JP2007157570A - Manufacturing method of reactant polymer-carrying porous film for battery separator and battery using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a cross-linking or a reactant polymer-carrying porous film for a separator which, while having a sufficient adhesiveness between an electrode and a separator, has a low inner resistance and is suitable for manufacturing a battery with high rate characteristics, and a manufacturing method of a battery using the above reactant polymer-carrying porous film. <P>SOLUTION: The cross-linking polymer-carrying porous film for a battery separator is manufactured in a process in which a cross-linking polymer and lithium salt are carried on a porous film. The reactant polymer-carrying porous film for a battery separator is manufactured in a process in which a cross-linking agent is made to react with a cross-linking polymer which can be reactant and cross-linked with the cross-linking agent. A manufacturing method of a battery using the above film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides, as a first invention, a crosslinkable polymer-supported porous film for a battery separator obtained by supporting a crosslinkable polymer together with a lithium salt on a porous film, and a second invention as a crosslinkable polymer. Reactive polymer-supported porous film for battery separator, in which a reactive polymer obtained by reacting with a cross-linking agent and partially crosslinked is supported on a porous film together with a lithium salt, and such a cross-linkable polymer supported The present invention relates to a method for producing a battery in which an electrode is bonded to a separator using a porous film or a reactive polymer-supported porous film.

  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 it into a battery container made of, for example, a metal can. It is manufactured through a process of injecting an electrolytic solution into a battery container, sealing, and sealing.

  However, in recent years, the demand for further miniaturization and weight reduction of the above-described small portable electronic devices is very strong. Therefore, further thinning and weight reduction of lithium ion secondary batteries are also demanded. 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 are deteriorated.

  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, conventionally, in order to solve such problems, it is possible to join the electrode and the separator with an adhesive resin composed of an electrolyte solution phase, a polymer gel layer containing the electrolyte solution, and a polymer solid phase. It has been proposed (see, for example, Patent Document 1). In addition, after applying a binder resin solution containing polyvinylidene fluoride resin as a main component to the separator, the electrode is superimposed on the separator and dried to form an electrode laminate, and the electrode laminate is charged into a battery container. It has also been proposed to obtain a battery in which an electrolytic solution is injected into a battery container and an electrode is adhered to a separator (see, for example, Patent Document 2).

  In addition, the separator impregnated with the electrolytic solution and the positive and negative electrodes are joined and adhered by the porous adhesive resin layer, and the electrolytic solution is held in the through-hole of the adhesive resin layer to separate the separator. It has also been proposed to use a battery in which an electrode is bonded to (see, for example, Patent Document 3).

  However, according to such a method, in order to obtain a sufficient adhesive force between the separator and the electrode, it is necessary to increase the thickness of the adhesive resin layer. Since the amount of the liquid cannot be increased, the obtained battery has a problem that the internal resistance becomes high and the cycle characteristics and the high rate discharge characteristics cannot be sufficiently obtained.

  Furthermore, as described above, in a battery in which a separator and an electrode are bonded using an adhesive resin, the adhesive strength between the separator and the electrode is lowered when placed in a high temperature environment. There is a risk of causing a short circuit between the electrodes due to contraction. Further, in the battery, the adhesive resin is swollen by the electrolytic solution. However, since the diffusibility of the electrolyte ions is inferior to the electrolytic solution, the electrode is an adhesive resin layer to which the separator is bonded. Has a high internal resistance, which adversely affects battery characteristics.

  On the other hand, various manufacturing methods are conventionally known for porous films for battery separators. As one method, for example, a method of manufacturing a sheet made of a polyolefin resin and stretching the sheet at a high magnification is known (for example, see Patent Document 4). However, the battery separator made of a porous membrane obtained by stretching at a high magnification in this way is significantly shrunk under a high temperature environment such as when the battery is abnormally heated due to an internal short circuit or the like. There is a problem that it does not function as a partition between electrodes.

Therefore, in order to improve the safety of the battery, reduction of the thermal contraction rate of the battery separator under such a high temperature environment is an important issue. In this regard, for example, in order to suppress thermal contraction of the battery separator in a high temperature environment, for example, melt and knead ultra high molecular weight polyethylene and a plasticizer, and extrude the plasticizer from a die, and then extract and remove the plasticizer. And the method of manufacturing the porous film | membrane used for a battery separator is also known (refer patent document 5). However, according to this method, contrary to the above method, the obtained porous film has not been stretched, and thus there is a problem that the strength is not sufficient.
JP 09-161814 A JP 11-329439 A JP-A-10-172606 Japanese Patent Application Laid-Open No. 09-012756 Japanese Patent Laid-Open No. 05-310989

  The present invention has been made to solve the above-described problems in the production of a battery in which an electrode is bonded to a separator, and has sufficient adhesion between the electrode / separator and has a low internal resistance and a high level. Porous film carrying a crosslinkable polymer or a reactive polymer for a separator that can be suitably used for producing a battery having excellent rate characteristics, and such a crosslinkable polymer or reactive polymer-supported porous film It aims at providing the manufacturing method of the battery which uses a film.

  According to the present invention, as a first invention, there is provided a crosslinkable polymer-supported porous film for a battery separator, wherein the crosslinkable polymer and a lithium salt are supported on a porous film. .

  According to the present invention, as the second invention, a crosslinkable polymer that can be cross-linked by reacting with a cross-linking agent is reacted with a cross-linking agent, and a partially cross-linked reactive polymer and a lithium salt are porous. A reactive polymer-supported porous film for a battery separator is provided which is supported on a film. In the reactive polymer-supported porous film for battery separator, the cross-linking agent is preferably at least one selected from polycarboxylic acid and acid anhydride.

  Furthermore, according to the present invention, an electrode / crosslinkable polymer-supported porous film laminate or an electrode / reactive polymer-supported porous film obtained by laminating an electrode on the crosslinkable polymer-supported porous film or the reactive polymer-supported porous film. An electrode / crosslinkable polymer-supported porous film assembly or an electrode / reactive polymer-supported porous film assembly obtained therefrom is also provided.

  Moreover, according to this invention, the manufacturing method of the battery using the said crosslinkable polymer carrying | support porous film or a reactive polymer carrying | support porous film is provided. That is, if the crosslinkable polymer-supported porous film is used, an electrode is laminated on the crosslinkable polymer-supported porous film to obtain an electrode / crosslinkable polymer-supported porous film laminate. After the porous polymer laminate is loaded into the battery container, an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least a part of the crosslinkable polymer is cationically polymerized, thereby making the porous There is provided a method for producing a battery, comprising bonding a film and an electrode.

  On the other hand, if the reactive polymer-supported porous film is used, an electrode is laminated on the reactive polymer-supported porous film to obtain an electrode / reactive polymer-supported porous film laminate. The porous polymer laminate is loaded into the battery container, and then an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least a part of the reactive polymer is cationically polymerized to obtain a porous material. There is provided a method for producing a battery, comprising bonding a film and an electrode.

  According to the present invention, the crosslinkable polymer-supported porous film for the battery separator according to the first invention preferably has at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule. The reactive polymer-supporting porous film for a battery separator according to the second invention preferably has an oxetanyl group in the molecule and is supported by a porous film together with a lithium salt. A crosslinkable polymer having at least one reactive group selected from an epoxy group is reacted with a crosslinking agent, preferably at least one selected from a polycarboxylic acid and an acid anhydride, and a part of the crosslinkable polymer is obtained. It is crosslinked to form a reactive polymer, which is supported on a porous film together with a lithium salt.

  Therefore, an electrode is laminated on such a crosslinkable polymer-supported porous film or a reactive polymer-supported porous film to obtain an electrode / crosslinkable polymer-supported porous film laminate or a reactive polymer-supported porous film laminate, After charging this into the battery container, an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least in the vicinity of the interface between the porous film and the electrode, the crosslinkable polymer or the reactive polymer. At least a part is swollen in the electrolytic solution or eluted into the electrolytic solution, the reactive group of the crosslinkable polymer or reactive polymer is cationically polymerized, and the crosslinkable polymer or reactive polymer is further cross-linked to perform electrolysis. By gelling at least a part of the liquid, the porous film and the electrode are firmly bonded, and the electrode / porous film assembly is formed. Rukoto can.

  In particular, when the reactive polymer-supported porous film is used according to the present invention, the reactive polymer is partially crosslinked in advance, so that the electrode / reactive polymer-supported porous film laminate into the electrolyte solution During immersion, elution and diffusion of the reactive polymer from the electrode / reactive polymer-supported porous film laminate into the electrolyte solution is suppressed, and the reactive polymer swells. As a result, a small amount of the reactive polymer is removed. By using it, an electrode can be adhere | attached on a porous film (separator), and also a porous film is excellent in ion permeability, and functions well as a separator. Further, the reactive polymer is not excessively eluted and diffused in the electrolytic solution, and does not adversely affect the electrolytic solution.

  Furthermore, according to the present invention, the crosslinkable polymer-supported porous film or the reactive polymer-supported porous film supports a lithium salt together with the above polymer. When functioning as an adhesive layer that swells and bonds the electrode and separator, the porous polymer-supporting porous material even if the electrolyte salt or electrolyte ion from the electrolyte solution is insufficiently diffused into the adhesive layer Since the film or the reactive polymer-supported porous film is already loaded with lithium salt, the adhesive layer already has sufficient lithium salt, and therefore the internal resistance in the adhesive layer is low and excellent. A battery having characteristics can be obtained.

  Thus, according to the present invention, an electrode / separator assembly having strong adhesion between the electrode / separator is formed in situ in the battery manufacturing process, and a battery with low internal resistance and excellent high rate characteristics is produced. It can be easily obtained with good quality.

  In the present invention, a porous film having a thickness in the range of 3 to 50 μm is preferably used. 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 porous film has pores having an average pore diameter of 0.01 to 5 μm and a porosity in the range of 20 to 95%, preferably 30 to 90%, most preferably 35. A range of ˜85% is used. 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 porous film must be used. This is not preferable because the internal resistance of the battery increases.

  Further, a porous film having an air permeability of 1500 seconds / 100 cc or less, preferably 1000 seconds / 100 cc or less is used. 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. The strength of the porous film is preferably 1 N or more. This is because when the piercing strength is less than 1 N, the porous film may be broken when a surface pressure is applied between the electrodes, thereby causing an internal short circuit.

  According to the present invention, the porous film is not particularly limited as long as it has the above-described characteristics, but if considering solvent resistance and oxidation-reduction resistance, polyolefin such as polyethylene and polypropylene is used. A porous film made of a resin is preferred. However, among them, when heated, the resin melts and the pores are blocked. As a result, the battery can have a so-called shutdown function. Resin films are 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. According to the present invention, a laminated film of a porous film such as polytetrafluoroethylene or polyimide and the polyolefin resin porous film is also suitably used as a porous film because of its excellent heat resistance.

  According to the present invention, in the first invention, the crosslinkable polymer refers to a polymer that has cationic polymerizability by a reactive group in the molecule and can be cross-linked by this, and the battery separator according to the first invention The crosslinkable polymer-supported porous film for this purpose is formed by supporting such a crosslinkable polymer and a lithium salt on the porous film.

  In particular, according to the present invention, the crosslinkable polymer is preferably a polymer having at least one reactive group selected from an oxetanyl group and an epoxy group (oxiranyl group) in the molecule. The oxetanyl group is preferably a 3-oxetanyl group. The crosslinkable polymer having at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule can be cationically polymerized by the oxetanyl group or the epoxy group, and thus has crosslinkability.

  Furthermore, according to the present invention, such a crosslinkable polymer includes at least one radical polymerizable monomer selected from a radical polymerizable monomer having an oxetanyl group and a radical polymerizable monomer having an epoxy group, and other than these. It is a radical copolymer with the radically polymerizable monomer.

  Such a crosslinkable polymer is preferably at least one radical polymerizable monomer selected from a radical polymerizable monomer having an oxetanyl group and a radical polymerizable monomer having an epoxy group, and other radical polymerizable monomers other than these. And can be obtained by radical copolymerization.

  According to the present invention, when obtaining a crosslinkable polymer having at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule, an oxetanyl group-containing radical polymerizable monomer and / or an epoxy group-containing radical polymerization is obtained. The sex monomer is used in an amount of 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount. Therefore, in the case of obtaining a crosslinkable polymer containing an oxetanyl group, the oxetanyl group-containing radical polymerizable monomer is used in a range of 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount, Similarly, in the case of obtaining a crosslinkable polymer containing an epoxy group, the epoxy group-containing radical polymerizable monomer is used in the range of 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount. .

  Also, when a crosslinkable polymer having both an oxetanyl group and an epoxy group is obtained by using an oxetanyl group-containing radically polymerizable monomer and an epoxy group-containing radically polymerizable monomer in combination with another radically polymerizable monomer In addition, the total amount of the oxetanyl group-containing radical polymerizable monomer and the epoxy 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.

  When obtaining an oxetanyl group-containing crosslinkable polymer or an epoxy group-containing crosslinkable polymer, when the total amount of the oxetanyl group-containing radical polymerizable monomer and the epoxy group-containing radical polymerizable monomer is less than 5% by weight of the total monomer amount, As will be described later, since the amount of the crosslinkable polymer required for gelation of the electrolytic solution is increased, the performance of the obtained battery is deteriorated. 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.

  According to the present invention, the 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 oxetanyl group containing (meth) acrylate represented by these is used.

  Specific examples of such oxetanyl group-containing (meth) acrylates include, for example, 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, and 3-ethyl-3-oxetanylmethyl (meth). Examples thereof include acrylate, 3-butyl-3-oxetanylmethyl (meth) acrylate, 3-hexyl-3-oxetanylmethyl (meth) acrylate, and the like. 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.

  According to the present invention, the other radical polymerizable monomer copolymerized with the oxetanyl group-containing radical polymerizable monomer and / or the 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 or a fluorinated alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 3.)
(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,

(In each formula, R ₅ represents a hydrogen atom or a methyl group, and n is an integer of 0 to 3.)
Etc. In formula, n is an integer of 0-3.

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

  In particular, according to the present invention, as described later, a layer of a crosslinkable polymer is formed on a peelable sheet, and this is transferred onto the porous film without causing deformation, deterioration or melting of the porous film. The crosslinkable polymer preferably has a glass transition temperature of 70 ° C. or lower, and more preferably has a glass transition temperature in the range of 20 to 60 ° C.

  Thus, the crosslinkable polymer having a glass transition point of 70 ° C. or lower is, for example, ethyl as one of the other radical polymerizable monomers contained in the (meth) acrylate represented by the general formula (III). It can be obtained by using acrylate, butyl acrylate, propyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, or the like.

  As described above, the crosslinkable polymer is a radical polymerization of at least one radical polymerizable monomer selected from a radical polymerizable monomer having an oxetanyl group and a radical polymerizable monomer having an epoxy group and another radical polymerizable monomer. It can be obtained by radical copolymerization using an 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.

  Crosslinkable polymers having at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule as described above are described in JP-A Nos. 2001-176555 and 2002-110245. As is already known.

  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 less than 10,000, a large amount of the crosslinkable polymer is required to gel the electrolytic solution, so that the characteristics of the obtained battery are deteriorated. 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, preferably about 2.5 million so that the electrolytic solution can be held as a gel. 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.

  In the present invention, the lithium salt carried by the crosslinkable polymer-supported porous film is a salt containing lithium ions as a cation component and an inorganic acid or an organic acid as an anion component. Examples of the inorganic acid include hydrochloric acid, nitric acid, Examples thereof include phosphoric acid, sulfuric acid, borohydrofluoric acid, hydrofluoric acid, hexafluorophosphoric acid, perchloric acid, and examples of organic acids include organic carboxylic acids, organic sulfonic acids, and fluorine-substituted organic sulfones. An acid etc. can be mentioned.

  Accordingly, specific examples of such lithium salts include, for example, lithium acetate, lithium bromide, lithium chloride, lithium carbonate, lithium fluoride, lithium hydride, lithium hydroxide, lithium iodate, lithium lactate, lithium metaborate, Lithium metasilicate, lithium molybdate, lithium niobate, lithium nitrate, lithium oxalate, lithium phosphate, lithium stearate, lithium sulfate, lithium tetraborate, lithium tetrachloride cuprate, lithium tungstate, lithium perchlorate, Examples thereof include lithium bisfluoroethanesulfonylimide and lithium bis (trifluoromethylsulfonyl) imide. However, in the present invention, the lithium salt is not limited to these.

  In the present invention, the lithium salt is used in the range of 0.1 to 90% by weight, preferably 1 to 70% by weight, and most preferably 10 to 50% by weight, based on the total of the crosslinkable polymer and the lithium salt. It is done.

  According to the present invention, such a lithium salt is supported on a porous film together with the crosslinkable polymer and a crosslinking agent to form a crosslinkable polymer-supported porous film, and an electrode is laminated thereon to form an electrode / crosslinkable property. This is a polymer-supported porous film laminate, which can be used for battery production.

  The means and method for supporting the crosslinkable polymer together with the lithium salt on the porous film are not particularly limited, and examples thereof include the following methods. That is, as one method, the crosslinkable polymer is dissolved together with a lithium salt in an appropriate solvent such as acetone, ethyl acetate, butyl acetate, and a solution of the mixture of the crosslinkable polymer and the lithium salt is cast and sprayed on a porous film. After applying and impregnating by an appropriate means such as application, drying may be performed to remove the solvent used.

  However, one particularly preferred method according to the present invention is to apply a solution comprising a crosslinkable polymer and a lithium salt to the peelable sheet and dry it from the mixture of the crosslinkable polymer and the lithium salt on the peelable sheet. After this layer is formed, this peelable sheet is superimposed on the porous film and heated and pressed to transfer the layer of the mixture of the crosslinkable polymer and the lithium salt to the porous film.

  In particular, according to the present invention, when the crosslinkable polymer is produced, it is described above together with at least one radical polymerizable monomer selected from a radical polymerizable monomer having an oxetanyl group and a radical polymerizable monomer having an epoxy group. Thus, by selecting and using the other radical polymerizable monomers and copolymerizing them, the glass transition temperature of the resulting crosslinkable polymer can be preferably lowered to 70 ° C. or lower, so that By using a crosslinkable polymer, as described above, a layer of a mixture of the crosslinkable polymer and the lithium salt is formed on the releasable sheet, and this layer is at or above the glass transition temperature of the crosslinkable polymer, and The porous film is preferably heated while being heated to a temperature of 100 ° C. or lower so as not to cause deformation or melting of the porous film. If crimped Irumu, without adversely affecting the porous film, it is possible to transfer a layer of a mixture of a crosslinkable polymer and a lithium salt in a porous film.

  As the above-mentioned peelable sheet, a polypropylene resin sheet is typically preferably used, but is not limited thereto. For example, a sheet of polyethylene terephthalate, polyethylene, vinyl chloride, engineer plastic, paper (particularly, resin-impregnated paper) ), Synthetic paper, and laminates thereof. These sheets may be back-treated with a compound such as silicone or long-chain alkyl as necessary.

  Thus, when the layer of the mixture of the crosslinkable polymer and the lithium salt is transferred to the porous film to form the layer of the mixture of the crosslinkable polymer and the lithium salt on the porous film, for example, Unlike when a solution of a mixture of polymer and lithium salt is applied to the surface of the porous film, the mixture of crosslinkable polymer and lithium salt does not penetrate into the pores inside the porous film, and therefore A layer of a mixture of a crosslinkable polymer and a lithium salt can be reliably formed on the surface of the porous film without blocking the pores of the porous film.

In the present invention, the amount of the crosslinkable polymer and lithium salt supported in the porous film is usually in the range of 0.5 to 5 g / m ² , although it depends on the type of crosslinkable polymer and lithium salt used and the mode of support. Preferably, it is the range of 0.8-3 g / m < ² >. When the amount of the crosslinkable polymer and lithium salt supported on the porous film is too small, sufficient adhesive force cannot be obtained between the separator and the electrode in the obtained battery. On the other hand, when the amount is too large, the characteristics of the obtained battery are deteriorated, which is not preferable.

  According to the present invention, in the second invention, the crosslinkable polymer has a reactive group in the molecule, and can react with the crosslinking agent by the reactive group to be crosslinked, and cationic polymerization is performed by the reactive group. Refers to a possible polymer. Therefore, the reactive polymer-supported porous film for a battery separator according to the second aspect of the invention reacts with a crosslinking agent that can be crosslinked by reacting with the crosslinking agent in this way, and is partially crosslinked. The reactive polymer and lithium salt formed are supported on a porous film.

  Here, according to the present invention, the lithium salt is as described above, and such a lithium salt is 0.1 to 90% by weight, preferably 1%, based on the total of the reactive polymer and the lithium salt. It is used in the range of ˜70% by weight, most preferably 10 to 50% by weight. The cross-linking agent is preferably at least one selected from polycarboxylic acids and acid anhydrides.

  A reactive polymer-supported porous film for such a battery separator is obtained by reacting a cross-linkable polymer as described above with a cross-linking agent to partially cross-link it into a reactive polymer, which is combined with the lithium salt. It is made to carry | support to a porous film, it is set as a reactive polymer carrying | support porous film, an electrode is laminated | stacked on this, and it is set as an electrode / reactive polymer carrying | support porous film laminated body, and this can be used for manufacture of a battery.

  For example, as described in JP-A-11-43540 and JP-A-11-116663, a crosslinkable polymer having at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule, It can be crosslinked by reaction with a crosslinking agent comprising a polycarboxylic acid or an acid anhydride and can be cationically polymerized.

  Therefore, according to a preferred embodiment of the present invention, the reactive polymer-supported porous film for a battery separator according to the second aspect of the present invention utilizes such reactivity of oxetanyl group and epoxy group, First, a crosslinkable polymer having at least one reactive group selected from an oxetanyl group and an epoxy group is reacted with the crosslinker with these reactive groups to form a partially crosslinked reactive polymer, This is supported on a porous film to obtain a reactive polymer-supported porous film for a battery separator.

  Thus, in the present invention, the reactive polymer means a polymer obtained by reacting the above-described crosslinkable polymer with a crosslinking agent preferably made of polycarboxylic acid or acid anhydride, and partially crosslinking the reactive polymer. The polymer-supported porous film refers to a film in which such a reactive polymer is supported on a porous film together with the lithium salt.

  In the present invention, the polycarboxylic acid for partially crosslinking the crosslinkable polymer has 2 or more carboxyl groups in the molecule, preferably 2 to 6 in the molecule, particularly preferably in the molecule. It is an organic compound having 2 to 4 carboxyl groups.

  Examples of the dicarboxylic acid having two carboxyl groups in the molecule include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid. C2-C20 straight chain aliphatic saturated dicarboxylic acid such as acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, methylmalonic acid, Branched aliphatic saturated dicarboxylic acids having 3 to 20 carbon atoms such as ethylmalonic acid, n-propylmalonic acid, n-butylmalonic acid, methylsuccinic acid, ethylsuccinic acid, 1,1,3,5-tetramethyloctylsuccinic acid Acid, maleic acid, fumaric acid, citraconic acid, γ-methylcitraconic acid, mesaconic acid, γ-methylmesaconic acid, Linear or branched aliphatic unsaturated dicarboxylic acids such as itaconic acid and glutaconic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, methylhexahydroxyphthalic acid, methylhexaisophthalic acid, methylhexahydroterephthalic acid , Cyclohexene-1,2-dicarboxylic acid, cyclohexene-1,6-dicarboxylic acid, cyclohexene-3,4-dicarboxylic acid, cyclohexene-4,5-dicarboxylic acid, etc. tetrahydrophthalic acid, cyclohexene-1,3-dicarboxylic acid Tetrahydroisophthalic acid such as cyclohexene-1,5-dicarboxylic acid and cyclohexene-3,5-dicarboxylic acid, tetrahydroterephthalic acid such as cyclohexene-1,4-dicarboxylic acid and cyclohexene-3,6-dicarboxylic acid, 1,3 -Siku Hexadiene-1,2-dicarboxylic acid, 1,3-cyclohexadiene-1,6-dicarboxylic acid, 1,3-cyclohexadiene-2,3-dicarboxylic acid, 1,3-cyclohexadiene-5,6-dicarboxylic acid 1,4-cyclohexadiene-1,2-dicarboxylic acid, dihydrophthalic acid such as 1,4-cyclohexadiene-1,6-dicarboxylic acid, 1,3-cyclohexadiene-1,3-dicarboxylic acid, Dihydroisophthalic acid such as 3-cyclohexadiene-3,5-dicarboxylic acid, 1,3-cyclohexadiene-1,4-dicarboxylic acid, 1,3-cyclohexadiene-2,5-dicarboxylic acid, 1,4-cyclo Dihydroterephthalic acid such as hexadiene-1,4-dicarboxylic acid, 1,4-cyclohexadiene-3,6-dicarboxylic acid, methyl tet Hydrophthalic acid, endomethylenetetrahydrophthalic acid, endocis-bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid, methyl-endocis-bicyclo [2.2.1] hept-5-ene- Saturated or unsaturated carboxylic acid such as 2,3-dicarboxylic acid, chlorendic acid, phthalic acid, terephthalic acid, isophthalic acid, 3-methylphthalic acid, 3-ethylphthalic acid, 3-n-propylphthalic acid, 3-isopropyl 3-alkylphthalic acid such as phthalic acid, 3-n-butylphthalic acid, 3-isobutylphthalic acid, 3-s-butylphthalic acid, 3-t-butylphthalic acid, 2-methylphthalic acid, 4-ethylphthalic acid, 4-n -Propylphthalic acid, 4-isopropylpyrphthalic acid, 4-n-butylphthalic acid, 4-isobutylphthalic acid, 4-s-butylphthalic acid Acid, 4-alkylphthalic acid such as 4-t-butylphthalic acid, 2-methylisophthalic acid, 2-ethylisophthalic acid, 2-n-propylphthalic acid, 2-isopropylpropylphthalic acid, 2-n-butylphthalic acid 2-alkylphthalic acid such as 2-isobutylphthalic acid, 2-s-butylphthalic acid, 2-t-butylphthalic acid, 4-methylisophthalic acid, 4-ethylisophthalic acid, 4-n-propylisophthalic acid, 4- 4-alkylisophthalic acid such as isopropylpyrophthalic acid, 4-n-butylisophthalic acid, 4-isobutylisophthalic acid, 4-s-butylisophthalic acid, 4-t-butylisophthalic acid, 5-methylisophthalic acid, 5 -Ethylisophthalic acid, 5-n-propylisophthalic acid, 5-isopropyl-isophthalic acid, 5-n-butylisophthalic acid, 5-isobu 5-alkylisophthalic acid such as ruisophthalic acid, 5-s-butylisophthalic acid, 5-t-butylisophthalic acid, methyl terephthalic acid, ethyl terephthalic acid, n-propyl terephthalic acid, isopropyl terephthalic acid, n-butyl terephthalic acid Acid, isobutyl terephthalic acid, s-butyl terephthalic acid, alkyl terephthalic acid such as t-butyl terephthalic acid, naphthalene-1,2-dicarboxylic acid, naphthalene-1,3-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, Naphthalene-1,5-dicarboxylic acid, naphthalene-1,6-dicarboxylic acid, naphthalene-1,7-dicarboxylic acid, naphthalene-1,8-dicarboxylic acid, naphthalene-2,3-dicarboxylic acid, naphthalene-2,6 -Dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, anthracene 1,3-dicarboxylic acid, anthracene-1,4-dicarboxylic acid, anthracene-1,5-dicarboxylic acid, anthracene-1,9-dicarboxylic acid, anthracene-2,3-dicarboxylic acid, anthracene-9,10-dicarboxylic acid Specific examples include aromatic dicarboxylic acids such as acids, 2,2′-bis (carboxychiphenyl) hexafluoropropane, and the like.

  Examples of the polycarboxylic acid having three or more carboxyl groups in the molecule include aliphatic tricarboxylic acids such as tricarballylic acid, citric acid, isocitric acid and aconitic acid, aromatic tricarboxylic acids such as hemimellitic acid and trimellitic acid, C4-C13 aliphatic tetracarboxylic acid such as 2,3,4-butanetetracarboxylic acid, alicyclic tetracarboxylic acid such as maleated methylcyclohexene tetracarboxylic acid, merophanic acid, planitic acid, pyromellitic acid, Specific examples include aromatic tetracarboxylic acids such as benzophenone tetracarboxylic acid, hexahydromellitic acid, benzenepentacarboxylic acid, and mellitic acid.

  In the present invention, a polyol ester of a polycarboxylic acid and a polyol as described above, preferably a diol ester of a dicarboxylic acid and a diol, particularly a (poly) alkylene glycol or polymethylene diol, is also used as the polycarboxylic acid. be able to. Examples of such diol esters include ethylene glycol didipate.

  Furthermore, in the present invention, the polycarboxylic acid may be a polymer carboxylic acid having a plurality of carboxyl groups in the molecule. Examples of such a polymer carboxylic acid include a copolymer of (meth) acrylic acid and (meth) acrylic acid ester.

  In the present invention, a polyol ester of a polycarboxylic acid and a polyol as described above, preferably a diol ester of a dicarboxylic acid and a diol, particularly a (poly) alkylene glycol or polymethylene diol, is also used as the polycarboxylic acid. be able to. Examples of such diol esters include ethylene glycol didipate.

  In the present invention, the acid anhydride for partially crosslinking the crosslinkable polymer is represented by 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, as monofunctional acid anhydrides where n is 1, for example, malonic anhydride, succinic anhydride, dodecyl succinic anhydride, maleic anhydride, glutaric anhydride, α , Α'-diethylglutaric anhydride, citraconic anhydride, itaconic anhydride, glutaconic anhydride, diglycolic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, Endocis-bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid anhydride (trade name nadic anhydride), methyl-endocis-bicyclo [2.2.1] hept-5-ene- 2,3-dicarboxylic acid anhydride (trade name: methylnadic anhydride), endomethylenetetrahydrophthalic anhydride, methylendomethylene Examples thereof include tetrahydrophthalic anhydride, chlorendic anhydride, phthalic anhydride, nitrophthalic anhydride, diphenic anhydride, and naphthalic anhydride.

  Among the acid anhydrides represented by the above general formula, as bifunctional acid anhydrides where n is 2, for example, pyromellitic anhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, Examples thereof include ethylene glycol bis (anhydrotrimate), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, and the like. 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.

  Furthermore, examples of the acid anhydride having a free carboxyl group include β, γ-aconitic anhydride, glycolic anhydride, trimellitic anhydride, polyazeline acid anhydride, and the like.

  A reactive polymer-supported porous film for a battery separator according to a second invention is obtained by reacting the crosslinkable polymer with a crosslinking agent comprising a polycarboxylic acid or an acid anhydride as described above, and partially crosslinking the polymer. Thus, a reactive polymer is formed and supported on a porous film.

  The means and method for supporting such a reactive polymer together with a lithium salt on a porous film are not particularly limited. For example, as described above, a crosslinkable polymer and a lithium salt are porous together with a crosslinking agent. After having been supported on a porous film, the crosslinkable polymer is reacted with a cross-linking agent and partially crosslinked to obtain a reactive polymer and a porous film carrying the lithium salt. it can.

  Therefore, in order to support the crosslinkable polymer and the lithium salt on the porous film together with the crosslinker, for example, the crosslinkable polymer, the lithium salt and the crosslinker are dissolved in an appropriate solvent such as acetone, ethyl acetate or butyl acetate. The solution of the mixture of the crosslinkable polymer, the lithium salt and the crosslinking agent is applied and impregnated on the porous film by an appropriate means such as casting or spray coating, and then dried to remove the solvent used. That's fine. As described above, if necessary, an onium salt may be supported on a porous film as a catalyst together with a mixture of a crosslinkable polymer, a lithium salt, and a crosslinking agent. As such an onium salt, those described later can be used.

  As another method, a solution containing a crosslinkable polymer and a lithium salt is applied to a porous film and dried, and then a solution of a crosslinking agent is applied to such a porous film, impregnated, and dried. Also, a mixture of a crosslinkable polymer, a lithium salt, and a crosslinking agent can be supported on the porous film.

  However, one particularly preferred method according to the present invention is to apply a solution comprising a crosslinkable polymer, a lithium salt and a crosslinker to the peelable sheet, and then dry and crosslink the crosslinkable polymer, the lithium salt and the crosslinkable sheet on the peelable sheet. After forming a layer composed of a mixture with an agent, a peelable sheet is superimposed on the porous film and heated and pressed to transfer the layer composed of a mixture of a crosslinkable polymer, a lithium salt and a crosslinking agent to the porous film. is there.

  In particular, according to the present invention, as described above, by using a crosslinkable polymer having a glass transition temperature of preferably 70 ° C. or lower, the mixture of the crosslinkable polymer, the lithium salt, and the crosslinker on the peelable sheet. A layer is formed, and the layer is heated while being heated to a temperature of 100 ° C. or lower, preferably at a temperature not lower than the glass transition temperature of the crosslinkable polymer and not deforming or melting the porous film. By pressure bonding to the film, the layer of the mixture of the crosslinkable polymer, the lithium salt and the crosslinking agent can be transferred to the porous film without adversely affecting the porous film.

  As described above, the layer of the mixture of the crosslinkable polymer, the lithium salt, and the crosslinker is thus transferred to the porous film, and the mixture of the crosslinkable polymer, the lithium salt, and the crosslinker is formed on the porous film. When forming a layer, for example, unlike the case where a solution of a mixture of a crosslinkable polymer, a lithium salt, and a crosslinker is applied to the surface of the porous film, the crosslinkable polymer is placed in the pores inside the porous film. A layer of a mixture of a crosslinkable polymer, a lithium salt and a crosslinking agent on the surface of the porous film without intruding the mixture of the lithium film and the lithium salt and the crosslinking agent, and thus without blocking the pores of the porous film. It can be reliably formed.

  In this way, after the crosslinkable polymer, the lithium salt, and the crosslinker are supported on the porous film, the crosslinkable polymer is reacted with the crosslinker by heating to an appropriate temperature and partially crosslinked. A reactive polymer-supported porous film containing a lithium salt can be obtained.

  Furthermore, as another method, after preparing a solution containing a crosslinkable polymer, a lithium salt, and a crosslinker, the crosslinkable polymer is reacted with a crosslinker in advance and partially crosslinked to obtain a reactive polymer. The solution containing the reactive polymer may be applied to an appropriate peelable sheet, dried, and then transferred to a porous film.

  According to the present invention, the reactive polymer obtained by partially crosslinking the crosslinkable polymer in this way usually has an insoluble fraction in the range of 1 to 90%, preferably 3 to 75%. And most preferably has an insoluble fraction in the range of 10 to 65%. Here, the insoluble fraction is, as will be described later, 2 with stirring a porous film carrying a partially crosslinked reactive polymer in an ethylene carbonate / diethyl carbonate (volume ratio 1/1) mixed solvent at room temperature. It refers to the ratio of the reactive polymer remaining on the porous film when immersed in ethyl methyl carbonate after being immersed for a period of time.

  Thus, although it is not limited to reacting a crosslinkable polymer with a crosslinking agent and partially crosslinking to obtain a reactive polymer having an insoluble fraction in the range of 1 to 90%, usually, The carboxyl group of the polycarboxylic acid or acid anhydride is 0.01 to 1.0 mole part, preferably 0.05 to 0.8 mole part, based on 1 mole part of the reactive group of the crosslinkable polymer. Particularly preferably, it is used so as to be 0.1 to 0.7 mol part, and the heating reaction condition between the crosslinkable polymer and the crosslinking agent may be adjusted, and thus has a desired insoluble fraction. A reactive polymer can be obtained.

  As an example, with respect to 1 mol part of the reactive group of the crosslinkable polymer, the carboxyl group of the polycarboxylic acid or acid anhydride is used so as to be 0.5 to 1.0 mol part, A reactive polymer having an insoluble fraction of 1 to 90% can be obtained by heating and reacting with an acid anhydride at 50 ° C. for 10 to 500 hours.

  In the present invention, it is preferable that the crosslinkable polymer or the reactive polymer is supported on the entire surface of the porous film. However, in some cases, the porous film is partially on the porous film, that is, for example, streaks, spots, It may be partially supported in a lattice shape, a stripe shape, a turtle shell shape, or the like.

  According to the present invention, the crosslinkable polymer-supported porous film according to the first invention is laminated with the positive electrode and the negative electrode sandwiched therebetween, and preferably, pressurizing and pressurizing under heating to bond the positive electrode and the negative electrode. An electrode / crosslinkable polymer-supported porous film laminate can be obtained by temporarily adhering to and bonding to the crosslinkable polymer-supporting porous film.

  Similarly, a positive electrode and a negative electrode are laminated on the reactive polymer-supporting porous film according to the second invention, and the positive electrode and the negative electrode are preferably pressed under pressure and pressure-bonded to form a reactive polymer. An electrode / reactive polymer-supported porous film laminate can be obtained by temporarily adhering to and bonding to the supported porous film.

  Hereinafter, for the sake of simplicity, the electrode / crosslinkable polymer-supported porous film laminate or the electrode / reactive polymer-supported porous film laminate may be simply referred to as an electrode / porous film laminate.

  In the present invention, the electrode, that is, the negative electrode and the positive electrode differ depending on the battery, but in general, a sheet in which an active material and, if necessary, a conductive agent are supported on a conductive base material using a resin binder. The shape is used. Therefore, in the present invention, the negative electrode and the positive electrode are sometimes referred to as a negative electrode sheet or a positive electrode sheet.

  In the present invention, the electrode / porous film laminate may have an electrode laminated on a crosslinkable polymer-supported porous film or a reactive polymer-supported porous film. Therefore, for example, a negative electrode / porous film / positive electrode, a negative electrode / porous film / positive electrode / porous film, etc. are used as the electrode / porous film laminate according to the structure and form of the battery. The electrode / porous film laminate may be in the form of a sheet or may be wound.

  The crosslinkable polymer-supported porous film or the reactive polymer-supported porous film according to the present invention can be suitably used for battery production.

  First, the production of a battery using the crosslinkable polymer-supported porous film as the first invention will be described. An electrode is laminated on a crosslinkable polymer-supported porous film or rolled to obtain an electrode / crosslinkable polymer-supported porous film laminate, and this laminate is then placed in a battery container made of a metal can, a laminate film, or the like. When charging, terminal welding, etc. are required, a predetermined amount of an electrolytic solution in which a cationic polymerization catalyst is dissolved is injected into the battery container, and the battery container is sealed and sealed to form a crosslinkable polymer. Cationic polymerization of the crosslinkable polymer supported on the supported porous film by at least partially swelling the electrolyte in the vicinity of the interface between the porous film and the electrode, or elution and diffusion in the electrolyte. And at least a part of the electrolyte solution is gelled, and the electrode is adhered to the porous film. Thus, the porous film is used as a separator, and the electrode is attached to the separator. It can be obtained glued battery to a solid.

  In the production of a battery using a crosslinkable polymer-supported porous film, the crosslinkable polymer supported on the porous film is used as it is as an adhesive, so to speak, the electrode is temporarily bonded to the separator, and finally In other words, the crosslinkable polymer gels the electrolyte solution at least in the vicinity of the interface between the porous film and the electrode by crosslinking of the reactive group by cationic polymerization, so that the electrode and the porous film are, This is the final bond.

  Next, when the reactive polymer-supported porous film as the second invention is used, the electrode is laminated on the reactive polymer-supported porous film, or wound, and the electrode / reactive polymer-supported porous film is laminated. Then, this laminate is placed in a battery container made of a metal can, a laminate film, etc., and if necessary, welding of the terminal is performed, and then the cationic polymerization catalyst is dissolved in the battery container. A predetermined amount of the electrolyte is injected, the battery container is sealed and sealed, and the reactive polymer supported on the reactive polymer-supported porous film is at least one in the vicinity of the interface between the porous film and the electrode. The part is swollen in the electrolytic solution, or eluted and diffused in the electrolytic solution, crosslinked by cationic polymerization, and at least a part of the electrolytic solution is gelled, so that the electrode is a porous film. Bonded, thus, the porous film as a separator, the electrode of this separator can be obtained strongly adhered cells.

  Again, the reactive polymer functions in the same manner as the crosslinkable polymer. That is, the reactive polymer supported on the porous film is used as it is as an adhesive, so to speak, the electrode is temporarily attached to the separator, and finally, the reactive polymer is the remaining reactive polymer. The electrolyte solution is gelled at least in the vicinity of the interface between the porous film and the electrode by crosslinking of the group by cationic polymerization, and the electrode and the porous film are so-called bonded.

  However, compared with the case of manufacturing a battery using a crosslinkable polymer-supported porous film, the manufacture of a battery using a reactive polymer-supported porous film has a structural characteristic in which the reactive polymer is partially crosslinked. Based on the advantages. That is, the reactive polymer is obtained by reacting the crosslinkable polymer with the crosslinking agent in advance and partially cross-linking it to have an insoluble content within the above-described range. Elution and diffusion into the inside are suppressed. Therefore, if an electrode / porous film laminate containing such a reactive polymer is charged into a battery container and then an electrolyte containing an electrolyte containing a cationic polymerization catalyst is injected into the battery container, the porous film and electrode In the vicinity of the interface, only a part of the reactive polymer in the electrode / porous film laminate swells in the electrolytic solution or elutes into the electrolytic solution and is not used for partial cross-linking with the cross-linking agent. Due to the remaining reactive groups, the reactive polymer is cationically polymerized by an electrolyte that also serves as a cationic polymerization catalyst in the electrolytic solution, and preferably also serves as a cationic polymerization catalyst. Thus, it is possible to obtain an electrode / porous film (ie, separator in a battery to be obtained) bonded body.

  That is, according to the present invention, the reactive polymer has an insoluble fraction within the above range. Therefore, even when immersed in the electrolytic solution, elution and diffusion into the electrolytic solution are prevented or reduced. Since it is effectively used for adhesion between the electrode and the porous film, the use of a relatively small amount of the reactive polymer makes it possible to bond the electrode and the porous film stably and more firmly.

  In the present invention, the crosslinkable polymer or the reactive polymer carried by the porous film depends on its structure, the amount carried on the porous film, and the type and amount of the cationic polymerization catalyst. It can also be crosslinked, but cationic polymerization can be promoted by heating. 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 24 hours. In addition, in order to swell, elute or diffuse an amount of polymer sufficient to adhere the electrode to the porous film, the electrolyte may be poured into the battery container and then left at room temperature for several hours.

  According to the present invention, in the battery obtained, the adhesive force obtained between the electrode and the separator (porous film) is usually 0.03 N / cm, although it depends on the heat shrinkage characteristics of the porous film used. It is above, Preferably, it is 0.05 N / cm or more. When this adhesive force is too low, the separator may be thermally contracted, or the separator may be inferior in the function of keeping the distance between the electrodes constant. Further, the above-mentioned adhesive force is not particularly limited at the upper limit for the purpose of the present invention, but in order to increase the adhesive force, it is necessary to increase the amount of the adhesive used, and this As described above, when the amount of the adhesive to be used is increased, the characteristics of the obtained battery may be deteriorated. Therefore, in view of the thermal characteristics of the porous film used for the battery separator and the function of the separator to keep the distance between the electrodes constant, the adhesive force is preferably 1.0 N / cm or less.

  The porous film in the electrode / porous film assembly thus obtained functions as a separator after being incorporated into a battery. Here, in such an electrode / porous film assembly according to the present invention, since the electrode and the porous film are firmly bonded as described above, the separator (porous film) is, for example, 150. Even when placed in a high temperature environment such as ° C., the area heat shrinkage rate is small, usually 20% or less, and preferably 15% or less.

  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, alkaline earth metals such as calcium and strontium, tertiary or quaternary ammonium salts, and the like as cationic 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 trifluoroacetate such as lithium trifluoroacetate Mention may be made of metals and alkali metals of trifluoromethane sulfonate such as lithium trifluoromethane sulfonate.

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

  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 gel electrolyte obtained.

  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 above-described electrolyte salts, 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.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following, the physical properties and battery characteristics of the substrate porous film 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− (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 cm / second.

(Insoluble fraction of reactive polymer)
The reactive polymer-supported porous film supporting a known amount A of the reactive polymer was weighed and its weight B was measured. Next, this reactive polymer-supported porous film was immersed in a mixed solvent of ethylene carbonate / diethyl carbonate (1/1 volume ratio) at room temperature for 2 hours, then immersed in ethyl methyl carbonate, washed, and air-dried. Then, the reactive polymer carrying | support porous film processed in this way was weighed, and the weight C was measured. The insoluble fraction of the reactive polymer was calculated by the following formula.

              Insoluble fraction (%) = ((A− (BC)) / A) × 100

(Glass transition temperature of crosslinkable polymer)
The glass transition temperature of the crosslinkable polymer was measured as follows. After the solution of the crosslinkable polymer was cast on a release paper and dried, a sheet having a thickness of 0.2 to 0.5 mm and a width of 5 mm was obtained. The sheet was made a distance of 10 mm between chucks, and manufactured by Seiko Electronics Industry Co., Ltd. Using DMS120, the glass transition temperature was determined at 10 kHz in bending mode. The glass transition temperature was determined from the peak temperature of tan δ at a temperature increase rate of 5 ° C./min and a temperature range of 20 to 200 ° C.

(Measurement of area heat shrinkage of separator (porous film) / electrode assembly)
Preparation of reference battery, positive electrode / porous film / negative electrode laminate obtained in each example or each comparative example was punched to a predetermined size, and lithium hexafluorophosphate was dissolved in this at a concentration of 1.0 mol / L A sample was impregnated with an electrolytic solution composed of a mixed solvent of ethylene carbonate / diethyl carbonate (weight ratio 1/1).

As shown in FIG. 1, a container in which an O-ring 3 is fitted to an annular upper end surface 2 of a peripheral wall of a SUS circular container 1 is prepared, the sample 4 is placed on the bottom of the container, and 9 g / The weight 5 was placed so as to give a surface pressure of m ² , and then the lid 6 was put on the container to seal the inside of the container. Thus, after putting the container containing the sample into a dryer at 150 ° C. for 1 hour, it is allowed to cool, the sample is taken out from the container, the sample separator (porous film) is peeled off from the positive and negative electrodes, and read by the scanner. Thus, the area heat shrinkage rate was determined in comparison with the area of the porous film used first.

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 a vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.) was mixed, and this was mixed with a slurry using N-methyl-2-pyrrolidone so that the solid concentration was 15% by weight. did. The slurry was applied to an aluminum foil (current collector) having a thickness of 20 μm to a thickness of 200 μm, vacuum-dried at 80 ° C. for 1 hour, and 120 ° C. for 2 hours, and then pressed by a roll press to obtain a thickness of the active material layer. A positive electrode sheet having a thickness of 100 μm 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 Is mixed with 10 parts by weight of vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.), and N-methyl-2-pyrrolidone is used so that the solid content concentration becomes 15% by weight. A slurry was obtained. This slurry was applied onto a copper foil (current collector) having a thickness of 20 μm, applied to a thickness of 200 μm, dried at 80 ° C. for 1 hour, dried at 120 ° C. for 2 hours, and then pressed with a roll press, A negative electrode sheet having an active material layer thickness of 100 μm was prepared.

(Production of reference battery)
A porous film (separator) made of polyethylene resin having a thickness of 16 μm, a porosity of 40%, an air permeability of 300 seconds / 100 cc, and a puncture strength of 3.0 N was prepared. The negative electrode sheet obtained in Reference Example 1, the porous film, and the positive electrode sheet obtained in Reference Example 1 were laminated in this order to obtain a positive electrode / porous film / negative electrode laminate. After charging this into an aluminum laminate package, an electrolytic solution made of an ethylene carbonate / diethyl carbonate (weight ratio 1/1) mixed solvent in which lithium hexafluorophosphate was dissolved at a concentration of 1.0 mol / L was injected into the package. Then, the package was sealed and a lithium ion secondary battery was assembled. The battery was charged and discharged three times at a rate of 0.1 CmA, then charged at 0.1 CmA, and then discharged at 5 CmA to obtain a 5 CmA discharge capacity A. Further, the area heat shrinkage rate of the separator in the positive electrode / porous film / negative electrode laminate was 72%.

(Discharge characteristics of batteries according to examples or comparative examples)
About the laminate seal type lithium ion secondary battery obtained in the following examples or comparative examples, after charging and discharging three times at a rate of 0.1 CmA, charging at 0.1 CmA, and thereafter at 5 CmA The battery was discharged to obtain a 5 CmA discharge capacity B, and the battery characteristics were evaluated by the percentage (%) of the discharge capacity B to the discharge capacity A of the reference battery.

(Measurement of adhesion between electrode sheet and separator)
The obtained battery is disassembled before charging / discharging, the positive electrode / separator / negative electrode assembly is taken out, the negative electrode / separator interface is peeled over 5 mm from the end of this assembly, and this is sandwiched between chucks of a tensile tester. Thereafter, the chuck was moved in the 180 ° direction at a speed of 1 mm / min to measure the adhesive force, and this was divided by the sample width (cm) to obtain the negative electrode / separator adhesive force (N / cm). Next, the interface between the positive electrode and the separator was peeled over 5 mm from the end of the joined body, and the positive electrode / separator adhesive force (N / cm) was determined in the same manner as in the case of the negative electrode.

Production Example 1
(Production of Oxetanyl Group-Containing Crosslinkable Polymer A (Oxetanyl Group-Containing Monomer Component 25% by Weight, Weight Average Molecular Weight 518000))
In a 500 mL three-necked flask equipped with a reflux condenser, 60.0 g of methyl methacrylate, 20.0 g of 3-ethyl-3-oxetanylmethyl methacrylate, 158.0 g of ethyl acetate and N, N′-azobisisobutyronitrile After introducing 0.16 g and stirring and mixing for 30 minutes while introducing nitrogen gas, radical polymerization was started at 60 ° C. When about 2 hours had elapsed, the viscosity of the reaction mixture began to increase, and polymerization was continued for another 8 hours. Thereafter, the mixture was cooled to about 10 ° C., 0.16 g of N, N′-azobisisobutyronitrile was added again, and then heated again to 70 ° C. for polymerization for 8 hours.

  After completion of the reaction, the reaction mixture is cooled to about 40 ° C., 295 g of ethyl acetate is added, and the mixture is stirred and mixed until the whole becomes uniform to obtain an ethyl acetate solution of the oxetanyl group-containing crosslinkable polymer A (concentration: 15% by weight). It was.

  Next, the solution of the crosslinkable polymer A was poured into 600 mL of methanol while stirring with a high speed mixer to precipitate the polymer. The polymer was separated by filtration, and after washing with methanol several times, dried nitrogen gas (dew point temperature of −150 ° C. or lower) in which liquid nitrogen was vaporized was circulated in a drying tube and dried. It was vacuum-dried in a desiccator for 6 hours to obtain a white powdery oxetanyl group-containing crosslinkable polymer A. As a result of molecular weight measurement by GPC, the weight average molecular weight was 518,000, and the number average molecular weight was 231,000. The glass transition temperature was 116 ° C.

Production Example 2
(Production of epoxy group-containing crosslinkable polymer B (epoxy group-containing monomer component 25% by weight, weight average molecular weight 466000))
In the same manner as in Production Example 1, 60.0 g of methyl methacrylate, 20.0 g of 3,4-epoxycyclohexylmethyl acrylate, 158.0 g of ethyl acetate, and N, N′— were added to a 500 mL three-necked flask equipped with a reflux condenser. After charging 0.32 g of azobisisobutyronitrile and stirring and mixing for 30 minutes while introducing nitrogen gas, the mixture was heated to 70 ° C. to initiate radical polymerization. When about 1 hour had passed, the viscosity of the reaction mixture began to rise and polymerization was continued for another 8 hours. Thereafter, the resulting reaction mixture was cooled to 40 ° C., 0.32 g of N, N′-azobisisobutyronitrile was added again, and then reheated to 70 ° C. to further carry out radical polymerization for 8 hours. went.

  After completion of the reaction, the obtained reaction mixture was cooled to 40 ° C., 162 g of ethyl acetate was added, and the mixture was stirred and mixed until the whole became homogeneous, and an ethyl acetate solution of epoxy group-containing crosslinkable polymer B (concentration 15 wt%). Got.

  Thereafter, in the same manner as in Production Example 1, a polymer was precipitated from this polymer solution, filtered, washed several times, and dried to obtain a white powdery epoxy group-containing crosslinkable polymer B. . As a result of molecular weight measurement by GPC, the weight average molecular weight was 466000, and the number average molecular weight was 228,000. The glass transition temperature was 120 ° C.

Production Example 3
(Production of crosslinkable polymer C (3,4-epoxycyclohexylmethyl methacrylate monomer component 5 wt%, oxetanyl group-containing monomer component 20 wt% and methyl methacrylate monomer component 75 wt%))
In a 500 mL three-necked flask equipped with a reflux condenser, 60.0 g of methyl methacrylate, 16.0 g of 3-ethyl-3-oxetanylmethyl methacrylate, 4.0 g of 3,4-epoxycyclohexylmethyl methacrylate, 226.6 g of ethylene carbonate Then, 0.15 g of N, N′-azobisisobutyronitrile was charged, and the mixture was stirred and mixed for 30 minutes while introducing nitrogen gas, and then heated to 70 ° C. to carry out radical polymerization for 8 hours. After this, the resulting reaction mixture was cooled to 40 ° C. To this reaction mixture, 226.6 g of diethyl carbonate and 0.15 g of N, N′-azobisisobutyronitrile were added, and the mixture was heated again to 70 ° C., and radical polymerization was further performed for 8 hours. Thereafter, the obtained reaction mixture was cooled to 40 ° C. to obtain an ethylene carbonate / diethyl carbonate mixed solvent solution (concentration: 15% by weight) of the crosslinkable polymer C.

  Next, 100 g of this polymer solution was added to 600 mL methanol while stirring with a high-speed mixer to precipitate the polymer. The polymer was filtered off, washed several times with methanol, put in a drying tube, dried by circulating dry nitrogen gas (dew point temperature of −150 ° C. or lower) in which liquid nitrogen was vaporized. Then, it was vacuum-dried in a desiccator for 6 hours to obtain a crosslinkable polymer C. The crosslinkable polymer C thus obtained was a pure white powder. As a result of molecular weight measurement by GPC, the weight average molecular weight was 344400 and the number average molecular weight was 174500. The glass transition temperature was 116 ° C.

Production Example 4
(Production of crosslinkable polymer D (25% by weight of oxetanyl group-containing monomer component, 50% by weight of methyl methacrylate monomer component and 25% by weight of n-butyl acrylate monomer component, weight average molecular weight 224200))
Partially saponified polyvinyl alcohol (polymerization degree 2000, saponification degree 78-87 mol%) 0.05 g, fully saponified polyvinyl alcohol (polymerization degree 2000, saponification degree) in a 500 mL three-necked flask equipped with a reflux condenser. 98.5 to 99.4 mol%) and 2.5 g of ion-exchanged water were charged, and while stirring, nitrogen gas was introduced and the temperature was raised to 95 ° C. to dissolve the polyvinyl alcohol in water. . After confirming that the polyvinyl alcohol was completely dissolved, it was cooled to about 30 ° C.

  Next, 50.0 g of methyl methacrylate, 25.0 g of 3-ethyl-3-oxetanylmethyl methacrylate, 25.0 g of n-butyl methacrylate, 0.4 g of N, N′-azobisisobutyronitrile and 1.0 g were added to the flask. 6.0 g of a diethyl carbonate solution of n-dodecanethiol having a concentration of% by weight was charged, stirred and mixed for 30 minutes while introducing nitrogen gas, and then heated to 70 ° C. to carry out radical suspension polymerization for 5 hours. Thereafter, the obtained reaction mixture is filtered using a 500 mesh filter screen, washed with water, returned to a 500 mL three-necked flask, added with 300 mL of ion-exchanged water, and heated to 95 ° C. with stirring. Warm and hot water wash to remove residual polyvinyl alcohol. Next, after filtering, washing with water using a 500 mesh filter screen, repeating hot water washing and water washing again, washing with methanol to remove residual moisture, vacuum drying at room temperature, and crosslinking ability Polymer D was obtained.

  The crosslinkable polymer D thus obtained was a pure white powder. As a result of molecular weight measurement by GPC, the weight average molecular weight was 224200, and the number average molecular weight was 79800. The glass transition temperature was 41 ° C.

Example 1
10 g of the crosslinkable polymer A was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer A / lithium salt mixture was prepared. This coating solution was applied to both front and back surfaces of a polyethylene resin porous film (thickness 16 μm, porosity 40%, air permeability 300 seconds / 100 cc, puncture strength 3.0 N) using a # 8 wire bar, and then acetic acid. Ethyl was stripped, and thus a crosslinkable polymer-supported porous film was obtained. In this crosslinkable polymer-supported porous film, the thickness of the crosslinkable polymer / lithium salt mixture layer per side of the film is 2.5 μm, and the amount of the crosslinkable polymer / lithium salt mixture supported is 2.0 g / m ^2. Met.

  The negative electrode sheet obtained in Reference Example 1, the crosslinkable polymer-supported porous film and the positive electrode sheet obtained in Reference Example 1 were laminated in this order to obtain an electrode / crosslinkable polymer-supported porous film laminate. Was injected into an aluminum laminate package, and an electrolyte solution consisting of ethylene carbonate / diethyl carbonate (weight ratio 1/1) mixed solvent in which lithium hexafluorophosphate was dissolved at a concentration of 1.0 mol / L was injected. Sealed. After that, by heating at 70 ° C. for 7 hours, the crosslinkable polymer is cationically polymerized, crosslinked, the electrode sheet is brought into contact with the porous film (separator), and the electrolyte is partially gelled, A laminate seal type battery was obtained.

  The 5 CmA discharge capacity of this battery was 95% of the discharge capacity of the reference battery, and the adhesive force between the electrode sheet and the separator was 0.19 N / cm for the positive electrode and 0.02 N / cm for the negative electrode. Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained by using the crosslinkable polymer-supported porous film was 5.0%.

Example 2
In Example 1, the crosslinkability of the crosslinkable polymer / lithium salt mixture carrying amount of 2.1 g / m ² per one side of the film was the same except that the crosslinkable polymer B was used instead of the crosslinkable polymer A. A polymer-supported porous film was obtained, and using this, a laminate seal type battery was obtained in the same manner as in Example 1. The 5 CmA discharge capacity of this battery was 92% of the discharge capacity of the reference battery, and the adhesive force between the electrode sheet and the separator was 0.27 N / cm for the positive electrode and 0.03 N / cm for the negative electrode. Further, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the above crosslinkable polymer-supported porous film was 4.0%.

Example 3
10 g of the crosslinkable polymer B was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added, and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer B / lithium salt mixture was prepared. Separately, an ethanolic solution of adipic acid having a concentration of 10% by weight was prepared. While stirring the coating solution, the adipic acid solution was slowly added dropwise thereto to prepare a solution of the crosslinkable polymer B / lithium salt / adipic acid mixture. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

The solution of this crosslinkable polymer / lithium salt / adipic acid mixture was applied to both sides of a polyethylene resin porous film (film thickness 16 μm, porosity 40%, air permeability 300 seconds / 100 cc, puncture strength 3.0 N). After coating with a wire bar, the mixture is heated to 50 ° C. to volatilize ethyl acetate and ethanol in the mixed solution, and thus the crosslinkable polymer / lithium salt / adipic acid mixture is applied to one side of the polyethylene resin porous film. A crosslinkable polymer-supported porous film supported at a coating density of 2.2 g / m ² was obtained.

  Next, the crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 12 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 30%.

  The negative electrode sheet obtained in Reference Example 1, the reactive polymer-supported porous film and the positive electrode sheet obtained in Reference Example 1 were laminated in this order to obtain an electrode / reactive polymer-supported porous film laminate. Was injected into an aluminum laminate package, and an electrolyte solution consisting of ethylene carbonate / diethyl carbonate (weight ratio 1/1) mixed solvent in which lithium hexafluorophosphate was dissolved at a concentration of 1.0 mol / L was injected. Sealed. After that, by heating at 70 ° C. for 7 hours, the reactive polymer is cationically polymerized, crosslinked, the electrode sheet is brought into contact with the porous film (separator), and the electrolyte is partially gelled, A laminate seal type battery was obtained.

  The 5 CmA discharge capacity of this battery was 91% of the discharge capacity of the reference battery, and the adhesive strength between the electrode sheet and the separator was 0.18 N / cm for the positive electrode and 0.09 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 2.7%.

Example 4
In Example 3, the crosslinkable polymer C was used instead of the crosslinkable polymer B, and the crosslinkable polymer C / lithium salt / adipic acid mixture was applied to one side of the polyethylene resin porous film in the same manner as in Example 3. A crosslinkable polymer-supported porous film supported at a coating density of 2.2 g / m ² was obtained. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

  This crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 48 hours, the crosslinkable polymer C supported on the porous film is reacted with adipic acid, and this crosslinkable polymer is partially crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 19%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 97% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.21 N / cm for the positive electrode and 0.10 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 2.2%.

Example 5
10 g of the crosslinkable polymer D was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer D / lithium salt mixture was prepared. Separately, an ethanolic solution of adipic acid having a concentration of 10% by weight was prepared. While stirring the coating solution, the adipic acid solution was slowly added dropwise thereto to prepare a solution of the crosslinkable polymer D / lithium salt / adipic acid mixture. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

After this solution of the crosslinkable polymer / lithium salt / adipic acid mixture was applied to the surface of the release paper with a # 7 wire bar, it was heated to 50 ° C. to volatilize ethyl acetate and ethanol in the mixed solution, Thus, a layer of crosslinkable polymer D / lithium salt / adipic acid mixture was produced on the release paper. This release paper is a polyethylene resin porous film (film thickness: 16 μm, porosity: 40%, air permeability: 300 sec / 100 cc, puncture strength: 3.0 N) with the crosslinkable polymer D / lithium salt / adipic acid mixture layer. The porous film was placed so as to face each other and passed through a heating roll at 70 ° C., and then the release paper was removed to give a crosslinkable polymer D / lithium salt / adipic acid mixture at a coating density of 1.1 g / side. A crosslinkable polymer-supported porous film obtained by holding at m ² was obtained.

  Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 60 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 65%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 97% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.17 N / cm for the positive electrode and 0.18 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 2.3%.

Example 6
A solution of a crosslinkable polymer D / lithium salt / adipic acid mixture was prepared in the same manner as in Example 5 except that 8.1 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was used. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

In the same manner as in Example 5, a crosslinkable polymer-supported porous film in which the crosslinkable polymer / lithium salt / adipic acid mixture was held at a coating density of 1.1 g / m ² per side was obtained. Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 60 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 65%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 98% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.13 N / cm for the positive electrode and 0.15 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 3.5%.

Example 7
A solution of a crosslinkable polymer D / lithium salt / adipic acid mixture was prepared in the same manner as in Example 5 except that 1.1 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was used. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

In the same manner as in Example 5, a crosslinkable polymer-supported porous film in which the crosslinkable polymer / lithium salt / adipic acid mixture was held at a coating density of 1.1 g / m ² per side was obtained. Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 60 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 65%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 95% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.18 N / cm for the positive electrode and 0.20 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 2.0%.

Example 8
In Example 5, as a lithium salt, instead of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium perchlorate 2.5 g was used in the same manner, and the crosslinkable polymer D / lithium salt / A solution of adipic acid mixture was prepared. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

In the same manner as in Example 5, a crosslinkable polymer-supported porous film in which the crosslinkable polymer / lithium salt / adipic acid mixture was held at a coating density of 1.1 g / m ² per side was obtained. Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 60 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 65%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 96% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.16 N / cm for the positive electrode and 0.19 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 2.5%.

Example 9
In Example 5, the crosslinkable polymer D / lithium salt / adipine was similarly used except that 2.5 g of lithium iodide was used instead of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) as the lithium salt. A solution of the acid mixture was prepared. The ratio of the carboxyl group of adipic acid to the number of moles of reactive groups possessed by the crosslinkable polymer was 0.5.

In the same manner as in Example 5, a crosslinkable polymer-supported porous film in which the crosslinkable polymer / lithium salt / adipic acid mixture was held at a coating density of 1.1 g / m ² per side was obtained. Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 60 hours, the crosslinkable polymer supported on the porous film is reacted with adipic acid, and a part of the crosslinkable polymer is crosslinked. Thus, a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 65%.

  Next, a laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 96% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.18 N / cm for the positive electrode and 0.18 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 1.9%.

Example 10
10 g of the crosslinkable polymer D was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer D / lithium salt mixture was prepared. Separately, an ethanol solution of phthalic anhydride having a concentration of 10% by weight was prepared. While stirring the coating solution, the phthalic anhydride solution was slowly added dropwise thereto to prepare a solution of the crosslinkable polymer D / lithium salt / phthalic anhydride mixture. The ratio of the carboxyl group of phthalic anhydride to the number of moles of reactive groups of the crosslinkable polymer was 0.05.

After the solution of the crosslinkable polymer / lithium salt / phthalic anhydride mixture was applied to the surface of the release paper with a # 8 wire bar, it was heated to 50 ° C. to volatilize ethyl acetate and ethanol in the mixed solution. Thus, a layer of crosslinkable polymer D / lithium salt / phthalic anhydride mixture was produced on the release paper. This release paper is a polyethylene resin porous film having a crosslinkable polymer D / lithium salt / phthalic anhydride mixture layer (film thickness 16 μm, porosity 40%, air permeability 300 seconds / 100 cc, puncture strength 3.0 N) The porous film was placed so as to face each other, passed through a heating roll at 70 ° C., the release paper was removed, and the crosslinkable polymer D / lithium salt / phthalic anhydride mixture was applied at a coating density of 1. A crosslinkable polymer-supported porous film obtained at 3 g / m ² was obtained.

  Next, this crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 48 hours, the crosslinkable polymer supported on the porous film is reacted with phthalic anhydride, and a part of the crosslinkable polymer is obtained. Crosslinking was thus obtained to obtain a reactive polymer-supported porous film. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 40%.

  A laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 99% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.14 N / cm for the positive electrode and 0.18 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 1.4%.

Example 11
In Example 10, the ratio of the carboxyl group of phthalic anhydride to the number of moles of reactive groups possessed by the crosslinkable polymer was set to 0.5, and the crosslinkable polymer supported on which the crosslinkable polymer / lithium salt / phthalic anhydride mixture was supported The porous film is put into a thermostat at 50 ° C. for 12 hours, the crosslinkable polymer supported on the porous film is reacted with phthalic anhydride, and the crosslinkable polymer is partially crosslinked, thus reacting. A porous polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 85%.

  A laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 91% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.10 N / cm for the positive electrode and 0.09 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 6.0%.

Example 12
10 g of the crosslinkable polymer D was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer D / lithium salt mixture was prepared. Separately, an ethanol solution of succinic anhydride having a concentration of 10% by weight was prepared. While stirring the coating solution, the succinic anhydride solution was slowly added dropwise thereto to prepare a solution of the crosslinkable polymer D / lithium salt / succinic anhydride mixture. The ratio of the carboxyl group of succinic anhydride to the number of moles of reactive groups of the crosslinkable polymer was 0.5.

After the solution of the crosslinkable polymer / lithium salt / succinic anhydride mixture was applied to the surface of the release paper with a # 8 wire bar, it was heated to 50 ° C. to volatilize the ethyl acetate and ethanol in the mixed solution. Thus, a layer of crosslinkable polymer D / lithium salt / succinic anhydride mixture was produced on the release paper. This release paper is a polyethylene resin porous film having a crosslinkable polymer D / lithium salt / succinic anhydride mixture layer (film thickness 16 μm, porosity 40%, air permeability 300 seconds / 100 cc, puncture strength 3.0 N) The porous film was placed so as to face each other, passed through a heating roll at 70 ° C., the release paper was removed, and the crosslinkable polymer D / lithium salt / succinic anhydride mixture was applied at a coating density of 1. A crosslinkable polymer-supported porous film obtained at 3 g / m ² was obtained.

  Next, this crosslinkable polymer-supported porous film is put in a thermostat at 50 ° C. for 300 hours, the crosslinkable polymer supported on the porous film is reacted with succinic anhydride, and a part of the crosslinkable polymer is obtained. Crosslinking was thus obtained to obtain a reactive polymer-supported porous film. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 50%.

  A laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 92% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.18 N / cm for the positive electrode and 0.10 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 1.9%.

Example 13
10 g of the crosslinkable polymer D was dissolved in ethyl acetate at room temperature to prepare a 10 wt% crosslinkable polymer solution, to which 2.5 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added and stirred at room temperature. By mixing, a coating solution containing a crosslinkable polymer D / lithium salt mixture was prepared. Separately, an ethanol solution of 10% by weight α, α′-diethylglutaric anhydride was prepared. While stirring the coating solution, the α, α′-diethylglutaric anhydride solution is slowly added dropwise to the mixture so that the crosslinkable polymer D / lithium salt / α, α′-diethylglutaric anhydride mixture is mixed. A solution was prepared. The ratio of the carboxyl group of α, α′-diethylglutaric anhydride to the number of moles of reactive groups of the crosslinkable polymer was 0.25.

After the solution of the crosslinkable polymer / lithium salt / α, α′-diethylglutaric anhydride mixture was applied to the surface of the release paper with a # 8 wire bar, the solution was heated to 50 ° C. to obtain acetic acid in the mixed solution. Ethyl and ethanol were stripped, thus producing a layer of crosslinkable polymer D / lithium salt / α, α′-diethylglutaric anhydride mixture on the release paper. The release paper was made of a crosslinkable polymer D / lithium salt / α, α′-diethylglutaric anhydride mixture layer having a polyethylene resin porous film (film thickness 16 μm, porosity 40%, air permeability 300 seconds / 100 cc, The porous film was laminated so as to face the puncture strength of 3.0 N), passed through a heating roll at 70 ° C., and then the release paper was removed to form a crosslinkable polymer D / lithium salt / α, α′− A crosslinkable polymer-supported porous film obtained by holding a diethylglutaric anhydride mixture at a coating density of 1.3 g / m ² per side was obtained.

  Next, this crosslinkable polymer-supported porous film was put into a thermostat at 50 ° C. for 120 hours, the crosslinkable polymer supported on the porous film was reacted with α, α′-diethylglutaric anhydride, A part of the crosslinkable polymer was crosslinked, and thus a reactive polymer-supported porous film was obtained. In this reactive polymer-supported porous film, the insoluble content of the reactive polymer was 35%.

  A laminate seal type battery was obtained in the same manner as in Example 1 except that this reactive polymer-supported porous film was used. The 5 CmA discharge capacity of this battery was 92% of the discharge capacity of the reference battery, and the adhesion between the electrode sheet and the separator was 0.29 N / cm for the positive electrode and 0.22 N / cm for the negative electrode. . Moreover, the area heat shrinkage rate of the separator in the separator / electrode assembly obtained using the reactive polymer-supported porous film was 1.6%.

Comparative Example 1
A poly (vinylidene fluoride / hexafluoropropylene) copolymer (Kynar 2801 manufactured by Elf Atchem) was dissolved in N-methyl-2-pyrrolidone to prepare a polymer solution having a concentration of 10% by weight. After this polymer solution was applied to both sides of a polyethylene resin porous film (film thickness 16 μm, porosity 40%, air permeability 300 sec / 100 cc, puncture strength 3.0 N) with a wire bar (# 20), 60 By heating to 0 ° C., N-methyl-2-pyrrolidone was volatilized, and thus a polyethylene resin porous film having a poly (vinylidene fluoride / hexafluoropropylene) copolymer supported on both sides was obtained.

The negative electrode sheet obtained in Reference Example 1, the porous film carrying the poly (vinylidene fluoride / hexafluoropropylene) copolymer and the positive electrode sheet obtained in Reference Example 1 were laminated in this order, and the temperature was 80 The separator / electrode laminate was obtained by press-bonding at 1 ° C. and a pressure of 5 kgf / cm ² for 1 minute. An electrolytic solution comprising an ethylene carbonate / diethyl carbonate (weight ratio 1/1) mixed solvent in which the separator / electrode laminate is charged in an aluminum laminate package and lithium hexafluorophosphate is dissolved at a concentration of 1.0 mol / L. After the injection, the package was sealed to obtain a laminate seal type battery.

  The 5 CmA discharge capacity of this battery was 50% of the discharge capacity of the reference battery, and the adhesive strength between the electrode and the separator was 0.20 N / cm for the positive electrode and 0.09 N / cm for the negative electrode. Further, the area heat shrinkage rate of the separator in the separator / electrode laminate was 30%.

Comparative Example 2
A laminated seal type battery was obtained in the same manner as in Comparative Example 1 except that the concentration of the poly (vinylidene fluoride / hexafluoropropylene) copolymer solution was changed to 5% by weight. The 5 CmA discharge capacity of this battery was 90% of the discharge capacity of the reference battery, and the adhesive strength between the electrode sheet and the separator was 0.05 N / cm for the positive electrode and 0.0 N / cm for the negative electrode. . Further, the area heat shrinkage rate of the separator in the separator / electrode laminate was 60%.

In an Example, it is a figure which shows the apparatus for measuring a separator (porous film) / electrode assembly and its area heat shrinkage rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylindrical container 4 ... Sample (Separator (porous film) / electrode assembly)
5 ... Weight 6 ... Lid

Claims (16)

  A crosslinkable polymer-supported porous film for a battery separator, wherein a crosslinkable polymer and a lithium salt are supported on a porous film.   The crosslinkable polymer-supported porous film for a battery separator according to claim 1, wherein the crosslinkable polymer is a polymer having at least one reactive group selected from an oxetanyl group and an epoxy group in the molecule.   An electrode / crosslinkable polymer-carrying porous film laminate obtained by laminating an electrode on the crosslinkable polymer-carrying porous film according to claim 1 or 2.   An electrode / crosslinkable polymer-supported porous film assembly obtained by cationically polymerizing the crosslinkable polymer in the electrode / crosslinkable polymer-supported porous film laminate according to claim 3 and bonding the porous film and the electrode. .   An electrode is laminated on the crosslinkable polymer-supported porous film according to claim 1 to obtain an electrode / crosslinkable polymer-supported porous film laminate, and the electrode / crosslinkable polymer-supported porous film laminate is used as a battery. After being charged into the container, an electrolyte containing a cationic polymerization catalyst is injected into the battery container, and at least a part of the crosslinkable polymer is cationically polymerized, thereby bonding the porous film and the electrode. Battery manufacturing method.   The method for producing a battery according to claim 5, wherein the cationic polymerization catalyst is an onium salt.   The method for producing a battery according to claim 5 or 6, wherein the electrolytic solution contains at least one selected from lithium hexafluorophosphate and lithium tetrafluoroborate as an electrolyte salt serving also as a cationic polymerization catalyst.   A battery separator comprising: a crosslinkable polymer that can be cross-linked by reacting with a cross-linking agent and a cross-linking agent; and a partially reactive cross-linked polymer and a lithium salt are supported on a porous film. Reactive polymer-supported porous film for.   The reactive polymer-supported porous film for battery separator according to claim 8, wherein the crosslinkable polymer is a polymer having at least one reactive group selected from oxetanyl group and epoxy group in the molecule.   The reactive polymer-supported porous film for battery separator according to claim 8, wherein the crosslinking agent is at least one selected from polycarboxylic acid and acid anhydride.   The reactive polymer-supported porous film according to any one of claims 8 to 10, wherein the reactive polymer has an insoluble fraction of 1 to 90%.   An electrode / reactive polymer-carrying porous film laminate obtained by laminating an electrode on the reactive polymer-carrying porous film according to any one of claims 8 to 11.   An electrode / reactive polymer-supported porous film joint obtained by further cationically polymerizing the reactive polymer in the electrode / reactive polymer-supported porous film laminate according to claim 12 and bonding the porous film and the electrode. body.   An electrode is laminated on the reactive polymer-supported porous film according to claim 8 to obtain an electrode / reactive polymer-supported porous film laminate, and the electrode / reactive polymer-supported porous film laminate. After the body is charged into the battery container, an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least a part of the reactive polymer is cationically polymerized to bond the porous film and the electrode. A battery manufacturing method characterized by the above.   The method for producing a battery according to claim 14, wherein the cationic polymerization catalyst is an onium salt. The method for producing a battery according to claim 14 or 15, wherein the electrolytic solution contains at least one selected from lithium hexafluorophosphate and lithium tetrafluoroborate as an electrolyte salt serving also as a cationic polymerization catalyst.

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