JP2008204858A - Electrode integrated polymer electrolyte membrane and electrochemical element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode integrated polymer electrolyte membrane in which a deformation under a high temperature is controlled. <P>SOLUTION: An electrolyte membrane precursor composed of a partially cross-linked polymer containing a structure unit as shown in a formula (1) gets impregnation of electrolyte solution containing an ion species and an oligomer as shown in a formula (2) and is cross-linked while it is pinched between a pair of electrodes and is integrated with electrodes while the precursor serves as an electrolyte membrane and the electrolyte membrane is obtained. In the formula (1), R<SB>1</SB>is for H or CH<SB>3</SB>, R<SB>2</SB>for CH<SB>3</SB>or C<SB>2</SB>H<SB>6</SB>and n for a natural number of 2-12. In the formula (2), R<SB>3</SB>is for CH<SB>3</SB>, C<SB>2</SB>H<SB>6</SB>or C<SB>3</SB>H<SB>8</SB>, R<SB>4</SB>for H or CH<SB>3</SB>and m for a natural number of 3-12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrode-integrated polymer electrolyte membrane in which a polymer electrolyte membrane and an electrode are integrated, and an electrochemical device using the same.

  A substance that exhibits ionic conductivity in a solid state is called a solid electrolyte. In particular, a polymer solid electrolyte (polymer electrolyte) based on a polymer (polymer) is excellent in flexibility of shape processing and adhesion to an electrode based on a property derived from a polymer having excellent flexibility and flexibility. In recent years, it has attracted attention as a next-generation electrolyte for use in electrochemical devices (hereinafter also simply referred to as “devices”) such as lithium secondary batteries.

  Devices using polymer electrolytes are more susceptible to liquid leakage than devices using general electrolyte solutions (for example, solutions in which electrolyte salts such as lithium salts as ionic species are dissolved in a non-aqueous solvent). There is no safety. Further, by using a membrane-shaped polymer electrolyte (polymer electrolyte membrane), the degree of freedom of the element shape can be increased, and application to a power source used for information and portable devices is expected. When a polymer electrolyte membrane is used for an electrochemical device, the device usually has a structure in which the polymer electrolyte membrane is held between a pair of electrodes (a positive electrode and a negative electrode).

In addition, as a polymer (base polymer) serving as a base of a polyelectrolyte, many polymers having an alkylene oxide group such as polyethylene oxide and polypropylene oxide in the side chain have been studied (for example, described in Patent Document 1). The polymer described in Patent Document 1 is a polyether copolymer containing a structural unit having a propylene oxide group in the side chain.
JP-A-10-204172

  When a conventional base polymer such as the polymer described in Patent Document 1 is combined with an ionic species to form an electrolyte membrane, and the electrochemical membrane is sandwiched between a pair of electrodes to form an electrochemical device, abnormal heat generation, etc. When the element is in a high temperature atmosphere, the electrolyte membrane may be deformed, typically contracted. If the electrolyte membrane is deformed, the function as an element is lost, and if the degree becomes too severe, in the worst case, it may lead to a short circuit between the electrodes.

  Therefore, the present invention is capable of realizing an element capable of holding the function longer than that of the conventional element even when the deformation of the electrolyte membrane under high temperature (for example, 100 ° C. or more) is suppressed and the atmosphere becomes a high temperature atmosphere. An object is to provide a polymer electrolyte membrane (electrode-integrated polymer electrolyte membrane) in which an electrolyte membrane and an electrode are integrated.

  The electrode-integrated polymer electrolyte membrane of the present invention comprises a membrane-like electrolyte membrane precursor made of a partially crosslinked polymer containing an alkylene oxide group in the side chain and containing a first structural unit represented by the following chemical formula (1). The precursor is made into an electrolyte membrane by impregnating an electrolyte solution containing a seed and an alkylene oxide oligomer represented by the following chemical formula (2) and further cross-linking in a state of being sandwiched by a pair of electrodes. It is an electrolyte membrane obtained by integrating with a pair of electrodes.

In the above formula (1), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less. In the above formula (2), R ₃ is CH ₃ , C ₂ H ₆ or C ₃ H ₈ , R ₄ is H or CH ₃ , and m is a natural number of 3 or more and 12 or less.

  The electrochemical element of the present invention is an electrochemical element including a pair of electrodes and an electrolyte membrane sandwiched between the pair of electrodes, and the electrode integrated type of the present invention is used as the pair of electrodes and the electrolyte membrane. A polymer electrolyte membrane is provided.

  According to the electrode-integrated polymer electrolyte membrane of the present invention, an electrochemical device that can suppress deformation of the electrolyte membrane at a high temperature and can maintain a longer function than a conventional device even in a high temperature atmosphere. realizable.

(Electrolyte membrane precursor)
The electrode-integrated polymer electrolyte membrane of the present invention is formed from a membrane-shaped electrolyte membrane precursor made of a partially crosslinked polymer containing a first structural unit represented by the following chemical formula (1). In Formula (1), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less.

The first structural unit represented by the above formula (1) has an alkylene oxide group in its side chain. Such a structural unit can be formed by polymerization of a (meth) acrylic acid ester monomer represented by the following chemical formula (4) having an alkylene oxide group in the side chain. In Formula (4), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less.

In addition, the notation of “(meth) acrylic acid” in the present specification means acrylic acid (R ₁ = H) or methacrylic acid (R ₁ = CH ₃ ). Similarly, “(meth) acrylate” means acrylate or methacrylate.

  The electrolyte membrane precursor is made of a partially crosslinked polymer including the first structural unit. This partially crosslinked polymer is obtained by further crosslinking (hereinafter, this crosslinking is also referred to as “secondary crosslinking”) performed in a state where the precursor is impregnated with an electrolytic solution and the precursor is held between a pair of electrodes. The base polymer of the electrolyte membrane of the present invention. The “partially crosslinked polymer” refers to a polymer that has a crosslinked structure inside and can be further crosslinked by a crosslinking agent or the like.

  The gel fraction of the electrolyte membrane precursor (the gel fraction determined from the weight of the portion insoluble in ethyl acetate) is not particularly limited, but it usually only needs to exceed 10% to form an electrolyte membrane having higher ionic conductivity. 20% or more is preferable, and 40% or more is more preferable because integration with the electrode at the time of secondary crosslinking can be performed more reliably (that is, deformation of the electrolyte membrane under high temperature can be further suppressed). The upper limit of the gel fraction varies depending on the specific structure of the first structural unit, but is usually about 50 to 95%.

  The swelling ratio when the electrolyte membrane precursor is impregnated with ethyl acetate is preferably 2 times or more. When the swelling rate is less than twice, the ionic conductivity as the electrolyte membrane may be insufficient.

  The reason why the swelling rate of the precursor affects the ionic conductivity of the electrolyte membrane formed by secondary crosslinking is not clear, but in the case of a precursor with an excessively low swelling rate, the electrolyte solution impregnated in the precursor In some cases, the polymer structure may be formed such that side chain movement in the first structural unit is inhibited, which is considered to contribute to ionic conduction.

  The swelling rate is more preferable in the order of 5 times or more and 15 times or more because an electrolyte membrane having higher ionic conductivity can be formed. However, a high swelling rate of the precursor does not immediately lead to an improvement in the ionic conductivity of the electrolyte membrane formed by secondary cross-linking, and the ionic conductivity of the electrolyte membrane depends on the gel fraction and the precursor. Other factors such as the components of the electrolyte to be impregnated are also greatly affected.

  The upper limit of the swelling rate varies depending on the specific structure of the first structural unit, but is usually about 5 to 100 times.

  The value of n in the first structural unit is a natural number of 2 or more and 12 or less. When the value of n is less than 2, the length of the side chain considered to contribute to ionic conduction becomes excessively short, and the ionic conductivity as an electrolyte membrane becomes insufficient. When the value of n exceeds 12, crystallization is facilitated by increasing the length of the side chain, the flexibility as the electrolyte membrane is impaired, and integration with the electrode by secondary crosslinking becomes difficult.

  The value of n is basically unchanged even when the precursor is subjected to secondary crosslinking to form an electrolyte membrane.

  The value of n can be determined by performing GPC (gel permeation chromatography) measurement and / or NMR (nuclear magnetic resonance) measurement after the precursor or electrolyte membrane is hydrolyzed. The measurement value of n is not necessarily a natural number because it is measured as an average value reflecting the variation among the plurality of first structural units included in the film.

  The value of n is preferably a natural number of 3 or more and 11 or less, and preferably a natural number of 7 or more and 11 or less, because higher ionic conductivity can be secured for the electrolyte membrane.

  The electrolyte membrane precursor can be formed, for example, by polymerizing and crosslinking a monomer group including a (meth) acrylic acid monomer represented by the above formula (4) and a functional monomer capable of forming a crosslinking point. In addition, in this specification, the said bridge | crosslinking performed when forming a partially crosslinked polymer from the monomer group containing the (meth) acrylic-ester acid monomer shown to said Formula (4) with respect to "secondary bridge | crosslinking" mentioned above. Called “primary crosslinking”. The crosslinking reaction at the time of primary crosslinking and the crosslinking reaction at the time of secondary crosslinking may be the same or different, and each crosslinking may be based on a plurality of crosslinking reactions. Although the functional monomer capable of forming a crosslinking point is a “crosslinking agent”, in the present specification, the functional monomer added to the monomer group at the time of primary crosslinking is also referred to as a “first crosslinking agent”.

  The functional monomer is not particularly limited as long as it has a molecular structure that can be copolymerized with the (meth) acrylic acid monomer represented by the above formula (4) and can form a crosslinking point during the copolymerization. It may be a containing monomer, a hydroxyl group (hydroxyl group) containing monomer, or the like.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyl (meth) acrylate, maleic acid, itaconic acid, crotonic acid and the like, and the monomer includes acid anhydrides such as maleic anhydride and itaconic anhydride. It may be.

  Examples of the hydroxyl group-containing monomer include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-3-hydroxypropyl, (meth) acrylic acid-4-hydroxybutyl, and (meth) acrylic acid-6- Examples include hydroxyhexyl, (meth) acrylic acid-8-hydroxyoctyl, (meth) acrylic acid-10-hydroxydecyl, (meth) acrylic acid-12-hydroxylauryl, (4-hydroxymethylcyclohexyl) -methyl acrylate, and the like. .

  The amount of the functional monomer contained in the monomer group at the time of primary crosslinking is not particularly limited, and is, for example, about 0.01 to 20 parts by weight with respect to 100 parts by weight of all monomers other than the functional monomer, and 0.05 About 5 parts by weight is preferable.

  In addition, this functional monomer can also be used for a crosslinking reaction at the time of secondary crosslinking, and considering the utilization at such secondary crosslinking, the amount of the functional monomer contained in the monomer group at the time of primary crosslinking Is, for example, about 0.05 to 40 parts by weight and preferably about 0.1 to 10 parts by weight with respect to 100 parts by weight of all monomers other than the functional monomer.

  The polymerization and the crosslinking method for forming the partially crosslinked polymer from the monomer group are not particularly limited, and various polymerization methods such as solution polymerization using a general polymerization solvent such as ethyl acetate or toluene, and UV polymerization using ultraviolet rays. Can be used.

  As the solution polymerization, radical polymerization using a polymerization initiator such as benzoyl peroxide or 2,2'-azobisisobutyronitrile (AIBN) is generally used. In addition, it may be a polymerization method in a high-pressure liquid phase of carbon dioxide or in a supercritical state. In this method, even when the monomer group includes a bifunctional monomer as a functional monomer, excessive progress of primary crosslinking is suppressed. And it can suppress that the gel fraction of the formed partially crosslinked polymer becomes large too much, or swelling rate becomes too small.

  In the UV polymerization method, for example, a method in which a functional monomer such as divinylbenzene or trimethylolpropane-tri (meth) acrylate is added to the monomer group to form a thin layer and the polymerization proceeds by irradiation with ultraviolet rays, The partially crosslinked polymer can be directly formed. In addition, this method has such a feature that the progress of polymerization is hardly inhibited even when the monomer group includes a bifunctional monomer as a functional monomer.

  When the partially crosslinked polymer formed by polymerization is in the form of a solution, the method for forming the polymer into a film is not particularly limited. For example, the solution-like partially crosslinked polymer is applied to a support film having a surface subjected to a peeling treatment. After the application, the applied polymer may be dried (if necessary). For the support film, for example, paper peeled with silicone or the like, or a resin film such as polyethylene or polyethylene terephthalate (PET) can be suitably used.

  If necessary, the partially crosslinked polymer formed by polymerization may be further crosslinked to form a film-like partially crosslinked polymer. Specifically, for example, a crosslinking agent (third crosslinking agent) is added to the formed polymer solution, and the polymer solution to which the third crosslinking agent is added is crosslinked under a predetermined condition in which a crosslinking reaction is caused by the crosslinking agent. You can proceed. This crosslinking is a part of “primary crosslinking” for obtaining a film-like partially crosslinked polymer, not “secondary crosslinking”.

  When the partially crosslinked polymer formed by polymerization is in the form of a solution, the molecular weight of the polymer is 10 in terms of a weight average molecular weight from the viewpoint of ease of forming into a film and easy handling when forming into a film. 10,000 or more are preferable. The molecular weight of the partially crosslinked polymer can be controlled by selecting a polymerization system.

  A partially crosslinked polymer obtained by polymerizing and crosslinking a monomer group containing a (meth) acrylic acid monomer represented by the above formula (4) and a functional monomer capable of forming a crosslinking point is a copolymer of both monomers. Although it is, it includes a first structural unit and a structural unit corresponding to the functional monomer.

  Thus, the partially crosslinked polymer constituting the electrolyte membrane precursor may contain a structural unit other than the first structural unit. In this case, the partially crosslinked polymer is a copolymer of a (meth) acrylic acid monomer represented by the above formula (4) and another monomer (copolymerization monomer) corresponding to a structural unit other than the first structural unit. Such a partially crosslinked polymer is obtained by polymerization of a monomer group including the (meth) acrylic acid monomer represented by the above formula (4) and another monomer corresponding to a structural unit other than the first structural unit. Can be formed.

  Specifically, for example, the partially crosslinked polymer further includes a second structural unit that causes a crosslinking reaction in the presence of an ionic species, typically lithium ions, contained in the electrolyte solution impregnated in the precursor. Also good. In this case, at the time of secondary crosslinking, a crosslinking reaction having the second structural unit in the partially crosslinked polymer as a crosslinking point can proceed. In this case, the partially crosslinked polymer is a copolymer of a monomer group including a (meth) acrylic acid monomer represented by the above formula (4) and a monomer corresponding to the second structural unit.

Examples of the second structural unit include a structural unit having an oxetane group in the side chain. Specifically, the second structural unit may be a structural unit represented by the following chemical formula (3). R ₅ in the following formula (3) is H or CH ₃ .

The structural unit represented by the above formula (3) is obtained by polymerization of 3-methyl-3-oxetanylmethyl (meth) acrylate, which is a (meth) acrylate monomer having an oxetane group in the side chain, represented by the following chemical formula (5). Can be formed. R ₅ in the following formula (5) is H or CH ₃ .

  When the partially crosslinked polymer includes the second structural unit, the ratio of the second structural unit to the total structural units in the polymer is not particularly limited, but is, for example, in the range of about 2 to 50%.

  The partially crosslinked polymer containing the second structural unit is formed by polymerization of a monomer group including a (meth) acrylic acid monomer represented by the above formula (4) and a (meth) acrylate monomer represented by the above formula (5). However, the monomer group preferably contains an epoxy group-containing monomer such as 3,4-epoxycyclohexyl (meth) acrylate or an alicyclic epoxy compound. These substances are present in the partially crosslinked polymer in a state of being copolymerized together with the (meth) acrylic ester acid monomer and the (meth) acrylate monomer, or in a single state, and the secondary of the polymer in the presence of an ionic species. It has the effect of improving the crosslinking reactivity.

  Further, for example, the partially crosslinked polymer may contain one or more structural units formed by polymerization of the following monomers as structural units other than the first structural unit: (meth) acrylic acid Alkyl ester—The molecular structure may be linear or branched, and may contain a cyclic structure. As for carbon number of an alkyl group, about 1-18 are preferable. For example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octadecyl (meth) acrylate, isobornyl (meth) acrylate; polyester (meth) acrylate, urethane (meth) acrylate; N-methylol ( Acrylamides such as (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide; N-substituted (meta) typified by (meth) acrylamide, N, N-dimethylacrylamide, acryloylmorpholine, etc. ) Amide monomers such as acrylamide; Amino group-containing monomers such as diaminoethyl (meth) acrylate; Vinyl acetate and styrene and their derivatives; Vinylene carbonate, N-bivinyl Vinyl monomers such as lupyrrolidone and N-vinylcarboxylic acid amides; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Tetrahydrofurfuryl (meth) acrylate, fluorinated alkyl (meth) acrylate, alkoxyalkyl (meth) acrylate Various monomers such as

  When the partially crosslinked polymer contains these structural units, depending on the type, the mechanical and / or thermal properties of the polymer can be controlled, and the polymer and an alkylene oxide oligomer contained in the electrolyte impregnated in the polymer The affinity with can be improved.

(Secondary cross-linking)
The electrode-integrated polymer electrolyte membrane of the present invention has a state in which an electrolyte membrane precursor is impregnated with an electrolytic solution containing an ionic species and an alkylene oxide oligomer represented by the following chemical formula (2), and is narrowed by a pair of electrodes. The electrolyte membrane is obtained by further cross-linking (secondary cross-linking) in a held state, thereby making the precursor an electrolyte membrane and integrating the precursor with the pair of electrodes.

In the above formula (2), R ₃ is CH ₃ , C ₂ H ₆ or C ₃ H ₈ , R ₄ is H or CH ₃ , and m is a natural number of 3 or more and 12 or less.

  By this secondary crosslinking, the electrolyte membrane precursor is impregnated with the electrolytic solution to become an electrolyte membrane, and the electrolyte membrane and the electrode are joined to form a polymer electrolyte membrane in which the electrodes are integrated. Such an electrolyte membrane can suppress deformation, typically shrinkage, at a higher temperature than conventional electrolyte membranes, and an electrochemical device including such an electrolyte membrane is supposed to have a high-temperature atmosphere. Even in such a case, the function can be maintained longer than that of the conventional element.

  The method for secondary crosslinking of the precursor is not particularly limited. For example, the precursor is impregnated with an electrolytic solution further containing a crosslinking agent (second crosslinking agent), and the precursor impregnated with the electrolytic solution is cross-linked with the precursor. What is necessary is just to carry out on the conditions where the crosslinking reaction which makes an agent a crosslinking point occurs.

  The second crosslinking agent is not particularly limited as long as the partially crosslinked polymer can be further crosslinked. For example, when the partially crosslinked polymer has a hydroxyl group in the polymer, a multifunctional isocyanate compound is used. When the crosslinked polymer has a carboxyl group in the polymer, it is preferable to use a polyfunctional epoxy compound. In this case, the reactivity of the crosslinking reaction at the time of secondary crosslinking can be improved.

  Examples of the polyfunctional isocyanate compound include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate (above bifunctional), trimethylolpropane adduct, and isocyanuric. And isocyanurates which are acid salts (trifunctional).

  Examples of the polyfunctional epoxy compound include tetraglycidylxylenediamine and bis- (diglycidylaminomethyl) cyclohexane.

  When the partially crosslinked polymer contains the second structural unit that causes a crosslinking reaction in the presence of an ionic species contained in the electrolyte solution impregnated in the precursor, a crosslinking reaction using the structural unit as a crosslinking point during secondary crosslinking. Can proceed. In this case, the electrolytic solution may or may not contain the second crosslinking agent.

  The electrolytic solution impregnated in the precursor contains an alkylene oxide oligomer represented by the above formula (2). It is necessary to impregnate an electrolytic solution containing such an oligomer in order to suppress deformation of the obtained electrolyte membrane at a high temperature. Moreover, it can be set as the electrolyte membrane which is excellent in ionic conductivity by impregnating the electrolyte solution containing such an oligomer.

  The value of m in the above formula (2) is a natural number of 3 or more and 12 or less. If the value of m is less than 3, since the molecular weight is too low, the volatility of the oligomer becomes excessively large, and the effect of suppressing deformation of the electrolyte membrane at high temperatures cannot be sufficiently obtained. If the value of m exceeds 12, on the contrary, the molecular weight is too high, the viscosity of the electrolytic solution increases excessively, making it difficult to impregnate the precursor, or the ionic conductivity of the obtained electrolyte membrane decreases. To do.

  The value of m is basically unchanged after secondary crosslinking.

  The value of m can be obtained by performing GPC measurement and / or NMR measurement of the electrolytic solution, etc., but is measured as an average value reflecting variation among a plurality of oligomers contained in the electrolytic solution. The measured value of m is not necessarily a natural number.

  The value of m is preferably a natural number of 4 or more and 11 or less because deformation of the electrolyte membrane at a high temperature can be more reliably suppressed and better ionic conductivity can be secured as the electrolyte membrane.

  The electrolytic solution impregnated in the precursor contains an ionic species, and this ionic species is a species transported via the structural unit represented by the above formula (1) and the alkylene oxide oligomer represented by the above formula (2), that is, an electrolyte. It is not particularly limited as long as it is a species having conductivity as a film, and is typically lithium ion. When the ionic species is lithium ion, the electrolyte membrane of the present invention can be used for lithium primary / secondary batteries, capacitors, and the like.

  The electrolytic solution containing the oligomer and ionic species represented by the above formula (2) can be formed, for example, by dissolving the oligomer and the salt of the ionic species in a solvent capable of dissolving both. The electrolytic solution further containing the second crosslinking agent can be formed by dissolving the oligomer, the salt of the ionic species, and the crosslinking agent in a solvent capable of dissolving them all. As such a solvent (electrolytic solution solvent), for example, ethyl acetate, tetrahydrofuran (THF), dimethyl carbonate, or the like may be used. When the ionic species is lithium ion, the electrolyte solution solvent is preferably a non-aqueous solvent (a solvent that substantially does not contain water).

If the ionic species is lithium ion, the ion species of the salt is not particularly limited, for _{example, LiClO 4, LiCF 3 SO 3} , LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiN (CF 3 SO 2) 2 _{, LiN (C 2 F 5 SO} 2) 2, LiAlF 4, LiGaF 4, LiInF 4, LiSiF 6, LiN (CF 3 SO 2) (C 4 F 9 SO 2) or the like may be used. What is necessary is just to set the quantity of the ionic species to mix according to the quantity of ionic species required as an electrolyte membrane. It is preferable to use LiBF ₄ and / or LiPF ₆ because an electrolyte membrane having better ionic conductivity can be formed.

  The content of the oligomer in the electrolytic solution is not particularly limited, but in order to form an electrolyte membrane excellent in ionic conductivity, for example, the number of Li atoms relative to one oxygen atom of the alkyl oxide of the polymer and oligomer is 0.01. It may be about -1.0, and the number is preferably about 0.02-0.2.

  When the electrolytic solution contains the second cross-linking agent, the content of the second cross-linking agent in the electrolytic solution is not particularly limited. For example, the amount of the functional group (functional group capable of forming a cross-linking point) contained in the precursor On the other hand, it may be about 0.9 to 2 equivalents. If the content is excessively large, unreacted crosslinking agent may remain in the obtained electrolyte membrane, which may adversely affect the ionic conductivity of the electrolyte membrane. When the content is excessively small, sufficient secondary crosslinking is not performed, and the obtained electrolyte membrane may be easily deformed at high temperatures.

  The method for impregnating the precursor with the electrolytic solution is not particularly limited. Depending on the degree of crosslinking of the precursor or the viscosity of the electrolyte, it may be difficult to impregnate the precursor with the electrolyte. In this case, however, the volatility does not adversely affect the components contained in the electrolyte. The solvent may be volatilized after adding the solvent to the electrolytic solution to reduce the viscosity and impregnating the precursor with the electrolytic solution having the reduced viscosity.

  In order to sandwich the precursor between the pair of electrodes, for example, the electrodes may be disposed on both main surfaces of the film-shaped precursor, and the electrodes may be disposed before the electrolyte is impregnated with the precursor. You can do it later or later. In addition, since the handling at the time of impregnation is easy, it is preferable to impregnate electrolyte solution after arrange | positioning an electrode in at least one main surface in a film-form precursor.

  When the electrolyte membrane of the present invention is used for an electrochemical device, the electrolyte membrane is usually contained in a container constituting the device, for example, a battery can or a case 7 shown in FIG. In this case, secondary crosslinking may be performed in the container. Specifically, for example, a membrane-like electrolyte membrane precursor is sandwiched between a pair of electrodes to form a laminate, and after the laminate is accommodated together with the electrolyte in the container, a predetermined reaction for proceeding with the crosslinking reaction is performed. What is necessary is just to carry out secondary crosslinking, hold | maintaining on conditions.

  The electrolyte membrane of the present invention may contain materials other than the base polymer and the electrolytic solution as necessary, and may contain, for example, insulating particles made of a polymer or an inorganic substance. These particles are preferably not dissolved in the environment where the electrolyte membrane is used (for example, in the secondary battery). By appropriately selecting the kind of particles, the mechanical properties as the electrolyte membrane, for example, the strength, can be improved, and the short-circuit suppressing effect between the electrodes holding the electrolyte membrane can be improved.

  The size of the insulating particles is preferably about 1 to 100 μm in terms of average particle size.

  Specific types of insulating particles are not particularly limited. For example, inorganic particles such as alumina particles and silica particles, and polystyrene particles such as crosslinked polystyrene particles, polymer particles such as polyolefin particles, and polytetrafluoroethylene particles may be used. Can be mentioned.

  When the electrolyte membrane of the present invention contains insulating particles, the content thereof is not particularly limited, and may be, for example, about 10 to 1000 parts by weight with respect to 100 parts by weight of the base polymer.

The ionic conductivity of the electrolyte membrane of the present invention at 23 ° C. is usually 1 × 10 ⁻⁵ (S / cm) or more, and depending on the configuration of the electrolyte membrane, 1 × 10 ⁻⁴ (S / cm) or more or 2 × 10 ⁻⁴ S / cm) or more.

  Regarding the method for producing the electrolyte membrane of the present invention, the above description can be summarized as follows.

  That is, in the method for producing an electrode-integrated polymer electrolyte membrane of the present invention, a membrane-like electrolyte membrane comprising a partially crosslinked polymer having an alkylene oxide group in the side chain and containing a first structural unit represented by the following chemical formula (1) The precursor is impregnated with a nonaqueous electrolytic solution containing an ionic species and an alkylene oxide oligomer represented by the following chemical formula (2), and further crosslinked in a state of being sandwiched by a pair of electrodes, thereby the precursor. Is made into an electrolyte membrane and integrated with the pair of electrodes.

In the above formula (1), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less. In the above formula (2), R ₃ is CH ₃ , C ₂ H ₆ or C ₃ H ₈ , R ₄ is H or CH ₃ , and m is a natural number of 3 or more and 12 or less.

  The electrolyte membrane precursor includes, for example, a (meth) acrylic acid ester monomer represented by the following chemical formula (4) having an alkylene oxide group in the side chain, and a functional monomer (first crosslinking agent) capable of forming a crosslinking point: The monomer group containing can be formed by polymerization and crosslinking (primary crosslinking).

In the above formula (4), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less.

  The membrane electrolyte membrane precursor can be formed by, for example, forming a partially crosslinked polymer formed by primary crosslinking into a film shape. However, when UV polymerization is used as a polymerization method for the monomer group, primary membrane crosslinking is performed. A film-like partially crosslinked polymer can be directly formed. When a partially crosslinked polymer is obtained as a polymer solution, such as when solution polymerization is used as a polymerization method for the monomer group, for example, the polymer solution may be applied on a support film and then dried. If necessary, a third crosslinking agent may be added to the polymer solution, and crosslinking with the added crosslinking agent may be used in combination. This crosslinking is part of the primary crosslinking to obtain the electrolyte membrane precursor.

  The electrochemical element of the present invention is an element including a pair of electrodes (positive electrode and negative electrode) and an electrolyte membrane sandwiched between the pair of electrodes, and the electrode of the present invention is used as the pair of electrodes and electrolyte membrane. An integral polymer electrolyte membrane is provided. Since the electrolyte membrane of the present invention is an electrolyte membrane in which shrinkage at a high temperature is suppressed as compared with the conventional electrolyte membrane, the device of the present invention is more effective than the conventional device even in a high temperature atmosphere. The function can be maintained for a long time.

  The specific configuration of the element of the present invention is not particularly limited. A primary battery, a secondary battery, a capacitor, a sensor, etc. can be comprised by selecting the structure of a positive electrode and a negative electrode, the ion seed | species contained in electrolyte membrane (electrolytic solution), etc.

  FIG. 1 shows an example of the electrochemical device of the present invention. The electrochemical element 1 shown in FIG. 1 is a coin-type lithium secondary battery. The element 1 is sandwiched between a negative electrode 2 including a negative electrode active material capable of reversibly occluding and releasing lithium ions, a positive electrode 3 including a positive electrode active material capable of reversibly occluding and releasing lithium ions, and the negative electrode 2 and the positive electrode 3. The electrolyte membrane 4 is included. Here, the negative electrode 2, the positive electrode 3, and the electrolyte membrane 4 are the electrode-integrated electrolyte membrane of the present invention described above. The electrolyte membrane 4 is impregnated with lithium ions as ion species and an electrolyte solution containing the above-described alkylene oxide oligomer, and the electrolyte membrane 4 has lithium ion conductivity.

  The negative electrode 2, the positive electrode 3, and the electrolyte membrane 4 are accommodated in a case 7 that also serves as a positive electrode terminal, and the opening of the case 7 is sealed with a sealing plate 8 that also serves as a negative electrode terminal and an insulating gasket 9. The case 7 and the sealing plate 8 are made of, for example, a stainless steel plate plated with nickel.

  The negative electrode 2 is made of, for example, plate-like lithium metal or graphite, and is electrically connected to the case 7 via a negative electrode current collector 5 such as a copper net. The positive electrode 3 is prepared, for example, by mixing a positive electrode active material typified by a lithium manganese composite oxide and a conductive material typified by graphite with a binder resin such as polyethylene, polypropylene or polytetrafluoroethylene, It has a structure obtained by pressure molding. The positive electrode 3 is electrically connected to the sealing plate 8 via a positive electrode current collector 6 such as an aluminum net.

  The electrochemical element 1 can be formed by applying a general manufacturing method of a lithium secondary battery, except for the formation of the electrolyte membrane 4 integrated with the negative electrode 2 and the positive electrode 3.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

(Preparation of polymer solution)
-Solution A-
80 parts by weight of an acrylate ester monomer having an alkylene oxide group (n (average value) = 7) whose side chain is methyl ether (R ₂ in formula (4) is a methyl group) in the side chain, and acrylonitrile 20 as a copolymerization monomer And a monomer group consisting of 0.5 parts by weight of 4-hydroxybutyl acrylate as a first crosslinking agent, 100 parts by weight of ethyl acetate and 50 parts by weight of dimethylformamide (DMF) as a polymerization solvent, and 100 g of a polymerization solution added with 0.3 part by weight of 2,2′-azobisisobutyronitrile (AIBN) as a polymerization initiator was put into a flask having an internal volume of 300 ml, and the flask was stirred while stirring the polymerization solution with a stirring blade. After replacing the air inside with nitrogen gas, the whole was kept at 60 to 70 ° C. By to give a polymer concentration of 25 wt% polymer solution (solution A). In addition, when the weight average molecular weight of the polymer in the obtained solution A was separately measured by gel permeation chromatography (GPC), it was about 280,000.

-Solution B-
For the solution A obtained as described above, reprecipitation was repeated three times using hexane and a mixed solution of ethyl acetate and DMF (ethyl acetate: DMF (volume ratio) = 2: 1) to obtain a polymer concentration of 15 A weight percent polymer solution (Solution B) was obtained.

-Solution C-
A monomer group to be polymerized, 100 parts by weight of an acrylate monomer having an alkylene oxide group (n (average value) = 7) in the side chain of which the terminal is methyl ether (R ₂ in formula (4) is a methyl group); A polymer solution (solution C) having a polymer concentration of 25% by weight was obtained in the same manner as the solution A, except that a monomer group consisting of 0.4 parts by weight of acrylic acid-4-hydroxybutyl was used as the first crosslinking agent. . In addition, when the weight average molecular weight of the polymer in the obtained solution C was separately measured by GPC, it was about 330,000.

-Solution D-
A monomer group to be polymerized, 80 parts by weight of an acrylate monomer having an alkylene oxide group (n (average value) = 11) in the side chain of which the terminal is methyl ether (R ₂ in formula (4) is a methyl group); The polymer concentration is 25% by weight in the same manner as in the solution A except that the monomer group is composed of 20 parts by weight of acrylonitrile as a copolymerization monomer and 0.6 parts by weight of 4-hydroxybutyl acrylate as a first crosslinking agent. A polymer solution (solution D) was obtained. In addition, when the weight average molecular weight of the polymer in the obtained solution D was separately measured by GPC, it was about 250,000.

-Solution E-
A monomer group to be polymerized, 75 parts by weight of an acrylate monomer having an alkylene oxide group (n (average value) = 7) in the side chain of which the terminal is methyl ether (R ₂ in formula (4) is a methyl group); 20 parts by weight of (3-methyl-3-oxetanyl) methyl acrylate and 5 parts by weight of 3,4-epoxycyclohexylmethyl methacrylate as copolymerizable monomers, and 0.2 parts by weight of acrylate-4-hydroxylbutyl acrylate as the first cross-linking agent A polymer solution (solution E) having a polymer concentration of 25% by weight was obtained in the same manner as in the solution A except that the monomer group consisting of In addition, it was about 260,000 when the weight average molecular weight of the polymer in the obtained solution E was measured separately by GPC.

-Solution F-
A monomer group to be polymerized, 75 parts by weight of an acrylate monomer having an alkylene oxide group (n (average value) = 7) in the side chain of which the terminal is methyl ether (R ₂ in formula (4) is a methyl group); A polymer having a polymer concentration of 25% by weight in the same manner as in solution A, except that the monomer group is composed of 20 parts by weight of acrylonitrile as a copolymerization monomer and 5 parts by weight of 4-hydroxybutyl acrylate as a first crosslinking agent. A solution (Solution F) was obtained. In addition, it was about 270,000 when the weight average molecular weight of the polymer in the obtained solution F was separately measured by GPC.

-Solution G-
A monomer group to be polymerized, 75 parts by weight of an acrylate monomer having an alkylene oxide group (n (average value) = 3) in the side chain of which the terminal is methyl ether (R ₂ in formula (4) is a methyl group); It consists of 20 parts by weight of acrylonitrile as a copolymerization monomer and 0.2 parts by weight of 4-hydroxybutyl acrylate (containing 0.03% by weight of poly-4-methylpentene (p-MP)) as a first crosslinking agent. A polymer solution (solution G) having a polymer concentration of 25% by weight was obtained in the same manner as in solution A except that the monomer group was used. In addition, it was about 240,000 when the weight average molecular weight of the polymer in the obtained solution G was measured separately by GPC.

  Table 1 below collectively shows the value of n of the acrylic acid monomer used for the preparation of the solutions A to G, the types of the copolymerization monomer and the crosslinking agent, and the parts by weight of the respective components.

(Preparation of electrolyte)
The electrolyte solution to be impregnated in the electrolyte membrane precursor (the preparation method will be described later) was prepared as follows.

-Electrolyte A-
Under an argon atmosphere, 2.8 g of lithium-bis-trifluoromethanesulfonimide (LiTFSI: manufactured by Kishida Chemical Co., Ltd.) as an alkali metal salt, 2.0 g of tetraethylene glycol dimethyl ether (manufactured by Wako Pure Chemical Industries, Ltd.) as an alkylene oxide oligomer, A trifunctional isocyanate (Coronate C / HL manufactured by Nippon Polyurethane Co., Ltd.) in a 200-fold dilution of tetrahydrofuran (THF) 0.3 times as a second cross-linking agent and THF 3 g as an electrolyte solvent are mixed, and LiTFSI is completely contained in the solvent. Then, a vacuum drying treatment was performed at room temperature for 3 hours and then at 50 ° C. for 3 hours to obtain an electrolytic solution A.

-Electrolyte B-
As the alkylene oxide oligomer, an electrolytic solution B was prepared in the same manner as the electrolytic solution A except that polyethylene glycol dimethyl ether (average molecular weight 500: m (average value) = 11: manufactured by Aldrich) was used instead of tetraethylene glycol dimethyl ether. Produced.

-Electrolytic solution C-
An electrolytic solution C was produced in the same manner as the electrolytic solution A except that the second crosslinking agent (trifunctional isocyanate) was not added.

-Electrolyte D-
Electrolytic solution B was produced in the same manner as electrolytic solution A, except that diethylene glycol dimethyl ether (manufactured by Wako Pure Chemical Industries, Ltd.) was used as the alkylene oxide oligomer.

-Electrolyte E-
LiTFSI (manufactured by Kishida Chemical Co., Ltd.) (2.1 g) as an alkali metal salt and ethylene carbonate (1.0 g) and dimethyl carbonate (2.0 g) as a solvent were mixed, and LiTFSi was completely dissolved in the solvent to obtain an electrolytic solution E.

(Preparation of electrolyte membrane precursor and electrolyte membrane sample)
Next, an electrolyte membrane precursor is formed using the polymer solution prepared as described above, and the electrolyte membrane precursor thus formed is impregnated with an electrolytic solution. Seven types of Examples (Samples 1 to 6, 12), Four types of comparative membrane samples (samples 7 to 10) were prepared. A method for manufacturing each sample is shown below.

-Sample 1-
A trifunctional isocyanate (manufactured by Nippon Polyurethane Co., Coronate C / HL) as a third crosslinking agent is added to the polymer solution A in an amount of 0.5 parts by weight with respect to 100 parts by weight of the polymer in the solution A to obtain a blended solution. The liquid is applied to the surface of a polyethylene terephthalate (PET) film, which is a support film subjected to a release treatment, and dried, and then held at 50 ° C. for 5 days to advance crosslinking with a third crosslinking agent. An electrolyte membrane precursor (disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on the PET film.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 1) was produced.

  In addition to the preparation of Sample 1, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnating with the electrolytic solution were evaluated as follows.

Part of the electrolyte membrane precursor was weighed and Wp (g) was cut out, and the cut pieces were immersed in ethyl acetate at room temperature for 7 days, and then the whole was filtered through an 80 mesh nylon bottle and remained on the nylon bottle. After wiping off the ethyl acetate on the surface of the gel, the weight Wb (g) of the gel was measured, the weight Wg (g) of the dried gel obtained by drying the gel was measured, and the following calculation formula (A) From (B), the gel fraction and swelling degree of the electrolyte membrane precursor were determined. In addition, the immersion in ethyl acetate and the measurement of each weight were performed at 23 degreeC.
(Swelling degree) = Wb / Wg (times) (A)
(Gel fraction) = Wg / Wp × 100 (%) (B)

-Sample 2-
The electrolyte membrane precursor (thickness) was formed on the PET film in the same manner as in Sample 1, except that the amount of the trifunctional isocyanate added to the polymer solution A was 1.5 parts by weight with respect to 100 parts by weight of the polymer in the solution A. A disk having a diameter of about 10 μm and a diameter of about 20 mm).

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 2) was produced.

  In addition to the preparation of Sample 2, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 3-
An electrolyte membrane precursor (disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film in the same manner as in Sample 1, except that the solution B was used instead of the solution A as the polymer solution.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 3) was produced.

  In addition to the preparation of Sample 3, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 4-
The surface of the PET film, which is a support film having a mixture solution formed on the surface in the same manner as Sample 1, except that the solution C was used instead of the solution A as the polymer solution. The polymer film (thickness of about 5 μm) was formed on the PET film.

  Next, after the alumina particles having an average particle diameter of about 20 μm are uniformly disposed on the surface of the formed polymer film opposite to the PET film side, 200 parts by weight with respect to 100 parts by weight of the formed polymer film. Then, another polymer film formed in the same manner is laminated and pressure-bonded so that the polymer film is in contact with the alumina particles, and the whole is held at 50 ° C. for 5 days to proceed with the crosslinking by the third crosslinking agent contained in the polymer film. An electrolyte membrane precursor (a disk shape having a thickness of about 10 μm and a diameter of about 20 mm) sandwiched between a pair of PET films and having alumina particles dispersed therein was formed.

  Next, the formed electrolyte membrane precursor and one PET film are peeled off, a circular platinum electrode plate having a diameter of 18 mm is attached to the peeling surface of the electrolyte membrane precursor, and then the other PET film is peeled off, The entire precursor was impregnated with 0.05 g of the electrolytic solution A with a dropper and allowed to stand at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 4) was produced.

  In addition to the preparation of Sample 4, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 5-
An electrolyte membrane precursor (disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film in the same manner as in Sample 1, except that the solution D was used instead of the solution A as the polymer solution.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of B was applied and impregnated with a dropper, and left at room temperature for 3 hours.

  After confirming that the electrolyte solution precursor was sufficiently impregnated with the electrolytic solution B by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 5) was produced.

  In addition to the preparation of Sample 5, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnating with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 6
An electrolyte membrane precursor (disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film in the same manner as in Sample 1, except that the solution E was used instead of the solution A as the polymer solution.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of C was applied and impregnated with a dropper, and left at room temperature for 3 hours.

  After confirming that the electrolyte solution precursor was sufficiently impregnated with the electrolytic solution C by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate on which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 6) was produced.

  In addition to the preparation of Sample 6, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 7 (comparative example)-
In the same manner as Sample 1, an electrolyte membrane precursor (a disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. D0.05g was applied and impregnated with a dropper, and left at room temperature for 3 hours.

  After confirming that the electrolyte D was sufficiently impregnated with the electrolyte D by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched between the precursor impregnated with the electrolyte and the platinum electrode plate already attached. A plate was newly affixed to the precursor, and the whole was held at 50 ° C. for 7 days for secondary crosslinking to produce an electrolyte membrane sample (sample 7) as a comparative example.

-Sample 8 (comparative example)-
The solution F is used instead of the solution A as the polymer solution, and the amount of the third crosslinking agent (trifunctional isocyanate) added to the polymer solution is 18 parts by weight with respect to 100 parts by weight of the polymer in the solution F. In the same manner as Sample 1, an electrolyte membrane precursor (a disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. A plate was newly affixed to the precursor, and the whole was held at 50 ° C. for 7 days for secondary crosslinking to produce an electrolyte membrane sample (sample 8) as a comparative example.

  In addition to the preparation of Sample 8, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

-Sample 9 (comparative example)-
An electrolyte membrane was formed on the PET film in the same manner as in Sample 1, except that 1 part by weight of benzyl isocyanate was added to 100 parts by weight of the polymer in Solution A instead of the third crosslinking agent (trifunctional isocyanate). A precursor (a disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. A plate was newly affixed to the precursor, and the whole was held at 50 ° C. for 7 days for secondary crosslinking to produce an electrolyte membrane sample (sample 9) as a comparative example.

  In addition to the preparation of Sample 9, when the gel fraction and swelling degree of the electrolyte membrane precursor before impregnating the electrolyte solution were evaluated in the same manner as Sample 1, the gel fraction was almost 0%, Since the whole precursor was dissolved in ethyl acetate, the degree of swelling could not be evaluated.

-Sample 10 (comparative example)-
In the same manner as Sample 1, an electrolyte membrane precursor (a disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. E0.05 g was applied and impregnated with a dropper, and allowed to stand at room temperature for 3 hours.

  After confirming that the electrolyte solution precursor was sufficiently impregnated with the electrolytic solution E by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate already pasted with the precursor impregnated with the electrolytic solution. A plate was newly attached to the precursor to obtain an electrolyte membrane sample (sample 10) as a comparative example.

-Sample 11 (conventional example)-
Separately from the electrolyte membrane samples of Examples and Comparative Examples, as a conventional example, a polypropylene porous membrane (thickness 20 μm) was impregnated with an electrolytic solution E, and then the porous membrane impregnated with the electrolytic solution was paired with It was sandwiched by a platinum electrode plate (circular with a diameter of 18 mm) to obtain a conventional electrolyte membrane sample (sample 11).

-Sample 12-
An electrolyte membrane precursor (disk shape having a thickness of about 10 μm and a diameter of about 20 mm) was formed on a PET film in the same manner as in Sample 1, except that the solution G was used instead of the solution A as the polymer solution.

  Next, after attaching a circular platinum electrode plate having a diameter of about 18 mm to the surface opposite to the PET film side of the formed electrolyte membrane precursor, the precursor and the PET film are peeled off, and the electrolyte solution is applied to the entire precursor. 0.05 g of A was applied with a dropper and impregnated, and left at room temperature for 3 hours.

  After confirming that the electrolyte membrane precursor was sufficiently impregnated with the electrolytic solution A by this standing, a circular platinum electrode having a diameter of about 18 mm was sandwiched with the platinum electrode plate to which the precursor impregnated with the electrolytic solution was already attached. An electrolyte membrane sample (sample) in which a plate is newly affixed to a precursor, and the whole is held at 50 ° C. for 7 days for secondary crosslinking, and an electrolyte membrane and a pair of platinum electrodes sandwiching the electrolyte membrane are integrated. 12) was produced.

  In addition to the preparation of Sample 12, the gel fraction and the degree of swelling of the electrolyte membrane precursor before impregnation with the electrolytic solution were evaluated in the same manner as Sample 1.

(Evaluation of ionic conductivity)
The ionic conductivity of each electrolyte membrane sample thus produced was measured. The measurement was performed as follows.

An impedance measuring device (263A potentiostat + 5210 amplifier: manufactured by Princeton Applied Research) is connected to the platinum electrode plate of each electrolyte membrane sample, and the whole is housed in a glove box under an argon atmosphere and kept at 23 ° C. A real impedance component R (Ω), which is the intersection of the arc on the high frequency side and the straight line on the low frequency side, was obtained by the impedance analysis method. The ionic conductivity σ (S / cm) of the electrolyte sample is the impedance component R (Ω), the thickness d (cm) of the electrolyte sample, and the area A (cm ² ) where the platinum electrode is in contact with the electrolyte sample. From this, it was obtained by the formula σ = d / (R · A).

(Evaluation of heat resistance)
Each electrolyte membrane sample was housed in a glove box under an argon atmosphere, heated at 150 ° C. for 1 hour, then returned to room temperature, and the change in shape was visually confirmed. When the electrolyte membrane shape change (shrinkage) is large and its ionic conductivity cannot be measured, “X” is indicated, and when the degree of shape change is small or rarely observed and the ionic conductivity can be measured, “○ " About the sample of "(circle)", the ionic conductivity was evaluated again by the said method.

  The evaluation results of the gel fraction and swelling degree of each electrolyte membrane precursor are shown in Table 2 below, and the ionic conductivity and heat resistance evaluation results of each electrolyte membrane sample are shown in Table 3 below.

As shown in Tables 2 and 3, in Example Samples 1 to 6 and 12, a high ion conductivity of 5 × 10 ⁻⁵ (S / cm) or more was obtained at 23 ° C. Further, even after heating at 150 ° C. for 1 hour, the degree of shrinkage of the electrolyte membrane was small, and a high ion conductivity of 2 × 10 ⁻⁵ (S / cm) or more could be secured.

In contrast, Comparative Example Sample 7 in which the precursor was impregnated with an electrolyte containing an alkylene oxide oligomer having a value of m of 2, and the precursor had a gel fraction of 0 (that is, the precursor was partially crosslinked) In Comparative Example Sample 9, which is not a polymer), LiTFSI, Comparative Example Sample 10 in which an electrolytic solution E which is a mixture of ethylene carbonate and dimethyl carbonate is impregnated in the precursor, and Conventional Example Sample 11, 2 × Although a high ion conductivity of 10 ⁻⁵ (S / cm) or higher was obtained, the electrolyte membrane was greatly contracted by heating at 150 ° C. for 1 hour, and the ion conductivity after heating could not be measured. Further, in the comparative sample 8 in which the swelling rate of the precursor was 1.5 and a value less than 2, the ionic conductivity could be measured even after heating at 150 ° C. for 1 hour, but the value was 8 × 10 ^-7 (S / cm), which was significantly lower than that of the example sample.

  According to the present invention, it is possible to provide an electrode-integrated polymer electrolyte membrane in which deformation at high temperatures is suppressed. According to this electrolyte membrane, the function is longer than that of a conventional device even in a high temperature atmosphere. An electrochemical element that can be held can be realized.

  The electrolyte membrane of the present invention can be used for various electrochemical elements such as primary batteries, secondary batteries, electric double layer capacitors, chemical capacitors, sensors, and electrochromic devices.

It is a schematic diagram which shows an example of the electrochemical element of this invention.

Explanation of symbols

1 Electrochemical element (lithium secondary battery)
2 Negative Electrode 3 Positive Electrode 4 Electrolyte Membrane 5 Negative Electrode Current Collector 6 Positive Electrode Current Collector 7 Case 8 Sealing Plate 9 Gasket

Claims (13)

A membrane-like electrolyte membrane precursor comprising a partially cross-linked polymer containing a first structural unit represented by the following chemical formula (1) having an alkylene oxide group in the side chain,
The precursor is used as an electrolyte membrane by impregnating an electrolytic solution containing an ionic species and an alkylene oxide oligomer represented by the following chemical formula (2) and further cross-linking in a state of being sandwiched by a pair of electrodes. An electrode-integrated polymer electrolyte membrane obtained by integrating with the pair of electrodes.

In the above formula (1), R ₁ is H or CH ₃ , R ₂ is CH ₃ or C ₂ H ₆ , and n is a natural number of 2 or more and 12 or less.
In the above formula (2), R ₃ is CH ₃ , C ₂ H ₆ or C ₃ H ₈ , R ₄ is H or CH ₃ , and m is a natural number of 3 or more and 12 or less.   2. The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the gel fraction of the precursor determined from the weight of a portion insoluble in ethyl acetate is 20% or more.   2. The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the gel fraction of the precursor obtained from the weight of a portion insoluble in ethyl acetate is 55% or more.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the swelling rate of the precursor when impregnated with ethyl acetate is 2 times or more.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the swelling rate of the precursor when impregnated with ethyl acetate is 5 times or more.   2. The electrode-integrated polymer electrolyte membrane according to claim 1, wherein n is a natural number of 3 or more and 11 or less.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the m is a natural number of 4 or more and 11 or less.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the electrolytic solution further contains a crosslinking agent.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the partially crosslinked polymer further comprises a second structural unit that causes a crosslinking reaction in the presence of the ionic species. The electrode-integrated polymer electrolyte membrane according to claim 9, wherein the second structural unit is a structural unit represented by the following chemical formula (3) having an oxetane group in a side chain.

In the above formula (3), R ₅ is H or CH ₃ .   2. The electrode-integrated polymer electrolyte membrane according to claim 1, wherein insulating particles having an average particle size of about 1 to 100 μm are disposed inside the electrolyte membrane.   The electrode-integrated polymer electrolyte membrane according to claim 1, wherein the ionic species is lithium ion. A pair of electrodes;
An electrochemical device including an electrolyte membrane sandwiched between the pair of electrodes,
An electrochemical device comprising the electrode-integrated polymer electrolyte membrane according to claim 1 as the pair of electrodes and the electrolyte membrane.

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