JP2009252681A - Nonaqueous electrolytic solution for primary cell, and nonaqueous electrolytic solution primary cell using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution which is less in cell resistance elevation when stored at high temperatures, and is operated stably in a nonaqueous electrolytic solution primary cell. <P>SOLUTION: In the nonaqueous electrolytic solution for the primary cell having a positive electrode and a negative electrode containing metal lithium or lithium alloy, the nonaqueous electrolytic solution contains a solute, a nonaqueous solvent, and monofluoro phosphate and/or difluoro phosphate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte for a primary battery and a non-aqueous electrolyte primary battery using the same.

  Lithium primary batteries that use lithium metal or its alloys for the negative electrode have a high energy density and a large capacity, and can be used stably over a long period of time. Used for applications.

  In recent years, there has been a movement to mount a pressure sensor for monitoring air pressure on a tire, and a lithium primary battery has been cited as a candidate for the power source for the pressure sensor. However, when left in a high-temperature environment exceeding 100 ° C. such as the inside of a tire, the lithium of the negative electrode and the electrolytic solution react violently, and gas generation and formation of a high resistance film on the electrode surface tend to occur. It is in. As a result, there is a problem that the resistance of the battery is increased, and the battery voltage is lowered due to an overvoltage during discharge.

  In order to solve such problems, attempts have been made to improve high-temperature storage characteristics by adding cyclic sultone derivatives and acid anhydrides to the battery electrolyte (see Patent Documents 1 and 2). .

Japanese Patent No. 3722374 Japanese Patent No. 3866191

However, the methods described in Patent Document 1 and Patent Document 2 described above have not been sufficiently improved in performance such as high-temperature storage characteristics, and further improvements have been expected.
The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a non-aqueous electrolyte solution that can stably operate in a non-aqueous electrolyte primary battery with a small increase in battery resistance during high-temperature storage.

  As a result of intensive studies to solve the above problems, the present inventor has found that the non-aqueous electrolyte contains at least one monofluorophosphate or difluorophosphate, which is higher in temperature than conventional. The present inventors have found that a non-aqueous electrolyte primary battery that has a small increase in resistance during storage and operates stably can be obtained, and has completed the present invention.

  Techniques for adding monofluorophosphate and difluorophosphate to the electrolyte solution are described in JP-A-11-67270, JP-A-2007-180016, etc., both of which are secondary batteries. It is intended to improve the above, and is not supposed to be used at a high temperature of 100 ° C. or higher. The present invention relates to a non-aqueous electrolyte primary battery, and is intended to be used at a high temperature of 100 ° C. or higher.

  That is, the gist of the present invention is a non-aqueous electrolyte for a primary battery having a positive electrode and a negative electrode comprising metallic lithium or a lithium alloy, wherein the non-aqueous electrolyte is a solute, a non-aqueous solvent, and , Monofluorophosphate and / or difluorophosphate, which resides in a non-aqueous electrolyte for a primary battery (claim 1).

  At this time, the monofluorophosphate and / or difluorophosphate is preferably contained in an amount of 0.01% by weight or more and 5% by weight or less in 100% by weight of the non-aqueous electrolyte.

  Moreover, it is preferable that this non-aqueous solvent contains a cyclic carboxylic acid ester compound and / or a chain ether compound.

  At this time, the cyclic carboxylic acid ester compound is preferably γ-butyrolactone and / or γ-valerolactone.

  The chain ether compound is preferably at least one selected from the group consisting of 1,2-dimethoxyethane, 1,2-diethoxyethane, and diethylene glycol dimethyl ether.

The solute preferably contains at least one selected from the group consisting of LiBF ₄ , LiClO ₄ , and LiCF ₃ SO ₃ (claim 6).

  Another gist of the present invention resides in a non-aqueous electrolyte primary battery comprising a positive electrode, a negative electrode comprising metallic lithium or a lithium alloy, and the non-aqueous electrolyte described above (Claim 7).

At this time, it is preferable that the positive electrode contains fluorinated graphite or fluorocarbon represented by the formula {(CF _x ) _n ; 0 <X ≦ 1}.

  Moreover, it is preferable that this positive electrode contains manganese dioxide (Claim 9).

  According to the non-aqueous electrolyte of the present invention, it is possible to provide a non-aqueous electrolyte primary battery that operates stably with a small increase in resistance during high-temperature storage.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these elements unless departing from the elements. It is not specified in the contents of.

[I. Nonaqueous electrolyte for primary battery]
The nonaqueous electrolytic solution for a primary battery of the present invention is a nonaqueous electrolytic solution for a primary battery (hereinafter simply referred to as “lithium primary battery”) having a positive electrode and a negative electrode containing metallic lithium or a lithium alloy. . The nonaqueous electrolytic solution for a primary battery of the present invention contains a solute, a nonaqueous solvent, and a monofluorophosphate and / or a difluorophosphate.

(Solute)
As the solute, a lithium salt is usually used. The lithium salt is not limited as long as it can be used for a non-aqueous electrolyte of a lithium primary battery, and examples thereof include the following.

(1) Inorganic lithium _salt: LiAsF _6, LiPF _6, inorganic fluoride salts LiBF ₄ or the _like, LiClO _4, LiBrO _4, perhalogenate of LiIO _4, and the like.

(2) Organic lithium salt: lithium borate such as LiB (C ₂ O ₄ ) ₂ and LiB (C ₆ H ₅ ) ₄ , alkane sulfonate such as LiCH ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , perfluoroalkanesulfonic acid imide salts such as LiN (SO ₂ C ₂ F ₅ ) ₂ , and perfluoroalkanesulfonic acid salts such as LiCF ₃ SO ₃ .

Among these, LiBF ₄ , LiClO ₄ , LiCF ₃ SO _{3 and the} like are preferable from the viewpoint of stability of battery characteristics during high-temperature storage.
One of these lithium salts may be used alone, or two or more thereof may be used in any combination and ratio.
Moreover, you may use together solutes other than lithium salt with lithium salt as needed.

  The concentration of the solute in the non-aqueous electrolyte for a primary battery of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. The concentration of the lithium salt is usually 0.1 mol / liter or more, preferably 0.5 mol / liter or more, and usually 2.5 mol / liter or less, preferably 1.5 mol / liter or less. If the concentration of the lithium salt is too high or too low, the electric conductivity of the electrolytic solution tends to decrease. When the concentration is within the above range, a decrease in the conductivity of the electrolytic solution is suppressed, and good battery characteristics are easily obtained.

(Non-aqueous solvent)
There is no restriction | limiting in particular as a non-aqueous solvent, It can select suitably from the non-aqueous solvents currently used as a solvent of the well-known non-aqueous electrolyte solution for lithium primary batteries.

  Specific examples of such a non-aqueous solvent include cyclic carbonates (cyclic carbonates), chain carbonates (chain carbonates), cyclic esters (cyclic carboxylic acid esters), chain esters (chain carboxylic acids). Esters), cyclic ethers, chain ethers, cyclic sulfones and the like.

Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate and the like.
Examples of chain carbonates include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
Examples of cyclic esters include γ-butyrolactone and γ-valerolactone.
Examples of chain esters include methyl acetate and methyl propionate.
Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1,4-dioxane, 1,3-dioxane and the like.
Examples of chain ethers include diethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.
Examples of cyclic sulfones include sulfolane.
One of these non-aqueous solvents may be used alone, or two or more thereof may be used in any combination and ratio.

The nonaqueous solvent is preferably used in combination with a high dielectric constant solvent and a low viscosity solvent from the viewpoint of the electric conductivity of the electrolytic solution.
Here, the high dielectric constant solvent means a solvent having a relative dielectric constant of 20 or more at 25 ° C., and the low viscosity solvent means a solvent having a viscosity of less than 1 mPa · S at 25 ° C.

Examples of the high dielectric constant solvent include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, and the like.
Examples of the low viscosity solvent include dimethyl carbonate, methyl acetate, methyl propionate, 1,2-dimethoxyethane, 1,2-diethoxyethane, and diethylene glycol dimethyl ether.

  Among them, as the high dielectric constant solvent, cyclic esters such as γ-butyrolactone and γ-valerolactone are preferable. The low viscosity solvent is preferably a chain ether such as 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether. Use of these non-aqueous solvents is particularly preferable because of excellent stability in storage at high temperatures.

(Monofluorophosphate, difluorophosphate)
The nonaqueous electrolytic solution for a primary battery of the present invention contains at least one fluorophosphate selected from the group consisting of a monofluorophosphate and a difluorophosphate in addition to the above solute and nonaqueous solvent. To do.

The counter cation of the monofluorophosphate and difluorophosphate used in the present invention is not limited.
Specific examples include metal element cations such as Li, Na, K, Mg, Ca, Fe, and Cu; NR ¹ R ² R ³ R ⁴ (wherein R ^{1 to} R ⁴ are each independently a hydrogen atom or carbon Represents an organic group having a number of 1 or more and 12 or less.)

Examples of the organic group having 1 to 12 carbon atoms of R ^{1 to} R ⁴ include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom, and a halogen atom. An aryl group which may be present, a nitrogen atom-containing heterocyclic group, and the like.
Among these, as R ^{1 to} R ⁴ , a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen atom-containing heterocyclic group, and the like are preferable.

Among these counter cations, Li, Na, K, Mg, Ca, NR ¹ R ² R ³ R ⁴ are preferable, and Li is particularly preferable from the viewpoint of battery characteristics when used for a lithium primary battery.
In the present invention, monofluorophosphate and difluorophosphate may be used alone, or two or more compounds may be used in any combination and ratio.

  The total concentration of monofluorophosphate and difluorophosphate contained in the non-aqueous electrolyte is usually 0.01% by weight or more, preferably 0.2% by weight or more in 100% by weight of the non-aqueous electrolyte. More preferably, it is 0.5% by weight or more, usually 5% by weight or less, preferably 3% by weight or less, more preferably 1.5% by weight or less. Below this range, performance improvements during high temperature storage tend to be insufficient. Moreover, when it exceeds this range, battery characteristics other than high-temperature storage characteristics tend to be deteriorated.

When monofluorophosphate and / or difluorophosphate is contained in the non-aqueous electrolyte for primary batteries, the non-aqueous electrolyte primary battery using the non-aqueous electrolyte for primary batteries is placed in a high-temperature environment. Even in this case, since the resistance increase is small, the operation is stable.
The reason is estimated as follows.
When the non-aqueous electrolyte primary battery is placed in a high temperature environment, the lithium in the negative electrode and the electrolyte react violently to generate gas and form a high resistance film on the electrode surface. As a result, there is a problem that the resistance of the battery is increased and the battery voltage is lowered due to the overvoltage at the time of discharging.
However, since the non-aqueous electrolyte for a primary battery of the present invention contains monofluorophosphate and / or difluorophosphate, they react on the negative electrode comprising metallic lithium and / or a lithium alloy, It is considered that a high temperature resistant and low resistance protective film is formed on the negative electrode surface. Thereby, it is presumed that the abnormal reaction between the negative electrode and the electrolyte component occurring during high-temperature storage can be suppressed, and good discharge characteristics can be maintained even after high-temperature storage.

(Other ingredients)
In any embodiment, the nonaqueous electrolytic solution for a primary battery of the present invention contains other components in addition to the solute, nonaqueous solvent, monofluorophosphate, and difluorophosphate as necessary. be able to.

Examples of the other components include various additives for forming a film on the active material surface of the battery. Examples of such a film forming additive include vinylene carbonate, vinyl ethylene carbonate, propane sultone, ethylene sulfite succinic anhydride, benzoic acid esters, aromatic dicarboxylic acid esters, and the like.
One of these may be used alone, or two or more may be used in any combination and ratio. Moreover, the density | concentration of the additive with respect to the non-aqueous electrolyte for primary batteries will not have a restriction | limiting, unless the effect of this invention is impaired.

(Method for producing non-aqueous electrolyte for primary battery)
There is no limitation on the method for producing the non-aqueous electrolyte for primary batteries of the present invention. A non-aqueous electrolyte obtained by finally mixing a solute, a non-aqueous solvent, and a monofluorophosphate and / or difluorophosphate is provided. It only has to be obtained. Therefore, as long as the effects of the present invention are not impaired, there is no limitation on the mixing method such as mixing order, mixing speed, mixing temperature, presence / absence of stirring, and its speed, and any known method can be used. it can.

[II. Nonaqueous electrolyte primary battery]
The non-aqueous electrolyte primary battery of the present invention has a positive electrode, a negative electrode comprising metallic lithium or a lithium alloy, and the non-aqueous electrolyte of the present invention. Hereinafter, the non-aqueous electrolyte primary battery of the present invention will be described in detail.

(Battery configuration)
The configuration of the known non-aqueous electrolyte primary battery can be arbitrarily applied to the non-aqueous electrolyte primary battery of the present invention for configurations other than the non-aqueous electrolyte for primary battery of the present invention. The specific configuration usually includes a positive electrode and a negative electrode through a separator impregnated with the non-aqueous electrolyte for a primary battery of the present invention, and has a form in which they are housed in an exterior body.

(Nonaqueous electrolyte)
As the non-aqueous electrolyte for primary battery, the above-described non-aqueous electrolyte for primary battery of the present invention is used.

(Positive electrode)
Although there is no restriction | limiting in the positive electrode of the nonaqueous electrolyte primary battery of this invention, Usually, what contains a positive electrode active material, a binder, and a electrically conductive material is used.

Examples of the positive electrode active material include MnO ₂ , fluorinated graphite, or carbon fluoride {(CF _X ) _n ; 0 <X ≦ 1}, V ₂ O ₅ , CuO, CuS, FeS ₂ , TiS ₂ , Ag ₂ CrO. ₄ , MoO ₃ , Bi ₂ O ₃ , Bi ₂ Pb ₂ O ₅ , Cu ₄ O (PO ₄ ) _{2 and the} like.
Among these, MnO ₂ , graphite fluoride, carbon fluoride {(CF _X ) _n ; 0 <X ≦ 1} and the like are particularly preferable from the viewpoint of long-term reliability of battery characteristics.
One type of positive electrode active material may be used alone, or two or more types may be used in any combination and ratio.

Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, styrene / butadiene rubber, isoprene rubber, and budadiene rubber.
One type of binder may be used alone, or two or more types may be used in any combination and ratio.

Examples of the conductive material include metal powders such as acetylene black, carbon black, graphite, powdered nickel, aluminum, titanium, and stainless steel.
One type of conductive material may be used alone, or two or more types may be used in any combination and ratio.

There is no restriction | limiting about the method of manufacturing a positive electrode, Any well-known method can be used.
For example, the above-described positive electrode active material is mixed with the above-described binder, the above-described conductive material, thickener, solvent, and the like as necessary to form a slurry, which is applied to the substrate of the positive-electrode current collector and dried. Can be manufactured.

At this time, examples of the thickener include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.
One thickener may be used alone, or two or more thickeners may be used in any combination and ratio.

The solvent is not particularly limited as long as it is a solvent that can dissolve or disperse a compound serving as a positive electrode material such as a positive electrode active material, a binder, and a conductive material, and any of an aqueous solvent and an organic solvent can be used. May be used.
One type of solvent may be used alone, or two or more types may be used in any combination and ratio.

Examples of the material of the positive electrode current collector that can be used for the positive electrode include metals such as aluminum, titanium, tantalum, and stainless steel, or alloys of these metals. Among these, aluminum and its alloys are preferable.
As the material for the positive electrode current collector, one type may be used alone, or two or more types may be used in any combination and ratio.

  As another example of producing the positive electrode, the active material may be roll-formed as it is to form a sheet electrode, or a compression-molded pellet electrode.

(Negative electrode)
As the negative electrode, one formed by including metallic lithium or a lithium alloy is used.
Examples of the lithium alloy include Li—Al, Li—Si, Li—Sn, Li—NiSi, Li—Pb, and the like. One lithium alloy may be used alone, or two or more lithium alloys may be used in any combination and ratio.
Note that only one of the metal lithium and the lithium alloy may be used, or both may be used in combination at any ratio.

There is no restriction | limiting about the method of manufacturing a negative electrode, Any well-known method can be used.
For example, it can be manufactured by punching a sheet of metallic lithium or lithium alloy into a desired size.

As the binder, the conductive material, the thickener, and the like that can be used for the negative electrode, the same materials as those for the positive electrode can be used.
Examples of the material of the negative electrode current collector that can be used for the negative electrode include metals such as copper, nickel, and stainless steel, or alloys thereof. Of these, copper is preferable.
As the material for the negative electrode current collector, one type may be used alone, or two or more types may be used in any combination and ratio.

(Separator)
In the nonaqueous electrolyte primary battery of the present invention, a separator is usually interposed between the positive electrode and the negative electrode in order to prevent a short circuit. When the separator can be impregnated with a liquid, the nonaqueous electrolytic solution of the present invention is usually used by impregnating the separator.

  There is no restriction | limiting about the material and shape of a separator, A well-known thing can be used arbitrarily unless the effect of this invention is impaired. Among these, it is preferable to use a porous sheet or a nonwoven fabric that is formed of a material that is stable with respect to the non-aqueous electrolyte solution of the present invention and has excellent liquid retention.

At this time, as a material for the separator, for example, polyethylene, polypropylene, polyphenylene sulfide, or the like can be used.
In addition, the material of a separator may be used individually by 1 type, and may use 2 or more types by arbitrary combinations and a ratio.

(Exterior body)
The non-aqueous electrolyte primary battery of the present invention is usually configured by housing the non-aqueous electrolyte of the present invention, a positive electrode, a negative electrode, a separator and the like in an exterior body. There is no restriction | limiting in this exterior body, A well-known thing can be arbitrarily employ | adopted unless the effect of this invention is impaired remarkably.

Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum, or an alloy thereof, nickel, titanium, or the like is used.
As the material for the exterior body, one type may be used alone, or two or more types may be used in any combination and ratio.

  The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

(Method for producing non-aqueous electrolyte for primary battery of the present invention)
There is no restriction | limiting about the method of manufacturing the nonaqueous electrolyte primary battery of this invention, It can select suitably from well-known methods.
Specific examples of the nonaqueous electrolyte primary battery according to the present invention include a cylinder type in which a sheet electrode and a separator are spiraled, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a pellet electrode and a separator. Can be manufactured.

  The present invention will be described more specifically based on examples, but the present invention is not limited to the following examples unless departing from the gist thereof.

[Production and evaluation of batteries]
The production and evaluation of the nonaqueous electrolyte primary battery were performed as follows.

(Preparation of positive electrode)
After kneading a mixture consisting of 80% by weight of the compound selected for each of Examples and Comparative Examples as the positive electrode active material, 10% by weight of acetylene black as the conductive material, and 10% by weight of polytetrafluoroethylene as the binder, It was pressure-molded at a pressure of 50 kgf / cm ² to form a disk-shaped molded body having a diameter of 12 mm and a thickness of 0.5 mm, and this was used as a positive electrode.

(Preparation of negative electrode)
A metal lithium sheet having a thickness of 0.5 mm was punched into a disk shape having a diameter of 14 mm, and this was used as a negative electrode.

(Battery assembly)
A lithium primary battery was fabricated using a 2032 type stainless steel coin cell case in a dry box in an argon atmosphere. Specifically, a positive electrode was first placed on a positive electrode can, a polypropylene non-woven fabric was placed thereon as a separator, pressed with a polypropylene gasket, a negative electrode was placed, and a thickness adjusting spacer was placed. Next, an electrolytic solution selected for each of the examples and comparative examples was added, and the battery was sufficiently impregnated. Then, the lithium primary battery was obtained by mounting a negative electrode can and sealing a battery.
In addition, the capacity | capacitance of the battery in an Example and a comparative example was designed to become about 40 mAh with the discharge minimum 2.0V.

(Battery evaluation)
The evaluation of the non-aqueous electrolyte primary battery was carried out by storing the produced non-aqueous electrolyte primary battery in an environment of 125 ° C. for 3 hours, performing a constant current discharge of 1 mA at −40 ° C., and measuring the battery voltage immediately after the start of discharge. Compared.
A high battery voltage means that the voltage drop due to overvoltage is small, and can operate stably even after high-temperature storage.

[Example 1]
Fluorinated graphite was used as the positive electrode active material.
As the nonaqueous electrolytic solution, a nonaqueous electrolytic solution in which LiBF ₄ was dissolved in γ-butyrolactone at a concentration of 1 mol / liter and lithium difluorophosphate was contained at a concentration of 1% by weight was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Example 2]
Fluorinated graphite was used as the positive electrode active material.
As the nonaqueous electrolytic solution, a nonaqueous electrolytic solution in which lithium difluorophosphate was contained at a concentration of 1% by weight in a solution obtained by dissolving LiBF ₄ in propylene carbonate at a concentration of 1 mol / liter was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Example 3]
Fluorinated graphite was used as the positive electrode active material.
As the non-aqueous electrolyte, a non-aqueous electrolyte was used in which LiPF ₆ was dissolved in γ-butyrolactone at a concentration of 1 mol / liter and lithium difluorophosphate was contained at a concentration of 1% by weight.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Example 4]
Fluorinated graphite was used as the positive electrode active material.
As a non-aqueous electrolyte, a solution in which LiBF ₄ was dissolved at a concentration of 1 mol / liter in a non-aqueous solvent in which γ-butyrolactone and 1,2-dimethoxyethane were mixed at a volume ratio of 3: 2 was used. A nonaqueous electrolytic solution containing lithium difluorophosphate at a concentration of 1% by weight was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Example 5]
Manganese dioxide was used as the positive electrode active material.
LiCF ₃ SO ₃ is dissolved at a concentration of 0.5 mol / liter in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane are mixed at a volume ratio of 3: 2 as a non-aqueous electrolyte. A non-aqueous electrolyte solution containing 1% by weight of lithium difluorophosphate was used as the solution.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Example 6]
Manganese dioxide was used as the positive electrode active material.
A solution in which LiClO ₄ is dissolved at a concentration of 0.5 mol / liter in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane are mixed at a volume ratio of 3: 2 as a non-aqueous electrolyte. In addition, a nonaqueous electrolytic solution containing lithium difluorophosphate at a concentration of 1% by weight was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 1]
Fluorinated graphite was used as the positive electrode active material.
As the nonaqueous electrolytic solution, a nonaqueous electrolytic solution containing nothing except that LiBF ₄ was dissolved in γ-butyrolactone at a concentration of 1 mol / liter was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 2]
Fluorinated graphite was used as the positive electrode active material.
As the nonaqueous electrolytic solution, a nonaqueous electrolytic solution containing nothing except that LiBF ₄ was dissolved in propylene carbonate at a concentration of 1 mol / liter was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 3]
Fluorinated graphite was used as the positive electrode active material.
As the nonaqueous electrolytic solution, a nonaqueous electrolytic solution containing nothing except that LiPF ₆ was dissolved in γ-butyrolactone at a concentration of 1 mol / liter was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 4]
Fluorinated graphite was used as the positive electrode active material.
As a non-aqueous electrolyte, except that LiBF ₄ was dissolved at a concentration of 1 mol / liter in a non-aqueous solvent in which γ-butyrolactone and 1,2-dimethoxyethane were mixed at a volume ratio of 3: 2. A non-aqueous electrolyte solution containing nothing was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 5]
Manganese dioxide was used as the positive electrode active material.
LiCF ₃ SO ₃ is dissolved at a concentration of 0.5 mol / liter in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane are mixed at a volume ratio of 3: 2 as a non-aqueous electrolyte. Except for the above, a non-aqueous electrolyte solution containing nothing was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 6]
Manganese dioxide was used as the positive electrode active material.
As a non-aqueous electrolyte, LiClO ₄ was dissolved at a concentration of 0.5 mol / liter in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane were mixed at a volume ratio of 3: 2. Used a non-aqueous electrolyte containing nothing.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[Comparative Example 7]
Manganese dioxide was used as the positive electrode active material.
A solution in which LiClO ₄ is dissolved at a concentration of 0.5 mol / liter in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane are mixed at a volume ratio of 3: 2 as a non-aqueous electrolyte. In addition, a non-aqueous electrolyte solution containing 1,3-propane sultone at a concentration of 1% by weight was used.
In accordance with the method described in [Preparation / Evaluation of Batteries], the produced nonaqueous electrolyte primary battery was subjected to a discharge test after high-temperature storage. The results are shown in Table 1.

[result]
The results of Examples 1 to 6 and Comparative Examples 1 to 7 are shown in Table 1 below.

The non-aqueous electrolyte primary batteries of Examples 1 to 6 using the non-aqueous electrolyte for primary batteries of the present invention have a smaller resistance increase during high-temperature storage and operate stably than the corresponding Comparative Examples 1 to 6, respectively. You can see that
In Comparative Example 7, the cyclic sultone used in Japanese Patent No. 3866191 is used as an example of a conventionally known additive. Specifically, 1,3-propane sultone is contained in the non-aqueous electrolyte for primary batteries. Comparing the present Comparative Example 7 and Example 6, it can be seen that Example 6 has a smaller resistance increase during high temperature storage and can be operated stably.

  INDUSTRIAL APPLICABILITY The present invention can provide a non-aqueous electrolyte solution that has a small resistance increase during high-temperature storage and can operate stably even in a high-temperature environment in a non-aqueous electrolyte primary battery.

Claims (9)

A non-aqueous electrolyte for a primary battery having a positive electrode and a negative electrode comprising metallic lithium or a lithium alloy,
The nonaqueous electrolytic solution for a primary battery, wherein the nonaqueous electrolytic solution contains a solute, a nonaqueous solvent, and a monofluorophosphate and / or a difluorophosphate. The primary battery according to claim 1, wherein the monofluorophosphate and / or difluorophosphate is contained in an amount of 0.01 wt% to 5 wt% in 100 wt% of the nonaqueous electrolyte. Non-aqueous electrolyte for use. The nonaqueous electrolytic solution for a primary battery according to claim 1 or 2, wherein the nonaqueous solvent contains a cyclic carboxylic acid ester compound and / or a chain ether compound. The non-aqueous electrolyte for a primary battery according to claim 3, wherein the cyclic carboxylic acid ester compound is γ-butyrolactone and / or γ-valerolactone. 5. The chain ether compound is at least one selected from the group consisting of 1,2-dimethoxyethane, 1,2-diethoxyethane, and diethylene glycol dimethyl ether. Nonaqueous electrolyte for primary batteries. 6. The non-primary battery for a primary battery according to claim 1, wherein the solute contains at least one selected from the group consisting of LiBF ₄ , LiClO ₄ , and LiCF ₃ SO _3. Water electrolyte. A non-aqueous electrolyte primary battery comprising: a positive electrode; a negative electrode comprising metallic lithium or a lithium alloy; and the non-aqueous electrolyte according to claim 1. The non-aqueous electrolyte primary battery according to claim 7, wherein the positive electrode contains fluorinated graphite or carbon fluoride represented by the formula {(CF _X ) _n ; 0 <X ≦ 1}. The non-aqueous electrolyte primary battery according to claim 7, wherein the positive electrode contains manganese dioxide.