JP4653425B2 - Battery positive electrode / reactive polymer-supported porous film / negative electrode laminate - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is useful for manufacturing a battery, and can contribute to safety during use of the battery thus manufactured, and a positive electrode / reactive polymer-supported porous film / negative electrode laminate and a battery using the same It relates to a manufacturing method.

  Conventionally, as a method of manufacturing a battery, a positive electrode and a negative electrode are laminated with a separator for preventing a short circuit between the electrodes, or a positive (negative) electrode, a separator, a negative (positive) electrode, and a separator are laminated. It is known that the electrode / separator laminate is stacked in order and wound into an electrode / separator laminate, and after the electrode / separator laminate is charged into the battery container, an electrolytic solution is injected into the battery container and sealed. (For example, see Patent Documents 1 and 2).

  However, as a problem with the battery thus obtained, if the battery is left in a high temperature environment for a long time, overcharged, or if a short circuit occurs between the electrodes inside or outside the battery, the battery Abnormal heat generation caused the temperature to rise suddenly, and the electrolyte inside the battery was ejected to the outside, and in some cases, it could even be destroyed.

  On the other hand, especially in the production of stacked batteries, in many cases, the polyvinylidene fluoride resin solution is used as an adhesive, the electrode and the separator are bonded, and then the solvent used in the resin solution is removed under reduced pressure. The method to do is adopted. However, according to such a method, there are problems that the process is complicated, the quality of the obtained product is difficult to stabilize, and the adhesion between the electrode and the separator is not sufficient (for example, patent document) 3).

  In addition, 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. It can be suitably used to manufacture a battery with excellent rate characteristics, and after the battery is manufactured, it does not melt or break even if it is placed in a high-temperature environment. A battery positive electrode / reactive polymer-supported porous film / negative electrode laminate including a porous film functioning as a small separator, and a battery manufacturing method using such a positive electrode / reactive polymer-supported porous film / negative electrode laminate The purpose is to provide.

According to the present invention, a crosslinkable polymer having at least one reactive group selected from a 3-oxetanyl group and an epoxy group in a molecule is prepared, and this crosslinkable polymer is reacted with a polycarboxylic acid, A positive electrode / reaction in which a reactive polymer formed by crosslinking is supported on a porous film to form a reactive polymer-supported porous film, and a positive electrode and a negative electrode are laminated with the reactive polymer-supported porous film sandwiched therebetween. In the porous polymer-supported porous film / negative electrode laminate, the amount of the reactive polymer supported on one side of the reactive polymer-supported porous film is in the range of 0.3 to 5.0 g / m ² , The ratio of the loading amount of the reactive polymer on the porous film / the loading amount of the reactive polymer on the porous film on the negative electrode side is in the range of 0.1 to 1.0. Positive electrode / reactive polymer-supported porous film / negative electrode laminate for battery is provided.

  Furthermore, according to the present invention, after the positive electrode / reactive polymer-supported porous film / negative electrode assembly is charged into the battery container, an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least porous In the vicinity of the interface between the porous film and the electrode, at least a part of the reactive polymer is swollen in the electrolytic solution, or eluted into the electrolytic solution, and cationically polymerized to gel at least a part of the electrolytic solution. Thus, there is provided a battery manufacturing method characterized in that a porous film and an electrode are adhered.

  In the positive electrode / reactive polymer-supported porous film / negative electrode laminate according to the present invention, the reactive polymer is partially cross-linked by polycarboxylic acid, and further, by the unreacted reactive group, It has cationic polymerizability.

  Therefore, after preparing such a positive electrode / reactive polymer-supported porous film / negative electrode laminate in a battery container, an electrolytic solution containing a cationic polymerization catalyst is injected into the battery container, and at least the porous film and electrode In the vicinity of the interface, at least a part of the reactive polymer is swollen in the electrolytic solution or eluted into the electrolytic solution, the reactive group of the reactive polymer is cationically polymerized, and the reactive polymer is further A battery having an electrode / porous film assembly in which the porous film and the electrode are firmly bonded can be obtained by crosslinking and gelling at least a part of the electrolytic solution.

  Here, in the positive electrode / reactive polymer-supported porous film / negative electrode laminate, since the reactive polymer is partially crosslinked in advance, the positive electrode / reactive polymer-supported porous film / negative electrode laminate is electrolyzed. When immersed in the solution, the reactive polymer swells while suppressing elution and diffusion from the electrode / reactive polymer-supported porous film laminate into the electrolyte, and as a result, a small amount of the reactive polymer is added. By using it, the electrode can be adhered to the porous film (separator), and the porous film is excellent in ion permeability, so that it 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, in the positive electrode / reactive polymer-supported porous film / negative electrode laminate, the amount of the reactive polymer supported on one side of the porous film and the reactive polymer on the porous film on the positive electrode side are By setting the ratio of the supported amount / the supported amount of the reactive polymer on the negative electrode side porous film to a predetermined range, in the obtained battery, the characteristics and the relationship between the electrode and the porous film (separator) It is possible to have an appropriate balance between the adhesive properties and furthermore, the porous film functioning as a separator and the electrode can be firmly bonded, so that the separator can be used even in a high temperature environment. Since it does not melt and break, and heat shrinkage is small, a battery with excellent safety can be obtained.

  Thus, by using the positive electrode / reactive polymer-supported porous film / negative electrode laminate of the present invention, an electrode / separator assembly having strong adhesion between the electrode / separator is formed in situ in the battery manufacturing process. In addition, a balance is achieved between the adhesion between the porous film and the electrode and the battery characteristics, and a battery with excellent safety can be easily obtained.

The present invention provides a crosslinkable polymer having at least one reactive group selected from a 3-oxetanyl group and an epoxy group in the molecule, and reacting the crosslinkable polymer with a polycarboxylic acid, in part, A positive electrode / reactive polymer in which a reactive polymer formed by crosslinking is supported on a porous film to form a reactive polymer-supported porous film, and a positive electrode and a negative electrode are laminated with the reactive polymer-supported porous film sandwiched therebetween. In the supported porous film / negative electrode laminate, the amount of the reactive polymer supported on one side of the reactive polymer-supported porous film is in the range of 0.3 to 5.0 g / m ² and the positive-side porous The ratio of the loading amount of the reactive polymer on the film / the loading amount of the reactive polymer on the porous film on the negative electrode side is in the range of 0.1 to 1.0.

  In this invention, since a porous film functions as a separator after manufacture of a battery, the thing of the film thickness of 3-100 micrometers is good. When the film thickness is less than 3 μm, the strength is insufficient and there is a possibility of causing an internal short circuit when used as a separator in a battery. On the other hand, when it exceeds 100 μm, the distance between the electrodes is too large, The internal resistance of the battery becomes excessive. Particularly preferably, the substrate porous film has a film thickness in the range of 5 to 50 μm. The porous film has pores having an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 80%, preferably 25 to 75%. When the porosity of the porous film 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.

  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, polyethylene has a property that when heated, the resin melts and the pores are blocked, so that the battery can have a so-called shutdown function. Particularly preferred. Here, the polyethylene includes not only a homopolymer of ethylene but also a copolymer of ethylene with an α-olefin such as propylene, butene, and hexene. However, 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.

  In the present invention, the crosslinkable polymer means a polymer having at least one reactive group selected from a 3-oxetanyl group and an epoxy group in the molecule, and preferably a radical polymerizable monomer having a 3-oxetanyl group A radical copolymer of at least one first radical polymerizable monomer selected from radical polymerizable monomers having an epoxy group and a second radical polymerizable monomer other than the first radical polymerizable monomer.

  Particularly preferably, in the present invention, the crosslinkable polymer refers to a polymer having a 3-oxetanyl group and an epoxy group in the molecule, or a polymer having an epoxy group in the molecule. Is preferably a radical copolymerization of a radical polymerizable monomer having a 3-oxetanyl group with a radical polymerizable monomer having an epoxy group and another radical polymerizable monomer, or a radical polymerizable monomer having an epoxy group and another radical polymerizable monomer. It can be obtained by radical copolymerization with a radical polymerizable monomer.

  As already known, 3-oxetanyl groups and epoxy groups can react with carboxyl groups and can be cationically polymerized. According to the present invention, by utilizing such reactivity of the 3-oxetanyl group and the epoxy group possessed by the crosslinkable polymer, the crosslinkable polymer is first reacted with a polycarboxylic acid and partially crosslinked. Is called a reactive polymer, and this is supported on a porous substrate film to form a reactive polymer-supported porous film.

  Thus, according to the present invention, the reactive polymer is obtained by reacting a crosslinkable polymer with a polycarboxylic acid and partially crosslinking the crosslinkable polymer. For convenience, the total weight of the crosslinkable polymer and the polycarboxylic acid is used.

  In the present invention, the positive electrode / reactive polymer-supported porous film / negative electrode laminate (hereinafter sometimes referred to as an electrode / porous film laminate) is a part of the crosslinkable polymer. A positive electrode and a negative electrode are pressure-bonded to a porous film carrying a reactive polymer, and are preferably bonded by temporary adhesion.

  The positive electrode / reactive polymer-supported porous film / negative electrode assembly (hereinafter sometimes referred to as an electrode / porous film assembly) refers to the reactive polymer in the electrode / porous film laminate as described above. It refers to a structure in which an electrode and a porous film are bonded to each other by reacting and crosslinking.

According to the present invention, in the electrode / porous film laminate, the amount of the reactive polymer supported on one side of the reactive polymer-supported porous film is in the range of 0.3 to 5.0 g / m ² , and the positive electrode side The ratio of the amount of the reactive polymer supported on the porous film / the amount of the reactive polymer supported on the negative electrode porous film is in the range of 0.1 to 1.0.

  The battery electrode / reactive polymer-supported porous film laminate according to the present invention and the production of a battery using the same will be described in detail below.

  In the present invention, the crosslinkable polymer includes a first radical polymerizable monomer having at least one reactive group selected from a 3-oxetanyl group and an epoxy group in the molecule, and a second radical polymerizable monomer other than this. Can be obtained by radical copolymerization according to a conventional method.

  According to the present invention, a first radical polymerizable monomer having at least one reactive group selected from a 3-oxetanyl group and an epoxy group in the molecule is copolymerized with another second radical polymerizable monomer. Thus, when the crosslinkable polymer is obtained, the first radical polymerizable monomer is used in a range of 5 to 50% by weight, preferably 10 to 30% by weight of the total amount of monomers. Therefore, if a crosslinkable polymer containing a 3-oxetanyl group is obtained as a reactive group, the 3-oxetanyl group-containing radical polymerizable monomer is 5 to 50% by weight of the total monomer amount, preferably 10 to 10%. It is used in the range of 30% by weight. Similarly, in the case of obtaining a crosslinkable polymer containing an epoxy group as a reactive group, the epoxy group-containing radical polymerizable monomer is 5 to 50% by weight, preferably 10 to 30% by weight of the total monomer amount. It is used in the range.

  In addition, when a 3-oxetanyl group-containing radical polymerizable monomer and an epoxy group-containing radical polymerizable monomer are used in combination to obtain a crosslinkable polymer having both a 3-oxetanyl group and an epoxy group as reactive groups, 3 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, more preferably 3-oxetanyl. Of the group-containing radical polymerizable monomer and the epoxy group-containing radical polymerizable monomer, the epoxy group-containing radical polymerizable monomer is used so as to be 90% by weight or less.

  When the crosslinkable polymer is obtained, if the amount of the first radical polymerizable monomer is less than 5% by weight in the total monomer amount, as will be described later, the amount of the reactive polymer required for gelation of the electrolytic solution is increased. Therefore, the performance of the obtained battery is lowered. On the other hand, when it is more than 50% by weight, the retention property of the electrolyte solution of the formed gel is lowered, and the adhesion between the electrode / porous film (separator) in the obtained battery is lowered.

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

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

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

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

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

Or formula (2)

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

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

  The second radical polymerizable monomer used for copolymerization with the first radical polymerizable monomer described above 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,

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 the present invention, the crosslinkable polymer can be obtained as a copolymer by radically copolymerizing the first and second radical polymerizable monomers described above using a radical polymerization initiator. Such radical copolymerization may be carried out by any polymerization method such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc., but from the viewpoint of ease of polymerization, adjustment of molecular weight, post-treatment, etc. Preference is given to suspension polymerization.

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

  In the present invention, the crosslinkable polymer preferably has a weight average molecular weight of 10,000 or more. When the weight average molecular weight of the crosslinkable polymer is smaller than 10,000, since a large amount of the reaction product polymer obtained from the electrolyte solution is required for gelling the electrolytic solution, 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 so that the reactive polymer obtained therefrom can hold the electrolyte as a gel, preferably, It is about 2.5 million. In particular, according to the present invention, the crosslinkable polymer preferably has a weight average molecular weight in the range of 100,000 to 2,000,000.

  Thus, according to the present invention, the crosslinkable polymer has at least one reactive group selected from a 3-oxetanyl group and an epoxy group, and this reactive group is reacted with a polycarboxylic acid to crosslink. The reactive polymer is partially crosslinked to obtain a reactive polymer.

  Crosslinkable polymers having at least one reactive group selected from a 3-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.

  The reactive polymer-supported porous film for a battery separator according to the present invention is obtained by reacting a crosslinkable polymer as described above with a polycarboxylic acid, and partially crosslinking the substrate as a reactive polymer. It is carried on. Crosslinking of such a crosslinkable polymer with a polycarboxylic acid is, for example, as described in Japanese Patent Application Laid-Open No. 11-43540 and Japanese Patent Application Laid-Open No. 11-116663, and 3-oxetanyl group or epoxy which the crosslinkable polymer has. And a polycarboxylic acid (that is, a carboxyl group). According to the present invention, by utilizing this reactivity of a 3-oxetanyl group or an epoxy group, a crosslinkable polymer is reacted with polycarboxyl and partially crosslinked to obtain a reactive polymer.

  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.

  The reactive polymer-supported porous film according to the present invention is obtained by reacting the cross-linkable polymer with the polycarboxylic acid as described above, and partially crosslinking it to obtain a reactive polymer, which is supported on the porous film. It is. Thus, in order to carry the reactive polymer on the porous film, it is not particularly limited. For example, the crosslinkable polymer is mixed with a polycarboxylic acid in an appropriate solvent such as acetone, ethyl acetate, or butyl acetate. Dissolve and apply this solution to the substrate porous film by casting, spray coating, etc. and impregnate it, and then dry it to remove the solvent used. A porous film carrying a polymer and a polycarboxylic acid is heated to an appropriate temperature to cause the crosslinkable polymer to react with the polycarboxylic acid, and partially crosslink the crosslinkable polymer as described above. In this way, a reactive polymer-supported porous film for a battery separator according to the present invention is obtained.

  In the present invention, the means and method for supporting the reactive polymer obtained by partially crosslinking the crosslinkable polymer with the polycarboxylic acid on the substrate porous film are not limited to the above examples. The solution may be applied to a porous film and dried, and then the polycarboxylic acid solution may be applied to and impregnated into such a porous film, dried, and then heated to an appropriate temperature. Moreover, after apply | coating the solution containing a crosslinkable polymer and polycarboxylic acid to a peelable sheet, drying and transferring this to a base material porous film, you may heat to appropriate temperature.

  According to the present invention, the reactive polymer obtained by partially crosslinking the crosslinkable polymer in this way has a gel fraction in the range of 5 to 90%, preferably an insoluble fraction in the range of 3 to 60%. It is desirable to have. Here, the gel fraction means that a porous film is loaded with a crosslinkable polymer A part by weight and a polycarboxylic acid B part by weight, the crosslinkable polymer and the polycarboxylic acid are reacted, and a part of the crosslinkable polymer is obtained. After crosslinking to make a reactive polymer, this porous film was immersed in ethyl acetate at a temperature of 23 ° C. for 7 days and then dried, and then the reactive polymer remaining on the porous film was added by C parts by weight. Is a value defined as (C / (A + B)) × 100 (%).

  Thus, in order to obtain a reactive polymer having a gel fraction in the range of 5 to 90% by reacting a crosslinkable polymer with a polycarboxylic acid and partially crosslinking the polymer, it is not limited. Usually, the carboxyl group of the polycarboxylic acid is 0.01 to 5.0 mole parts, preferably 0.05 to 3.0 mole parts with respect to 1 mole part of the reactive group of the crosslinkable polymer. And the heating reaction conditions between the crosslinkable polymer and the polycarboxylic acid may be adjusted, and thus a reactive polymer having a desired gel fraction can be obtained.

  As an example, while using so that the carboxyl group which polycarboxylic acid has may be 0.5-2.0 mol part with respect to 1 mol part of reactive groups which a crosslinkable polymer has, crosslinkable polymer, polycarboxylic acid, Can be reacted at 50 ° C. for 12 hours to 7 days to obtain a reactive polymer having a gel fraction of 5 to 90%.

  When the gel fraction of the reactive polymer is less than 5%, as will be described later, an electrode is pressure-bonded to a porous film carrying such a reactive polymer to form an electrode / porous film laminate, When this is immersed in the electrolytic solution, most of the reactive polymer is eluted and diffused in the electrolytic solution, and even if the reactive polymer is further cationically polymerized and crosslinked, it is effective between the electrode and the porous film. Adhesion cannot be obtained. On the other hand, when the insoluble fraction of the reactive polymer is more than 90%, an electrode / porous film laminate is obtained, and when this is immersed in an electrolyte, the reactive polymer has low swelling and the resulting electrode / porous A battery having a quality film assembly has a high internal resistance, which is not preferable for battery characteristics.

  In the present invention, if the ratio of the porous film carrying the reactive polymer on its surface is called the reactive polymer carrying ratio, for example, the porous film carries the reactive polymer on the entire surface of one surface. The loading rate on one surface is 100%. For example, the porous film carries the reactive polymer in the form of streaks or dots on both the front and back surfaces, and the proportion of the loading of the reactive polymer. Is 50% of the area on each surface, the loading is 50% on both the front and back surfaces.

  According to the present invention, the loading ratio of the reactive polymer is preferably in the range of 5 to 100%, particularly preferably in the range of 10 to 90%. For example, when the reactive polymer is supported on the porous film, it is supported partially, that is, for example, in the form of stripes, spots, lattices, stripes, turtle shells, etc. Is preferably in the range of 10 to 90%. In this way, by partially supporting the reactive polymer on the porous film, not only a strong adhesion is obtained between the electrode and the porous film (and thus the separator), but also the porous film (separator). By ensuring ion permeability, a battery having excellent characteristics can be obtained.

  In the electrode / porous film laminate according to the present invention, the positive electrode and the negative electrode are laminated with the porous film formed by supporting the reactive polymer in this manner, and preferably pressurized and heated under pressure. Then, the positive electrode and the negative electrode can be obtained by temporarily adhering and bonding the reactive polymer-supported porous film.

  In the present invention, the negative electrode and the positive electrode differ depending on the battery, but in general, a sheet-like material in which an active material and, if necessary, a conductive agent are supported on a conductive base material using a resin binder is used. Used.

  In the present invention, the electrode / porous film laminate may have an electrode laminated on 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.

According to the present invention, in the positive electrode / reactive polymer-supported porous film / negative electrode laminate, the amount of the reactive polymer supported per side of the reactive polymer-supported porous film is 0.3 to 5.0 g / m ^2. And the ratio of the amount of the reactive polymer supported on the positive electrode porous film / the amount of the reactive polymer supported on the negative porous film (hereinafter referred to as the ratio of the reactive polymer supported amount). It is in the range of 0.1 to 1.0.

When the loading amount of the reactive polymer per side of the porous film is less than 0.3 g / m ² , the adhesion between the electrode and the porous film (separator) is not sufficient in the finally obtained battery. . On the other hand, when the loading amount of the reactive polymer per side of the porous film is more than 5.0 g / m ² , the internal resistance between the electrode and the porous film (separator) in the battery finally obtained is Becomes large, and the battery characteristics are remarkably deteriorated.

  Further, when the ratio of the amount of the reactive polymer supported on the porous film is smaller than 0.1, the amount of the reactive polymer supported on the positive electrode-side porous film is too small, and the positive electrode and the porous film ( Adhesion with the separator) is insufficient. However, when the ratio of the amount of the reactive polymer supported on the porous film is larger than 1.0, a balance is lost between the adhesion between the electrode and the porous film (separator) and the battery characteristics.

  In preparing such a positive electrode / reactive polymer-supported porous film / negative electrode laminate, the reactive polymer is the same on the positive electrode side (positive electrode side) and negative electrode side (negative electrode side) of the porous film. In a lithium ion secondary battery obtained using such a laminate when supported at a ratio, due to the difference in particle diameter between the granular material used as the positive electrode active material and the granular material used as the negative electrode active material The adhesiveness between the reactive polymer-supported porous film and the negative electrode is lower than the adhesiveness between the reactive polymer-supporting porous film and the positive electrode.

  That is, in lithium ion secondary batteries, lithium cobaltate is typically used as the positive electrode active material, and various carbonaceous materials are used as the negative electrode active material. Here, cobalt used as the positive electrode active material is used. Lithium acid is a granular material having an average particle size of 1 to 10 μm, preferably about 3 to 5 μm. On the other hand, the carbonaceous material used as the negative electrode active material has an average particle size of about 15 to 100 μm, preferably The carbonaceous material used as the negative electrode active material has a larger average particle diameter than the lithium cobaltate used as the positive electrode active material.

  Lithium ion diffusion rate is significantly lower in lithium cobaltate than in carbon, and some of the initially charged lithium ions form a film on the surface of the carbonaceous material that is the negative electrode active material and discharge Conventionally, in lithium ion secondary batteries, lithium cobaltate used as a positive electrode active material has a small average particle diameter, and lithium ions are diffused. While promoting, the carbonaceous material which is a negative electrode active material has taken the countermeasure which makes the surface area of the film formed by lithium ion as small as possible by using a thing with a large average particle diameter.

  On the other hand, according to the present invention, in the obtained battery, the reactive polymer supported on the porous film (separator) is a gel layer only in the vicinity of the interface between the positive electrode or the negative electrode and the porous film (separator). The reactive polymer layer forms a resistance layer against lithium ion diffusion. As described above, since the diffusion rate of lithium ions is smaller in lithium cobaltate than in carbon, the reactive polymer layer on the positive electrode side inhibits the diffusion of lithium ions, leading to deterioration of battery characteristics. However, the reactive polymer layer on the negative electrode side does not significantly affect the battery characteristics because the diffusion of lithium ions into the carbonaceous material is fast.

  Therefore, according to the present invention, considering that the adhesion of the electrode to the porous film (separator) by the reactive polymer is due to the anchor effect of the reactive polymer in the gel state into the pores of the electrode, the positive electrode Based on the difference in the average particle size of the active material and the negative electrode active material, the amount of the reactive polymer supported on the negative electrode side is made larger than the amount of the reactive polymer supported on the positive electrode side within a predetermined range, and the reactive polymer By setting the loading amount of the reactive polymer per one side of the supported porous film within a predetermined range, the negative electrode and the porous film are formed between the positive electrode and the porous film without causing deterioration of the characteristics of the obtained battery. The same degree of adhesive strength can be given during the period.

  That is, according to the present invention, in the positive electrode / reactive polymer-supported porous film / negative electrode laminate, the reactive polymer support amount per one side of the porous film and the reactive polymer support ratio are set within a predetermined range, respectively. By doing so, the obtained battery can have an appropriate balance between the characteristics and the adhesive characteristics between the electrode and the porous film (separator).

In particular, according to the present invention, in the electrode / porous film laminate, the adhesion between the porous film (separator) and the characteristics of the obtained battery is excellent. The amount of the reactive polymer supported is within the range of 0.3 to 0.9, and the amount of the reactive polymer supported per side of the reactive polymer-supported porous film is 0.5 to 3.0 g / m ^2. It is preferable to be in the range.

  In the present invention, specific examples of the positive electrode active material can include, for example, lithium cobalt oxide, lithium complex oxide of at least one selected from cobalt, nickel and manganese, and such complex oxidation. The product may contain various transition metals and the like. Specific examples of the carbonaceous material that is the negative electrode active material include coke, graphite, and mesocarbon microbeads. However, in the present invention, the positive electrode active material and the negative electrode active material of the lithium ion secondary battery are not limited to the above examples, and any known materials can be used as appropriate. it can.

  Thus, the electrode / porous film laminate according to the present invention can be suitably used particularly as an electrode / porous film laminate for producing a lithium ion secondary battery.

  As already known, the 3-oxetanyl group and epoxy group, which are reactive groups of the reactive polymer, have reactivity with polycarboxylic acids and have cationic polymerizability. Therefore, according to the present invention, when manufacturing a battery, such an electrode / porous film laminate is immersed in an electrolytic solution containing a cationic polymerization catalyst, preferably an electrolytic solution containing an electrolyte that also serves as a cationic polymerization catalyst. The reactive polymer has at least a part of the reactive polymer carried by the porous film in the electrode / porous film laminate in the electrolytic solution, or is eluted and diffused in the electrolytic solution. The reactive polymer is further cross-linked by cationic polymerization of the remaining reactive groups, and the electrolyte is gelled in the vicinity of the interface between the porous film and the electrode, thereby bonding the electrode and the porous film, and thus the electrode / porous A quality film assembly is obtained. That is, the electrode is actually bonded to the porous film. Therefore, in such an electrode / porous film assembly, the porous film and the electrode are firmly bonded.

  Moreover, according to the present invention, the partially crosslinked reactive polymer has a gel fraction in the above range, and therefore, even when immersed in the electrolytic solution, elution and diffusion into the electrolytic solution are prevented, Or it can be reduced and effectively used for adhesion between the electrode and the porous film, so that the electrode and the porous film can be bonded stably and more firmly by using a relatively small amount of the reactive polymer. Can do.

  As described above, in the present invention, the reactive polymer is obtained by gelling the electrolytic solution at least in the vicinity of the interface between the porous film and the electrode by crosslinking the reactive group by cationic polymerization. Functions to adhere to the film.

  In the present invention, the reactive polymer can be cationically polymerized and crosslinked even at room temperature, depending on its structure, the amount supported on the porous film, and the type and amount of the cationic polymerization catalyst. However, cationic polymerization of reactive polymers 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.

  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, the porous film (that is, the separator) has a small area heat shrinkage even at high temperatures, and is usually 20% or less, 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

(Reaction polymer gel fraction)
The porous film is loaded with a crosslinkable polymer A part by weight and a polycarboxylic acid B part by weight and reacted to partially crosslink the crosslinkable polymer to form a reactive polymer. When the reactive polymer remaining on the porous film is C parts by weight after being immersed in ethyl acetate at 7 ° C. for 7 days and then dried, the gel fraction of the reactive polymer is (C / (A + B) ) × 100 (%).

(Ratio of the amount of the reactive polymer supported on the porous film and the amount of the reactive polymer supported on the positive electrode side and the negative electrode side)
The total amount of the crosslinkable polymer and polycarboxylic acid supported on the porous film is defined as the amount of the reactive polymer supported. After the crosslinkable polymer and polycarboxylic acid are supported on the porous film, the weight of the porous film The load was determined by reducing the weight. In addition, on the positive electrode side and the negative electrode side of the porous film, the carrying amount was obtained as described above, and the carrying amount ratio was obtained from this.

Reference example 1
(Preparation of electrode sheet)
85 parts by weight of lithium cobalt oxide (Nippon Chemical Industry Co., Ltd., Cellseed C-5H, average particle size 5 μm) and acetylene black (Denka Black, Denki Kagaku Kogyo Co., Ltd.) as a conductive additive Part and 5 parts by weight of vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.) as a binder are mixed, and this is mixed with N-methyl-2-pyrrolidone so as to have a solid content concentration of 15% by weight. To make a slurry. 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 the thickness of the active material layer A positive electrode sheet having a thickness of 100 μm was prepared.

  Also, 80 parts by weight of mesocarbon microbeads (MCMB25-28 manufactured by Osaka Gas Chemical Co., Ltd., average particle size 25 μm) as negative electrode active material and acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive auxiliary agent. 10 parts by weight and 10 parts by weight of a vinylidene fluoride resin (KF Polymer L # 1120 manufactured by Kureha Chemical Industry Co., Ltd.) as a binder are mixed, and this is mixed with N-methyl-2 so that the solid content concentration becomes 15% by weight. -It was made into a slurry using pyrrolidone. This slurry was applied to a copper foil (current collector) having a thickness of 20 μm to a thickness of 200 μm, dried at 80 ° C. for 1 hour, dried at 120 ° C. for 2 hours, and then pressed by a roll press to form an active material layer. A negative electrode sheet having a thickness of 100 μm was prepared.

Reference example 2
(Preparation of crosslinkable polymer)
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 copolymerization 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. to further carry out radical copolymerization for 8 hours. Thereafter, the obtained reaction mixture was cooled to 40 ° C. to obtain a reactive polymer solution (concentration: 15% by weight) using an ethylene carbonate / diethyl carbonate (volume ratio 1/1) mixture as a solvent.

  Next, 100 g of this crosslinkable 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, A crosslinkable polymer was obtained by vacuum drying in a desiccator for 6 hours. This crosslinkable polymer was a pure white powder. As a result of molecular weight measurement by GPC, the weight average molecular weight was 344000, and the number average molecular weight was 175000.

Example 1
The crosslinkable polymer obtained in Reference Example 2 was dissolved in ethyl acetate to obtain a 10% by weight crosslinkable polymer solution. Separately, an ethanolic solution of adipic acid having a concentration of 10% by weight was prepared. While stirring the crosslinkable polymer solution, the ethanol solution of the adipic acid was dropped into the solution to prepare a solution containing the crosslinkable polymer and adipic acid. The ratio of the number of moles of carboxyl groups of adipic acid to the number of moles of reactive groups of the crosslinkable polymer was 0.5.

A solution containing this crosslinkable polymer and adipic acid is applied at a rate of 0.76 g / m ^{2 with} a wire bar on the side where the positive electrode of a polyethylene resin porous film (film thickness 17 μm, porosity 42%) is laminated. In addition, after coating at the rate of 1.3 g / m ² with the same wire bar on the side where the negative electrode is laminated, it is heated at 50 ° C., and the solvent ethyl acetate and ethanol are volatilized to support the crosslinkable polymer. A porous film was obtained.

  Next, the crosslinkable polymer-supported porous film is put into a thermostat at 50 ° C. for 96 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 gel fraction of the reactive polymer was 55%, and the ratio of the amount of the reactive polymer supported on the porous film was 0.58.

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 and pressed at a temperature of 80 ° C. and a pressure of 10 kg / cm ^{2 for} 1 minute. A positive electrode / reactive polymer-supported porous film / negative electrode laminate was formed by pressure bonding, and this was charged into a 2016 size coin-type battery can that also serves as a positive / negative electrode plate. Then, after injecting an electrolyte solution composed of a mixed solvent of ethylene carbonate / diethyl carbonate (weight ratio 1/2) in which lithium hexafluorophosphate was dissolved at a concentration of 1.2 mol / L into the battery can, the battery can Was sealed. Thereafter, the reactive polymer is cationically polymerized and crosslinked at 50 ° C. for 24 hours, and the electrode sheet is adhered to the porous film (separator), and the electrolytic solution is partially gelled, A coin-type battery was obtained.

  This battery was charged and discharged three times at a rate of 0.2 CmA, and after determining the discharge capacity in the third discharge, it was charged at a rate of 0.2 CmA, and thereafter, a rate of 1.0 CmA. The discharge capacity at a rate of 1.0 CmA was obtained, and the discharge capacity retention rate was evaluated by the ratio of the discharge capacity at a rate of 1.0 CmA / the discharge capacity at a rate of 0.2 CmA. It was 96%.

  Moreover, when this battery was disassembled and the adhesive force between the electrode sheet and the separator was measured, it was 0.12 N / cm for the positive electrode and 0.11 N / cm for the negative electrode.

  Further, the positive electrode / reactive polymer-supported porous film / negative electrode laminate obtained above was impregnated with the electrolyte solution, and then sandwiched between glass plate cans. Wrapped with a fluororesin sheet. The positive electrode / reactive polymer-supported porous film / negative electrode laminate thus wrapped with 100 g of weight is placed on the positive electrode / reactive polymer-supported porous film / negative electrode laminate in this manner and placed in a temperature-controlled room at 50 ° C. for 24 hours. The reactive polymer carried by the porous film in the carried porous film / negative electrode laminate was subjected to cationic polymerization and crosslinking, and positive and negative electrodes were adhered to the porous film to obtain a positive electrode / porous film / negative electrode assembly. .

  Thereafter, the positive electrode / porous film / negative electrode assembly was sandwiched between glass plates and placed in a dryer at a temperature of 150 ° C. for 1 hour. Next, after this positive electrode / porous film / negative electrode assembly was taken out from between the glass plates, the porous film was peeled off from the positive and negative electrodes of this assembly, and this was read with a scanner. The area heat shrinkage rate was found to be 14% as compared with the area of the porous film used for the preparation.

Example 2
In Example 1, the porous positive electrode side 0.90 g / m ² the supporting amount of the reactive polymer to the film, the negative 1.1 g / m ^2, except that the reactive polymer-supported amount ratio 0.82, performed In the same manner as in Example 1, a reactive polymer-supported porous film was obtained. Using this reactive polymer-supported porous film, a coin-type battery was obtained in the same manner as in Example 1, and the 1.0 CmA / 0.2 CmA discharge capacity retention rate was determined to be 94%. Moreover, when this battery was disassembled and the adhesive force between the electrode sheet and the separator was measured, it was 0.15 N / cm for the positive electrode and 0.09 N / cm for the negative electrode. The area heat shrinkage rate of the porous film obtained in the same manner as in Example 1 was 4%.

Example 3
In Example 1, the porous positive electrode side 0.53 g / m ² the supporting amount of the reactive polymer to the film, the negative 2.2 g / m ^2, except that the reactive polymer-supported amount ratio 0.24, performed In the same manner as in Example 1, a reactive polymer-supported porous film was obtained. Using this reactive polymer-supported porous film, a coin-type battery was obtained in the same manner as in Example 1, and the 1.0 CmA / 0.2 CmA discharge capacity retention rate was determined to be 91%. Moreover, when this battery was disassembled and the adhesive force between the electrode sheet and the separator was measured, it was 0.10 N / cm for the positive electrode and 0.20 N / cm for the negative electrode. The area heat shrinkage rate of the porous film obtained in the same manner as in Example 1 was 0%.

Comparative Example 1
In Example 1, a coin-type battery was obtained in the same manner as in Example 1 using the porous film as it was without supporting the crosslinkable polymer. The 1.0 CmA / 0.2 CmA discharge capacity retention rate of this battery was 97%. The area heat shrinkage rate of the porous film obtained in the same manner as in Example 1 was 81%.

Comparative Example 2
In Example 1, the porous positive electrode side 2.5 g / m ² the supporting amount of the reactive polymer to the film, the negative 0.70 g / m ^2, except that the reactive polymer-supported amount ratio 3.57 is carried out In the same manner as in Example 1, a reactive polymer-supported porous film was obtained. Using this reactive polymer-supported porous film, a coin-type battery was obtained in the same manner as in Example 1, and the 1.0 CmA / 0.2 CmA discharge capacity retention rate was found to be 74%. Moreover, when this battery was disassembled and the adhesive force between the electrode sheet and the separator was measured, it was 0.33 N / cm for the positive electrode and 0.05 N / cm for the negative electrode. The area heat shrinkage rate of the porous film obtained in the same manner as in Example 1 was 2%.

Claims (9)

Positive electrode for lithium ion secondary battery / reactive polymer-supported porous film / negative electrode laminate using a granular material composed of a lithium composite oxide as a positive electrode active material and a granular material composed of a carbonaceous material as a negative electrode active material A crosslinkable polymer having at least one reactive group selected from 3-oxetanyl group and epoxy group in the molecule is prepared, and this crosslinkable polymer is reacted with a polycarboxylic acid to be partially crosslinked. As a reactive polymer, a reactive polymer-supported porous film supported on a porous film is formed, and a positive electrode / reactive property obtained by laminating a positive electrode and a negative electrode with the reactive polymer-supported porous film sandwiched therebetween. In the polymer-supported porous film / negative electrode laminate, the reactive polymer per one side of the reactive polymer-supported porous film With the amount of lifting is in the range of 0.3 to 5.0 g / m ^2, the ratio of the porous support amount of the film on the reactive polymer / negative electrode side of the porous supporting amount of the reactive polymer on the film of the positive side Is in the range of 0.24 to 0.9. Battery positive electrode / reactive polymer-supported porous film / negative electrode laminate. 2. The battery according to claim 1, wherein the ratio of the amount of the reactive polymer supported on the positive electrode side porous film / the amount of the reactive polymer supported on the negative electrode side porous film is in the range of 0.3 to 0.9. Positive electrode / reactive polymer-supported porous film / negative electrode laminate. The amount of the reactive polymer supported per one side of the reactive polymer-supported porous film is 0.5 to 3.0 g / m. ² The battery positive electrode / reactive polymer-supported porous film / negative electrode laminate according to claim 1 or 2, wherein the battery positive electrode / reactive polymer-supported porous film / negative electrode laminate is present. The positive electrode for a battery / reactive polymer-supported porous film / negative electrode laminate according to any one of claims 1 to 3, wherein the reactive polymer has a gel fraction of 5 to 90%. The positive electrode for a battery / reactive polymer-supported porous film / negative electrode laminate according to any one of claims 1 to 4 is cationically polymerized, and the reactive polymer is further cross-linked to form an electrode and a porous film. A positive electrode for a battery / reactive polymer-supported porous film / negative electrode assembly. The battery positive electrode / reactive polymer-supported porous film / negative electrode assembly according to claim 5 , wherein the area heat shrinkage ratio after the porous film is heated at 150 ° C. for 1 hour is 20% or less. They were charged positive electrode / reactive polymer-supported porous film / negative electrode laminate for battery according to any one of claims 1 to 4 in the battery container, the electrolyte solution containing a cationic polymerization catalyst is injected into the battery container Then, at least in the vicinity of the interface between the porous film and the electrode, at least a part of the reactive polymer is swollen in the electrolytic solution, or is eluted into the electrolytic solution, and is cationically polymerized, so that at least one of the electrolytic solutions is obtained. A method for producing a battery, comprising gelling a part and bonding a porous film and an electrode. The method for producing a battery according to claim 7 , wherein the cationic polymerization catalyst is an onium salt. The method for producing a battery according to claim 8 , wherein the electrolytic solution contains at least one selected from lithium hexafluorophosphate and lithium tetrafluoroborate as an electrolyte salt that also serves as a cationic polymerization catalyst.