JP4830314B2 - Composition for ion conductive electrolyte, ion conductive electrolyte, and secondary battery using the ion conductive electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for an ion conductive electrolyte showing excellent ion conductivity, and an ion conductive electrolyte, as well as a secondary cell showing an excellent cell performance by using the above ion conductive electrolyte. <P>SOLUTION: The composition for an ion conductive electrolyte includes a polymer synthesized by including a salt monomer structured by onium cation with a polymerizing functional group and organic anion with a polymerizing functional group, and having a structure of an ionic bond of the salt monomer substantially retained. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a composition for an ion conductive electrolyte, an ion conductive electrolyte, and a secondary battery using the ion conductive electrolyte.

As electronic devices become smaller and lighter and more portable, research and development of lithium secondary batteries having characteristics such as high voltage and high energy density are being actively conducted. Particularly in recent portable electronic devices, power consumption is also rapidly increasing with rapid performance improvement. In such a background, a lithium secondary battery capable of realizing higher voltage and higher energy density is required.
In order to cope with such a secondary battery, a lithium ion conductive electrolyte that exhibits high ionic conductivity has been required, and in order to realize excellent ionic conductivity, an amine component having a double bond and By a method using a salt monomer composed of an acid component having a double bond (for example, see Patent Document 1) or a method using a polymer having an alkylene oxide skeleton, an acid deprotonated residue, and a nitrogen-containing compound cation. An electrolyte that obtains good ionic conductivity has been proposed (see, for example, Patent Document 2).

  However, in the method disclosed here, an ionic component having no polymerizable functional group is introduced, or even in the case of a compound having a polymerizable functional group, the ionic bond is dissociated in the electrolyte. Then, a dissociative ion component is introduced into the electrolyte. Since the dissociative anion component causes ionic interaction with lithium ions, it restricts the movement of ions and hinders high ionic conductivity. Further, in the method using a cation component that does not have a polymerizable functional group, the cation component is liberated in the electrolyte, and the liberated cation freely moves to the electrode and easily causes side reactions on the electrode surface. This causes an increase in the resistance of the electrolyte and causes deterioration of the charge / discharge characteristics of the battery.

Even if these electrolytes are used, it cannot be said that sufficient ionic conductivity is achieved for practical use, and the battery characteristics, particularly the cycle characteristics, of the secondary battery are not sufficient. From such a background, there has been a demand for an ion conductive electrolyte capable of realizing good ion conductivity and excellent cycle characteristics.
JP 2003-142160 A (paragraph 0011) JP 2002-298644 A (paragraph 0009)

  An object of this invention is to provide the composition for ion conductive electrolytes which can implement | achieve the outstanding ion conductivity and the outstanding cycling characteristics, an ion conductive electrolyte, and a secondary battery using the same.

  As a result of intensive studies to achieve the above object, the present inventors have synthesized a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group. By including a polymer and a polymer having a structure in which the ionic bond of the salt monomer is substantially retained, an ion conductive electrolyte capable of exhibiting high ion conductivity and excellent cycle characteristics of a secondary battery can be obtained. The present invention was completed through further investigations.

That is, the present invention provides an ion conductive electrolyte composition comprising a polymer obtained by polymerizing a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group, Is a composition for an ion conductive electrolyte, characterized by having a structure in which the ionic bond of the salt monomer is substantially retained.
In the composition for an ion conductive electrolyte of the present invention, the polymer polymerized including a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group contains a nonionic monomer. A polymerized one is preferred.
Moreover, it is preferable that the composition for ion conductive electrolytes of this invention further contains the salt monomer comprised from the onium cation which has a polymerizable functional group, and the organic anion which has a polymerizable functional group.

Moreover, this invention is comprised with the said composition for ion conductive electrolytes, It is an ion conductive electrolyte characterized by the above-mentioned.
Furthermore, the present invention is a secondary battery comprising the ion-conductive electrolyte as a constituent element.

  ADVANTAGE OF THE INVENTION According to this invention, the ion conductive electrolyte which expresses the outstanding ion conductivity can be provided, and the secondary battery using this expresses a favorable charging / discharging characteristic.

  The composition for an ion conductive electrolyte of the present invention includes a polymer synthesized by including a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group, The polymer is characterized in that it has a structure in which the ionic bond of the salt monomer is substantially retained. Thereby, not only the dissociation promotion of electrolyte salt, for example, Li salt, but also the mobility of dissociated ions can be improved, and an ion conductive electrolyte excellent in ionic conductivity can be obtained.

  The polymer having a structure in which the ionic bond of the salt monomer used in the present invention is retained may be a polymer having a structure in which the ionic bond is retained in the electrolyte obtained from the composition for an ion conductive electrolyte of the present invention. There is no particular limitation. In the polymer, the structure in which the ionic bond is retained is an ion by a Coulomb force between a cation atom in the onium cation having a polymerizable functional group constituting the salt monomer and an anion atom in the organic anion having the polymerizable functional group. This indicates that the bond is retained in the polymer.

Examples of a method for obtaining such a polymer include the following methods.
First, there is a method in which a polymer is obtained by polymerizing with a salt monomer alone in the absence of an ionic compound other than the salt monomer. This method is most preferred, but a polymer having a structure in which the ionic bond of the salt monomer is retained is obtained. If possible, an ionic compound other than the salt monomer may be included. Further, as a method other than polymerizing the salt monomer alone, a method of copolymerizing the salt monomer and a nonionic monomer can be mentioned, and a polymer having a structure in which the ionic bond of the salt monomer is retained can be obtained. . In these polymerizations, it is possible to use a solvent in consideration of workability and the like.
In the synthesis of the polymer, even when the same salt monomer as in the present invention is used, the case where the salt monomer has an ionic bond structure in the polymer and the salt monomer ion in the polymer is used. In the case where the bond is dissociated, the contribution to ionic conductivity is considered to be different.

The salt monomer used in the present invention is composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group.
The polymerizable functional group of the salt monomer is not limited as long as it is a functional group that can be polymerized by radical polymerization, ionic polymerization, coordination polymerization, redox polymerization, or the like, but a group having a carbon-carbon double bond is available. Preferably, radical polymerization is possible with active energy rays or heat. Examples of such a functional group include (meth) acryloyl group, (meth) acryloyloxy group, (meth) acrylamide group, allyl group, vinyl group, styryl group and the like. When a plurality of polymerizable functional groups are contained in the salt monomer, they may be the same or different.

Examples of the onium cation having a polymerizable functional group constituting the salt monomer include fluonium (FR ₂ ⁺ ), oxonium (OR ₃ ⁺ ), sulfonium (SR ₃ ⁺ ), ammonium (NR ₄ ⁺ ), phosphonium (PR ₄ ⁺ ) And the like. However, the cation is not particularly limited as long as it is a cationic onium cation. From the viewpoint of versatility and workability, a phosphonium cation, a sulfonium cation, and an ammonium cation are more preferable, and among them, an ammonium cation is most preferable.

Specific examples of the sulfonium cation include cations in which a sulfur atom is substituted with three functional groups R. At least one of the three functional groups R is a group containing a polymerizable functional group. Functional group R is a substituted or unsubstituted, alkyl _group: C _{n H 2n-1,} an aryl _{group: (R ') n -C 6} H 5-n -, an aralkyl _{group: (R') m -C 6} H _{5-m -C n H 2n -} , alkenyl group: R'-CH = CH-R'- , aralkenyl _{group: (R ') n -C 6} H 5-n -CH = CH-R'-, alkoxyalkyl Group: R′—O—C _n H _2n —, acyloxyalkyl group: R′—COO—C _n H _2n — and the like can be exemplified. Moreover, the functional group R may contain a hetero atom or a halogen atom. The three Rs may be different or the same. In the functional group R in the sulfonium cation, R ′ is hydrogen or a substituted or unsubstituted alkyl group having 20 or less carbon atoms, and when there are a plurality thereof, they may be different from each other, and m is an integer of 1 or more and 5 or less. Yes, n is an integer of 1-20.

Specific examples of the phosphonium cation include cations in which a phosphorus atom is substituted with four functional groups R. At least one of the four functional groups R is a group containing a polymerizable functional group. Functional group R is a substituted or unsubstituted, alkyl _group: C _{n H 2n-1,} an aryl _{group: (R ') n -C 6} H 5-n -, an aralkyl _{group: (R') m -C 6} H _{5-m -C n H 2n -} , alkenyl group: R'-CH = CH-R'- , aralkenyl _{group: (R ') n -C 6} H 5-n -CH = CH-R'-, alkoxyalkyl Group: R′—O—C _n H _2n —, acyloxyalkyl group: R′—COO—C _n H _2n — and the like can be exemplified. Moreover, the functional group R may contain a hetero atom or a halogen atom. The four Rs may be different or the same. In the functional group R in the phosphonium cation, R ′ is hydrogen or a substituted or unsubstituted alkyl group having 20 or less carbon atoms, and when there are a plurality thereof, they may be different from each other, and m is an integer of 1 or more and 5 or less. Yes, n is an integer of 1-20.

The ammonium cation is a cation that can be generated from an amine compound, and the amine compound includes all of an aliphatic amine, an aromatic amine, a nitrogen-containing heterocyclic amine, and the like. If it has, it will not specifically limit. Specific examples include cations in which a nitrogen atom is substituted with four functional groups R. At least one of the four functional groups R is a group containing a polymerizable functional group. Functional group R is a substituted or unsubstituted, alkyl _group: C _{n H 2n-1,} an aryl _{group: (R ') n -C 6} H 5-n -, an aralkyl _{group: (R') m -C 6} H _{5-m -C n H 2n -} , alkenyl group: R'-CH = CH-R'- , aralkenyl _{group: (R ') n -C 6} H 5-n -CH = CH-R'-, alkoxyalkyl Group: R′—O—C _n H _2n —, acyloxyalkyl group: R′—COO—C _n H _2n — and the like can be exemplified. Moreover, the functional group R may contain a hetero atom or a halogen atom. The four Rs may be different or the same. In the functional group R in the ammonium cation, R ′ is hydrogen or a substituted or unsubstituted alkyl group having 20 or less carbon atoms, and when there are a plurality of them, they may be different from each other, and m is an integer of 1 or more and 5 or less. Yes, n is an integer of 1-20.
Other ammonium cations other than the above ammonium cations include aromatic ammonium cations such as pyridinium cation, pyraridinium cation and quinolinium cation, and aliphatic heterocyclic ammonium such as pyrrolidinium cation, piperidinium cation and piperazinium cation. Mention may also be made of ammonium cations such as cations, heterocyclic ammonium cations containing heteroatoms other than nitrogen such as morpholine cations, and unsaturated nitrogen-containing heterocyclic cations such as imidazolium cations. Further, the cyclic ammonium cation may be a cation having a different nitrogen position, a cation having a substituent on the ring, or a cation having a substituent containing a hetero atom.

  Specific examples of the cation constituting the salt monomer include (meth) acryloyloxyethyltrimethylammonium cation, (meth) acryloyloxyethyltriethylammonium cation, (meth) acryloyloxyethyltri-n-propylammonium cation, (meth) Acryloyloxyethyltri-iso-propylammonium cation, (meth) acryloyloxyethyltri-n-butylammonium cation, (meth) acryloyloxyethyltri-iso-butylammonium cation, (meth) acryloyloxyethyltri-tert-butyl Ammonium cation, (meth) acryloyloxyethyltriethylammonium cation, (meth) acryloyloxyethyldiethyl-n-hexyla Monium cation, (meth) acryloyloxyethyltridecylammonium cation, (meth) acryloyloxyethyltrioctylammonium cation, (meth) acryloyloxyethyldodecyldimethylammonium cation, (meth) acryloyloxydimethylbenzylammonium cation, (meth) acryloyl Oxyethyldodecylhexylmethylammonium cation, diallyldimethylammonium cation, bisstyrylmethyldimethylammonium cation, bisstyrylethyldimethylammonium cation, (meth) acrylamidoethyltrimethylammonium cation, (meth) acrylamidepropyltrimethylammonium cation, (meth) acrylamidoethyl Triethylammonium Thione, (meth) acrylamide ethyl tri-n-propylammonium cation, (meth) acrylamidoethyl tri-iso-propylammonium cation, (meth) acrylamidoethyl tri-n-butylammonium cation, (meth) acrylamidoethyl tri-iso- Butylammonium cation, (meth) acrylamidoethyltri-tert-butylammonium cation, (meth) acrylamidoethyltriethylammonium cation, (meth) acrylamidoethyldiethyl-n-hexylammonium cation, (meth) acrylamidoethyltridecylammonium cation, ( (Meth) acrylamidoethyltrioctylammonium cation, (meth) acrylamidoethyldodecyldimethylammonium Various cations such as cations, (meth) acrylamidoethyldodecylhexylmethylammonium cations, styrylmethylmethylpyrrolidinium cations, bisstyrylmethylpiperidinium cations, N, N ′-((meth) acryloyloxyethylmethyl) piperazi Examples thereof include a nium cation, a (meth) acrylamidoethylmethylmorpholinium cation, and a (meth) acryloyloxyethylmethylimidazolium cation.

The organic anion constituting the salt monomer is not particularly limited as long as it is an anion having a polymerizable functional group. For example, an anion from which a proton of a hydroxyl group-containing organic compound such as alcoholate and phenolate is eliminated: RO ^- anion, Anions from which protons such as thiolate and thiophenolate are removed: RS ^- anion, sulfonate anion: RSO ₃ ⁻ , carboxylate anion: RCOO ⁻ , and a part of hydroxyl groups of phosphoric acid and phosphorous acid are substituted with organic groups Phosphorus-containing derivative anion: R _x (OR) _y (O) _z P ⁻ , where x, y and z are integers of 0 or more and x + y + 2z = 3 or x + y + 2z = 5), substituted borate anion: ^{_{R x (oR) y B -}} , ( provided that, x, y is 0 or an integer, and, x + y = 4), substituted Arumini _{Muanion: R x (OR) y Al} -, ( provided that, x, y is 0 or an integer, and, x + y = 4), carbanions _(EA) 3 C ^-, nitrogen anion _(EA) 2 N ^- and Can be mentioned. EA represents a hydrogen atom or an electron withdrawing group. As the organic anion, RSO ₃ ⁻ , RCOO ⁻ , RPO ₃ ²⁻ and (RO ₂ S) ₂ N ^{− which} are anions derived from a sulfoxyl group, a carboxyl group, a phosphoxyl group and a sulfonimide group are particularly preferable. (Where R is hydrogen, substituted or unsubstituted alkyl group C _n H _2n-1 , aryl group (R ′) _n —C ₆ H _5-n —, aralkyl group (R ′) _m —C _{6 H 5-m -C n H 2n} -, alkenyl group R'-CH = CH-R'-, aralkenyl group _{(R ') n -C 6 H} 5-n -CH = CH-R'-, alkoxyalkyl group R′—O—C _n H _2n — and an acyloxyalkyl group R′—COO—C _n H _2n —, which may have a ring structure and include heteroatoms If there are two or more Rs in the molecule, they may be the same or different from each other, but in the case of an anion having one functional group R, the R may be a plurality of functional groups R. When having at least one group containing a polymerizable functional group, In the case of an anion having one functional group EA, when the EA has a plurality of functional groups EA, at least one is a group containing a polymerizable functional group, wherein R ′ in R is hydrogen or substituted Or an unsubstituted alkyl group having 20 or less carbon atoms, which may be different from each other, m is an integer of 1 to 5 and n is an integer of 1 to 20). Those in which some or all of the hydrogen atoms on the carbon of R are substituted with halogen atoms are also included.

  Specific examples of the anion of the salt monomer include 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-[(2-propenyloxy) methoxy] ethenesulfonic acid, and 3- (2-propenyloxy) -1-propene. -1-sulfonic acid, vinyl sulfonic acid, 2-vinyl benzene sulfonic acid, 3-vinyl benzene sulfonic acid, 4-vinyl benzene sulfonic acid, 4-vinyl benzyl sulfonic acid, 2-methyl-1-pentene-1-sulfonic acid 1-octene-1-sulfonic acid, 4-vinylbenzenemethanesulfonic acid, acrylic acid, methacrylic acid, 2-acrylamido-2-methyl-1-propanephosphoric acid, 2- (meth) acryloyloxy-1-ethanephosphoric acid And various anions derived from the above.

  Examples of the salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group used in the present invention include, for example, metal salts such as silver salts of the organic anion having the polymerizable functional group, and These can be synthesized by reacting with a halide of an onium cation having a polymerizable functional group, but the synthesis method is not limited as long as the target salt monomer can be obtained.

  As a method for synthesizing a polymer having a structure in which an ionic bond is used for the present invention, a polymer having a strong ionic bond is obtained by polymerizing the salt monomer alone in the absence of other ionic compounds. Obtainable. Specific methods include dissolving a salt monomer in an organic solvent such as methanol or acetonitrile, adding a radical polymerization initiator as necessary, heating, irradiating light in the visible / ultraviolet region, or electron beam. The desired polymer can be obtained by polymerizing by irradiating the radiation. Examples of the radical polymerization initiator include a 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-isobutyronitrile), and 2,2′-azobis ( 2,4-dimethylvaleronitrile) and other azo polymerization initiators, and peroxide polymerization initiators such as benzoyl peroxide, dicumyl peroxide and diisopropyl peroxycarbonate. The method is applicable. In the case of irradiation with light, for example, acetophenone, benzophenone, 2,2-dimethoxy-2-phenylacetophenone and the like can be mentioned as radical polymerization initiators. In the case of using a radical polymerization initiator, the addition amount is preferably 0.01 to 30 wt%, more preferably 0.03 to 20 wt% in the monomer. In the synthesis, polymerization may be performed in a solvent in consideration of workability.

  In addition to polymerizing the salt monomer alone, a polymer having a structure in which the ionic bond of the salt monomer is retained can also be obtained by copolymerizing the nonionic monomer and the salt monomer. Thereby, characteristics, such as intensity | strength and a softness | flexibility when it is set as an electrolyte, can be improved. As a specific reaction method, a method similar to the method of polymerizing alone in the absence of an ionic compound other than the salt monomer can be used. Nonionic monomers used here include polymerization of methylenebisacrylamide, ethylene glycol di (meth) acrylate, divinylbenzene, diallylmethylamine and diallylethylamine, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, diallyl phthalate, etc. Monomers having a plurality of functional groups, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, stearyl acrylate, diacetone acrylamide, 1-adamantyl (meth) acrylate and (meth) acrylic acid 2 -Monomers having one polymerizable functional group such as ethyladamantyl. The composition ratio of the nonionic monomer and the salt monomer (weight ratio of nonionic monomer / salt monomer) is preferably 3/97 to 80 to 20, and more preferably 5/95 to 60/40.

  The ion-conducting electrolyte composition of the present invention includes an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group, in addition to the polymer obtained in the above, in which the ionic bond of the salt monomer is substantially retained. Also by mixing a salt monomer composed of, and then curing, the contribution to the ionic conductivity of the polymer substantially retaining the ionic bond is manifested. The preferred addition amount of the polymer (polymer) of the salt monomer obtained above and the copolymer (polymer) of the nonionic monomer and the salt monomer is preferably 5 to 95 wt%, and 10 to 90 wt% in the electrolyte composition. More preferred.

An ion conductive electrolyte can be obtained by adding an electrolyte salt such as a lithium salt to the composition for an ion conductive electrolyte of the present invention. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiBF ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) _{3 and the} like, and these may be used alone or in combination of two or more. The amount of the lithium salt used is preferably 0.1 to 90 wt%, more preferably 3 to 80 wt% in the electrolyte composition.

  Moreover, a plasticizer can also be added as needed. Examples of the plasticizer include cyclic carbonates such as ethylene carbonate and propylene carbonate, and chain carbonates such as ethyl methyl carbonate and diethyl carbonate, and a mixture thereof may be added. In addition, a room temperature molten salt or a flame retardant electrolyte salt solubilizer may be added. A room temperature molten salt is a compound that has at least one ionic bond in the molecule and is liquid at room temperature. Flame retardant electrolyte salt solubilizers include compounds that exhibit self-extinguishing properties and contribute to dissolving electrolyte salts in the presence of electrolyte salts, and are generally added to electrolytes for non-aqueous electrolyte batteries. Flame retardant solvents such as phosphate esters, halogen compounds and phosphazenes.

As an example of the method for producing the ion conductive electrolyte of the present invention, the salt substantially composed of a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group may be used. The ion conductive electrolyte composition of the present invention containing a polymer having a structure in which the ionic bond of the monomer is retained, lithium salt, etc. are dissolved in an alcohol such as methanol or a polar solvent such as acetonitrile, and then vacuum dried. The method of manufacturing by removing a solvent from etc. can be utilized.
In addition, when using a nonionic monomer together or when using a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group, those monomers, lithium salt, polymerizable functional group A polymer having a structure in which the ionic bond of the salt monomer is substantially retained and synthesized, including a salt monomer composed of an onium cation having an organic anion having a polymerizable functional group, and the like. The method of manufacturing by adding the radical polymerization initiator of this, and making it harden | cure by heating or actinic light is also mentioned.

The secondary battery of the present invention comprises the ion conductive electrolyte obtained above as a constituent element, and can be manufactured by combining a positive electrode and a negative electrode in addition to the ion conductive electrolyte.
The active material used for the positive electrode used in the battery of the present invention is preferably a transition metal oxide containing lithium having a high energy density and excellent reversible desorption / insertion of lithium ions, such as LiCoO ₂ . Examples include lithium cobalt oxide, lithium manganese oxide such as LiMn ₂ O ₄ , lithium nickel oxide such as LiNiO ₂ , a mixture of these oxides, and a part of nickel in LiNiO ₂ substituted with cobalt or manganese. . Examples of the negative electrode active material include carbon-based materials from which lithium ions can be inserted and desorbed. Examples thereof include natural graphite, artificial graphite, mesocarbon microbeads, and graphite.

Examples of a method for producing a secondary battery using the polymer solid electrolyte of the present invention include a positive electrode active material such as LiCoO ₂ , a conductive agent such as graphite, and a binder such as poly (vinylidene fluoride). Are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in N-methyl-2-pyrrolidone to obtain a slurry-like positive electrode mixture. This positive electrode mixture is uniformly applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm, etc., dried, and then compression molded with a roll press to obtain a positive electrode.
Next, a negative electrode active material such as graphite powder and a binder such as poly (vinylidene fluoride) are mixed to prepare a negative electrode mixture, and this negative electrode mixture is dispersed in N-methyl-2-pyrrolidone. To make a slurry-like negative electrode mixture. This negative electrode mixture is uniformly applied to both surfaces of a negative electrode current collector made of a copper foil having a thickness of 15 μm, etc., dried, and then compression molded with a roll press to obtain a negative electrode.
The positive electrode, the ion conductive electrolyte, and the negative electrode obtained as described above were bonded to form a single layer cell. This cell is inserted and sealed in an exterior body made of a laminate film having a three-layer structure of polyester film-aluminum film-modified polyolefin film to obtain a secondary battery.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited at all by this.

<Synthesis of Salt Monomer 1>
Dissolve 10.36 g (50 mmol) of 2-acrylamido-2-methyl-1-propanesulfonic acid in 500 ml of water, add 8.28 g (30 mmol) of silver carbonate to the solution, stir for 8 hours, and after filtration, colorless and transparent A liquid was obtained. The solution was concentrated with an evaporator and left in a freezer for 3 days to precipitate white plate crystals. The white crystals were collected by filtration and washed with acetone. 6.28 g (20 mmol) of the obtained compound was dissolved in 30 ml of methanol / acetonitrile (mixing ratio: volume 1/1), and 4.15 g (20 mmol) of commercially available 2-methacryloyloxyethyltrimethylammonium chloride was added dropwise with stirring. I let you. White silver chloride precipitated as the reaction progressed. After completion of dropping, the mixture was stirred at room temperature for 1 hour and allowed to stand. The reaction solution was filtered to remove silver chloride. The obtained filtrate was concentrated with an evaporator, the solvent was completely removed, and a colorless and transparent liquid salt monomer 1 was obtained. The obtained salt monomer ¹ confirmed the product by ¹ H-NMR.

<Synthesis of salt monomer 2>
In the synthesis of the salt monomer 1, a colorless and transparent liquid salt monomer 2 was used in the same manner except that 13.2 g (20 mmol) of diallyldimethylammonium chloride (50 wt% methanol solution) was used instead of 2-methacryloyloxyethyltrimethylammonium chloride. Got. The obtained salt monomer 2 confirmed the product by ¹ H-NMR.

<Synthesis of Polymer 21>
20 g of salt monomer 1 was completely dissolved in 60 ml of methanol and degassed from the solution, and then 0.6 g of benzoyl peroxide was added to obtain a uniform transparent solution. This solution was heated at 80 ° C. for 10 minutes to obtain a slightly viscous transparent solution. When this solution was added dropwise to a large amount of acetone, a white polymer 21 was precipitated. The polymer was collected by filtration and vacuum dried at 80 ° C. for 24 hours. The obtained polymer 21 was confirmed by using ¹ H-NMR to eliminate the double bond of the polymerizable functional group and to proceed the polymerization. In addition, it was confirmed that the peak positions of other peaks did not change as compared with the monomer, and the ionic bond of the salt monomer was retained in the electrolyte.

<Synthesis of polymer 22>
20 g of salt monomer 2 and 10 g of N, N-dimethylacrylamide (hereinafter referred to as monofunctional monomer 11) were completely dissolved in 60 ml of methanol and degassed from the solution. Benzoyl peroxide was added to obtain a uniform transparent liquid. This solution was heated at 80 ° C. for 30 minutes to obtain a viscous transparent solution. When this solution was dropped into a large amount of acetone, a white polymer 22 was precipitated. The polymer was collected by filtration and vacuum dried at 80 ° C. for 24 hours. The obtained polymer 22 was confirmed by using ¹ H-NMR to eliminate the double bond of the polymerizable functional group and to proceed the polymerization. In addition, it was confirmed that the peak positions of other peaks did not change as compared with the monomer, and the ionic bond of the salt monomer was retained in the electrolyte.

[Example 1]
4.4 g of the polymer 21 and 0.9 g of LiClO ₄ that were sufficiently dried in a dry argon atmosphere (dew point temperature: −60 ° C. or lower) were weighed and completely dissolved in 10 ml of dehydrated methanol. The obtained solution was cast on a Teflon (registered trademark) sheet, and after removing the solvent at room temperature, it was heated at 80 ° C. for 2 hours to obtain a white translucent film-like ion conductive electrolyte. About the ion conductive electrolyte obtained above, ion conductivity was measured by the alternating current impedance method. The frequency range during measurement was 50 Hz to 30 MHz, and the voltage was 0.5 V. As a result of the measurement, the ionic conductivity at room temperature (20 ° C.) was 2.1 × 10 ⁻⁴ S / cm. The results are shown in Table 1.
Further, as a positive electrode active material, 85% by weight of LiCoO ₂ , 5% by weight of graphite as a conductive agent, and 10% by weight of poly (vinylidene fluoride) as a binder are mixed to obtain a positive electrode mixture. This positive electrode mixture was prepared and dispersed in N-methyl-2-pyrrolidone to obtain a slurry-like positive electrode mixture. This positive electrode mixture was uniformly applied to both surfaces of a 20 μm thick aluminum foil used as a positive electrode current collector, dried, and then compression molded with a roll press to obtain a positive electrode.
A negative electrode mixture was prepared by mixing 90% by weight of pulverized graphite powder as a negative electrode active material and 10% by weight of poly (vinylidene fluoride) as a binder, and this negative electrode mixture was mixed with N-methyl. A slurry-like negative electrode mixture was prepared by dispersing in 2-pyrrolidone. This negative electrode mixture was uniformly applied to both surfaces of a 15 μm thick copper foil used as a negative electrode current collector, dried, and then compression molded with a roll press to obtain a negative electrode. The positive electrode, the ion conductive electrolyte and the negative electrode obtained above are bonded to form a single-layer cell, and this cell is inserted into an exterior body made of a laminate film having a three-layer structure of polyester film-aluminum film-modified polyolefin film and sealed. To obtain a secondary battery. After the battery was assembled, constant current voltage charging at 25 ° C. and 500 mA was performed for 2 hours to an upper limit of 4.2 V, and then discharging at 500 mA (1 hour rate discharge) was performed to a final voltage of 2.5 V. With this as one cycle, 100 cycles of charge / discharge were performed, and the capacity retention rate at the 100th cycle was determined with the discharge capacity at the first cycle being 100%. The capacity retention rate after 100 cycles was 95%.

[Example 2]
2.2 g of the polymer 21 sufficiently dried in a dry argon atmosphere (dew point temperature: −60 ° C. or lower), 2.2 g of the salt monomer 2, 0.9 g of LiClO ₄ , 0.015 g of benzoyl peroxide, respectively Weighed and completely dissolved with 10 ml of dehydrated methanol. The obtained solution was cast on a Teflon (registered trademark) sheet, and after removing the solvent at room temperature, it was heated at 80 ° C. for 2 hours to obtain a white translucent film-like ion conductive electrolyte. As a result of measuring the ionic conductivity in the same manner as in Example 1, the ionic conductivity at room temperature (20 ° C.) was 1.8 × 10 ⁻⁴ S / cm. The results are shown in Table 1. Further, when the cycle characteristics of the secondary battery were evaluated in the same manner as in Example 1, the capacity retention rate after 100 cycles was 96%. The results are shown in Table 1.

[Example 3]
An ion-conducting electrolyte was obtained in the same manner as in Example 2 except that polymer 21, salt monomer 2, and monofunctional monomer 11 were used instead of polymer 21 and salt monomer 2 used in Example 2. As a result of measuring the ionic conductivity in the same manner as in Example 1, the ionic conductivity at room temperature (20 ° C.) was 1.5 × 10 ⁻⁴ S / cm. The results are shown in Table 1. Further, when the cycle characteristics of the secondary battery were evaluated in the same manner as in Example 1, the capacity retention rate after 100 cycles was 93%. The results are shown in Table 1.

[Example 4]
An ion conductive electrolyte was obtained in the same manner as in Example 1 except that the polymer 22 was used instead of the polymer 21 used in Example 1. As a result of measuring the ionic conductivity in the same manner as in Example 1, the ionic conductivity at room temperature (20 ° C.) was 1.9 × 10 ⁻⁴ S / cm. The results are shown in Table 1. Further, when the cycle characteristics of the secondary battery were evaluated in the same manner as in Example 1, the capacity retention rate after 100 cycles was 93%. The results are shown in Table 1.

[Example 5]
An ion-conducting electrolyte was obtained in the same manner as in Example 2 except that polymer 22 and salt monomer 1 were used instead of polymer 21 and salt monomer 2 used in Example 2. As a result of measuring the ionic conductivity in the same manner as in Example 1, the ionic conductivity at room temperature (20 ° C.) was 1.6 × 10 ⁻⁴ S / cm. The results are shown in Table 1. Further, when the cycle characteristics of the secondary battery were evaluated in the same manner as in Example 1, the capacity retention rate after 100 cycles was 94%. The results are shown in Table 1.

[Comparative Example 1]
4.4 g of salt monomer 1 sufficiently dried in a dry argon atmosphere (dew point temperature: −60 ° C. or lower) and 0.9 g of LiClO ₄ were weighed and completely dissolved in 10 ml of dehydrated methanol. The obtained solution was cast on a Teflon (registered trademark) sheet, and after removing the solvent at room temperature, it was heated at 80 ° C. for 2 hours to obtain a white translucent film-like ion conductive electrolyte. As a result of measuring the ionic conductivity in the same manner as in Example 1, the ionic conductivity at room temperature (20 ° C.) was 8.3 × 10 ⁻⁵ S / cm. The results are shown in Table 1. When the cycle characteristics of the secondary battery were evaluated in the same manner as in Example 1, the capacity retention rate after 100 cycles was 75%. The results are shown in Table 1.

  ADVANTAGE OF THE INVENTION According to this invention, the ion conductive electrolyte which shows the outstanding ion conductivity can be provided, and this can be applied to the secondary battery excellent in performance. The electrolyte can also be applied to all electrochemical elements such as capacitors and electrochromic elements.

Claims (5)

  An ion conductive electrolyte composition comprising a polymer polymerized by including a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group, wherein the polymer is substantially An ion conductive electrolyte composition having a structure in which an ionic bond of the salt monomer is retained.   The composition for an ion conductive electrolyte according to claim 1, wherein the polymer is polymerized by containing a nonionic monomer.   The ion conductive electrolyte according to claim 1 or 2, wherein the composition for an ion conductive electrolyte further comprises a salt monomer composed of an onium cation having a polymerizable functional group and an organic anion having a polymerizable functional group. Composition.   An ion conductive electrolyte comprising the composition for ion conductive electrolyte according to any one of claims 1 to 3.   A secondary battery comprising the ion conductive electrolyte according to claim 4 as a constituent element.