JP5680241B2 - Battery separator - Google Patents

Description

  The present invention relates to a battery separator, and more specifically, an object of the present invention is to provide a battery separator that strongly adheres to an electrode and provides a battery having excellent oxidation resistance.

  In recent years, lithium ion secondary batteries having high energy density have been widely used as power sources for small portable electronic devices such as mobile phones and notebook personal computers. Such a lithium ion secondary battery is obtained by laminating or winding sheet-like positive and negative electrodes and, for example, a polyolefin resin porous film, and charging the battery into a battery container made of, for example, a metal can. It is manufactured through a process of injecting an electrolytic solution into a container, sealing, and sealing.

  However, in recent years, there has been a strong demand for further downsizing and weight reduction of the above-described small or portable electronic devices. Therefore, further thinning and weight reduction of lithium ion secondary batteries are also required. In place of the conventional metal can container, a laminate film type battery container is also used.

  According to such a laminated film type battery container, the surface pressure for maintaining the electrical connection between the separator and the electrode cannot be sufficiently applied to the electrode surface as compared with the conventional metal can container. Due to the expansion and contraction of the electrode active material during charging and discharging, the distance between the electrodes partially increases with time, the internal resistance of the battery increases, the battery characteristics deteriorate, and the resistance varies within the battery. However, there arises a problem that the battery characteristics deteriorate.

  Further, when manufacturing a sheet battery having a large area, the distance between the electrodes cannot be kept constant, and there is a problem that battery characteristics cannot be sufficiently obtained due to variations in resistance inside the battery.

  Therefore, in order to solve such problems, it has been proposed to adhere an electrode to a separator using an adhesive containing a polyfunctional vinyl monomer and a monofunctional vinyl monomer (see Patent Document 1). . Thus, if the electrodes are bonded to the separator, the distance between the electrodes can be kept constant regardless of the pressure from the battery container. However, the above-mentioned adhesive has low oxidation-reduction resistance, and when used in a lithium battery having a high voltage output, the adhesive causes an oxidation or reduction reaction by contact with the electrode, and the adhesive is decomposed. Not only does the adhesive strength decrease, but the decomposition products cause side reactions in the battery, leading to a significant decrease in battery characteristics.

  In addition, in a nonaqueous battery, it has been proposed that an electrode and a separator are bonded using a porous resin layer containing an inorganic filler such as alumina as an adhesive (see Patent Document 2). In addition, since it does not swell in the electrolyte for a non-aqueous battery, the porous resin layer has a problem that the ion conductivity is lost correspondingly and the battery characteristics are deteriorated.

Japanese Patent Laid-Open No. 10-302843 International Publication No. 01/95421 Pamphlet

  The present invention has been made in order to solve the above-described problems in the production of a battery in which an electrode is bonded to a separator, and is used for a battery that strongly adheres to an electrode and provides a battery with excellent oxidation resistance. An object is to provide a separator.

  According to the present invention, a reactive polymer layer containing a plurality of cationically polymerizable functional groups in the molecule and having a crosslinked structure and containing organically swellable synthetic mica particles is supported on the porous film. A battery separator is provided. Hereinafter, the organically swellable synthetic mica may be simply referred to as an organically swellable synthetic mica.

  Furthermore, according to the present invention, an electrode is laminated on the battery separator to form an electrode / separator laminate, and after charging the battery container, an electrolytic solution containing a cationically polymerizable catalyst is placed in the battery container. An electrode / separator assembly obtained by injecting and bringing the reactive polymer of the electrode / separator laminate into contact with the electrolytic solution to cause cationic polymerization of the reactive polymer is provided.

  The battery separator according to the present invention has a crosslinked polymer structure having a plurality of cationically polymerizable functional groups in the molecule, and further has a reactive polymer layer containing organically swellable synthetic mica particles supported on a porous film. In addition to providing an electrode / separator assembly excellent in adhesion therebetween, and using such a battery separator, a battery having the electrode / separator assembly as described above can be obtained. it can.

  The battery separator according to the present invention has a plurality of cationically polymerizable functional groups in the molecule, a crosslinked structure, and a reactive polymer layer containing organically swellable synthetic mica particles on a porous film. It is made to carry.

(Substrate porous film)
In the present invention, the substrate porous film preferably has a thickness in the range of 3 to 50 μm. When the thickness of the porous film is less than 3 μm, the strength is insufficient, and the electrode may cause an internal short circuit when used as a separator in a battery. On the other hand, when the thickness of the porous film exceeds 50 μm, a battery using such a porous film as a separator has a too large distance between electrodes, and the internal resistance of the battery becomes excessive.

  The substrate porous film has pores having an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 95%%, preferably 30 to 90%, most preferably Is in the range of 40 to 85%. When the porosity is too low, when used as a battery separator, the ion conduction path is reduced, and sufficient battery characteristics cannot be obtained. On the other hand, when the porosity is too high, when used as a battery separator, the strength is insufficient, and in order to obtain the required strength, a thick substrate porous film must be used. This is not preferable because the internal resistance of the battery increases.

  Furthermore, the base porous film has a permeability of 1500 seconds / 100 cc or less, preferably 1000 seconds / 100 cc or less. When the air permeability is too high, the ion conductivity is low when used as a battery separator, and sufficient battery characteristics cannot be obtained.

  Moreover, it is preferable that the base material porous film has a puncture strength of 1 N or more. This is because when the piercing strength is less than 1 N, the substrate may be broken when a surface pressure is applied between the electrodes, thereby causing an internal short circuit.

  According to the present invention, the substrate porous film is not particularly limited as long as it has the characteristics as described above, but in consideration of solvent resistance and oxidation-reduction resistance, polyethylene, polypropylene, etc. A porous film made of a polyolefin resin is suitable. However, among them, when heated, the resin melts and the pores are blocked, and as a result, the battery can have a so-called shutdown function. A polyethylene resin film is particularly suitable. Here, the polyethylene resin includes not only a homopolymer of ethylene but also a copolymer of ethylene with an α-olefin such as propylene, butene and hexene.

  In addition, according to the present invention, a laminated film of a porous film such as polytetrafluoroethylene or polyimide and the above-mentioned polyolefin resin porous film is also suitably used as a substrate porous film because of its excellent heat resistance. It is done.

(Crosslinkable polymer)
According to the present invention, the cationically polymerizable functional group possessed by the reactive polymer is preferably at least one selected from a 3-oxetanyl group and an epoxy group. A reactive polymer having a plurality of cationically polymerizable functional groups in the molecule and having a crosslinked structure can be obtained by various methods. For example, a reactive polymer can be obtained by utilizing the fact that the cationic polymerizable functional group reacts with a carboxyl group containing an acid anhydride group. That is, first, a crosslinking polymer having a plurality of the cationic polymerizable functional groups in the molecule is prepared, and an amount of the crosslinking agent necessary for reacting a part of the cationic polymerizable functional groups with the crosslinking polymer; Preferably, by reacting at least one selected from monocarboxylic acid, polycarboxylic acid and acid anhydride, reacting a part of the cationically polymerizable functional group and crosslinking, a plurality of cationically polymerizable groups in the molecule A reactive polymer having a functional group and a crosslinked structure can be obtained. Hereinafter, this method may be referred to as a first method for obtaining a reactive polymer having a cationically polymerizable functional group in the molecule and a crosslinked structure.

  As another method, a crosslinkable polymer having a plurality of isocyanate-reactive groups having active hydrogen such as a hydroxyl group and a carboxyl group capable of reacting with an isocyanate group in the molecule is prepared together with the cationic polymerizable functional group. Also, by reacting the above-mentioned isocyanate-reactive group of such a crosslinkable polymer with a polyfunctional isocyanate as a crosslinker to crosslink the crosslinkable polymer, the crosslinkable polymer has a plurality of cationically polymerizable functional groups in the molecule and crosslinks. A reactive polymer having a structure can be obtained. Hereinafter, this method may be referred to as a second method for obtaining a reactive polymer having a cationically polymerizable functional group in the molecule and a crosslinked structure.

  The crosslinkable polymer having a plurality of at least one cationically polymerizable functional group selected from a 3-oxetanyl group and an epoxy group in the molecule is preferably a radical polymerizable monomer having a 3-oxetanyl group (a 3-oxetanyl group-containing radical). Polymerizable monomer), radically polymerizable monomer having an epoxy group (epoxy group-containing radically polymerizable monomer) and other radically polymerizable monomer, or 3-oxetanyl group-containing radically polymerizable monomer and epoxy It can be obtained by radical copolymerization of any of the group-containing radical polymerizable monomers with other radical polymerizable monomers.

  As described above, polymers having a 3-oxetanyl group or an epoxy group in the molecule are already known as described in, for example, JP-A Nos. 2002-110245 and 2001-176555.

  In particular, according to the present invention, the 3-oxetanyl group-containing radical polymerizable monomer is preferably represented by the general formula (I)

(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)
The 3-oxetanyl group containing (meth) acrylate represented by these is used.

  Specific examples of such a 3-oxetanyl group-containing (meth) acrylate include, for example, 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl ( Examples include meth) acrylate, 3-butyl-3-oxetanylmethyl (meth) acrylate, and 3-hexyl-3-oxetanylmethyl (meth) acrylate. These (meth) acrylates are used alone or in combination of two or more.

  Further, according to the present invention, the epoxy group-containing radical polymerizable monomer is preferably represented by the general formula (II)

(In the formula, R ₃ represents a hydrogen atom or a methyl group, and R ₄ represents the formula (1)

  Or formula (2)

The epoxy group containing group represented by these is shown. )
The epoxy group containing (meth) acrylate represented by these is used.

  Specific examples of such an epoxy group-containing (meth) acrylate include, specifically, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl (meth) acrylate, and the like. These (meth) acrylates are used alone or in combination of two or more.

  The other radical polymerizable monomer copolymerized with such a 3-oxetanyl group-containing radical polymerizable monomer or an epoxy group-containing radical polymerizable monomer is preferably represented by the general formula (III)

(In the formula, R ₅ represents a hydrogen atom or a methyl group, A represents an oxyalkylene group having 2 or 3 carbon atoms (preferably an oxyethylene group or an oxypropylene group), and R ₆ represents 1 to 1 carbon atoms. 6 represents an alkyl group having 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 12.)
(Meth) acrylate represented by the general formula (IV)

(In the formula, R ₇ represents a methyl group or an ethyl group, and R ₈ represents a hydrogen atom or a methyl group.)
It is at least 1 sort (s) chosen from vinyl ester represented by these.

  Specific examples of the (meth) acrylate represented by the general formula (III) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2,2,2 -Trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, etc. can be mentioned.

  Besides these, for example,

Etc. In the formula, R ₅ represents a hydrogen atom or a methyl group, and n is an integer of 0 to 12.

  Specific examples of the vinyl ester represented by the general formula (IV) include vinyl acetate and vinyl propionate.

  According to the present invention, as described above, when the reactive polymer is obtained by the first method, the crosslinkable polymer is reacted with the crosslinker by a part of the cationically polymerizable functional group, and partially crosslinked. A reactive polymer, and this is supported on a porous substrate film to form a reactive polymer-supported porous film, and an electrode is laminated thereon to form an electrode / reactive polymer-supported porous film laminate. It is immersed in an electrolytic solution containing a cationic polymerization catalyst, preferably an electrolytic solution containing an electrolyte that also serves as a cationic polymerization catalyst, and the reactive polymer of the electrode / reactive polymer-supported porous film laminate is brought into contact with the electrolytic solution. Then, a part of the reactive polymer is swollen in the electrolytic solution, or is eluted and diffused in the electrolytic solution, and is crosslinked by cationic polymerization to form a boundary between the porous film and the electrode. By gelling the electrolyte solution in the vicinity of, it is possible to adhere the electrodes and the porous film.

  Therefore, according to the present invention, when obtaining a crosslinkable polymer containing a 3-oxetanyl group and / or an epoxy group, the 3-oxetanyl group-containing radical polymerizable monomer and / or the epoxy group-containing radical polymerizable monomer are: The total amount is 5 to 50% by weight of the total monomer amount, preferably 10 to 30% by weight. Therefore, in the case of obtaining a crosslinkable polymer containing a 3-oxetanyl group, the 3-oxetanyl group-containing radical polymerizable monomer is in the range of 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount. In the same manner, in the case of obtaining a crosslinkable polymer containing an epoxy group, the epoxy group-containing radical polymerizable monomer is 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount. Used in a range.

  Further, a crosslinkable polymer having a 3-oxetanyl group and an epoxy group by using a 3-oxetanyl group-containing radical polymerizable monomer and an epoxy group-containing radical polymerizable monomer together and copolymerizing these with another radical polymerizable monomer Is used such that the proportion of the epoxy group-containing radical polymerizable monomer in the total amount of the 3-oxetanyl group-containing radical polymerizable monomer and the epoxy group-containing radical polymerizable monomer is 90% by weight or less.

  When obtaining a 3-oxetanyl group-containing crosslinkable polymer or an epoxy group-containing crosslinkable polymer, the total amount of the 3-oxetanyl group-containing radical polymerizable monomer and the epoxy group-containing radical polymerizable monomer is more than 5% by weight of the total monomer amount. When the amount is small, as described above, the amount of the reactive polymer required for gelation of the electrolytic solution is increased, so that the performance of the obtained battery is lowered. On the other hand, when it is more than 50% by weight, the retention property of the electrolyte solution of the formed gel is lowered, and the adhesion between the electrode / separator in the obtained battery is lowered.

  Next, the crosslinkable polymer having in its molecule a plurality of isocyanate-reactive groups having an active hydrogen such as a hydroxyl group or a carboxyl group capable of reacting with an isocyanate group together with the cationic polymerizable functional group is preferably an isocyanate reaction. Polymerizable group-containing radical polymerizable monomer (isocyanate-reactive group-containing radical polymerizable monomer), 3-oxetanyl group-containing radical polymerizable monomer (3-oxetanyl group-containing radical polymerizable monomer), and epoxy group-containing radical polymerizable property It can be obtained by a radical copolymer of at least one radical polymerizable monomer selected from monomers (epoxy group-containing radical polymerizable monomers) and other radical polymerizable monomers.

  Examples of the isocyanate-reactive group-containing radical polymerizable monomer include carboxyl group-containing radical copolymerizable monomers such as (meth) acrylic acid, itaconic acid, maleic acid, 2-hydroxyethyl (meth) acrylate, 2- Mention may be made of hydroxyl group-containing radical copolymerizable monomers such as hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, in particular hydroxylalkyl (meth) acrylate. . In the present invention, (meth) acrylate means acrylate or (meth) acrylate.

  According to the present invention, in this way, when obtaining a crosslinkable polymer having a cationic polymerizable functional group together with an isocyanate reactive group, the isocyanate reactive group-containing radical polymerizable monomer is 0.1 to 0.1% of the total monomer amount. It is used in an amount of 10% by weight, preferably 0.5 to 5% by weight. When the above-mentioned isocyanate-reactive group-containing radically polymerizable monomer is more than 10% by weight of the total monomer amount, the crosslinking density is obtained by reacting the resulting crosslinkable polymer with polyfunctional isocyanate to crosslink the crosslinkable polymer. The reactive polymer produced is dense, and when the electrode is joined to the reactive polymer-supported porous film to form an electrode / separator assembly, the reactive polymer swells sufficiently in the electrolyte. Since it becomes difficult, a battery having excellent characteristics cannot be obtained. However, on the contrary, when the isocyanate-reactive group-containing radical polymerizable monomer is less than 0.1% by weight of the total monomer amount, elution and diffusion of the reactive polymer obtained by crosslinking the crosslinkable polymer into the electrolyte solution Is not sufficiently suppressed, and most of the reactive polymer elutes and diffuses in the electrolyte, so that sufficient adhesion cannot be obtained between the reactive polymer-supporting porous film and the electrode. You can't get a good battery.

  According to the present invention, when a reactive polymer is obtained by the second method, the crosslinkable polymer as described above is reacted with a polyfunctional isocyanate to be crosslinked to form a reactive polymer, which is a porous substrate. The film is supported on a reactive polymer-supported porous film, and then an electrode is laminated thereon to form an electrode / porous film laminate, which is an electrolytic solution containing a cationic polymerization catalyst, preferably a cationic polymerization catalyst. Dipping in an electrolytic solution containing an electrolyte that also serves as an electrolyte, bringing the reactive polymer supported on the porous film into contact with the electrolytic solution, and swelling at least a part thereof in the electrolytic solution, or eluting into the electrolytic solution By diffusing, crosslinking by cationic polymerization, and gelling the electrolyte in the vicinity of the interface between the reactive polymer-supporting porous film and the electrode, It can be adhered to porous films.

  Therefore, according to the present invention, a 3-oxetanyl group-containing radical polymerizable monomer and / or an epoxy group-containing radical can be obtained in obtaining a crosslinkable polymer containing a 3-oxetanyl group and / or an epoxy group together with an isocyanate-reactive group. The polymerizable monomer is used in the amount described above.

  If necessary, the crosslinkable polymer having a plurality of 3-oxetanyl groups and / or epoxy groups in the molecule together with isocyanate-reactive groups preferably contains isocyanate-reactive groups as described above. A radical copolymer can be obtained by radically copolymerizing a monomer, a 3-oxetanyl group and / or an epoxy-containing radical polymerizable monomer, and another radical polymerizable monomer using a radical polymerization initiator. This radical copolymerization may be carried out by any polymerization method such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc., but solution polymerization or suspension polymerization in terms of ease of polymerization, adjustment of molecular weight, post-treatment, etc. Is preferred.

  The radical polymerization initiator is not particularly limited, and examples thereof include N, N′-azobisisobutyronitrile, dimethyl N, N′-azobis (2-methylpropionate), and benzoyl peroxide. Lauroyl peroxide is used. In this radical copolymerization, a molecular weight modifier such as mercaptan can be used as necessary.

  In the present invention, the crosslinkable polymer preferably has a weight average molecular weight of 10,000 or more. When the weight average molecular weight of the crosslinkable polymer is smaller than 10,000, the electrolyte solution is gelled by the cationic polymerization, so a large amount of the reactive polymer obtained from this is required, so the characteristics of the obtained battery are deteriorated. Let On the other hand, the upper limit of the weight average molecular weight of the crosslinkable polymer is not particularly limited, but is about 3 million so that the reactive polymer obtained therefrom can hold the electrolytic solution as a gel by cationic polymerization, Preferably, it is about 2.5 million. In particular, according to the present invention, the crosslinkable polymer preferably has a weight average molecular weight in the range of 100,000 to 2,000,000.

(Reactive polymer)
As described above, it is already known that 3-oxetanyl groups and epoxy groups can react with carboxyl groups and acid anhydride groups and can be cationically polymerized. Therefore, according to the present invention, when a reactive polymer is obtained by the first method, the reactivity of 3-oxetanyl group which is a cationic polymerizable functional group of the reactive polymer and an epoxy group is used. Then, by using a part of the cationic polymerizable functional group, the crosslinkable polymer having the cationic polymerizable functional group is reacted with a carboxylic acid or an acid anhydride as a cross-linking agent, and partially crosslinked. Then, a reactive polymer is formed and supported on the porous substrate film to form a reactive polymer-supported porous film. Thus, the battery separator according to the present invention can be obtained.

  According to the present invention, it is desirable that the reactive polymer obtained by partially crosslinking the crosslinkable polymer in this way has a gel fraction in the range of 5 to 80%. Here, the gel fraction is, as will be described later, remaining on the porous film after immersing the porous film carrying the reactive polymer in ethyl acetate at 23 ° C. for 7 days and then drying. Refers to the percentage of reactive polymer.

  When the gel fraction of the reactive polymer is less than 5%, an electrode is pressure-bonded to a porous film supporting such a reactive polymer to form an electrode / porous film laminate, which is used as an electrolyte solution. When immersed, most of the reactive polymer elutes and diffuses into the electrolyte, and even if the reactive polymer is further cationically polymerized and crosslinked, effective adhesion can be obtained between the electrode and the porous film. Can not. On the other hand, when the gel fraction of the reactive polymer is more than 80%, an electrode / porous film laminate is formed, and when this is immersed in an electrolytic solution, the reactive polymer has low swelling and the resulting electrode / porous A battery having a quality film assembly has a high internal resistance, which is not preferable for battery characteristics. In particular, according to the present invention, the gel fraction of the reactive polymer is preferably in the range of 10-60%, most preferably in the range of 10-50%.

  In this way, a reactive polymer having a gel fraction in the range of 5 to 80% is obtained by reacting a crosslinkable polymer having a cationic polymerizable functional group in the molecule with a mono- or polycarboxylic acid and partially crosslinking the polymer. In order to obtain, although it is not limited, the carboxyl group which mono- or polycarboxylic acid has is 0.01-1.0 mol part normally with respect to 1 mol part of cationically polymerizable functional group which a crosslinkable polymer has. In addition, it is preferably used so as to be 0.05 to 1.0 mol part, and the heating reaction conditions between the crosslinkable polymer and the mono- or polycarboxylic acid may be adjusted, and thus a desired gel fraction is obtained. A reactive polymer having can be obtained.

  As an example, with respect to 1 mol part of the cationically polymerizable functional group of the crosslinkable polymer, the carboxyl group of the mono- or polycarboxylic acid is used so as to be 0.5 to 1.0 mol part, A reactive polymer having a gel fraction of 5 to 80% can be obtained by subjecting a mono- or polycarboxylic acid to a heat reaction at 50 ° C. for 10 to 500 hours, usually 12 to 250 hours.

  On the other hand, there is no limitation to reacting a crosslinkable polymer with an acid anhydride and partially crosslinking to obtain a reactive polymer having a gel fraction in the range of 5 to 80%. The acid anhydride group of the acid anhydride is 0.005 to 0.5 mol part, preferably 0.01 to 0.4 mol part with respect to 1 mol part of the cationically polymerizable functional group of the crosslinkable polymer. The heating reaction conditions between the crosslinkable polymer and the acid anhydride may be adjusted.

  As an example, with respect to 1 mol part of the cationically polymerizable functional group of the crosslinkable polymer, the acid anhydride group of the acid anhydride is used so as to be 0.25 to 0.1 mol part, A reactive polymer having a gel fraction of 5 to 80% can be obtained by heating and reacting with an acid anhydride at 50 ° C. for 10 to 500 hours.

  In the present invention, the monocarboxylic acid is an organic acid having one carboxyl group in the molecule, and any monocarboxylic acid can be used without particular limitation. Examples of such molar carboxylic acids include aliphatic monocarboxylic acids, aromatic monocarboxylic acids, and alicyclic monocarboxylic acids. Such a monocarboxylic acid may be a saturated compound or an unsaturated compound, and has an inert substituent such as an alkyl group, a hydroxy group, an alkoxy group, an amino group, or a nitro group in the molecule. May be.

  Accordingly, specific examples of monocarboxylic acids include, for example, saturated aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, stearic acid, unsaturated aliphatic monocarboxylic acids such as linoleic acid, oleic acid, benzoic acid, Mention may be made of aromatic monocarboxylic acids such as butylbenzoic acid and alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid.

  The polycarboxylic acid is an organic compound having two or more carboxyl groups in the molecule, preferably 2 to 6, particularly preferably 2 to 4 carboxyl groups in the molecule. . Examples of the dicarboxylic acid having two carboxyl groups in the molecule include aliphatic saturated dicarboxylic acids such as glutaric acid and adipic acid, aliphatic unsaturated dicarboxylic acids such as maleic acid, and aromatic dicarboxylic acids such as phthalic acid. Can be mentioned.

  Examples of the polycarboxylic acid having 3 or more carboxyl groups in the molecule include aliphatic tricarboxylic acids such as citric acid, aromatic tricarboxylic acids such as trimellitic acid, 1,2,3,4-butanetetra Mention may be made of aliphatic tetracarboxylic acids such as carboxylic acids, and aromatic tetracarboxylic acids such as pyromellitic acid and benzophenone tetracarboxylic acid.

  In the present invention, the acid anhydride has the general formula (V)

(In the formula, n is an integer of 1 to 3, and R represents a 2n-valent hydrocarbon group.)
It is represented by

  In the present invention, the acid anhydride group means a divalent group in parentheses in the acid anhydride represented by the general formula (V). In the present invention, the hydrocarbon group does not adversely affect the reaction between the acid anhydride and the reactive group of the crosslinkable polymer, and further, is harmful to the battery finally obtained according to the present invention. As long as it does not have a significant influence, it may have an arbitrary substituent. Examples of such a substituent include a halogen atom, a nitro group, an alkoxyl group, and an allyloxy group. In the hydrocarbon group, a part of carbon atoms constituting the hydrocarbon group may be substituted with a hetero atom such as an oxygen atom or a nitrogen atom. Furthermore, according to the present invention, the hydrocarbon group may have a free carboxyl group.

  Among the acid anhydrides represented by the above general formula, examples of the monofunctional acid anhydride in which n is 1 include succinic anhydride and maleic anhydride. Further, among the acid anhydrides represented by the above general formula, examples of the bifunctional acid anhydride in which n is 2 include pyromellitic anhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride You can list things. Furthermore, among the acid anhydrides represented by the above general formula, examples of the trifunctional acid anhydride in which n is 3 include hexahydromellitic anhydride and mellitic anhydride. Examples of the acid anhydride having a free carboxyl group include trimellitic anhydride.

  As described above, according to the second method, a crosslinkable polymer having an isocyanate reactive group together with a cationic polymerizable functional group is reacted with a polyfunctional isocyanate as a crosslinking agent by using the isocyanate reactive group. The reactive polymer can be obtained by crosslinking and crosslinking.

  The polyfunctional isocyanate is not particularly limited. For example, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, tris. (Phenyl isocyanate) aromatic, araliphatic, alicyclic, aliphatic polyfunctional isocyanates such as thiophosphate, etc., and multivalent isocyanates of these isocyanates are used, but diisocyanates such as trimethylolpropane polyols A so-called isocyanate adduct obtained by adding bismuth is also preferably used.

  According to the present invention, when the crosslinkable polymer is reacted with a polyfunctional isocyanate by its isocyanate reactive group and crosslinked to obtain a reactive polymer by the second method as described above, as described above. In addition, the reactive polymer desirably has a gel fraction in the range of 5 to 80%.

  Thus, a reactive polymer having a gel fraction in the range of 5 to 80% is obtained by reacting a crosslinkable polymer having an isocyanate-reactive group together with a cationic polymerizable functional group with a polyfunctional isocyanate to cause crosslinking. Is not particularly limited, but usually, the isocyanate group possessed by the polyfunctional isocyanate is from 0.1 to 10 mole parts, preferably from 0.1 mole part to 1 mole part of the isocyanate reactive group possessed by the crosslinkable polymer. What is necessary is just to use in 3-5 mol part, Most preferably, in the range of 0.5-3 mol part.

  According to this invention, as long as the reactive polymer obtained has the said gel fraction, it is not necessarily necessary to make all the isocyanate reactive groups in a crosslinkable polymer react with polyfunctional isocyanate. The heat-curing temperature and the time for it depend on the crosslinkable polymer and polyfunctional isocyanate used, but these reaction conditions can be determined by experiments. Usually, if it is made to react for 48 hours at the temperature of 50 degreeC, a crosslinking reaction will be completed and the reactive polymer which has the said gel fraction and was characteristically stable can be obtained.

  Thus, in accordance with the present invention, the reactive polymer obtained by crosslinking the crosslinkable polymer is inhibited from leaching and diffusing into the electrolyte even when immersed in the electrolyte due to its crosslinked structure. . Therefore, a reactive polymer having such a gel fraction of 5 to 80% is supported on a porous film to form a reactive polymer-supporting porous film, and an electrode is laminated on the porous polymer to support the electrode / reactive polymer. The porous film laminate is prepared in a battery container, and then an electrolytic solution containing an electrolyte containing a cationic polymerization catalyst is injected into the battery container, and the electrode / reactive polymer-supported porous film laminate has the reaction. When the conductive polymer is brought into contact with the electrolytic solution, a part of the reactive polymer in the electrode / porous film laminate is swollen in the electrolytic solution or electrolyzed in the vicinity of the interface between the porous film and the electrode. Elution into the liquid, and further cationic polymerization by the cationic polymerization functional group in the electrolytic solution by the cationic polymerization functional group, preferably the electrolyte that also serves as the cationic polymerization catalyst, The solution was gelled, electrode porous film with good adhesion to strongly adhere and thus the electrode / porous film (i.e., a separator in a battery obtained) can be obtained joined body.

  Furthermore, according to the present invention, as described above, the reactive polymer is partially crosslinked in advance so as to have a gel fraction of 5 to 80%. , Elution and diffusion into the electrolytic solution is prevented or reduced, and it is effectively used for adhesion between the electrode and the porous film. Therefore, by using a relatively small amount of the reactive polymer, the electrode and the porous film Can be stably and more firmly bonded.

  Further, in the reactive polymer-supported porous film, the reactive polymer does not react and crosslink in the absence of a cationic polymerization catalyst, and is stable and stable even after storage for a long time. There is nothing to do.

  In the battery separator according to the present invention, the reactive polymer-supported porous film as described above comprises organically swellable synthetic mica particles in the polymer layer.

  Synthetic mica is typically fluorine mica, and thus organically swellable synthetic mica is typically Li-type fluorine teniolite, Na-type fluorine teniolite, Na-type tetrasilicon fluorine mica, Li-type tetrasilicon fluorine mica. Or the like is substituted with a quaternary alkyl ammonium ion. Examples of the quaternary alkylammonium salt include trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, didodecyldimethylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, distearyldibenzylammonium chloride, palmylylbenzyldimethyl. Ammonium chloride or the like is used. Such organically swellable synthetic mica swells in many organic solvents in addition to the organic solvent that constitutes the electrolyte for non-aqueous batteries.

  In the present invention, a commercially available organically swellable synthetic mica can be suitably used. Examples of commercially available organically swellable synthetic mica include Somasif MAE in which the sodium ions between the lipophilic synthetic mica Somasif ME-100 are replaced with distearyldimethylammonium ions, and Somasif MTE in which trioctylmethylammonium ions are substituted. In addition, for example, Somasif MEE, MPE, and the like can be given. Both are products of Coop Chemical Co., Ltd.

  In the present invention, such an organically swellable synthetic mica is usually contained in the reactive polymer in a range of 1 to 50% by weight in the total amount of the reactive polymer and the organically swellable synthetic mica. Is included in the range of 10 to 30% by weight.

(Battery separator, ie, reactive polymer-supported porous film)
According to the present invention, the reactive polymer has a plurality of cationically polymerizable functional groups in the molecule and a crosslinked structure, and further contains organically swellable synthetic mica particles. In order to obtain a battery separator according to the present invention by supporting such a reactive polymer on a substrate porous film, for example, a crosslinkable polymer and a crosslinking agent are dissolved and an organically swellable synthetic mica is dispersed. The applied coating solution is prepared and applied to the substrate porous film, and then heated to evaporate the solvent from the coating solution and react the crosslinkable polymer with the crosslinking agent. In particular, it is not limited to this method.

  For example, an organically swellable synthetic mica is dispersed in a solution of a crosslinkable polymer to form a coating solution, which is applied to a substrate porous film and dried, and thus contains an organically swellable synthetic mica. The solution of the crosslinking agent may be brought into contact with the layer of the crosslinkable polymer to be heated and heated. In addition, the reactivity in which the organically swellable synthetic mica is dispersed in the solution of the crosslinkable polymer, the crosslinkable polymer is reacted with the crosslinking agent in the dispersion, and is crosslinked to disperse the organically swellable synthetic mica. A polymer solution may be obtained, applied to a peelable sheet, dried, and then transferred to a substrate porous film.

  In particular, one of the preferred methods according to the present invention is to disperse the organically swellable synthetic mica in a solution containing both a crosslinkable polymer and a crosslinker to prepare a coating solution, which is applied to a peelable sheet. After drying, a layer of a mixture of organically swellable synthetic mica, crosslinkable polymer, and crosslinker is formed on the peelable sheet, and then the peelable sheet is layered on the substrate porous film and heated and pressurized to make it organic The layer of the mixture composed of the swellable synthetic mica, the crosslinkable polymer and the crosslinking agent is transferred to the porous film of the substrate, and then the layer of the mixture composed of the organically swellable synthetic mica, the crosslinkable polymer and the crosslinking agent is appropriately transferred. When heated to temperature, the crosslinkable polymer is reacted with a crosslinker and crosslinked, a layer of the reactive polymer containing the organically swellable synthetic mica can be formed on the substrate porous film.

  In this way, the layer of reactive polymer formed on the substrate porous film is substantially nonporous. Here, the reactive polymer layer is substantially non-porous means that the Gurley value of the reactive polymer layer measured in accordance with JIS P8117 is 5000 seconds / 100 cc or more, and the Gurley value is substantially This means that the air permeability is so low that it cannot be obtained.

(Manufacture of batteries)
Next, a battery manufacturing method using the battery separator thus obtained will be described.

  In the present invention, the electrodes, that is, the negative electrode and the positive electrode differ depending on the battery, but usually, an active material and, if necessary, a conductive agent are fixed to a conductive base material using a resin binder and supported. A sheet-like material is used.

  First, an electrode is laminated on the reactive polymer layer of the battery separator according to the present invention or wound to obtain an electrode / separator laminate, and then this laminate is a battery container made of a metal can, a laminate film, or the like. In this case, if necessary, the terminal is welded, etc., and after that, a predetermined amount of an electrolytic solution in which a cationic polymerization catalyst is dissolved is injected into the battery container, and the reactivity of the electrode / separator laminate is provided. The polymer is contacted with the electrolyte. Next, the battery container is sealed and sealed, and at least a part of the reactive polymer included in the separator is swollen in the electrolyte solution in the vicinity of the interface between the separator and the electrode, or eluted and diffused in the electrolyte solution. The electrode / separator junction is formed by cross-linking by cationic polymerization, gelling at least a part of the electrolytic solution, and adhering the electrode to the porous film through the reactive polymer, and thus firmly adhering the electrode to the separator. A battery with a body can be obtained.

  In the present invention, the reactive polymer functions to cause the electrolyte solution to gel at least in the vicinity of the interface with the electrode and to bond the electrode and the porous film by crosslinking by cationic polymerization.

  In the present invention, the reactive polymer can be cationically polymerized and crosslinked even at room temperature, although it depends on its structure, the amount supported on the porous film, and the type and amount of the cationic polymerization catalyst. Thus, cationic polymerization can be promoted. In this case, although it depends on the heat resistance and productivity of the material constituting the battery, the heating is usually performed at a temperature of about 40 to 100 ° C. for about 0.5 to 48 hours.

  In addition, in order to swell, elute, or diffuse the reactive polymer in an amount sufficient to adhere the electrode to the porous film, the electrolytic solution is injected into the battery container and then allowed to stand at room temperature for several hours. Good.

  In the present invention, the electrode / separator laminate is only required to have an electrode laminated on the reactive polymer layer of the separator. In the present invention, the separator is formed on the organic film only on one side of the porous film. You may have the reactive polymer layer containing a mica, and you may have the reactive polymer layer containing the organic-ized swelling synthetic mica on both surfaces of a porous film. Therefore, according to the present invention, the battery separator only needs to have a reactive polymer layer containing the organically swellable synthetic mica on at least one surface of the porous film, and the electrode is provided on such a reactive polymer layer. May be laminated. Therefore, in the present invention, the electrode / separator laminate can take various configurations depending on the structure and form of the battery, for example, negative electrode / porous film / positive electrode, negative electrode / porous film / positive electrode / porous. A film or the like is used.

  The electrolytic solution is a solution obtained by dissolving an electrolyte salt in an appropriate solvent. Examples of the electrolyte salt include alkali metals such as hydrogen, lithium, sodium and potassium, alkali metals such as calcium and strontium, tertiary or quaternary ammonium salts, etc. as cation components, hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid A salt containing an anionic component of an inorganic acid such as borohydrofluoric acid, hydrofluoric acid, hexafluorophosphoric acid or perchloric acid, or an organic acid such as carboxylic acid, organic sulfonic acid or fluorine-substituted organic sulfonic acid. it can. Among these, an electrolyte salt containing an alkali metal ion as a cation component is particularly preferably used.

  Specific examples of the electrolyte salt having such an alkali metal ion as a cation component include, for example, alkali perchlorate such as lithium perchlorate, sodium perchlorate, potassium perchlorate, lithium tetrafluoroborate, tetra Alkali metal tetrafluoroborate such as sodium fluoroborate and potassium tetrafluoroborate, alkali metal hexafluorophosphate such as lithium hexafluorophosphate and potassium hexafluorophosphate, alkali metal trifluoroacetate such as lithium trifluoroacetate And alkali metal trifluoromethanesulfonates such as lithium trifluoromethanesulfonate.

  In particular, when obtaining a lithium ion secondary battery according to the present invention, as the electrolyte salt, for example, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and the like are preferably used.

  Furthermore, any solvent can be used as the solvent for the electrolyte salt used in the present invention as long as it dissolves the electrolyte salt. Examples of the non-aqueous solvent include ethylene carbonate and propylene carbonate. , Cyclic esters such as butylene carbonate and γ-ptyrolactone, ethers such as tetrahydrofuran and dimethoxyethane, and chain esters such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, or a mixture of two or more thereof Can be used as

  Moreover, although the said electrolyte salt is suitably determined according to the kind and quantity of the solvent to be used, normally the quantity used as the density | concentration of 1 to 50 weight% is used in the obtained electrolyte solution.

  In the present invention, an onium salt is preferably used as the cationic polymerization catalyst. Examples of such onium salts include ammonium salts, phosphonium salts, arsonium salts, stibonium salts, iodonium salts, and other cationic components, tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonate, and perchloric acid. An onium salt comprising an anionic component such as a salt can be mentioned.

  However, according to the present invention, among the electrolyte salts described above, in particular, lithium tetrafluoroborate and lithium hexafluorophosphate also function as a cationic polymerization catalyst. Preferably used. In this case, either lithium tetrafluoroborate or lithium hexafluorophosphate may be used alone, or both may be used in combination.

  The battery separator according to the present invention has a reactive polymer layer having a crosslinked structure on a porous film, and this reactive polymer layer contains organically swellable synthetic mica particles as described above. According to the present invention, the oxidation-reduction resistance of the reactive polymer layer can be improved by including the organically swellable synthetic mica particles in the reactive polymer layer. The reason is not necessarily clear, but it seems to be because the contact area between the electrode and the reactive polymer layer is reduced, and the oxidation or reduction reaction of the reactive polymer due to the contact with the electrode is suppressed.

  Furthermore, in the battery separator according to the present invention, since the organically swellable synthetic mica particles swell well with respect to the organic solvent, the ion conductivity of the reactive polymer layer is reduced due to the presence of the synthetic mica particles in the layer. Is hardly observed, and as a result, the obtained battery characteristics are not deteriorated.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The characteristics of the porous film and the characteristics of the obtained battery were evaluated as follows.

(Thickness of porous film)
It was determined based on a measurement with a 1/10000 mm thickness gauge and a 10,000 times scanning electronic microscopic photograph of the cross section of the porous film.

(Porosity of porous film)
The weight was calculated from the weight W (g) per unit area S (cm ² ) of the porous film, the average thickness t (cm), and the density d (g / cm ³ ) of the resin constituting the porous film by the following equation.
Porosity (%) = (1− (100 W / S / t / d)) × 100

(Air permeability of porous film)
It calculated | required based on JISP8117.

(Puncture strength)
A piercing test was performed using a compression test kit KES-G5 manufactured by Kato Tech Co., Ltd. The maximum load was read from the load displacement curve obtained by the measurement, and the puncture strength was obtained. A needle having a diameter of 1.0 mm and a radius of curvature of the tip of 0.5 mm was used at a speed of 2 mm / second.

(Reaction polymer gel fraction)
A reactive polymer layer-carrying porous film carrying a known amount A of a reactive polymer layer was weighed and its weight B was measured. Next, this reactive polymer layer-supported porous film was immersed in ethyl acetate at 23 ° C. for 7 days and then dried. Then, the reactive polymer layer carrying porous film processed in this way was weighed, and the weight C was measured. The gel fraction of the reactive polymer was calculated by the following formula.
Gel fraction (%) = ((A− (BC)) / A) × 100

(Separator oxidation resistance test)
First, the battery was charged and discharged twice at a charge / discharge rate of 0.2 CmA, and then charged. Charging was performed at a constant current-constant voltage having an upper limit voltage of 4.2 V, and discharging was performed at a constant current having a final voltage of 2.7 V. All of these operations were performed in a thermostatic chamber at a temperature of 25 ° C. The charged battery was placed in an incubator at 60 ° C., charged at a constant voltage of 4.25 V, and the current value was measured. The time during which the current value rapidly increased was defined as the oxidation resistance time.

Reference example 1
(Preparation of electrode sheet)
85 parts by weight of lithium cobaltate (Nippon Chemical Industry Co., Ltd., Cellseed C-10) as a positive electrode active material and 10 parts by weight of acetylene black (Denka Black from Denki Kagaku Kogyo Co., Ltd.) as a conductive additive and a binder. 5 parts by weight of vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.) was mixed, and this was made into a slurry using N-methyl-2-pyrrolidone so as to have a solid concentration of 15% by weight. .

  This slurry was applied to an aluminum foil (current collector) having a thickness of 20 μm to a thickness of 200 μm, dried at 80 ° C. for 1 hour, and then at 120 ° C. for 2 hours, and then pressed by a roll press, so that the thickness of the active material layer was A 100 μm positive electrode sheet was prepared.

  In addition, 80 parts by weight of mesocarbon microbeads (MCMB6-28 manufactured by Osaka Gas Chemical Co., Ltd.) as a negative electrode active material, 10 parts by weight of acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive auxiliary agent, and a binder 10 parts by weight of vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.) is mixed, and this is slurried with N-methyl-2-pyrrolidone so as to have a solid concentration of 15% by weight. It was.

  This slurry was applied to a copper foil (current collector) having a thickness of 20 μm to a thickness of 200 μm, dried at 80 ° C. for 1 hour, dried at 120 ° C. for 2 hours, and then pressed by a roll press to form an active material layer. A negative electrode sheet having a thickness of 100 μm was prepared.

Production Example 1
(Production of crosslinkable polymer A (4-hydroxybutyl acrylate monomer component 0.84% by weight, 3-oxetanyl group-containing monomer component 24% by weight, epoxy group-containing monomer component 1% by weight))
In a 500 mL three-necked flask equipped with a reflux condenser, 50.4 g of methyl methacrylate, 11.89 g of 2-methoxyethyl acrylate, 20.16 g of (3-ethyl-3-oxetanyl) methyl methacrylate, 3,4-epoxycyclohexyl After adding 0.84 g of methyl acrylate, 0.706 g of 4-hydroxybutyl acrylate, 158 g of ethyl acetate and 0.16 g of N, N′-azobisisobutyronitrile, stirring and mixing for 30 minutes while introducing nitrogen gas And heated to 70 ° C.

  When about 1 hour had passed, the viscosity of the reaction mixture began to rise, and then polymerization was carried out for 8 hours. Subsequently, it cooled to about 40 degreeC, N, N'- azobisisobutyronitrile 0.16g was added again, and it heated again at 70 degreeC, and also post-polymerized for 8 hours. Then, it cooled to about 40 degreeC, ethyl acetate 38g was added, and it stirred and mixed until the whole became uniform, and obtained the 30 weight% concentration ethyl acetate solution of the crosslinkable polymer.

  Next, 100 g of this crosslinkable polymer solution was added into 600 mL of methanol while stirring with a high-speed mixer to precipitate the crosslinkable polymer. The precipitated crosslinkable polymer was separated by filtration, washed with methanol several times, put into a drying tube, and dried by passing it through dry nitrogen gas (dew point temperature of −150 ° C. or lower) in which liquid nitrogen was vaporized. Furthermore, it was vacuum-dried in a desiccator for 6 hours to obtain a crosslinkable polymer A. The crosslinkable polymer thus obtained was a pure white powder. As a result of molecular weight measurement by GPC, the weight average molecular weight was 248,000, and the number average molecular weight was 57,000.

Example 1
(Production of reactive polymer-supported porous film)
8 g of the crosslinkable polymer A was added to 92 g of toluene and stirred at room temperature to obtain a uniform crosslinkable polymer solution. 0.204 g of polyfunctional isocyanate (hexamethylene diisocyanate / trimethylolpropane adduct, ethyl acetate solution, solid content 75% by weight, Coronate HL manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent was added to this crosslinkable polymer solution, And dissolved by stirring.

  Separately, 30 g of organically swellable synthetic mica (Somasif MAE manufactured by Corp Chemical Co., Ltd.) was added to 270 g of toluene, stirred at room temperature for 8 hours, and then a high-pressure disperser (Nanomizer PEL-20 manufactured by Yoshida Kikai Co., Ltd.). To obtain a uniform dispersion.

  100 g of a toluene solution of the crosslinkable polymer A and the polyfunctional isocyanate thus obtained and 8.0 g of the above-mentioned organically swellable synthetic mica toluene dispersion were mixed and stirred at room temperature, and then the above organically swellable property. Using the same high-pressure disperser used for the preparation of the synthetic mica toluene dispersion, the same dispersion treatment was performed to obtain an organically swellable synthetic mica toluene dispersion in which the crosslinkable polymer and polyfunctional isocyanate were dissolved.

The toluene dispersion of the organically swellable synthetic mica in which the crosslinkable polymer and the polyfunctional isocyanate are dissolved is applied on a polypropylene film with a wire bar # 8, and then heated to 60 ° C. to volatilize the toluene, thus. A crosslinkable polymer layer was formed on the polypropylene film at a coating density of 0.4 g / m ² . Thereafter, the crosslinkable polymer layer was transferred to a polyethylene resin porous film (film thickness: 16 μm, porosity: 60%, air permeability: 100 seconds / 100 cc, puncture strength: 400 gf) using a hot roll laminator at 110 ° C. Then, a layer made of a mixture of the crosslinkable polymer A, the polyfunctional isocyanate, and the organically swellable synthetic mica was supported on the porous film.

  Next, the porous film carrying a layer composed of a mixture of this crosslinkable polymer, polyfunctional isocyanate and organically swellable synthetic mica was placed in a thermostat at 70 ° C. for 48 hours to carry the porous film on the porous film. A crosslinkable polymer and a polyfunctional isocyanate were reacted to crosslink the crosslinkable polymer, thus obtaining a reactive polymer-supported porous film containing an organically swellable synthetic mica. In the reactive polymer-supported porous film containing this organically swellable synthetic mica, the gel fraction of the reactive polymer was 20%. Also, the reactive polymer layer thus formed was substantially non-porous.

  A porous film carrying a reactive polymer containing this organically swellable synthetic mica is placed between the positive electrode and the negative electrode prepared in the reference example so that the reactive polymer layer on the porous film faces the positive electrode. And inserted into the laminate package. Next, an electrolytic solution in which lithium hexafluorophosphate was dissolved in an ethylene carbonate / diethyl carbonate mixed solvent (capacity ratio 1: 2) at a concentration of 1.4 mol / L in a glove box substituted with argon was placed in a laminate package. After the injection, the laminate package was sealed.

  Subsequently, this laminate package is put into a thermostat at a temperature of 50 ° C. for 24 hours, and the reactive polymer in the porous film supporting the reactive polymer containing the organically swellable synthetic mica is converted into its cationic polymerizable functional group. Thus, a battery having an electrode / separator assembly was obtained. When this battery was subjected to an oxidation resistance test, the oxidation resistance time was 103 hours.

Comparative Example 1
A reactive polymer-supported porous film was obtained in the same manner as in Example 1 except that the organically swellable synthetic mica was not used, and a battery was produced in the same manner as in Example 1. When this battery was subjected to an oxidation resistance test, the oxidation resistance time was 56 hours.

Comparative Example 2
The polyethylene resin porous film used in Example 1 was placed between the positive electrode and the negative electrode prepared in the reference example and inserted into a laminate package. Next, an electrolyte solution in which lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate (capacity ratio 1: 2) at a concentration of 1.4 mol / L in a laminate package in a glove box substituted with argon. Then, the laminate package was sealed to obtain a battery. When this battery was subjected to an oxidation resistance test, the oxidation resistance time was 59 hours.

Claims (9)

  A battery separator having a plurality of cationically polymerizable functional groups in the molecule, a crosslinked structure, and a reactive polymer layer containing organically swellable synthetic mica particles supported on a porous film, and the battery An electrode / separator laminate comprising electrodes laminated on a separator is contacted with an electrolytic solution obtained by dissolving a cationic polymerizable catalyst and an electrolyte salt in an organic solvent in a battery container, and the reactive polymer is obtained by cationic polymerization. A non-aqueous electrolyte battery characterized in that the organically swellable synthetic mica particles are swollen by the organic solvent. The cationic polymerizable functional group is at least one selected from a 3-oxetanyl group and an epoxy group, and the reactive polymer layer (a) is a crosslinkable polymer having a plurality of the cationic polymerizable functional groups in the molecule. Is it substantially non-porous by reacting a part of the cationic polymerizable functional group by reacting with an amount of a crosslinking agent necessary for reacting a part of the cationic polymerizable functional group? Or (b) the above-mentioned isocyanate-reactive group of a crosslinkable polymer having a plurality of isocyanate-reactive groups together with a plurality of cationically polymerizable functional groups in the molecule is reacted with a polyfunctional isocyanate as a cross-linking agent to be crosslinked. Is substantially non-porous,
The nonaqueous electrolyte battery according to claim 1.   The non-aqueous electrolyte battery according to claim 2, wherein the crosslinking agent is at least one selected from monocarboxylic acids, polycarboxylic acids, and acid anhydrides.   The nonaqueous electrolyte battery according to claim 2, wherein the isocyanate-reactive group is a group having active hydrogen.   The nonaqueous electrolyte battery according to claim 2, wherein the isocyanate-reactive group is a hydroxyl group or a carboxyl group.   The non-aqueous electrolyte battery according to claim 1, wherein the cationic polymerizable catalyst is an onium salt.   The non-aqueous electrolyte battery according to claim 1 or 2, wherein the electrolyte salt is at least one selected from lithium tetrafluoroborate and lithium hexafluorophosphate.   The non-aqueous electrolyte battery according to claim 2, wherein the reactive polymer layer has a Gurley value of 5000 seconds / 100 cc or more. The non-aqueous electrolyte battery according to claim 1, wherein the reactive polymer contains organically swellable synthetic mica particles in a range of 1 to 50% by weight of the total amount of the reactive polymer and the organically swellable synthetic mica.