytic liquid wherein, regarding the anion the salt contains, the maximum distance between the center of a charge center atom of the anion and the center of other atoms is 4 or more and the anion is an organic anion having an electron attractive group. CONSTITUTION:An anion of an alkali metal salt to be used as an electrolyte of an electrolytic liquid has a steric hindrance barrier structure. That is, the metal salt is a salt containing an organic anion which has the maximum distance 4 or more, preferably 6 or more, between the center of an atom to be charge center in the anion and the center of other atoms. Moreover, the organic anion is needed to have total 4 or more electron attractive groups. Halogen atoms, -COO- group, -CN group, etc., are among the electron attractive groups and one containing halogenated alkyl groups using fluorine as the halogen is especially preferable. Due to the electron attractive property of itself, the metal salt is stabilized and the storage ability of the electrolytic liquid can be improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an organic electrolyte and an organic electrolyte battery.

[0002]

2. Description of the Related Art Organic electrolyte batteries represented by a manganese dioxide-lithium battery have a high voltage of 3 V or more and a high energy density, and therefore, their demands are increasing more and more.

Conventionally, organic electrolytes of batteries of this type (hereinafter,
LiClO ₄ has been used as an electrolyte in (only referred to as an electrolytic solution except when it represents a battery), but recently, safety of the battery has been emphasized, and it is preferable to use a dangerous substance such as LiClO _4. There is no situation.

As a lithium salt other than LiClO ₄ , for example, a boron-based lithium salt such as LiBF ₄ or LiB (C ₆ H ₅ ) ₄ is used as an electrolyte.

[0005]

However, the above-mentioned LiB
An electrolyte solution using F ₄ , LiB (C ₆ H ₅ ) ₄ or the like as an electrolyte may be discolored when stored, or a part of the electrolyte solution solvent may be polymerized. Further, when the electrolytic solution is used in a battery, the storage property of the battery is lowered.

Therefore, an object of the present invention is to solve the problems of the above conventional products and to provide an electrolytic solution and an organic electrolytic solution battery having excellent storability.

[0007]

The present invention is characterized in that the anion of the alkali metal salt used as the electrolyte of the electrolytic solution has a steric hindrance barrier structure. Here, the steric hindrance barrier structure refers to a structure in which a cation does not easily approach the charge center of the anion, and more specifically, the maximum distance between the charge center atom of the anion and the center of another atom is 4
It is a metal salt containing Å or more, preferably 5 Å or more, and most preferably 6 Å or more organic anions.

The organic anion needs to further have an electron-withdrawing group. The total number of electron-withdrawing groups is preferably 4 or more. And when it is 5 or more, it is more preferable, and when it is 6 or more, it is most desirable and the storability is further improved.

As the electron-withdrawing group, a halogen atom, --C
Examples thereof include an OO- group and a -CN group, but it is preferable to have a halogen atom. The halogen atom reduces the coulomb attractive force between the anion center and the cation center and increases the distance between the ions. In particular, it is desirable to contain a halogenated alkyl group, and halogen is most desirably fluorine. The action of the above-mentioned halogenated alkyl group is that the metal salt can be stabilized due to its own electron-withdrawing property, and the storability of the electrolytic solution can be improved. And, it is desirable that the number of the halogenated alkyl groups is 4 or more. In order to further improve the storability, 5 or more is preferable,
More preferable characteristics are obtained when the number is 6 or more.

Further, the atom serving as the anion center includes O (oxygen), N (nitrogen), C (carbon), B (boron), Al (aluminum), etc., and is an atom of group IIIb-VIb of the periodic table. is there. Above all, three or more substituents can be bonded III
Group b-IVb atoms are preferred and group IIIb atoms are particularly preferred, which may have four bonds when the group IIIb atom such as B (boron) is the anion center and is sterically hindered by substituents around the anion center. Is easy to form. Further, among the IIIb group atoms, the B (boron) atom has the smallest molecular weight, and the molecular weight of the anion can be reduced, which is desirable. By using a metal salt containing such an anion, the storability of the electrolytic solution is improved,
Further, by using the electrolytic solution, the storability of the organic electrolytic solution battery can be improved.

In the present invention, the reason why the storage properties of the electrolytic solution and the battery are improved by using the above-mentioned electrolyte will be clarified in the concrete explanation of the above-mentioned electrolyte.

First, it is desirable that the cation forming the salt is composed of an alkali metal or an alkaline earth metal,
Lithium is particularly preferable.

General electron-withdrawing groups and steric hindrance barriers
Specific examples of the metal salt containing an anion having a structure include:
(CF ₃ SO ₂ ) ₂ N ・ ME, (CF ₃ SO ₂ ) ₃ C ・
ME, [C ₆ H ₄ (F)] ₄ B ・ ME, [C ₆ H ₄ (C
l)] Metal salts such as ₄ B · ME (here, M
E is a metal such as Li, Na or K). Also, C ₄ F
Those having more than 2 carbon atoms, especially those having more than 4 carbon atoms, such as ₉ SO ₃ Li, also have a steric hindrance barrier structure. Specific examples of particularly desirable metal salts include, for example, LiB [C ₆ H ₄ (CF ₃ )] ₄ and LiB [C ₆
H ₃ (CF _{3) 2] 4} (lithium tetrakis [3,5
Bis (trifluoromethyl) phenyl] borate) (hereinafter referred to as LiTFPB), LiB (C ₆ H ₃ A ₂ ] ₄
[Wherein, A is -C (CF _{3) 2} OCH _3], and the like. And so on.

In particular, the organoboron metal salt containing a halogen atom can improve the storage properties of the electrolytic solution and the battery for the following reason.

Boron (B) is capable of forming four bonds, which are larger than oxygen (O) and nitrogen (N) as an element contained in an organic substance, and many electrons can be formed on the basis of its various bond properties. It has the ability to bind to a substituent having an attractive property. Moreover, boron is more metallic than carbon (C) having four bonds, and is a convenient element for ionizing the bonded metal.

However, LiBR in which an electron-donating alkyl group or a benzene ring is simply bonded to the boron (B) atom
₄ (where R is an alkyl group or a phenyl group) has an increased electron density on the B atom, so that it becomes easier to emit electrons.

That is, when a positive electrode active material such as a metal oxide which is more easily oxidized and has high activity at high voltage is used,
Due to a partial reaction with the positive electrode, the storability of the battery is rather deteriorated.

Therefore, it is necessary to further introduce an electron-withdrawing group into the substituent that binds the B atom to prevent electrons from concentrating on the B atom. Typical examples of the electron-withdrawing group are an alkyl group containing a halogen atom and a halogen atom, and a fluoroalkyl group is particularly preferable because it forms a stronger bond. These electron-withdrawing groups are bonded to the B atom. By being introduced into the substituent, the electron is less likely to be released, the electrolytic solution is less likely to be oxidized, and the storability is improved.

In particular, the above-mentioned LiTFPB is also used in Examples described later, but the ortho position of the phenyl group bonded to the B atom,
It has two trifluoromethyl groups at the meta position, and has a total of eight electron-withdrawing groups, and is particularly excellent in characteristics. The maximum distance between the center of the anion charge center atom and another atom is about 6.1Å between the B atom and F atom centers in the case of LiTFPB.

Here, the chemical formula of LiTFPB is shown below.

[0021]

[Chemical 1]

These metal salts having a steric hindrance barrier structure are simply bulky when dissolved in an electrolyte solvent.
Although it is only a high molecule, assuming that these elute the metal component of the positive electrode current collector into the electrolytic solution under high voltage,
Usually, the metal component becomes a cation having a valence of 2 or more, and when these cations and the anion portion of the metal salt having the steric hindrance barrier structure serve as counterions, the steric hindrance becomes large because the metal salt is bulky. It is considered that the reaction does not proceed as described above and the elution of the metal component of the positive electrode current collector is suppressed.

The material of the positive electrode current collector is, for example, Al.
(Aluminum), Ti (titanium), Ni (nickel), Cu (copper) or an alloy containing them as a main component is used. Above all, when the metal material of the positive electrode current collector is eluted, the one with higher valence of cations is more difficult to elute. In this sense, Al is trivalent, which is more difficult to elute than other divalent metals. ,preferable. Since Ti is also trivalent to tetravalent, it is more preferable.

In the electrolyte composed of the metal salt having the steric hindrance barrier structure, it is desirable that the anion portion is not only an anion having a large steric hindrance but also the anion itself is stable to oxidation.

In producing a battery using the above-mentioned electrolytic solution, an alkaline metal or a compound containing an alkaline metal integrated with a current collecting material such as a stainless steel net is used for the negative electrode. Examples thereof include lithium, sodium, potassium, and the like.Examples of the compound containing an alkali metal include, for example, an alloy of an alkali metal and aluminum, lead, indium, potassium, cadmium, tin, magnesium, and the like, and a compound of an alkali metal and a carbon material. Examples thereof include compounds of low-potential alkali metals with metal oxides and sulfides.

The organic solvent used to dissolve the above-mentioned electrolyte in the preparation of the electrolytic solution is, for example,
1,2-dimethoxyethane, 1,2-dimethoxymethane, dimethoxypropane, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 4-
Examples thereof include ethers such as methyl-1,3-dioxolane, esters such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone and γ-valerolactone, and sulfolane. Among them, the esters are the above-mentioned steric hindrance barriers.
When used in combination with an electrolyte composed of a metal salt containing an anion having a structure, particularly a metal salt containing four or more halogenated alkyl groups or an organic boron-based metal salt containing halogen atoms, the storage stability of the electrolytic solution is further improved. Therefore, it is preferable.

The concentration of the electrolyte in the electrolytic solution is not particularly limited, but usually the electrolytic solution contains a metal salt or halogen atom containing four or more of the above halogenated alkyl groups as an electrolyte in the above organic solvent. 0.01 to 2 mol / l, especially 0.05 to 1 mo containing an organic boron-based metal salt
It is preferable to dissolve about 1 / l.

Here, it is more preferable that the metal salt used in the battery is previously treated with a non-halogen solvent because it is easily dissolved in the solvent. The present inventors first tried to dissolve various lithium salts in CH ₂ Cl ₂ which is a typical halogen-containing solvent in which a metal salt is difficult to dissolve, but many lithium salts are dissolved in this CH ₂ Cl ₂ . It almost does not melt and precipitates, and even if the conductivity as an electrolyte is measured, it is several tens of μS / c.
It was no more than m.

The same was true for other fluorocarbon-based solvents such as perfluorotrialkylamine, which is a halogen-containing solvent.

However, in the course of repeating various studies, the above-mentioned LiTFPB was dissolved in ether, vacuum-dried, and then CH ₂ Cl ₂ was added.
It became possible to quickly dissolve it in ₂ Cl ₂ in an amount of 20 mmol / l, the conductivity reached 820 μS / cm, and the conductivity was improved 10 times or more. This effect was confirmed not only with halogen-containing solvents but also with highly viscous esters.

From the above, it was revealed that even a metal salt which is hardly soluble in a halogen-containing solvent, an ester or the like can be treated with a non-halogen solvent in advance to increase the dissolution rate or solubility in the solvent.

A more desirable electrolyte of the present invention is prepared by previously treating (for example, dissolving, depositing, impregnating) the metal salt with a non-halogen solvent, and then adding the solvent to dissolve the alkali metal salt in the solvent. It It is particularly desirable that the weight ratio of the non-halogenated solvent to the treated metal salt is preferably 0.1 or less, more preferably 0.05 or less. Further, the content of the non-halogen solvent to the metal salt is preferably 0.0005 or more by weight ratio,
The above is more desirable.

Here, as a solvent for which treatment with a non-halogen solvent is effective, a halogen-containing solvent such as CH ₂ Cl ₂ or CH _{2 is used} .
Cl ₃ , CCl ₄ , CBrF ₃ , CF ₃ CF ₂ CHCl
₂ , a solvent containing a halogen element such as CClF ₂ CF ₂ CHClF, and other high viscosity propylene carbonate, ethylene carbonate, butylene carbonate, γ
It is also effective for esters such as -butyrolactone and γ-valerolactone, and sulfolane. The viscosity of a high-viscosity solvent for which treatment with a non-halogen solvent is effective is preferably 1 cp (centipoise) or more at 25 ° C.
More desirably, 2.0 cp or more is preferable.

Examples of the non-halogen solvent include ethers such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, glyme and polyethylene oxide, esters such as propylene carbonate, γ-butyrolactone and methyl formate, and other amines.
Ketones, sulfur-containing compounds, alcohols, protic solvents such as water, and the like, ethers,
Esters are preferable, and ethers are particularly preferable because they have high solubility of alkali metal salts and low reactivity with the negative electrode.

Since a protic solvent such as alcohol easily reacts with lithium or the like and has a bad influence on the negative electrode in many cases, it is rarely used in an organic electrolyte battery, but it is used as in the present invention. In the method, since the protic solvent is strongly bound to the alkali metal salt, the reactivity with the negative electrode becomes low.

For the positive electrode, for example, a metal oxide such as manganese dioxide, vanadium pentoxide, chromium oxide, lithium cobalt oxide, lithium nickel oxide or a metal sulfide such as molybdenum disulfide, or a positive electrode active material thereof is used. A mixture obtained by appropriately adding a conductive auxiliary agent, a binder such as polytetrafluoroethylene, or the like is finished into a molded body using a current collecting material such as aluminum foil or stainless steel net as a core material.

When a metal oxide is used as the positive electrode active material, a high voltage can be obtained. However, at such a high voltage, conventional LiBF ₄ and LiB (C ₆ H ₅ ) ₄ are more storable. Although worse, since the electrolyte used in the present invention does not deteriorate the storage property even under such a high voltage,
Its significance is great.

Taking the case of using Al for the positive electrode current collector as an example, the effect of suppressing the elution of Al into the electrolytic solution will be described. The electrolyte used in the present invention (a metal salt having a steric hindrance barrier structure containing a fluorine atom). Is the conventional CF ₃ SO ₃ L
A difference begins to appear from around 3.1 V as compared with the case where i is used.

At a potential higher than that, CF ₃ SO
_{In the 3} Li system, the oxidation current is completely raised (that is, the oxidation current flows in Al and Al itself is oxidized and eluted into the electrolytic solution), whereas, for example, C ₄ F ₉ SO ₃ L
When i is used, almost no oxidation current flows and a remarkable difference appears, and the oxidation current rises at about 4.6 V.
Is. Furthermore, about 10 V when using LiTFFP
Even when it became, it was a very stable metal salt without showing a region where the current suddenly rises.

Further, when using the electrolyte of the present invention, the use of Al or its alloy for the positive electrode current collector is a preferable combination in terms of safety.

That is, when the potential of the positive electrode becomes 350 mV or less on the basis of Li at the time of abnormal discharge of the battery, the positive electrode current collector is alloyed and becomes smashed, the current collection of the positive electrode cannot be obtained, and the current is cut off. This is because abnormal heat generation can be prevented.

To this end, the structural design must be proper,
You should pay attention to the following matters.

First, the setting of the place where the current is cut off is performed. The most suitable for cutting off this current is the tab portion of the current collector (which is connected to one side of the plate-shaped positive electrode and is made of metal). It is a lead portion which connects the positive electrode and the positive electrode terminal portion with the formed positive electrode current collecting member. When this portion is alloyed, only this portion is broken and drops off to interrupt the current.

Secondly, the place where the current should be cut off is wet with the electrolytic solution. That is, aluminum alloying occurs only in the presence of the electrolytic solution.
Therefore, it is desirable to fill the electrolytic solution up to the place where the electric current is cut off, or to cover the area with the electrolytic solution permeable material and keep it wet with the electrolytic solution.

Thirdly, tensile stress is applied to the portion where the current should be cut off. This is because, if a compressive stress is applied, even if a certain amount of Al alloy falls off, it will stick again.

However, the direction of the tensile stress does not matter. This is because even if some of them are broken apart and separated, they separate from each other in the lateral direction, so that the current can be reliably cut off.

A desirable condition is that the current interruption portion is thinner than the other portions. This is because if the lead body is cut at a portion other than the desired portion, a sufficient effect may not be obtained when the portion is subjected to shrinkage stress.

Here, although such a tensile stress may impair the stability of the current collector such as aluminum at 4.2 V or more, when the organometallic salt of the present invention is used, the influence thereof is slightly suppressed. Of. For example, between aluminum having a large strain formed by cold rolling and aluminum having a small strain annealed from a high temperature, the aluminum having a small strain was more stable. When LiCF ₃ SO ₃ or the like is used as the electrolyte, when aluminum with large strain is used, aluminum easily elutes at high voltage. However, in the case of the metal salt of the present invention, stability even with aluminum with large strain Was excellent. Therefore, when the metal salt of the present invention is used, even if the current collector such as aluminum is distorted due to tensile stress, its influence is small.

By the way, there is an advantage in aluminum whose strain is increased by rolling. By rolling, the grain boundaries of aluminum become smaller, and the alloying of aluminum and lithium proceeds more uniformly during abnormal battery discharge, contributing to reliable current interruption.
Moreover, even with a thin current collector having a thickness of 30 microns or less, the tensile strength is 10 to 12 kg / mm ² or more, and sufficient strength can be obtained.

Further, if the surface area of the positive electrode active material is reduced, the storability is further improved. The positive electrode active material used in the battery of the present invention preferably has a surface area of 50 m ² / g or less, preferably 30 m ² / g or less, and more preferably 2 m ² / g or less.
It is 0 m ² / g or less.

Further, it is preferable that the active surface of the metal oxide of the positive electrode active material is treated with an alkali metal or alkaline earth metal compound to contain an alkali metal or an alkaline earth metal, because the storability is further improved. In addition, the storability can be improved to some extent by performing preliminary discharge after the battery is manufactured.

[0051]

EXAMPLES Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to those examples.

Example 1 (CF ₃ SO ₂ ) ₃ C.Li, C ₄ F ₉ SO ₃ Li, L
iTFPB was dissolved in a non-halogen solvent, ethyl ether, and vacuum-dried to adjust the weight ratio of ethyl ether to a lithium salt to about 0.04. Then, propylene carbonate was added to and mixed with 0.1 mol / l LiTF.
PB + 0.1 mol / l (CF ₃ SO ₂ ) ₃ C · Li +
An electrolytic solution having a composition of 0.1 mol / l C ₄ F ₉ SO ₃ Li / PC was prepared.

LiTFPB in the electrolytic solution is an abbreviation for lithium tetrakis [3,5-bis (trifluoromethyl) phenyl] borate as described above, and PC is an abbreviation for propylene carbonate. Therefore, 0.1 mol / l LiTFPB + 0.
1 mol / l (CF ₃ SO ₂ ) ₃ C · Li + 0.1 m
In ol / l C ₄ F ₉ SO ₃ Li / PC, the electrolyte solution is lithium tetrakis [3,5] in propylene carbonate solvent.
- shows that bis and (trifluoromethyl) phenyl] borate _{(CF 3 SO 2) 3 C} · Li and C ₄ F ₉ SO ₃ Li is obtained by dissolving 0.1 mol / l each time. Here, the viscosity of propylene carbonate at 25 ° C. is 2.5 cp.

Further, after electrolytically manganese dioxide was heat-treated and then heat-treated with an aqueous solution of lithium hydroxide to obtain an active material having a surface area of 18 m ² / g, 100 parts by weight of this manganese dioxide, 5 parts by weight of carbon black and polytetrafluoroethylene were added. After mixing 5 parts by weight of the dispersed water-solvent mixed solution (weight in terms of solid content), this was applied to both surfaces using a 20-micron-thick aluminum foil as a core material and dried, and then 0.4 mm in thickness and 3 in width.
Molded into a sheet of 0 mm, the lead portion (thickness of 30 μm has large strain due to rolling and tensile tension of 17 kg / m
What became m ² . Its shape is shown in FIG. ) Was attached to the strip-shaped positive electrode to dry it at 250 ° C., and after drying, it was cooled to room temperature in a dry atmosphere.

Next, the above strip-shaped positive electrode was sandwiched with a separator made of a microporous polypropylene film having a thickness of 25 μm, and a strip-shaped negative electrode obtained by crimping a sheet-shaped lithium sheet having a thickness of 0.18 mm and a width of 30 mm to a stainless steel net was prepared. After stacking and spirally winding a spiral electrode body, the outer diameter 15
After filling in a cylindrical battery case having a bottom of 1 mm and spot welding of the positive electrode and negative electrode lead bodies, the above-mentioned electrolytic solution was injected into the battery case.

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

However, in the positive electrode current collector described above, stress in the tensile direction is applied in a specific manner to the portion immersed in the electrolytic solution, as will be described later.

Explaining the battery shown in FIG. 1, 1 is the positive electrode and 2 is the negative electrode. However, in FIG. 1, in order to avoid complication, the current collector and the like used in manufacturing the positive electrode 1 and the negative electrode 2 are not shown. And 3 is a separator and 4 is an electrolytic solution.

5 is a stainless steel battery case,
The battery case 5 also serves as a negative electrode terminal. An insulator 6 made of a polytetrafluoroethylene sheet is arranged at the bottom of the battery case 5, and an insulator 7 made of a polytetrafluoroethylene sheet is also arranged at the inner peripheral part of the battery case 5. The spiral electrode body including the negative electrode 2 and the separator 3, the electrolytic solution 4, and the like are contained in the battery case 5.

Reference numeral 8 is a stainless steel sealing plate, and a gas vent hole 8a is provided at the center of the sealing plate 8. Reference numeral 9 is a polypropylene-made annular packing, 10 is a flexible thin plate made of titanium, and 11 is an annular heat-deformable member made of polypropylene.

The above-mentioned thermal deformation member 11 acts to change the breaking pressure of the flexible thin plate 10 by being deformed by the temperature.

Reference numeral 12 denotes a nickel-plated terminal plate made of rolled steel. The terminal plate 12 is provided with a cutting edge 12a and a gas discharge hole 12b. When the internal pressure rises and the flexible thin plate 10 is deformed due to the increase in the internal pressure, the cutting blade 12a breaks the flexible thin plate 10 to discharge the gas inside the battery from the gas discharge hole 12b to the outside of the battery. Then, it is designed to prevent the destruction of the battery.

Reference numeral 13 is an insulating packing, 14 is a lead body (a part of the current collector), the lead body 14 electrically connects the positive electrode 1 and the sealing plate 8, and the terminal plate 12 is a sealing body. The contact with the plate 8 serves as a positive electrode terminal. Also, 1
Reference numeral 5 is a lead body that electrically connects the negative electrode 2 and the battery case 5.

A stress in the pulling direction is applied to the portion of the positive electrode current collector 14 immersed in the electrolytic solution 4, as shown below.

That is, when the terminal plate 12 is displaced in the A direction in advance for sealing, and the terminal plate 12 is laterally displaced and held at a predetermined position for sealing, the positive electrode current collector 14 has a point C. A stress in the B direction (which looks like a lateral stress in the figure, but a tensile stress on the positive electrode current collector 14) is applied. Further, the point C of the positive electrode current collector 14 is thinner than the other portions, as shown in FIG.

Comparative Example 1 LiB (C ₆ H ₅ ) ₄ was dissolved in a PC solvent to give 0.3 m.
An electrolytic solution having a composition of ol / l LiB (C ₆ H ₅ ) ₄ / PC was prepared.

PC in the above electrolytic solution is an abbreviation for propylene carbonate. Therefore, in the case of 0.1 mol / l LiB (C ₆ H ₅ ) ₄ / PC representing the above-mentioned electrolytic solution, the electrolytic solution is LiB (C
₆ H ₅ ) ₄ is dissolved at 0.3 mol / l. The maximum interatomic center distance between the anion center of LiB (C ₆ H ₅ ) ₄ and another atom was about 5.6Å, but it did not contain a halogen atom.

Comparative Example 2 CF ₃ SO ₃ Li was dissolved in a PC solvent to give 0.3 mol.
An electrolytic solution having a composition of / l CF ₃ SO ₃ Li / PC was prepared.

PC in the above electrolytic solution is an abbreviation for propylene carbonate. Therefore, 0.1 mol / l CF ₃ SO ₃ Li / PC indicating the above-mentioned electrolytic solution indicates that the electrolytic solution is obtained by dissolving CF ₃ SO ₃ Li in a propylene carbonate solvent at 0.3 mol / l. . CF ₃ SO ₃ Li contains halogen atoms, but the maximum distance between the centers of anions and other atoms is about 3.
It's just 9Å.

A tubular organic electrolyte battery having the structure shown in FIG. 1 was prepared in the same manner as in Example 1 using the above electrolyte solution.

Next, the minimum voltage when the battery of Example 1 and the batteries of Comparative Examples 1 and 2 were discharged at 0.3 A for 10 milliseconds was measured. Both batteries were discharged at a constant current of 50 mA, and the capacity after storage at 80 ° C. for 10 days was measured and compared with the capacity before storage. The results are shown in Table 1.

[0071]

[Table 1]

As shown in Table 1, the battery of Example 1 was
The voltage at the time of discharge at 0.3 A for 10 milliseconds was high, the capacity deterioration due to storage was small, and the storability was excellent. On the other hand, the batteries of Comparative Examples 1 and 2 could hardly be discharged after storage and had poor storability.

A part of the positive electrode current collector lead is not thin and is not stressed, or a battery prepared by applying a stress in the compressing direction is forcibly over-discharged at 10 A, and then -3 V is applied.
After that, an overdischarge experiment was performed at a constant voltage of -3 V. As a result, the interruption of the current was sometimes insufficient, and a highly reliable function could not be obtained. On the other hand, the batteries of Example 1 all exhibited safe behavior because the current was cut off during overdischarge.

[0074]

As described above, according to the present invention,
The storability of the electrolytic solution and the organic electrolytic solution battery can be improved.

[Brief description of drawings]

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

FIG. 2 is an enlarged view showing a stressed portion of a positive electrode current collector of the battery shown in FIG.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode 3 Separator 4 Electrolyte

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Sonoda 2-1-23 Hikarimachi, Hakata-ku, Fukuoka-shi, Fukuoka (72) Inventor Hiroshi Kobayashi 2-1-23 Hikari-cho, Hakata-ku, Fukuoka-shi, Fukuoka

Claims (10)

[Claims] 1. At least one electron-withdrawing group is bonded via an intermediate skeleton to a charge center atom of an anion consisting of any one element selected from groups IIIb to VIb of the periodic table, In this anion, an organic electrolyte solution is prepared by dissolving a metal salt containing an organic anion in which the maximum distance between the charge center atom and the center of another atom is 4Å or more in an organic solvent. 2. The organic electrolyte solution of the anion according to claim 1, wherein a metal salt containing an organic anion having a maximum distance between the charge center atom and the centers of other atoms is 5Å or more is dissolved in an organic solvent. 3. A metal salt containing an organic anion is (CF ₃ S
_{O 2) 2 N · ME,} (CF 3 SO 2) 3 C · ME, [C
₆ H ₄ (F)] ₄ B · ME, [C ₆ H ₄ (Cl)] ₄ B
ME (where ME is a metal such as Li, Na, K) or C _n F _{2n + 1} SO ₃ Li (where n is an integer of 2 or more) or LiB [C ₆ H ₄ (CF ₃ )] ₄ , LiB
[C ₆ H ₃ (CF ₃ ) ₂ ] ₄ (lithium tetrakis [3,5-bis (trifluoromethyl) phenyl] borate) (hereinafter referred to as LiTFPB), LiB (C ₆ H
₃ A ₂ ] ₄ [where A is -C (CF ₃ ) ₂ OCH ₃ ].
The organic electrolytic solution according to claim 1, which is one of the following: 4. The organic electrolyte solution according to claim 1, wherein a metal salt containing four or more halogenated alkyl groups or an organic boron metal salt containing a halogen atom is used as the electrolyte. 5. The organic electrolytic solution according to claim 4, wherein the electrolyte is a metal salt containing five or more halogenated alkyl groups. 6. The organic electrolytic solution according to claim 5, wherein the electrolyte is a metal salt having four benzene rings and at least two fluoroalkyl groups in at least one benzene ring. 7. The organic electrolytic solution according to claim 1, wherein the electrolyte is an organic boron-based lithium salt containing a halogen atom, and the organic solvent contains at least one of esters and carbonates. 8. At least one electron-withdrawing group is bonded via an intermediate skeleton to a charge center atom of an anion consisting of any one element selected from groups IIIb to VIb of the periodic table, In this anion, a battery using an organic electrolyte solution in which a metal salt containing an organic anion having a maximum distance between the charge center atom and the centers of other atoms is 4Å or more is dissolved in an organic solvent. 9. A battery using a metal containing aluminum or titanium as the positive electrode current collector.
A battery using the described electrolytic solution. 10. A positive electrode current collecting member made of a metal containing aluminum or titanium, which is connected to one side of a plate-shaped positive electrode and is in a state capable of contacting an electrolytic solution, is arranged in a state of being subjected to tensile stress. A battery comprising the electrolytic solution according to claim 1 in the battery.