JP2018206563A - Polymer electrolyte having fluorine-containing sulfonate structure and secondary battery - Google Patents

Abstract

To provide a polymer electrolyte having a fluorine-containing sulfonate structure that has a -CF-SOM structure at the end, that can be copolymerized with the conventional general-purpose monomer in a desired ratio even when a raw material monomer which can be industrially manufactured out of non-perfluorinated monomers, and has ionic conductivity equivalent to that of the conventional polymer electrolyte having a -CHF-CF-SOM'' structure at the side chain end.SOLUTION: There is provided a polymer electrolyte having a monomer containing a repeating unit represented by the general formula (1) and a fluorinated sulfonate structure and having a raw material monomer of 10 to 50 mol% having a structure which is not perfluorinated and does not have a monofluoromethylene chain.SELECTED DRAWING: None

Description

  The present invention relates to a polymer electrolyte having a novel fluorine-containing sulfonate structure and a secondary battery including the polymer electrolyte.

  Development using a solid polymer electrolyte instead of a conventional non-aqueous electrolyte as an electrolyte for a secondary battery is in progress. By using a solid polymer electrolyte instead of a non-aqueous electrolyte using an organic solvent having a high vapor pressure and a low flash point, the safety and reliability of the battery can be improved. Another advantage is that it is not necessary to use a thick, heavy and durable metal material as an external battery material to prevent leakage of flammable organic solvents, contributing to downsizing and weight reduction. To do. Furthermore, the degree of freedom of the shape is increased, and the capacity of the entire cell can be improved and the manufacturing process can be reduced in cost.

  However, while there are many advantages, problems still remain, and conventional polymer electrolytes used in secondary batteries such as lithium ion batteries, sodium ion batteries, and magnesium ion batteries have ease of cation migration. The ionic conductivity (cation conductivity) shown was low, which was insufficient for practical use.

Therefore, the development of polymer electrolytes with improved ion conductivity has been actively conducted, and Non-Patent Document 1 discloses that a side chain terminal has a —CF ₂ —SO ₃ M ′ (M ′ is lithium) structure. A polymer electrolyte with improved ionic conductivity is disclosed. Non-Patent Document 2 discloses a polymer electrolyte that has improved ion conductivity by having a —CHF—CF ₂ —SO ₃ M ″ (M ″ is lithium) structure at the end of the side chain.

J. Appl. Electrochem., 2004, 34, 1211-1214 Solid State Ionics, 1999, 123, 233-242

However, although the polymer electrolyte described in Non-Patent Document 1 shows good ionic conductivity, the raw material monomer having a —CF ₂ —SO ₃ M ′ structure at the terminal is fully fluorinated, and is compatible. In view of the low, when copolymerizing, the partner monomer is also limited to a perfluorinated monomer.

On the other hand, since the polymer electrolyte described in Non-Patent Document 2 does not use a fully fluorinated raw material monomer, it can be copolymerized with a general-purpose monomer such as acrylic acid or methacrylic acid at a desired ratio. However, since a monomer having a special structure having a —CHF—CF ₂ —SO ₃ M ″ structure at the side chain end is used as a raw material, there is a problem that its synthesis and acquisition are difficult. Specifically, in the synthesis of the monomer, since the reaction to form a lithium salt uses a compound that is not widely distributed such as lithium hydrogen sulfite (LiHSO ₃ ) and lithium sulfite (Li ₂ SO ₃ ), industrialization is Have difficulty.
Further, the side chain terminal is converted to a strong acid sulfonic acid (—CHF—CF ₂ —SO ₃ H) before polymerization. For this reason, there is a great limitation on the material of the reactor that can be used, such as that a metal reactor such as iron or stainless steel that can be corroded by the strong acidity of the monomer during production cannot be used.

Therefore, the present invention provides a raw material monomer that can be produced industrially among monomers that have a —CF ₂ —SO ₃ M (M is an alkali metal cation or alkaline earth metal cation) structure and are not fully fluorinated. Even when using
And Non-patent generic monomers such as acrylic acid or methacrylic acid as described in Reference 2 can be copolymerized in the desired proportions, in the side chain terminal _{-CHF-CF 2 -SO 3 M '} ' (M ' Provided a polymer electrolyte having a fluorine-containing sulfonate structure having ion conductivity equivalent to that of a conventional polymer electrolyte described in Non-Patent Document 2 having a “(lithium)” structure, and a secondary battery using the electrolyte The task is to do.

In order to solve the above-mentioned problems, the present inventors have intensively studied including molecular structure design. As a result, it has a —CF ₂ —SO ₃ M (M is an alkali metal cation or alkaline earth metal cation) structure (described as “fluorinated sulfonate structure” in the present invention) at the terminal, and is fully fluorinated. It has been found that even when a raw material monomer having a structure not formed and having no monofluoromethylene chain is used, copolymerization with a general-purpose monomer such as methacrylic acid can be easily performed. It was. Furthermore, when the polymer electrolyte has a predetermined amount of fluorine-containing sulfonate structure, the conventional polymer electrolyte has a —CHF—CF ₂ —SO ₃ M ″ (M ″ is lithium) structure at the end of the side chain. And having an ionic conductivity equivalent to the above.

（Ｒ^１は、水素原子又はメチル基である。Ｒ^２は、メチル基又はエチル基である。ａは、０〜２３の整数である。）

（Ｒ^３は、水素原子、フッ素原子、メチル基、又はトリフルオロメチル基である。
連結基Ｒ^４は、炭素数１〜６の直鎖状若しくは分岐状の非置換のアルキレン基、又は、
当該アルキレン基と、エーテル結合、エステル結合、アミド結合、又はウレタン結合とからなる結合構造である。
Ｍは、アルカリ金属カチオン又はアルカリ土類金属カチオンである。）

（Ｒ^３は、上記式（２）と同様である。
連結基Ｒ^５は、炭素数３〜６の直鎖状若しくは分岐状の非置換のアルキレン基、又は、
炭素数１〜６の直鎖状若しくは分岐状の非置換のアルキレン基と、エーテル結合、エステル結合、アミド結合、又はウレタン結合とからなる結合構造である。
Ｍは、アルカリ金属カチオン又はアルカリ土類金属カチオンである。） That is, the present invention
Containing a repeating unit represented by the following general formula (1),
A polymer electrolyte containing 10 to 50 mol% of at least one repeating unit selected from the group consisting of the following general formulas (2) and (3).

(R ¹ is a hydrogen atom or a methyl group. R ² is a methyl group or an ethyl group. A is an integer of 0 to 23.)

(R ³ represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
The linking group R ⁴ is a linear or branched unsubstituted alkylene group having 1 to 6 carbon atoms, or
The bond structure is composed of the alkylene group and an ether bond, an ester bond, an amide bond, or a urethane bond.
M is an alkali metal cation or an alkaline earth metal cation. )

(R ³ is the same as in the above formula (2).
The linking group R ⁵ is a linear or branched unsubstituted alkylene group having 3 to 6 carbon atoms, or
The bond structure is composed of a linear or branched unsubstituted alkylene group having 1 to 6 carbon atoms and an ether bond, an ester bond, an amide bond, or a urethane bond.
M is an alkali metal cation or an alkaline earth metal cation. )

  It is preferable to contain 10 to 30 mol% of at least one repeating unit selected from the group consisting of the general formulas (2) and (3).

Also, the linking group ^{R 4} _{is, -CH 2 -, - CH 2} -C (= O) -O-CH 2 -, or _{-CH 2 -CH 2 -N (H)} -C (= O) -O it is preferably - -CH _2.

  Moreover, it is preferable that said M is a lithium cation or a sodium cation.

Moreover, it is preferable that the repeating unit represented by the general formula (1) is at least one of the following.

  Moreover, this invention is a secondary battery provided with the polymer electrolyte in any one of said above, a positive electrode, and a negative electrode.

According to the present invention, even if a raw material monomer that can be produced industrially is used among monomers that have a —CF ₂ —SO ₃ M structure at the terminal and are not fully fluorinated, And a fluorine-containing sulfonate structure having ionic conductivity equivalent to that of a conventional polymer electrolyte having a —CHF—CF ₂ —SO ₃ M ″ structure at a side chain end. A polymer electrolyte and a secondary battery using the electrolyte can be provided.

  Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is an example of an embodiment of the present invention, and the specific contents thereof are not limited. Various modifications can be made within the scope of the gist.

上記単量体において、Ｒ^１、Ｒ^２、及びａは、それぞれ上記一般式（１）と同様である。 1. About monomer (raw material) The repeating unit represented by the above general formula (1) is a corresponding monomer as shown below (hereinafter sometimes referred to as “(1-monomer)”). The polymerizable double bond is formed by cleavage.

In the monomer, R ¹ , R ² and a are the same as those in the general formula (1).

上記単量体において、Ｒ^３、Ｒ^４、及びＭは、それぞれ上記一般式（２）と同様である。 In addition, the repeating unit represented by the general formula (2) is a polymerizable double of a corresponding monomer (hereinafter sometimes referred to as “(2-monomer)”) as shown below. The bond is cleaved and formed.

In the monomer, R ³ , R ⁴ and M are the same as those in the general formula (2).

上記単量体において、Ｒ^３、Ｒ^５、及びＭは、それぞれ上記一般式（３）と同様である。 Further, the repeating unit represented by the general formula (3) is a polymerizable double of a corresponding monomer (hereinafter sometimes referred to as “(3-monomer)”) as shown below. The bond is cleaved and formed.

In the monomer, R ³ , R ⁵ and M are the same as those in the general formula (3).

As mentioned above,
Having a fluorine-containing sulfonate structure,
The structure is not fully fluorinated, and
(2-monomer) and (3-monomer), which are raw material monomers having a structure not having a monofluoromethylene chain,
For example, industrial methods such as those described in JP 2009-007327 A, JP 2009-091350 A, JP 2009-091351 A, JP 2010-018573 A, and JP 2010-235600 A are used. Can be manufactured.

上記スキームにおいて、Ｒ^３、Ｒ^４、Ｒ^５、及びＭは、それぞれ上記一般式（２）及び（３）と同様である。
Ｙは、アンモニウムカチオン、Ｚは、ハロゲンアニオン、水酸化物アニオン（ＯＨ⁻）、酢酸アニオン（ＣＨ_３ＣＯ_２ ⁻）、炭酸アニオン（ＣＯ_３ ^２−）、過塩素酸アニオン（ＣｌＯ_４ ⁻）、テトラフルオロホウ酸アニオン（ＢＦ_４ ⁻）、ギ酸アニオン（ＨＣＯ_２ ⁻）、又はトリフルオロスルホンアニオン（ＣＦ_３ＳＯ_３ ⁻）を表す。 For example, (2-monomer) and (3-monomer) can be produced as in the following scheme. However, these manufacturing methods are merely examples, and are not limited to these manufacturing methods.

In the above scheme, R ³ , R ⁴ , R ⁵ , and M are the same as those in the general formulas (2) and (3), respectively.
Y is an ammonium cation, Z is a halogen anion, a hydroxide anion (OH ⁻ ), an acetate anion (CH ₃ CO ₂ ⁻ ), a carbonate anion (CO ₃ ²⁻ ), a perchlorate anion (ClO ₄ ⁻ ), It represents a tetrafluoroborate anion (BF ₄ ⁻ ), a formate anion (HCO ₂ ⁻ ), or a trifluorosulfone anion (CF ₃ SO ₃ ⁻ ).

The ammonium cation represented by Y is specifically an ammonium cation (NH ₄ ⁺ ), a methyl ammonium cation (MeNH ₃ ⁺ ), a dimethyl ammonium cation (Me ₂ NH ₂ ⁺ ), a trimethyl ammonium cation (Me ₃ NH ⁺ ), Ethylammonium cation (EtNH ₃ ⁺ ), diethylammonium cation (Et ₂ NH ₂ ⁺ ), triethylammonium cation (Et ₃ NH ⁺ ), n-propylammonium cation (n-PrNH ₃ ⁺ ), di-n-propylammonium cation ^{_{(n-Pr 2 NH 2 +}} ), tri -n- propyl ammonium cation ^{_{(n-Pr 3 NH +)}} , i- propyl ammonium cation (i-PrNH ₃ ^+), di -i- propyl ammonium cation (i-Pr ₂ NH ₂ ⁺ ), tri-i-propylammonium cation (i-Pr ₃ NH ⁺ ), n-butylammonium cation (n-BuNH ₃ ⁺ ), di-n-butylammonium cation (n-Bu ₂ NH ₂ ⁺ ) , Tri-n-butylammonium cation (n-Bu ₃ NH ⁺ ), sec-butylammonium cation (sec-BuNH ₃ ⁺ ), di-sec-butylammonium cation (sec-Bu ₂ NH ₂ ⁺ ), tri-sec - butylammonium cation ^{_{(sec-Bu 3 NH +)}} , tert- butyl ammonium cation (t-BuNH ₃ ^+), di -tert- butyl ammonium cation ^{_{(t-Bu 2 NH 2 +}} ), tri -tert- butyl ammonium cation ^{_{(t-Bu 3 NH +)}} , di -i- Puropirue Le ammonium cation ^{_{(i-Pr 2 EtNH +)}} , phenyl ammonium cation (PhNH ₃ ^+), diphenyl ammonium cation _(Ph ² _NH 2 +), triphenyl ammonium cation _(Ph 3 ^NH +), tetramethyl ammonium cation (Me ₄ n ^+), tetraethylammonium cations _(Et ^{4 n} +), trimethylethylammonium cation _(Me 3 ^EtN +), tetra -n- propyl ammonium cation ^{_{(n-Pr 4 n +)}} , tetra -i- propyl ammonium cation (i -Pr ₄ n ^+), tetra -n- butylammonium cation ^{_{(n-Bu 4 n +)}} , phenyl trimethyl ammonium cation _(Me 3 ^PhN +), benzyltrimethylammonium aminoalcohol cation _(Me 3 BnN ⁺ ), Benzyltriethylammonium cation (Et ₃ BnN ⁺ ).

  Y is preferably a trimethylammonium cation, a triethylammonium cation, a tri-n-propylammonium cation, a tetraethylammonium cation, a phenyltrimethylammonium cation, a benzyltrimethylammonium cation or a benzyltriethylammonium cation, particularly preferably a triethylammonium cation. , Benzyltrimethylammonium cation.

  Z is preferably a chloride anion, bromide anion, iodide anion, carbonate anion, perchlorate anion, more preferably a chloride anion, bromide anion, perchlorate anion, particularly preferably a bromide anion. It is.

  In the above scheme, the production method of the polymerizable fluorine-containing sulfonate having an ammonium cation shown on the left side of the reaction formula is described in, for example, JP2009-091351A, JP2010-235600A, or It can be manufactured accordingly.

  In addition, as the compound represented by “MZ”, a commercially available compound can be used as it is, or it can be prepared by a known method or a modification thereof.

  The amount of the compound represented by “MZ” is not particularly limited, but is usually 0.1% with respect to 1 mol of the polymerizable fluorine-containing sulfolate having an ammonium cation shown on the left side of the reaction formula. It is -20 mol, Preferably it is 0.5-10 mol, More preferably, it is 0.8-3 mol.

  The reaction of the above scheme may be performed without a solvent or may be performed in a solvent inert to the reaction. If the solvent used is illustrated, if it is a reaction inert solvent, it will not specifically limit. For example, ester solvents such as ethyl acetate, butyl acetate, γ-butyrolactone, ether solvents such as diethylene glycol dimethyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, tetrachloroethylene, chlorobenzene It is preferable to use a polar solvent such as halogen solvent such as orthochlorobenzene, acetonitrile, N, N-dimethylformamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide, sulfolane. These solvents may be used alone or in combination of two or more.

  There is no restriction | limiting in particular in the reaction temperature of the said scheme, Usually, it is the range of -78-150 degreeC, Preferably, it is -20-120 degreeC, More preferably, it is 20-80 degreeC. The reaction is preferably carried out with stirring.

  Although the reaction time of the above scheme depends on the reaction temperature, it is usually several minutes to 100 hours, preferably 30 minutes to 50 hours, and more preferably 1 to 24 hours. Using an analytical instrument such as (NMR), it is preferable to set the end point of the reaction at the point when the polymerizable fluorine-containing sulfophosphate having an ammonium cation shown on the left side of the reaction formula as a raw material is consumed.

  After completion of the reaction in the above scheme, (2-monomer) and (3-monomer) can be obtained by ordinary means such as extraction and column chromatography. Moreover, it can also refine | purify by recrystallization, reprecipitation, etc. as needed.

2. About polymerization By polymerizing the monomer (raw material), at least one repeating unit selected from the group consisting of the repeating unit represented by the general formula (1) and the general formulas (2) and (3) is provided. A polymer having a unit (hereinafter sometimes simply referred to as “resin”) can be obtained. In the polymerization reaction, the structure other than the polymerizable double bond is not changed, and the original structure is maintained.

  The polymerization method is not particularly limited as long as it is a generally used method, but radical polymerization, ionic polymerization and the like are preferable. In some cases, coordination anion polymerization, living anion polymerization, cationic polymerization, ring-opening metathesis polymerization, vinylene It is also possible to use polymerization, vinyl addition and the like. As each polymerization method, a known method can be applied. In the following, a method by radical polymerization will be described, but other methods can be easily polymerized by known literatures.

  Radical polymerization is carried out in the presence of a radical polymerization initiator or radical initiator by a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and is either batch-wise, semi-continuous, or continuous. You can do that.

  The radical polymerization initiator is not particularly limited, but examples include azo compounds, peroxide compounds, and redox compounds. Particularly, azobisisobutyronitrile, dimethyl 2,2′-azobis (2-methylpropionate), tert-butyl peroxypivalate, di-tert-butyl peroxide, i-butyryl peroxide, lauroyl peroxide, succinic acid peroxide, dicinnamyl peroxide, di-n-propyl peroxide Oxydicarbonate, tert-butyl peroxyallyl monocarbonate, benzoyl peroxide, hydrogen peroxide, ammonium persulfate and the like are preferable.

  The reaction vessel used for the polymerization reaction is not particularly limited. In the polymerization reaction, a polymerization solvent may be used. As the polymerization solvent, those which do not inhibit radical polymerization are preferable, and typical ones are ester-based solvents such as ethyl acetate and n-butyl acetate, ketone-based solvents such as acetone and methyl isobutyl ketone, and hydrocarbons such as toluene and cyclohexane. And alcohol solvents such as methanol, isopropyl alcohol, and ethylene glycol monomethyl ether. It is also possible to use a solvent such as water, ether, cyclic ether, chlorofluorocarbon, and aromatic. These solvents can be used alone or in admixture of two or more. Moreover, you may use together molecular weight regulators, such as a mercaptan. The reaction temperature of the copolymerization reaction is appropriately changed depending on the radical polymerization initiator or the radical polymerization initiator, and is usually preferably 20 to 200 ° C, particularly preferably 30 to 140 ° C.

  As a method for obtaining the resin by removing the organic solvent or water from the obtained resin solution or dispersion, methods such as reprecipitation, filtration, and heating distillation under reduced pressure are possible.

3. About the resin (copolymer), containing the repeating unit represented by the general formula (1),
The polymer electrolyte of the present invention containing 10 to 50 mol% of at least one repeating unit selected from the group consisting of the above general formulas (2) and (3),
It can be obtained by copolymerizing the above-mentioned (1-monomer) with at least one selected from the group consisting of the above-mentioned (2-monomer) and the above-mentioned (3-monomer). .
In addition, the resin (copolymer) obtained as described above can be used as a polymer electrolyte as it is, and the obtained resin (copolymer) is mixed (blended) with other resins as described later. The product can also be used as a polymer electrolyte.
The polymer electrolyte as described above has an alkali metal cation or alkaline earth metal cation in the molecular structure as described above, and the fluorine-containing sulfonic acid group has high acidity, and the cation is more dissociated. Since it is in a state, it exhibits high ionic conductivity. Therefore, it is considered that when used in a secondary battery, an effect of promoting the movement of cations on the electrode surface is produced.

[Repeating unit represented by general formula (1)]
When a in the general formula (1) is 0, an ester bond bonded to the main chain and a terminal methyl group or ethyl group are bonded.
In addition, since it has an ether bond when a is 1 or more, since the cation of the repeating unit represented by the said General formula (2) or (3) can be coordinated and moved effectively, it is preferable.

  Specific examples of the repeating unit represented by the general formula (1) are as follows. In the present invention, the above repeating unit may be one kind alone, or two or more kinds may be combined.

[Repeating unit represented by general formula (2)]
When the linking group R ⁴ is a linear or branched unsubstituted alkylene group having 1 to 6 carbon atoms, for example, methylene, ethylene, methylethylene, ethylethylene, n-propylethylene, i-propylethylene, n -Butylethylene, i-butylethylene, tert-butylethylene, n-propylene, i-propylene, n-butylene, 1-methylpropylene, 2-methylpropylene, tert-butylene, n-pentylene, i-pentylene, 1, Examples thereof include 1-dimethylpropylene, 1-methylbutylene, 1,1-dimethylbutylene, n-hexylene and the like. More preferable examples include methylene, ethylene, i-butylethylene, n-propylene, i-propylene and the like, and particularly preferable examples include methylene.

When the linking group R ⁴ is a bond structure composed of the above-described alkylene group and an ether bond, an ester bond, an amide bond, or a urethane bond, the linking group is such that at least both ends of the linking group R ⁴ are the above-described alkylene group. Is preferred.

  M represents an alkali metal cation or an alkaline earth metal cation, for example, a lithium cation, a sodium cation, a potassium cation, a magnesium cation, or a calcium cation. Lithium cation and sodium cation are preferable, and lithium cation is particularly preferable.

  Specifically, the repeating unit represented by the general formula (2) can be exemplified as follows. In the present invention, the above repeating unit may be one kind alone, or two or more kinds may be combined.

[Repeating unit represented by general formula (3)]
When the linking group R ⁵ is a linear or branched unsubstituted alkylene group having 3 to 6 carbon atoms, for example, methylethylene, ethylethylene, n-propylethylene, i-propylethylene, n-butylethylene, i-butylethylene, tert-butylethylene, n-propylene, i-propylene, n-butylene, 1-methylpropylene, 2-methylpropylene, tert-butylene, n-pentylene, i-pentylene, 1,1-dimethylpropylene 1-methylbutylene, 1,1-dimethylbutylene, n-hexylene and the like. More preferred examples include n-butylene and n-hexylene, and particularly preferred examples include n-butylene.

When the organic group R ⁵ is a bond structure composed of the above-described alkylene group and an ether bond, an ester bond, an amide bond, or a urethane bond, a linking group in which at least both ends of the linking group R ⁵ are the above-described alkylene groups. Is preferred.

  M represents an alkali metal cation or an alkaline earth metal cation, and specific examples thereof are the same as M in the general formula (2).

  Specifically, the repeating unit represented by the general formula (3) can be exemplified as follows. In the present invention, the above repeating unit may be one kind alone, or two or more kinds may be combined.

[Composition and structure of resin (copolymer)]
In the resin (copolymer), the repeating unit represented by the general formulas (2) and (3) is 10 to 50 mol%, and 10 to 30 mol% is particularly preferable. The remainder is preferably a repeating unit represented by the general formula (1). When the repeating unit represented by the general formulas (2) and (3) is less than 10 mol%, the cation concentration of the obtained resin is not sufficient, so that the ionic conductivity is lowered, and as a result, as a secondary battery. Performance will also be inferior. On the other hand, if it exceeds 50 mol%, the cation concentration is sufficient, but the number of repeating units represented by the general formula (1) is too small, and the moldability becomes insufficient. For example, even if molding (hot press method) that applies heat or pressure is attempted, it cannot be molded as a powdery solid, but molding (solution casting method) in which the solution is once casted on a substrate to remove the solvent is attempted. However, after removal of the solvent, it becomes a powdery solid and as a result cannot be molded.

  The resin (copolymer) may be a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer. Good. From the viewpoint of appropriately dispersing cations and effectively transferring cations, a random copolymer is preferable.

The molecular weight of the resin is preferably 1,000 to 1,000,000, and more preferably 2,000 to 500,000 as a mass average molecular weight measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. When the mass average molecular weight is less than 1,000, the strength as a polymer is lowered, and there is a possibility that the secondary battery cannot be secured, which is not preferable. On the other hand, if it exceeds 1,000,000, the cation conductivity tends to decrease due to the fact that the entanglement of the polymer chain seems to increase, which is not preferable.
The dispersity (Mw / Mn) is preferably 1.01 to 5.00, more preferably 1.01 to 4.00, particularly preferably 1.01 to 3.00, and most preferably 1.10 to 2.50. preferable.

[About mixing (blending) with other resins]
Also, by mixing (blending) the above resin (copolymer) with other resins,
Containing a repeating unit represented by the general formula (1),
A polymer electrolyte containing 10 to 50 mol% of at least one repeating unit selected from the group consisting of the general formulas (2) and (3) may be obtained.

As the above "other resins"
Examples thereof include a resin composed of a repeating unit represented by the above general formula (1) obtained by separately polymerizing the above (1-monomer). In particular, when a is 1 or more, since it has an ether bond, it is expected that the cations of the resin (copolymer) to be blended coordinate and move easily.

  The blending is performed, for example, by mixing the resins together and then homogenizing them. A solvent in which both resins dissolve is used in the mixing step, and the solvent may be removed after homogenization.

4). About secondary battery The secondary battery of this invention is equipped with said polymer electrolyte, a positive electrode, and a negative electrode at least.
The polymer electrolyte can be used as a so-called all-solid polymer electrolyte (dry polymer electrolyte) that does not require the addition of an organic solvent or an electrolyte. This is different from a so-called gel polymer electrolyte in which an aqueous or nonaqueous electrolytic system is immobilized with a polymer.

<Positive electrode>
A conventionally known positive electrode material can be used for the positive electrode.

Examples of positive electrode active materials include lithium transition metal composite oxides such as LiCoO ₂ , Li [Ni _1/2 Mn _1/2 ] O ₂ , and Li [Co _1/3 Ni _1/3 Mn _1/3 ] O ₂ . Examples thereof include lithium-containing olivine-type phosphates such as LiFePO ₄ and LiMnPO _4, and lithium manganese composite oxides such as LiMn ₂ O _4, but are not particularly limited thereto.

  The positive electrode has a positive electrode current collector. As the positive electrode current collector, for example, aluminum, stainless steel, nickel, titanium, or an alloy thereof can be used.

  A positive electrode active material layer is comprised by the above-mentioned positive electrode active material, a binder, and a electrically conductive agent as needed, for example. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, or styrene butadiene rubber (SBR) resin. As the conductive agent, for example, a carbon material such as acetylene black, ketjen black, carbon fiber, or graphite (granular graphite or flake graphite) can be used. In the positive electrode, it is preferable to use acetylene black or ketjen black having low crystallinity.

<Negative electrode>
A conventionally known negative electrode material can be used for the negative electrode.

Specific examples of materials that can be used as the negative electrode active material are given below.
As the negative electrode active material, a carbon material having a lattice plane (002 plane) d value of 0.340 nm or less in X-ray diffraction can be used. For example, pyrolytic carbons, cokes (for example, pitch coke, needle coke, petroleum coke, etc.), graphites, organic polymer compound fired bodies (for example, those obtained by firing and carbonizing phenol resins, furan resins, etc.) , Carbon fiber, activated carbon and the like, and these may be graphitized.

  Further, as the negative electrode active material, a carbon material having a d value of a lattice plane (002 plane) in X-ray diffraction exceeding 0.340 nm can be used. Examples of the substance include amorphous carbon, which is a carbon material whose stacking order hardly changes even when heat-treated at a high temperature of 2000 ° C. or higher. Examples thereof include non-graphitizable carbon (hard carbon), mesocarbon microbeads (MCMB) baked at 1500 ° C. or less, and mesopause bitch carbon fibers (MCF). Examples include Carbotron (registered trademark) P manufactured by Kureha Corporation.

  In addition, an oxide of one or more metals selected from Si, Sn, and Al can be used as the negative electrode active material, and lithium ion can be doped / dedoped. For example, silicon oxide, tin oxide, etc. Is mentioned.

  Further, one or more metals selected from Si, Sn, and Al, alloys containing these metals, or alloys of these metals or alloys and lithium can be used as the negative electrode active material, for example, metals such as silicon, tin, and aluminum , Silicon alloys, tin alloys, aluminum alloys, and the like, and materials in which these metals and alloys are alloyed with lithium during charge and discharge can also be used.

Moreover, lithium titanium oxide, for example, lithium titanate having a spinel structure, lithium titanate having a ramsdellite structure, or the like can be used as the negative electrode active material, and Li ₄ Ti ₅ O ₁₂ can be exemplified.

  The negative electrode has a negative electrode current collector. As the negative electrode current collector, for example, copper, stainless steel, nickel, titanium, or an alloy thereof can be used.

  In the negative electrode, for example, a negative electrode active material layer is formed on at least one surface of a negative electrode current collector. A negative electrode active material layer is comprised by the above-mentioned negative electrode active material, a binder, and a electrically conductive agent as needed, for example. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, or styrene butadiene rubber (SBR) resin. As the conductive agent, for example, a carbon material such as acetylene black, ketjen black, carbon fiber, or graphite (granular graphite or flake graphite) can be used.

In the case of a sodium ion secondary battery whose cation is mainly sodium, hard carbon, oxides such as TiO ₂ , V ₂ O ₅ , and MoO ₃ are used as the negative electrode active material. Moreover, sodium-containing transition metal composite oxides such as NaFeO ₂ , NaCrO ₂ , NaNiO ₂ , NaMnO ₂ , and NaCoO ₂ as positive electrode active materials, Fe, Cr, Ni, Mn, Co, etc. of these sodium-containing transition metal composite oxides A mixture of a plurality of transition metals in which a part of the transition metal of the sodium-containing transition metal composite oxide is replaced with a metal other than the transition metal, Na ₂ FeP ₂ O ₇ , NaCo ₃ (PO ₄ ) Transition metal phosphate compounds such as ₂ P ₂ O ₇ , sulfides such as TiS ₂ and FeS ₂ , conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, and polymers that generate radicals Carbon materials are used.

  Hereinafter, the present invention will be described in detail by way of examples. However, embodiments of the present invention are not limited to these examples.

１Ｌフラスコにベンジルトリメチルアンモニウム ２−メタクリロイロキシ−１，１−ジフルオロエタンスルホネート１００．１ｇ（純度９９％）とテトラヒドロフラン３０５ｇを入れ室温（約２３℃、以下同じ。）にて撹拌した。その溶液に、事前に調製したリチウムブロミド２５．２ｇをテトラヒドロフラン１００ｇに溶解した溶液を添加した。その後、室温にて３時間撹拌した。このとき^１Ｈ ＮＭＲ分析の結果は、変換率９９％であった。続いてろ過を行い、ベンジルトリメチルアンモニウムブロミドを除去した。得られたろ液を減圧濃縮した後、クロロホルム３０１ｇを加え室温にて２時間撹拌した。懸濁溶液をろ過し、得られた結晶を減圧乾燥することで、白色固体としてリチウム ２−メタクリロイロキシ−１，１−ジフルオロエタンスルホネート６１．２ｇ（純度９９％、以降、「Ｍ−１」と表記する）を得た。イオンクロマトグラフィを用いてＬｉの定量を行うと、Ｌｉ＞９９％であり、カチオン交換が行われていることを確認した。 [Monomer (M-1) Synthesis Example]

To a 1 L flask, 100.1 g (purity 99%) of benzyltrimethylammonium 2-methacryloyloxy-1,1-difluoroethanesulfonate and 305 g of tetrahydrofuran were added and stirred at room temperature (about 23 ° C., the same applies hereinafter). A solution prepared by dissolving 25.2 g of lithium bromide prepared in advance in 100 g of tetrahydrofuran was added to the solution. Then, it stirred at room temperature for 3 hours. At this time, the result of ¹ H NMR analysis was a conversion rate of 99%. Subsequently, filtration was performed to remove benzyltrimethylammonium bromide. The obtained filtrate was concentrated under reduced pressure, 301 g of chloroform was added, and the mixture was stirred at room temperature for 2 hours. The suspension solution was filtered, and the obtained crystals were dried under reduced pressure to obtain 61.2 g of lithium 2-methacryloyloxy-1,1-difluoroethanesulfonate (purity 99%, hereinafter “M-1” as a white solid). Notation). When Li was quantified using ion chromatography, it was confirmed that Li> 99% and cation exchange was performed.

<Physical properties of M-1>
¹ H NMR (measurement solvent: deuterated dimethyl sulfoxide, reference material: tetramethylsilane); δ = 6.08 (s, 1H), 5.75 (s, 1H), 4.62 (t, J = 16.0 Hz) , 2H), 1.88 (s, 3H) ppm.
¹⁹ F NMR (measurement solvent: deuterated dimethyl sulfoxide, reference substance: trichlorofluoromethane); δ = −11.57 (t, J = 16.0 Hz, 2F) ppm.

１Ｌフラスコにベンジルトリメチルアンモニウム ２−アクリロイロキシ−１，１−ジフルオロエタンスルホネート１００．０ｇ（純度９９％）とテトラヒドロフラン３００ｇを入れ室温（約２３℃、以下同じ。）にて撹拌した。その溶液に、事前に調製したリチウムブロミド２６．８ｇをテトラヒドロフラン１００ｇに溶解した溶液を添加した。その後、室温にて３時間撹拌した。このとき^１Ｈ ＮＭＲ分析の結果は、変換率９９％であった。続いてろ過を行い、ベンジルトリメチルアンモニウムブロミドを除去した。得られたろ液を減圧濃縮した後、クロロホルム３００ｇを加え室温にて２時間撹拌した。懸濁溶液をろ過し、得られた結晶を減圧乾燥することで、白色固体としてリチウム ２−アクリロイロキシ−１，１−ジフルオロエタンスルホネート５９．６ｇ（純度９８％、以降、「Ｍ−２」と表記する）を得た。イオンクロマトグラフィを用いてＬｉの定量を行うと、Ｌｉ＞９９％であり、カチオン交換が行われていることを確認した。 [Monomer (M-2) Synthesis Example]

To a 1 L flask, 100.0 g (purity 99%) of benzyltrimethylammonium 2-acryloyloxy-1,1-difluoroethanesulfonate and 300 g of tetrahydrofuran were added and stirred at room temperature (about 23 ° C., the same applies hereinafter). A solution prepared by dissolving 26.8 g of lithium bromide prepared in advance in 100 g of tetrahydrofuran was added to the solution. Then, it stirred at room temperature for 3 hours. At this time, the result of ¹ H NMR analysis was a conversion rate of 99%. Subsequently, filtration was performed to remove benzyltrimethylammonium bromide. The obtained filtrate was concentrated under reduced pressure, 300 g of chloroform was added, and the mixture was stirred at room temperature for 2 hours. The suspension solution was filtered, and the obtained crystals were dried under reduced pressure to obtain 59.6 g of lithium 2-acryloyloxy-1,1-difluoroethanesulfonate as a white solid (purity 98%, hereinafter referred to as “M-2”). ) When Li was quantified using ion chromatography, it was confirmed that Li> 99% and cation exchange was performed.

<Physical properties of M-2>
¹ H NMR (measurement solvent: deuterated dimethyl sulfoxide, reference material: tetramethylsilane); δ = 6.22 (dd, J = 17.4 Hz, 1.5 Hz, 1H), 5.96 (dd, J = 17.0. 4 Hz, 10.5 Hz, 1 H), 5.63 (dd, J = 10.4 Hz, 1.5 Hz, 1 H), 4.61 (t, J = 16.0 Hz, 2 H) ppm.
¹⁹ F NMR (measurement solvent: deuterated dimethyl sulfoxide, reference material: trichlorofluoromethane); δ = −11.59 (t, J = 16.0 Hz, 2F) ppm.

[Monomer (M-3 to M-4) Synthesis Example]
Monomers M-3 and M-4 shown in Table 1 below were synthesized in the same procedure as the monomer M-2. In place of benzyltrimethylammonium 2-acryloyloxy-1,1-difluoroethanesulfonate, M-3 was synthesized by using benzyltrimethylammonium 2-[(acryloyloxy) acetoxy] -1,1-difluoroethanesulfonate, and M-4. In the synthesis of 1, triethylammonium 1,1,2,2-tetrafluoro-6-acryloyloxy-1-hexane-sulfonate was used. Table 1 shows the structural formulas and purities of M-1 to M-4.

[Production of resin]
The following polymerizable monomers (A-1) to (A-3) were used as partners for copolymerization of M-1 to M-4 in the resin polymerization examples described below.

[Resin (P-1) polymerization example]
Monomer (M-1) 3.0 g and monomer (A-1) 9.4 g were added to tetrahydrofuran 15.0 g to prepare a monomer solution. Further, 1.6 g of dimethyl 2,2′-azobis (2-methylpropionate) was dissolved in 10.3 g of tetrahydrofuran to prepare an initiator solution. Further, a 500 ml three-necked flask charged with 37.1 g of tetrahydrofuran was purged with nitrogen for 30 minutes and then heated to 65 ° C. with stirring. The monomer solution and the initiator solution prepared in advance were added dropwise from the dropping funnel over 30 minutes. The dripping start was set at the start of polymerization, and the polymerization reaction was carried out for 3 hours. After completion of the polymerization, the polymerization solution was cooled to about 25 ° C. with water cooling and concentrated under reduced pressure. After 58.8 g of tetrahydrofuran was distilled off, the mixture was poured into 300.2 g of diisopropyl ether. After stirring for 1 hour at room temperature, phase separation of the resin P-1 was not observed with the naked eye. Thus, it was confirmed that the resin P-1 could be copolymerized with a general-purpose monomer such as acrylic acid without problems.
This polymer has a weight average molecular weight (Mw) of 38,800, and is hereinafter referred to as resin P-1. In the present invention, Mw is measured by GPC measurement using Tosoh Corp. standard polystyrene as a standard substance and Tosoh Corp. TSKgel α-M as a column.

[Resin (P-2 to P-11) polymerization example]
Resins P-2 to P-11 were produced in the same procedure as in the above resin polymerization example P-1, except that the raw material composition was changed as shown in Table 2. Since no phase separation was visually observed for the resins P-2 to P-11, it was confirmed that the resins P-2 to P-11 could be copolymerized without problems with general-purpose monomers such as acrylic acids and methacrylic acids.

  Next, production of a polymer electrolyte membrane was attempted using the resins P-1 to P-11. Hereinafter, details are shown in Examples 1 to 9 and Comparative Examples 1 and 2.

[Example 1]
251 mg of resin P-1 was dissolved in 4.9 g of methanol to prepare a resin solution. This solution was confirmed to be homogeneous. The resin solution was placed in a glass petri dish and left overnight at room temperature, dried under reduced pressure at 110 ° C., and peeled from the petri dish to obtain a polymer electrolyte membrane PE-1 having a film shape. In the obtained polymer electrolyte membrane PE-1, no phase separation was visually observed.

[Examples 2 to 9, Comparative Example 1]
A uniform resin solution is prepared using the resins P-2 to P-9 and P-10 in the same manner as in Example 1, and then the same operation as in Example 1 is performed, whereby a polymer electrolyte membrane that is in the form of a film is obtained. PE-2 to PE-9 and PE-10 were prepared. Table 3 summarizes the resins used and the polymer electrolyte membranes obtained. In any of the polymer electrolyte membranes PE-2 to PE-9 and PE-10, no phase separation was visually observed.

[Comparative Example 2]
A uniform resin solution was prepared using the resin P-11 in the same manner as in Example 1, and then the same operation as in Example 1 was performed to try to form a film. Couldn't get.

[Ionic conductivity evaluation]
Ionic conductivity was measured by the following method. Copper was used as the electrode and a PTFE membrane was used as the spacer. The electrolyte membrane and the copper foil electrode are brought into close contact with each other, and an electrochemical impedance measuring device (Solarton, 1255B type) is connected to the electrode, and AC impedance is measured at a frequency of 1 Hz to 1 MHz at 20 ° C. to obtain an AC resistance. It was. The ionic conductivity (σ) was calculated from the resistance value (R) obtained by the measurement, the interelectrode distance (L), and the area (S) of the electrolyte membrane. The formula used for the calculation is σ = L / (S × R). The ionic conductivity results are summarized in Table 3.

The ionic conductivity of the polymer electrolyte membrane of Comparative Example 1 was insufficient below 10 ⁻⁵ [S / cm], which is the ionic conductivity at 20 ° C. disclosed in Non-Patent Document 2.
On the other hand, the ionic conductivity of the polymer electrolyte membranes of Examples 1 to 9 was equivalent to 10 ⁻⁵ [S / cm], which is the ionic conductivity at 20 ° C. disclosed in Non-Patent Document 2. .

From the above results, the polymer electrolyte of the present invention is
This is a case of using a raw material monomer that has a —CF ₂ —SO ₃ M (M is an alkali metal cation or alkaline earth metal cation) structure at the end and can be industrially manufactured among monomers that are not perfluorinated. Even
And Non-patent generic monomers such as acrylic acid or methacrylic acid as described in Reference 2 can be copolymerized in the desired proportions, in the side chain terminal _{-CHF-CF 2 -SO 3 M '} ' (M ' It was confirmed that it has an ionic conductivity equivalent to that of the conventional polymer electrolyte described in Non-Patent Document 2 having a “(lithium)” structure.

Claims (6)

Containing a repeating unit represented by the following general formula (1),
A polymer electrolyte containing 10 to 50 mol% of at least one repeating unit selected from the group consisting of the following general formulas (2) and (3).

(R ¹ is a hydrogen atom or a methyl group. R ² is a methyl group or an ethyl group. A is an integer of 0 to 23.)

(R ³ represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
The linking group R ⁴ is a linear or branched unsubstituted alkylene group having 1 to 6 carbon atoms, or
The bond structure is composed of the alkylene group and an ether bond, an ester bond, an amide bond, or a urethane bond.
M is an alkali metal cation or an alkaline earth metal cation. )

(R ³ is the same as that in the formula (2).
The linking group R ⁵ is a linear or branched unsubstituted alkylene group having 3 to 6 carbon atoms, or
The bond structure is composed of a linear or branched unsubstituted alkylene group having 1 to 6 carbon atoms and an ether bond, an ester bond, an amide bond, or a urethane bond.
M is an alkali metal cation or an alkaline earth metal cation. ) The polymer electrolyte according to claim 1, comprising 10 to 30 mol% of at least one repeating unit selected from the group consisting of the general formulas (2) and (3). The linking group ^{R 4} _{is, -CH 2 -, - CH 2} -C (= O) -O-CH 2 -, or _{-CH 2 -CH 2 -N (H)} -C (= O) -O-CH ₂ - is, polymer electrolyte according to claim 1 or 2. The polymer electrolyte according to claim 1, wherein M is a lithium cation or a sodium cation. The polymer electrolyte according to any one of claims 1 to 4, wherein the repeating unit represented by the general formula (1) is at least one of the following.

A secondary battery comprising at least the polymer electrolyte according to claim 1, a positive electrode, and a negative electrode.