JP6327251B2 - Porous membrane slurry composition for lithium ion secondary battery, separator for lithium ion secondary battery, electrode for lithium ion secondary battery, and lithium ion secondary battery - Google Patents

Description

  The present invention relates to a porous membrane slurry composition for a lithium ion secondary battery, and a separator for a lithium ion secondary battery, an electrode for a lithium ion secondary battery, and a lithium ion secondary battery using the same.

  In recent years, portable terminals such as notebook computers, mobile phones, and PDAs (Personal Digital Assistants) have been widely used. Lithium ion secondary batteries are frequently used as secondary batteries used as power sources for these portable terminals.

In a lithium ion secondary battery, a separator is generally provided in order to prevent a short circuit between the positive electrode and the negative electrode. In addition, the separator may be provided with a porous film as necessary. By providing the separator with a porous film, it is possible to prevent the separator from being damaged by a foreign substance, so that the safety of the secondary battery can be improved.
It has also been proposed to provide the porous film on an electrode plate. When an electrode is provided with a porous film, it can prevent that the electrode active material which fell from the electrode becomes a foreign material, and damages a separator.

  Furthermore, techniques such as Patent Documents 1 to 4 are also known.

JP 2006-019274 A JP 2009-123523 A JP 2013-012357 A International Publication No. 2007-089979

  In a lithium ion secondary battery, gas may be generated during use. There are various causes for this gas, and an example thereof is halide ions in the electrolyte. When halide ions are contained in the battery, for example, the electrolyte may be decomposed, or SEI (Solid Electrolyte Interface) on the electrode surface may be decomposed to generate gas.

  When gas is generated in the lithium ion secondary battery, the cycle characteristics of the lithium ion secondary battery are lowered, and the life tends to be shortened. Therefore, a technique capable of suppressing the generation of gas in the lithium ion secondary battery has been demanded.

  The present invention was devised in view of the above problems, and a porous membrane slurry composition for a lithium ion secondary battery capable of producing a lithium ion secondary battery capable of suppressing gas generation, a separator for a lithium ion secondary battery, and An object of the present invention is to provide an electrode for a lithium ion secondary battery; and a lithium ion secondary battery capable of suppressing gas generation.

The inventor has intensively studied to solve the above problems. As a result, the slurry composition for forming a porous film in a lithium ion secondary battery includes a water-soluble polymer containing a combination of acid group-containing monomer units and amide monomer units in a predetermined ratio, thereby providing a gas. The inventors have found that the occurrence of the occurrence can be suppressed and completed the present invention.
That is, the present invention is as follows.

[1] A porous membrane slurry composition for a lithium ion secondary battery comprising non-conductive particles, a water-soluble polymer, a particulate polymer, and water,
A porous membrane slurry composition for a lithium ion secondary battery, wherein the water-soluble polymer comprises 20 wt% to 80 wt% of acid group-containing monomer units and 0.1 wt% to 10 wt% of amide monomer units.
[2] The porous membrane slurry composition for a lithium ion secondary battery according to [1], wherein the nonconductive particles are organic particles.
[3] The porous membrane slurry composition for a lithium ion secondary battery according to [2], wherein the non-conductive particles are polymer particles containing 0.1% by weight to 50% by weight of an amide monomer unit.
[4] The porous membrane slurry for a lithium ion secondary battery according to any one of [1] to [3], wherein the water-soluble polymer has a weight average molecular weight of 5,000 to 1,000,000. Composition.
[5] The lithium according to any one of [1] to [4], wherein the acid group-containing monomer unit has at least one group selected from the group consisting of a carboxylic acid group and a sulfonic acid group. A porous membrane slurry composition for an ion secondary battery.
[6] The porous membrane slurry composition for a lithium ion secondary battery according to any one of [1] to [5], including a carboxymethylcellulose salt.
[7] The lithium ion secondary battery according to any one of [1] to [6], wherein the water-soluble polymer contains 0.1% to 2.0% by weight of a crosslinkable monomer. Porous membrane slurry composition.
[8] a separator substrate;
A lithium ion secondary comprising a porous film obtained by applying the porous film slurry composition for a lithium ion secondary battery according to any one of [1] to [7] on the separator base material and drying the composition. Battery separator.
[9] An electrode plate;
A lithium ion secondary battery comprising: a porous film obtained by applying and drying the porous film slurry composition for a lithium ion secondary battery according to any one of [1] to [7] on the electrode plate Electrode.
[10] A lithium ion secondary battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator,
A lithium ion secondary battery, wherein the separator is the lithium ion secondary battery separator according to [8].
[11] A lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolyte solution,
A lithium ion secondary battery, wherein at least one of the positive electrode and the negative electrode is an electrode for a lithium ion secondary battery according to [9].

According to the porous membrane slurry composition for a lithium ion secondary battery, the separator for a lithium ion secondary battery, and the electrode for a lithium ion secondary battery of the present invention, a lithium ion secondary battery capable of suppressing gas generation can be produced.
The lithium ion secondary battery of the present invention can suppress the generation of gas.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be implemented with any modifications without departing from the scope of the claims of the present invention and the equivalents thereof.

  In the following description, (meth) acrylic acid includes acrylic acid and methacrylic acid. The (meth) acrylate includes acrylate and methacrylate. Furthermore, (meth) acrylonitrile includes acrylonitrile and methacrylonitrile.

  Furthermore, that a certain substance is water-soluble means that an insoluble content is not less than 0% by weight and less than 1.0% by weight when 0.5 g of the substance is dissolved in 100 g of water at 25 ° C. Further, that a certain substance is water-insoluble means that an insoluble content is 90% by weight or more and 100% by weight or less when 0.5 g of the substance is dissolved in 100 g of water at 25 ° C.

  In addition, in a polymer produced by copolymerizing a plurality of types of monomers, the proportion of the structural unit formed by polymerizing a certain monomer in the polymer is usually that unless otherwise specified. This coincides with the ratio (preparation ratio) of the certain monomer in the total monomers used for polymerization of the polymer.

  Further, the “electrode plate” includes not only a rigid plate member but also a flexible sheet and film.

[1. Porous film slurry composition for lithium ion secondary battery]
The porous membrane slurry composition for lithium ion secondary batteries of the present invention (hereinafter sometimes referred to as “porous membrane slurry composition” as appropriate) comprises non-conductive particles, a water-soluble polymer, a particulate polymer and water. Including.

[1.1. Non-conductive particles
Non-conductive particles are components filled in the porous film, and the gaps between the non-conductive particles can form pores of the porous film. Since the non-conductive particles have non-conductivity, the porous film can be made insulative, and therefore a short circuit in the secondary battery can be prevented. In general, non-conductive particles have high rigidity, which can increase the mechanical strength of the porous membrane. Therefore, even when a stress that tends to shrink is generated in the separator base material due to heat, the porous film can resist the stress, and therefore it is possible to prevent the occurrence of a short circuit due to the shrinkage of the separator base material.
As the non-conductive particles, inorganic particles or organic particles may be used.

  Inorganic particles are usually excellent in dispersion stability in water, hardly settled in the porous membrane slurry composition, and can maintain a uniform slurry state for a long time. In addition, when inorganic particles are used, the heat resistance of the porous film can usually be increased.

As the material for the non-conductive particles, an electrochemically stable material is preferable. From this point of view, preferable examples of inorganic materials for non-conductive particles include aluminum oxide (alumina), aluminum oxide hydrate (boehmite (AlOOH), gibbsite (Al (OH) ₃ ), silicon oxide, Oxide particles such as magnesium oxide (magnesia), magnesium hydroxide, calcium oxide, titanium oxide (titania), BaTiO ₃ , ZrO, alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; silicon, diamond And the like; Covalent crystal particles such as barium sulfate, calcium fluoride, barium fluoride, and the like; Clay fine particles such as talc and montmorillonite;

  Among these, oxide particles are preferable from the viewpoints of stability in an electrolytic solution and potential stability, and titanium oxide and aluminum oxide are particularly preferable from the viewpoint of low water absorption and excellent heat resistance (for example, resistance to high temperature of 180 ° C. or higher). Aluminum oxide hydrate, magnesium oxide and magnesium hydroxide are more preferable, aluminum oxide, aluminum oxide hydrate, magnesium oxide and magnesium hydroxide are more preferable, and aluminum oxide is particularly preferable.

  As the organic particles, polymer particles are usually used. The organic particles can control the affinity for water by adjusting the type and amount of the functional group on the surface of the organic particles, and thus can control the amount of water contained in the porous film. Organic particles are excellent in that they usually have less metal ion elution.

  Examples of the polymer forming the non-conductive particles include various polymer compounds such as polystyrene, polyethylene, melamine resin, and phenol resin. The polymer compound forming the particles may be used, for example, as a mixture, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, a crosslinked product, or the like. The organic particles may be formed of a mixture of two or more polymer compounds.

  Among the non-conductive particles described above, organic particles are preferable, and polymer particles containing amide monomer units are preferable. That is, the polymer that forms the non-conductive particles is preferably a polymer containing an amide monomer unit. An amide monomer unit is a structural unit having a structure formed by polymerizing an amide monomer. The amide monomer is a monomer having an amide group and includes not only an amide compound but also an imide compound. When the non-conductive particles include an amide monomer unit, gas generation can be effectively prevented in the lithium ion secondary battery. The reason why the generation of gas can be suppressed in this way is not necessarily clear, but the non-conductive particles containing the amide monomer unit trap the halide ions in the electrolyte, thereby causing the gas caused by the halide ions. It is presumed that the occurrence of the occurrence can be suppressed.

  Examples of the amide monomer include a carboxylic acid amide monomer, a sulfonic acid amide monomer, and a phosphoric acid amide monomer.

  The carboxylic acid amide monomer is a monomer having an amide group bonded to a carboxylic acid group. Examples of the carboxylic acid amide monomer include (meth) acrylamide, α-chloroacrylamide, N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) acrylamide, and N-hydroxymethyl (meta). ) Acrylamide, N-2-hydroxyethyl (meth) acrylamide, N-2-hydroxypropyl (meth) acrylamide, N-3-hydroxypropyl (meth) acrylamide, crotonic acid amide, maleic acid diamide, fumaric acid diamide, diacetone Unsaturated carboxylic acid amide compounds such as acrylamide; N-dimethylaminomethyl (meth) acrylamide, N-2-aminoethyl (meth) acrylamide, N-2-methylaminoethyl (meth) acrylamide, N-2-ethylamino Ethyl (meta Acrylamide, N-2-dimethylaminoethyl (meth) acrylamide, N-2-diethylaminoethyl (meth) acrylamide, N-3-aminopropyl (meth) acrylamide, N-3-methylaminopropyl (meth) acrylamide, N- And N-aminoalkyl derivatives of unsaturated carboxylic acid amides such as 3-dimethylaminopropyl (meth) acrylamide.

  The sulfonic acid amide monomer is a monomer having an amide group bonded to a sulfonic acid group. Examples of the sulfonic acid amide monomer include 2-acrylamido-2-methylpropanesulfonic acid and Nt-butylacrylamidesulfonic acid.

  The phosphoric acid amide monomer is a monomer having an amide group bonded to a phosphate group. Examples of the phosphoric acid amide monomer include acrylamide phosphonic acid and acrylamide phosphonic acid derivatives.

Among these amide monomers, carboxylic acid amide monomers are preferable, unsaturated carboxylic acid amide compounds are more preferable, and (meth) acrylamide and N-hydroxymethyl (meth) acrylamide are particularly preferable.
Moreover, an amide monomer and an amide monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The ratio of the amide monomer unit in the polymer forming the non-conductive particles is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, particularly preferably 0.5% by weight or more, Preferably it is 50 weight% or less, More preferably, it is 45 weight% or less, Most preferably, it is 40 weight% or less. By setting the ratio of the amide monomer unit to be equal to or higher than the lower limit of the above range, gas generation in the lithium ion secondary battery can be effectively suppressed. Moreover, since the elution to the electrolyte solution of the polymer which forms a nonelectroconductive particle can be prevented by setting it as an upper limit or less, durability of a porous film can be improved.

  When organic particles are used as the non-conductive particles, the organic particles may not have a glass transition temperature, but when the polymer compound forming the organic particles has a glass transition temperature, the glass transition temperature is preferably Is 150 ° C. or higher, more preferably 200 ° C. or higher, particularly preferably 250 ° C. or higher, and preferably 500 ° C. or lower.

  The method for producing the organic particles as the non-conductive particles is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method may be used. Among these, the emulsion polymerization method and the suspension polymerization method are preferable because they can be polymerized in water and used as they are as the material for the porous membrane slurry composition. Moreover, when manufacturing organic particles, it is preferable to include a dispersant in the reaction system. The organic particles are generally composed of a polymer that substantially constitutes the organic particles, but may be accompanied by any component such as an additive added during the polymerization.

  The non-conductive particles may be subjected to, for example, element substitution, surface treatment, solid solution, or the like as necessary. Further, the non-conductive particles may include one kind of the above materials alone in one particle, or may contain two or more kinds in combination at an arbitrary ratio. . Further, the non-conductive particles may be used in combination of two or more kinds of particles formed of different materials.

  Examples of the shape of the nonconductive particles include a spherical shape, an elliptical spherical shape, a polygonal shape, a tetrapod (registered trademark) shape, a plate shape, and a scale shape. Among these, tetrapod (registered trademark) shape, plate shape, and scale shape are preferable from the viewpoint of increasing the porosity of the porous membrane and suppressing the decrease in ion conductivity due to the porous membrane separator.

  The volume average particle diameter of the non-conductive particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, preferably 5 μm or less, more preferably 1 μm or less. By making the volume average particle diameter of the non-conductive particles equal to or more than the lower limit of the above range, the dispersibility of the non-conductive particles in the porous film can be improved, and thus a porous film having excellent uniformity can be obtained. . Moreover, the porous film excellent in durability can be obtained by making it into an upper limit or less. Here, the volume average particle diameter represents the particle diameter at which the cumulative volume calculated from the small diameter side becomes 50% in the particle diameter distribution measured by the laser diffraction method.

The BET specific surface area of the non-conductive particles is, for example, preferably 0.9 m ² / g or more, more preferably 1.5 m ² / g or more. Further, from the viewpoint of suppressing aggregation of non-conductive particles and optimizing the fluidity of the porous membrane slurry composition, the BET specific surface area is preferably not too large, for example, 150 m ² / g or less.

  The amount of non-conductive particles in the porous membrane is preferably 60% by weight or more, more preferably 65% by weight or more, and preferably 95% by weight or less. By setting the amount of the non-conductive particles in the porous film within this range, the gap between the non-conductive particles can be formed to the extent that the non-conductive particles have contact portions and the movement of ions is not hindered. . Therefore, by keeping the amount of the non-conductive particles within the above range, the strength of the porous film can be improved and the short circuit of the lithium ion secondary battery can be stably prevented.

[1.2. Water-soluble polymer)
The porous membrane slurry composition of the present invention contains a water-soluble polymer. In the porous membrane slurry composition, a part of the water-soluble polymer is released in water, while another part is adsorbed on the surface of the non-conductive particles to form a stable layer covering the non-conductive particles. Thus, it is possible to enhance the dispersibility and dispersion stability of the non-conductive particles. In addition, the water-soluble polymer has a function of binding non-conductive particles by interposing between non-conductive particles in the porous film, and between the non-conductive particles and the separator substrate or the electrode plate. By intervening, the effect of binding the porous film and the separator substrate or the electrode plate can be achieved.

  The water-soluble polymer includes an acid group-containing monomer unit. Here, the acid group-containing monomer unit refers to a structural unit having a structure formed by polymerizing an acid group-containing monomer. Moreover, an acid group containing monomer shows the monomer containing an acid group. Therefore, the water-soluble polymer having an acid group-containing monomer unit also contains an acid group. Since the affinity of the water-soluble polymer to water is increased by the action of the acid group, the water-soluble polymer is soluble in water. In addition, since the water-soluble polymer has high adsorptivity to non-conductive particles because it has a highly polar acid group, the water-soluble polymer containing an acid group-containing monomer unit is a water-soluble polymer. As described above, a part of the layer easily forms a stable layer on the surface of the non-conductive particles. Therefore, in the porous membrane slurry composition, it is possible to effectively increase the dispersibility of the nonconductive particles.

The acid group, for example, -COOH group (carboxylic acid group); - SO ₃ H group (sulfonic acid group); - _PO 3 _{H 2} group and -PO (OH) (OR) group (R is a hydrocarbon radical A phosphoric acid group such as Accordingly, examples of the acid group-containing monomer include monomers having these acid groups. In addition, for example, a monomer capable of generating the acid group by hydrolysis is also exemplified as the acid group-containing monomer. Specific examples of such acid group-containing monomers include acid anhydrides that can generate carboxylic acid groups by hydrolysis.

  Examples of the monomer having a carboxylic acid group (carboxylic acid monomer) include monocarboxylic acids, dicarboxylic acids, dicarboxylic acid anhydrides, and derivatives thereof. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, 2-ethylacrylic acid, and isocrotonic acid. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, and methylmaleic acid. Examples of the acid anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride and the like. Among these, monocarboxylic acid is preferable, and acrylic acid and methacrylic acid are more preferable.

  Examples of the monomer having a sulfonic acid group (sulfonic acid monomer) include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, and (meth) acrylic acid-2-sulfonic acid. Examples include ethyl, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, 2- (N-acryloyl) amino-2-methyl-1,3-propane-disulfonic acid, and the like. Among these, 2-acrylamido-2-methylpropanesulfonic acid is preferable.

  Examples of the monomer having a phosphoric acid group (phosphoric acid monomer) include phosphoric acid-2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, ethyl phosphate- ( And (meth) acryloyloxyethyl.

  Moreover, you may use the salt of the monomer mentioned above as an acid group containing monomer. Examples of such a salt include a sodium salt of styrene sulfonic acid such as p-styrene sulfonic acid.

  Among the acid group-containing monomers described above, a monomer having a carboxylic acid group and a monomer having a sulfonic acid group are preferable. That is, the acid group-containing monomer unit preferably has at least one group selected from the group consisting of a carboxylic acid group and a sulfonic acid group. Thereby, the adsorptivity with respect to the nonelectroconductive particle of a water-soluble polymer can be improved effectively, and the dispersibility of a nonelectroconductive particle can be improved more.

  Moreover, an acid group containing monomer and an acid group containing monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The ratio of the acid group-containing monomer unit in the water-soluble polymer is usually 20% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more, and usually 80% by weight or less, preferably 75% by weight. Hereinafter, it is more preferably 70% by weight or less. By making the ratio of the acid group-containing monomer unit more than the lower limit of the above range, the dispersibility of the nonconductive particles in the porous membrane slurry composition can be enhanced, and therefore the nonconductive particles in the porous membrane can be dispersed. Can increase the sex. Moreover, durability of a porous film can be improved by making it into an upper limit or less.

  The water-soluble polymer contains an amide monomer unit in combination with an acid group-containing monomer unit. Generation | occurrence | production of gas can be prevented in a lithium ion secondary battery because a water-soluble polymer contains an amide monomer unit. Moreover, this effect can be enhanced by combining the amide monomer unit and the acid group-containing monomer unit. Furthermore, since the water-soluble polymer is dissolved in the porous membrane slurry composition and spreads uniformly, it can effectively contribute to the prevention of gas generation in the formed porous membrane. The reason why the generation of gas can be suppressed in this way is not necessarily clear, but the water-soluble polymer containing the amide monomer unit traps the halide ions in the electrolytic solution, thereby causing the gas caused by the halide ions. It is presumed that the occurrence of the occurrence can be suppressed.

  Examples of the amide monomer include the same examples as those exemplified in the description of the non-conductive particles. Among these, from the viewpoint of enhancing the durability of the porous film, a carboxylic acid amide monomer is preferable, an unsaturated carboxylic acid amide compound is more preferable, and (meth) acrylamide and N-hydroxymethyl (meth) acrylamide are particularly preferable. Moreover, an amide monomer and an amide monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The ratio of the amide monomer unit in the water-soluble polymer is usually 0.1% by weight or more, preferably 0.2% by weight or more, more preferably 0.5% by weight or more, and usually 10% by weight or less, preferably Is 8% by weight or less, more preferably 5% by weight or less. By setting the ratio of the amide monomer in the water-soluble polymer to be equal to or higher than the lower limit of the above range, generation of gas due to halide ions in the lithium ion secondary battery can be suppressed. Moreover, by making it into the upper limit value or less, it is possible to prevent the water-soluble polymer from eluting into the electrolytic solution, and it is possible to suppress the generation of gas due to the decomposition of the amide monomer unit itself. Therefore, the action of water-soluble polymer such as the action of suppressing the generation of gas; the action of binding non-conductive particles to each other and the action of binding the porous film and the separator substrate or the electrode plate is stabilized. It will be possible to demonstrate.

  The water-soluble polymer preferably contains a crosslinkable monomer unit in combination with an acid group-containing monomer unit and an amide monomer unit. Here, the crosslinkable monomer unit is a structural unit having a structure obtained by polymerizing a crosslinkable monomer. The crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays. By including a crosslinkable monomer unit, the water-soluble polymer can be crosslinked, so that the strength and stability of the porous membrane can be increased. Thereby, it is possible to stably exhibit the action of the water-soluble polymer. Moreover, since the degree of swelling of the water-soluble polymer by the electrolytic solution can be prevented from becoming excessively high, the low-temperature output characteristics of the lithium ion secondary battery can be usually improved.

  As the crosslinkable monomer, a monomer capable of forming a crosslinked structure upon polymerization can be used. Examples of the crosslinkable monomer include monomers having two or more reactive groups per molecule. More specifically, a monofunctional monomer having a heat-crosslinkable crosslinkable group and one olefinic double bond per molecule, and a polyfunctional having two or more olefinic double bonds per molecule. Ionic monomers.

  Examples of the thermally crosslinkable group contained in the monofunctional monomer include an epoxy group, an oxetanyl group, an oxazoline group, and a combination thereof. Among these, an epoxy group is more preferable in terms of easy adjustment of crosslinking and crosslinking density.

  Examples of the crosslinkable monomer having an epoxy group as a thermally crosslinkable group and having an olefinic double bond include vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o-allylphenyl glycidyl. Unsaturated glycidyl ethers such as ether; butadiene monoepoxide, chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene Monoepoxides of dienes or polyenes such as; alkenyl epoxides such as 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene, 1,2-epoxy-9-decene; and glycidyl acrylate, glycidyl methacrylate, Glycidyl crotonate, glycidyl Unsaturated carboxylic acids such as -4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl-4-methyl-3-pentenoate, glycidyl ester of 3-cyclohexene carboxylic acid, glycidyl ester of 4-methyl-3-cyclohexene carboxylic acid Glycidyl esters; and the like.

  Examples of the crosslinkable monomer having an oxetanyl group as a heat crosslinkable group and having an olefinic double bond include 3-((meth) acryloyloxymethyl) oxetane, 3-((meth) Acryloyloxymethyl) -2-trifluoromethyloxetane, 3-((meth) acryloyloxymethyl) -2-phenyloxetane, 2-((meth) acryloyloxymethyl) oxetane, and 2-((meth) acryloyloxymethyl ) -4-trifluoromethyloxetane.

  Examples of the crosslinkable monomer having an oxazoline group as a thermally crosslinkable group and having an olefinic double bond include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2- Oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, and And 2-isopropenyl-5-ethyl-2-oxazoline.

  Examples of multifunctional monomers having two or more olefinic double bonds include allyl (meth) acrylate, ethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, Tetraethylene glycol di (meth) acrylate, trimethylolpropane-tri (meth) acrylate, dipropylene glycol diallyl ether, polyglycol diallyl ether, triethylene glycol divinyl ether, hydroquinone diallyl ether, tetraallyloxyethane, trimethylolpropane-diallyl Examples include ethers, allyls or vinyl ethers of polyfunctional alcohols other than those described above, triallylamine, and divinylbenzene.

Especially, as a crosslinkable monomer, ethylene dimethacrylate, allyl glycidyl ether, glycidyl methacrylate, and ethylene glycol dimethacrylate are preferable, and ethylene dimethacrylate, allyl glycidyl ether, and glycidyl methacrylate are more preferable.
Moreover, a crosslinking | crosslinked monomer and a crosslinking | crosslinked monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The proportion of the crosslinkable monomer unit in the water-soluble polymer is preferably 0.1% by weight or more, more preferably 0.15% by weight or more, particularly preferably 0.2% by weight or more, preferably 2. It is 0 wt% or less, more preferably 1.5 wt% or less, and particularly preferably 1.0 wt% or less. Since the mechanical strength of the water-soluble polymer can be increased by setting the ratio of the crosslinkable monomer unit in the water-soluble polymer to be equal to or higher than the lower limit of the above range, the connection between the porous film and the separator substrate or electrode plate can be increased. Wearability can be improved. Moreover, durability of a porous film can be improved by making it into an upper limit or less.

  The water-soluble polymer can contain a fluorine-containing monomer unit. The fluorine-containing monomer unit is a structural unit having a structure formed by polymerizing a fluorine-containing monomer. Since the fluorine-containing monomer unit usually has high ionic conductivity, the ionic conductivity of the water-soluble polymer may be increased to reduce the internal resistance of the lithium ion secondary battery.

  Examples of the fluorine-containing monomer include a fluorine-containing (meth) acrylic acid ester monomer and a fluorine-containing aromatic diene monomer, and among them, a fluorine-containing (meth) acrylic acid ester monomer is preferable.

  Examples of the fluorine-containing (meth) acrylic acid ester monomer include monomers represented by the following formula (I).

In the above formula (I), R ¹ represents a hydrogen atom or a methyl group.
In the above formula (I), R ² represents a hydrocarbon group containing a fluorine atom. The carbon number of the hydrocarbon group is preferably 1 or more, and preferably 18 or less. Moreover, the number of fluorine atoms contained in R ² may be one or two or more.

Examples of fluorine-containing (meth) acrylic acid ester monomers represented by formula (I) include (meth) acrylic acid alkyl fluoride, (meth) acrylic acid fluoride aryl, and (meth) acrylic acid fluoride. Aralkyl is mentioned. Of these, alkyl fluoride (meth) acrylate is preferable. Specific examples of such a monomer include 2,2,2-trifluoroethyl (meth) acrylate; β- (perfluorooctyl) ethyl (meth) acrylate; 3,3-tetrafluoropropyl; (meth) acrylic acid 2,2,3,4,4,4-hexafluorobutyl; (meth) acrylic acid 3 [4 [1-trifluoromethyl-2,2-bis [ Bis (trifluoromethyl) fluoromethyl] ethynyloxy] benzooxy] 2-hydroxypropyl; (meth) acrylic acid 1H, 1H, 9H-perfluoro-1-nonyl, (meth) acrylic acid 1H, 1H, 11H-perfluoro (Medec) such as undecyl, perfluorooctyl (meth) acrylate, perfluoroethyl (meth) acrylate, trifluoromethyl (meth) acrylate, etc. ) Acrylic acid perfluoroalkyl ester.
Moreover, a fluorine-containing monomer and a fluorine-containing monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The proportion of fluorine-containing monomer units in the water-soluble polymer is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. . By setting the ratio of the fluorine-containing monomer unit to be equal to or higher than the lower limit of the above range, the cycle characteristics of the lithium ion secondary battery may be improved. Moreover, the binding property of a porous membrane, a separator base material, or an electrode plate may be improved by making it into an upper limit or less.
On the other hand, by setting the ratio of the fluorine-containing monomer unit in the water-soluble polymer to less than 0.1% by weight, it becomes easy to form a porous film on the substrate with a uniform thickness, and the durability of the porous film is increased. The sex can be increased.

The water-soluble polymer may contain an arbitrary structural unit in addition to the acid group-containing monomer unit, amide monomer unit, crosslinkable monomer unit, and fluorine-containing monomer unit described above.
For example, the water-soluble polymer can contain (meth) acrylic acid ester monomer units. The (meth) acrylic acid ester monomer unit is a structural unit having a structure formed by polymerizing a (meth) acrylic acid ester monomer. However, among the (meth) acrylate monomers, those containing fluorine are distinguished from (meth) acrylate monomers as fluorine-containing (meth) acrylate monomers.

  Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, Acrylic acid alkyl esters such as 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate; and methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t -Butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl Methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n- tetradecyl methacrylate, methacrylic acid alkyl esters such as stearyl methacrylate. Moreover, a (meth) acrylic acid ester monomer and a (meth) acrylic acid ester monomer unit may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The proportion of the (meth) acrylic acid ester monomer unit in the water-soluble polymer is preferably 25% by weight or more, more preferably 30% by weight or more, particularly preferably 35% by weight or more, and preferably 75% by weight. % Or less, more preferably 70% by weight or less, and particularly preferably 65% by weight or less. By setting the amount of the (meth) acrylic acid ester monomer unit to be equal to or higher than the lower limit of the above range, the binding property of the porous membrane to the separator substrate or the electrode plate can be increased. Moreover, the softness | flexibility of a porous film can be improved by making it into an upper limit or less.

  Further examples of arbitrary structural units that the water-soluble polymer may contain include structural units having a structure formed by polymerizing the following monomers. That is, aromatic vinyl monomers such as styrene, chlorostyrene, vinyl toluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, hydroxymethyl styrene, α-methyl styrene, divinyl benzene, etc. Α, β-unsaturated nitrile compound monomers such as acrylonitrile and methacrylonitrile; Olefin monomers such as ethylene and propylene; Halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; Vinyl acetate and vinyl propionate Vinyl ester monomers such as vinyl butyrate and vinyl benzoate; vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether and butyl vinyl ether; methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, isopropyl And a structural unit having a structure formed by polymerizing one or more of vinyl ketone monomers such as nyl vinyl ketone; and heterocyclic ring-containing vinyl compound monomers such as N-vinyl pyrrolidone, vinyl pyridine and vinyl imidazole. . Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The weight average molecular weight of the water-soluble polymer is preferably 5,000 or more, more preferably 10,000 or more, particularly preferably 20,000 or more, preferably 1,000,000 or less, more preferably 750,000 or less, Particularly preferably, it is 500,000 or less. By setting the weight average molecular weight of the water-soluble polymer to be equal to or higher than the lower limit of the above range, the binding property between the porous membrane and the separator substrate or the electrode plate can be enhanced. Moreover, the cycle characteristic of a lithium ion secondary battery can be improved by being below an upper limit. Here, the weight average molecular weight of the water-soluble polymer can be determined by GPC as a value in terms of polystyrene using, as a developing solvent, a solution obtained by dissolving 0.85 g / ml sodium nitrate in a 10% by volume aqueous solution of dimethylformamide.

  The amount of the water-soluble polymer in the porous membrane slurry composition is preferably 0.2 parts by weight or more, more preferably 0.5 parts by weight or more, preferably 10 parts by weight with respect to 100 parts by weight of the non-conductive particles. Part or less, more preferably 5 parts by weight or less. By making the amount of the water-soluble polymer more than the lower limit of the above range, the adhesion of the porous membrane to the separator substrate or electrode plate can be enhanced. Moreover, the ion conductivity of a porous film can be made high by making it into an upper limit or less.

  The water-soluble polymer can be produced, for example, by polymerizing a monomer composition containing the above-described monomer in an aqueous solvent. At this time, the ratio of each monomer in the monomer composition is usually the same as the ratio of structural units in the water-soluble polymer.

As the aqueous solvent, a solvent capable of dispersing a water-soluble polymer can be used. Usually, the boiling point at normal pressure is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and preferably 350 ° C. or lower, more preferably 300 ° C. or lower. Examples of the aqueous solvent will be given below. In the following examples, the number in parentheses after the solvent name is the boiling point (unit: ° C) at normal pressure, and the value after the decimal point is a value rounded off or rounded down.
Examples of aqueous solvents include water (100); ketones such as diacetone alcohol (169) and γ-butyrolactone (204); ethyl alcohol (78), isopropyl alcohol (82), normal propyl alcohol (97) and the like. Alcohols: propylene glycol monomethyl ether (120), methyl cellosolve (124), ethyl cellosolve (136), ethylene glycol tertiary butyl ether (152), butyl cellosolve (171), 3-methoxy-3-methyl-1-butanol (174) ), Ethylene glycol monopropyl ether (150), diethylene glycol monobutyl ether (230), triethylene glycol monobutyl ether (271), dipropylene glycol monomethyl ether (188) Glycol ethers; and 1,3-dioxolane (75), 1,4-dioxolane (101), ethers such as tetrahydrofuran (66) and the like. Among these, water is particularly preferable from the viewpoint that it is not flammable and a polymer dispersion can be easily obtained. Further, water may be used as the main solvent, and an aqueous solvent other than the above-described water may be mixed and used within a range in which the dispersion state of the polymer can be ensured.

  The polymerization method is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used. As the polymerization method, any method such as ion polymerization, radical polymerization, and living radical polymerization can be used. Manufacturing efficiency, such as easy to obtain a high molecular weight, and no need for redispersion treatment because the polymer is obtained in a state of being dispersed in water as it is, and can be used for the production of a porous membrane slurry composition. From the viewpoint of the above, the emulsion polymerization method is particularly preferable.

  The emulsion polymerization method is usually performed by a conventional method. For example, the method is described in “Experimental Chemistry Course” Vol. 28, (Publisher: Maruzen Co., Ltd., edited by The Chemical Society of Japan). That is, water, an additive such as a dispersant, an emulsifier, a crosslinking agent, a polymerization initiator, and a monomer are added to a sealed container equipped with a stirrer and a heating device so as to have a predetermined composition. In this method, the composition is stirred to emulsify monomers and the like in water, and the temperature is increased while stirring to initiate polymerization. Or after emulsifying the said composition, it is the method of putting into a sealed container and starting reaction similarly.

  Examples of polymerization initiators include organic compounds such as lauroyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 3,3,5-trimethylhexanoyl peroxide, and the like. Peroxides; azo compounds such as α, α′-azobisisobutyronitrile; ammonium persulfate; and potassium persulfate. A polymerization initiator may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Additives such as emulsifiers, dispersants, polymerization initiators and the like are generally used in these polymerization methods, and the amount of the additives used is also generally used.

The polymerization temperature and polymerization time can be arbitrarily selected depending on the polymerization method and the type of polymerization initiator. Usually, the polymerization temperature is about 30 ° C. or more, and the polymerization time is about 0.5 to 30 hours.
Further, an additive such as amine may be used as a polymerization aid.

  Examples of the method for adjusting the molecular weight of the polymer include adjusting the molecular weight of the polymer by controlling the amount of the emulsifier, the amount of the molecular weight modifier such as a crosslinkable monomer, the amount of the polymerization initiator, and the reaction temperature. it can.

  A reaction solution containing a water-soluble polymer is usually obtained by polymerization. The obtained reaction solution is usually acidic, and the water-soluble polymer is often dispersed in an aqueous solvent. The water-soluble polymer dispersed in the water-soluble solvent as described above can be usually made soluble in an aqueous solvent by adjusting the pH of the reaction solution to, for example, 7 to 13. You may take out a water-soluble polymer from the reaction liquid obtained in this way. However, usually, water is used as an aqueous medium, and the porous membrane slurry composition of the present invention is produced using a water-soluble polymer dissolved in water.

  Examples of the method for alkalizing the reaction solution to pH 7 to pH 13 include alkali metal aqueous solutions such as lithium hydroxide aqueous solution, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution; alkaline earth such as calcium hydroxide aqueous solution and magnesium hydroxide aqueous solution. Metal aqueous solution: A method of mixing an alkaline aqueous solution such as an aqueous ammonia solution. One kind of the alkaline aqueous solution may be used alone, or two or more kinds may be used in combination at any ratio.

[1.3. (Particulate polymer)
The particulate polymer is a polymer particle. By including the particulate polymer, the following advantages are usually obtained. That is, the binding property of the porous film is improved, and the separator for lithium ion secondary battery of the present invention (hereinafter sometimes referred to as “separator” as appropriate) or the lithium ion secondary during handling such as winding and transportation. The strength against mechanical force applied to the battery electrode (hereinafter sometimes referred to as “electrode” as appropriate) can be improved. Further, since the shape of the particulate polymer is particulate, the particulate polymer can be bound to the non-conductive particles by a point instead of a surface. For this reason, since the hole in a porous film can be enlarged, the internal resistance of a lithium ion secondary battery can be made small.

  Various polymers can be used as the polymer constituting the particulate polymer, but a water-insoluble polymer is usually used. Examples of the polymer that forms the particulate polymer include polyethylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid derivatives, A polyacrylonitrile derivative or the like may be used.

Furthermore, the soft polymer particles exemplified below may be used as the particulate polymer. As a soft polymer, for example,
(I) Polybutyl acrylate, polybutyl methacrylate, polyhydroxyethyl methacrylate, polyacrylamide, polyacrylonitrile, butyl acrylate / styrene copolymer, butyl acrylate / acrylonitrile copolymer, butyl acrylate / acrylonitrile / glycidyl methacrylate copolymer, etc. An acrylic soft polymer which is a homopolymer of acrylic acid or a methacrylic acid derivative or a copolymer thereof with a monomer copolymerizable therewith;
(Ii) isobutylene-based soft polymers such as polyisobutylene, isobutylene-isoprene rubber, isobutylene-styrene copolymer;
(Iii) Polybutadiene, polyisoprene, butadiene / styrene random copolymer, isoprene / styrene random copolymer, acrylonitrile / butadiene copolymer, acrylonitrile / butadiene / styrene copolymer, butadiene / styrene / block copolymer, styrene・ Diene-based soft polymers such as butadiene, styrene, block copolymers, isoprene, styrene, block copolymers, styrene, isoprene, styrene, block copolymers;
(Iv) silicon-containing soft polymers such as dimethylpolysiloxane, diphenylpolysiloxane, dihydroxypolysiloxane;
(V) Liquid polyethylene, polypropylene, poly-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, ethylene / propylene / diene copolymer (EPDM), ethylene / propylene / styrene copolymer Olefinic soft polymers such as polymers;
(Vi) Vinyl-based soft polymers such as polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, vinyl acetate / styrene copolymer;
(Vii) epoxy-based soft polymers such as polyethylene oxide, polypropylene oxide, epichlorohydrin rubber;
(Viii) Fluorine-containing soft polymers such as vinylidene fluoride rubber and tetrafluoroethylene-propylene rubber;
(Ix) Other soft polymers such as natural rubber, polypeptide, protein, polyester thermoplastic elastomer, vinyl chloride thermoplastic elastomer, polyamide thermoplastic elastomer, and the like. Among these, a diene soft polymer and an acrylic soft polymer are preferable. In addition, these soft polymers may have a cross-linked structure or may have a functional group introduced by modification.
Moreover, a particulate polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The weight average molecular weight of the polymer constituting the particulate polymer is preferably 10,000 or more, more preferably 20,000 or more, preferably 1,000,000 or less, more preferably 500,000 or less. . By keeping the weight average molecular weight of the polymer constituting the particulate polymer in the above range, the strength of the porous film and the dispersibility of the non-conductive particles can be easily improved. Here, the weight average molecular weight of the polymer constituting the particulate polymer can be determined by gel permeation chromatography (GPC) as a value in terms of polystyrene using tetrahydrofuran as a developing solvent.

  The glass transition temperature of the particulate polymer is preferably −75 ° C. or higher, more preferably −55 ° C. or higher, particularly preferably −35 ° C. or higher, preferably 40 ° C. or lower, more preferably 30 ° C. or lower, and even more. Preferably it is 20 degrees C or less, Most preferably, it is 15 degrees C or less. By keeping the glass transition temperature of the particulate polymer within the above range, characteristics such as flexibility and winding properties of the separator and electrode provided with the porous membrane, and binding properties between the porous membrane and the separator substrate or electrode plate, etc. Is highly balanced and suitable. The glass transition temperature of the particulate polymer can be adjusted, for example, by combining various monomers.

  The volume average particle size of the particulate polymer is preferably 50 nm or more, more preferably 70 nm or more, preferably 500 nm or less, more preferably 400 nm or less. By keeping the volume average particle diameter of the particulate polymer in the above range, the strength and flexibility of the porous film can be improved.

  The amount of the particulate polymer is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, preferably 10 parts by weight or less, more preferably 100 parts by weight of non-conductive particles. 5 parts by weight or less. By setting the amount of the particulate polymer to be equal to or higher than the lower limit of the above range, the strength of the porous film can be increased. Moreover, the rate characteristic of a lithium ion secondary battery can be made favorable by setting it as below an upper limit. In addition, the amount of the particulate polymer in the above range usually has a high binding property between the non-conductive particles and the binding property between the porous membrane and the separator substrate or the electrode plate, It is also significant in that the flexibility of the porous membrane can be increased and the ion conductivity of the porous membrane can be increased.

  The weight ratio of the water-soluble polymer to the particulate polymer (water-soluble polymer / particulate polymer) is preferably within a predetermined range. Specifically, the weight ratio is preferably 0.01 or more, more preferably 0.1 or more, and is preferably 1.5 or less, more preferably 1.0 or less. By making the said weight ratio more than the lower limit of the said range, the dispersibility of a nonelectroconductive particle and the intensity | strength of a porous film can be improved. Moreover, stability of a porous membrane slurry composition can be improved by making it into an upper limit or less.

  The production method of the particulate polymer is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method may be used. Among these, the emulsion polymerization method and the suspension polymerization method are preferable because they can be polymerized in water and used as they are as the material for the porous membrane slurry composition. Moreover, when manufacturing a particulate polymer, it is preferable to include a dispersing agent in the reaction system. The particulate polymer is usually composed of a polymer substantially constituting it, but may be accompanied by any component such as an additive added during the polymerization.

[1.4. water〕
The porous membrane slurry composition of the present invention contains water. Water functions as a solvent or dispersion medium in the porous membrane slurry composition. Usually, in the porous membrane slurry composition, the water-soluble polymer is dissolved in water, and the particulate polymer is dispersed in water.

  Further, as the solvent, a solvent other than water may be used in combination with water. Examples of the solvent that can be used in combination with water include cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as ethyl methyl ketone and cyclohexanone; ethyl acetate and acetic acid Esters such as butyl, γ-butyrolactone, ε-caprolactone; nitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether: methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, and the like Alcohols; amides such as N-methylpyrrolidone (NMP) and N, N-dimethylformamide; and the like. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  The amount of the solvent in the porous membrane slurry composition is preferably set so that the solid content concentration of the porous membrane slurry composition falls within a desired range. The solid content concentration of the specific porous membrane slurry composition is preferably 10% by weight or more, more preferably 15% by weight or more, particularly preferably 20% by weight or more, preferably 80% by weight or less, more preferably 75%. % By weight or less, particularly preferably 70% by weight or less. Here, solid content means the substance which remains after drying of a porous membrane slurry composition.

[1.5. (Optional ingredients)
The porous membrane slurry composition may contain an optional component in addition to the above-described non-conductive particles, water-soluble polymer, particulate polymer and water. As such optional components, those which do not exert an excessively unfavorable influence on the battery reaction can be used. Arbitrary components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  For example, the porous membrane slurry composition preferably contains a carboxymethyl cellulose salt. Carboxymethylcellulose salt acts as a thickener in the porous membrane slurry composition. Therefore, since the viscosity of the porous membrane slurry composition can be increased by the carboxymethyl cellulose salt, the applicability of the porous membrane slurry composition can be improved. In addition, the carboxymethyl cellulose salt can usually increase the dispersion stability of the non-conductive particles in the porous membrane slurry composition, and can improve the binding property between the porous membrane and the separator substrate or the electrode plate. Examples of the carboxymethyl cellulose salt include a sodium salt and an ammonium salt. Moreover, carboxymethylcellulose salt may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the carboxymethyl cellulose salt is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, preferably 10 parts by weight or less, more preferably 7 parts by weight with respect to 100 parts by weight of the non-conductive particles. It is at most 5 parts by weight, particularly preferably at most 5 parts by weight. By setting the amount of the carboxymethyl cellulose salt in the above range, the viscosity of the porous membrane slurry composition can be adjusted to a suitable range that is easy to handle. Usually, carboxymethylcellulose salt is also contained in the porous membrane. Here, the intensity | strength of a porous film can be made high by making the quantity of a carboxymethylcellulose salt more than the lower limit of the said range. Moreover, the softness | flexibility of a porous film can be made favorable by setting it as below an upper limit.

  The porous membrane slurry composition is, for example, an isothiazoline-based compound, a chelate compound, a pyrithione compound, a dispersant, a leveling agent, an antioxidant, a thickener, an antifoaming agent, a wetting agent, and a function of inhibiting electrolyte decomposition. It may contain an electrolyte solution additive and the like.

[1.6. Properties of porous membrane slurry composition]
The porous membrane slurry composition of the present invention is usually excellent in dispersibility of each component contained in the composition. Therefore, the viscosity of the porous membrane slurry composition of the present invention can usually be easily lowered. The specific viscosity of the porous membrane slurry composition is preferably 10 mPa · s to 2000 mPa · s from the viewpoint of improving the applicability when producing the porous membrane. Here, the said viscosity is a value when it measures at 25 degreeC and rotation speed 60rpm using an E-type viscosity meter.

  Moreover, the porous membrane slurry composition of the present invention is usually excellent in dispersion stability. Here, the dispersion stability of the porous membrane slurry composition means that the dispersibility of the composition does not easily change over time, and specifically, the viscosity of the composition does not easily change over time. Represents. Therefore, even when a porous membrane slurry composition stored for a long time is used, a high-quality porous membrane can be obtained.

[1.7. Method for producing porous membrane slurry composition]
Although the manufacturing method of a porous film slurry composition is not specifically limited, Usually, each component mentioned above is mixed and obtained. There is no particular limitation on the mixing order. There is no particular limitation on the mixing method. Usually, in order to disperse non-conductive particles quickly, mixing is performed using a disperser as a mixing device.

  The disperser is preferably an apparatus capable of uniformly dispersing and mixing the above components. Examples include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, and a planetary mixer. Among them, a high dispersion apparatus such as a bead mill, a roll mill, or a fill mix is particularly preferable because a high dispersion share can be added.

[2. Porous membrane for secondary battery]
By applying the porous membrane slurry composition of the present invention on a suitable substrate and drying, a porous membrane can be produced as a membrane formed by the solid content of the porous membrane slurry composition. That is, a porous membrane is produced by a production method including a step of applying a porous membrane slurry composition onto a substrate to obtain a membrane of the porous membrane slurry composition, and a step of removing a solvent such as water from the membrane by drying. Can be manufactured. This porous film has an action of suppressing gas generation in a lithium ion secondary battery including the porous film.

  A base material is a member used as the object which forms the film | membrane of a porous membrane slurry composition. There is no restriction | limiting in a base material, For example, the film | membrane of a porous film slurry composition is formed in the surface of a peeling film, a solvent is removed from the film | membrane, a porous film may be formed, and a porous film may be peeled from a peeling film. However, normally, from the viewpoint of improving the production efficiency by omitting the step of peeling the porous film, the constituent elements of the battery are used as the base material. Examples of such battery components include separator substrates and electrode plates.

  Examples of the coating method include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method. Among these, the dip method and the gravure method are preferable in that a uniform porous film can be obtained.

  Examples of the drying method include drying with warm air, hot air, low-humidity air, and the like; vacuum drying; drying method by irradiation with infrared rays, far infrared rays, and electron beams.

  The temperature during drying is preferably 40 ° C. or higher, more preferably 45 ° C. or higher, particularly preferably 50 ° C. or higher, preferably 90 ° C. or lower, more preferably 80 ° C. or lower, particularly preferably 70 ° C. or lower. . By setting the drying temperature to be equal to or higher than the lower limit of the above range, the solvent and the low-molecular compound from the porous membrane slurry composition can be efficiently removed. Moreover, the deformation | transformation by the heat | fever of a base material can be suppressed by setting it as below an upper limit.

  The drying time is preferably 5 seconds or more, more preferably 10 seconds or more, particularly preferably 15 seconds or more, preferably 3 minutes or less, more preferably 2 minutes or less, and particularly preferably 1 minute or less. By setting the drying time to be not less than the lower limit of the above range, the solvent can be sufficiently removed from the porous membrane slurry composition, so that the output characteristics of the battery can be improved. Moreover, manufacturing efficiency can be improved by setting it as an upper limit or less.

In the method for producing a porous membrane, any operation other than those described above may be performed.
For example, the porous film may be subjected to pressure treatment by a pressing method such as a mold press and a roll press. By performing the pressure treatment, the binding property between the substrate and the porous film can be improved. However, from the viewpoint of keeping the porosity of the porous film within a preferable range, it is preferable to appropriately control the pressure and the pressurization time so as not to become excessively large.
In order to remove residual moisture, it is preferable to dry in, for example, vacuum drying or a dry room.
Further, for example, heat treatment is also preferable, whereby the thermal crosslinking group contained in the polymer component can be crosslinked to increase the binding force.

  The thickness of the porous membrane is preferably 0.1 μm or more, more preferably 0.2 μm or more, particularly preferably 0.3 μm or more, preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. By setting the thickness of the porous film to be equal to or more than the lower limit of the above range, the heat resistance of the porous film can be increased. Moreover, the fall of the ionic conductivity by a porous film can be suppressed by setting it as an upper limit or less.

[3. Secondary battery separator]
The separator of the present invention includes a separator substrate and a porous membrane. In the separator of the present invention, the provision of the porous film makes it possible to prevent the separator base material from being damaged by foreign substances and the separator base material from being contracted by heat. Therefore, the internal short circuit of a lithium ion secondary battery provided with this separator can be prevented, and the safety of the battery can be improved. Moreover, since the separator of this invention is equipped with the porous film which concerns on this invention, generation | occurrence | production of gas can be suppressed in a lithium ion secondary battery provided with the said separator.

[3.1. (Separator base material)
As the separator substrate, for example, a porous substrate having fine pores can be used. By using such a separator base material, it is possible to prevent a short circuit without interfering with charge / discharge of the battery in the secondary battery. When the specific example of a separator base material is given, the microporous film or nonwoven fabric containing polyolefin resin, such as polyethylene resin and a polypropylene resin, an aromatic polyamide resin, etc. are mentioned.

  The thickness of the separator substrate is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 10 μm or less. Within this range, the resistance due to the separator substrate in the secondary battery is reduced, and the workability during battery production is excellent.

[3.2. (Porous membrane provided in secondary battery separator)
The separator of this invention is equipped with the porous film mentioned above on the separator base material. That is, the separator of this invention is equipped with a separator base material and the porous film obtained by apply | coating a porous film slurry composition on the said separator base material, and drying. Such a separator can be manufactured, for example, by performing the above-described method for manufacturing a porous film using a separator base material as a base material. At this time, the porous film may be provided on only one surface of the separator base material, or may be provided on both surfaces.

[4. Secondary battery electrode]
The electrode of the present invention includes an electrode plate and a porous film. Further, the electrode plate usually includes a current collector and an electrode active material layer. In the electrode of the present invention, the provision of the porous film prevents detachment of particles such as electrode active material from the electrode active material layer, separation of the electrode active material layer from the current collector, and internal short circuit of the battery. Can be prevented. Moreover, since the electrode of this invention is equipped with the porous film which concerns on this invention, generation | occurrence | production of gas can be suppressed in a lithium ion secondary battery provided with the said electrode.

[4.1. Current collector]
The current collector may be made of a material having electrical conductivity and electrochemical durability. Usually, a metal material is used as the material of the current collector. Examples thereof include iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum and the like. Among them, the current collector used for the positive electrode is preferably aluminum, and the current collector used for the negative electrode is preferably copper. Moreover, the said material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The shape of the current collector is not particularly limited, but a sheet shape having a thickness of about 0.001 mm to 0.5 mm is preferable.

  In order to increase the adhesion strength with the electrode active material layer, the current collector is preferably used after roughening the surface in advance. Examples of the roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. In the mechanical polishing method, for example, an abrasive cloth paper to which abrasive particles are fixed, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like is used. In order to increase the adhesion strength and conductivity of the electrode active material layer, an intermediate layer may be formed on the surface of the current collector.

[4.2. Electrode active material layer
The electrode active material layer is a layer provided on the current collector and includes an electrode active material.
As the electrode active material of the lithium ion secondary battery, a material capable of reversibly inserting or releasing lithium ions by applying a potential in an electrolytic solution can be used. As the electrode active material, an inorganic compound or an organic compound may be used.

The positive electrode active material is roughly classified into those made of inorganic compounds and those made of organic compounds. Examples of the positive electrode active material made of an inorganic compound include transition metal oxides, composite oxides of lithium and transition metals, and transition metal sulfides. Examples of the transition metal include Fe, Co, Ni, and Mn. Specific examples of the inorganic compound used for the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiFeVO _{4 and} other lithium-containing composite metal oxides; TiS ₂ , TiS ₃ , non- Transition metal sulfides such as crystalline MoS ₂ ; transition metal oxides such as Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O _13, etc. Can be mentioned. On the other hand, examples of the positive electrode active material made of an organic compound include conductive polymers such as polyacetylene and poly-p-phenylene.

Furthermore, you may use the positive electrode active material which consists of a composite material which combined the inorganic compound and the organic compound.
Alternatively, for example, a composite material covered with a carbon material may be produced by reducing and firing an iron-based oxide in the presence of a carbon source material, and the composite material may be used as a positive electrode active material. Iron-based oxides tend to have poor electrical conductivity, but can be used as a high-performance positive electrode active material by using a composite material as described above.
Furthermore, you may use as a positive electrode active material what carried out the element substitution of the said compound partially.
These positive electrode active materials may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Moreover, you may use the mixture of the above-mentioned inorganic compound and organic compound as a positive electrode active material.

  The particle diameter of the positive electrode active material can be selected in consideration of other constituent elements of the lithium ion secondary battery. From the viewpoint of improving battery characteristics such as load characteristics and cycle characteristics, the volume average particle diameter of the positive electrode active material is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 50 μm or less, more preferably 20 μm or less. It is. When the volume average particle size of the positive electrode active material is within this range, a battery having a large charge / discharge capacity can be obtained, and handling of the electrode slurry composition and the electrode is easy.

  The ratio of the positive electrode active material in the electrode active material layer is preferably 90% by weight or more, more preferably 95% by weight or more, and preferably 99.9% by weight or less, more preferably 99% by weight or less. By setting the amount of the positive electrode active material in the above range, the capacity of the lithium ion secondary battery can be increased, and the flexibility of the positive electrode and the binding property between the current collector and the positive electrode active material layer can be improved. .

  Examples of the negative electrode active material include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads, and pitch-based carbon fibers; and conductive polymers such as polyacene. Further, metals such as silicon, tin, zinc, manganese, iron and nickel, and alloys thereof; oxides of the metals or alloys; sulfates of the metals or alloys; Further, metallic lithium; lithium alloys such as Li—Al, Li—Bi—Cd, and Li—Sn—Cd; lithium transition metal nitride; silicon and the like may be used. Furthermore, an electrode active material having a conductive material attached to the surface by a mechanical modification method may be used. These negative electrode active materials may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The particle diameter of the negative electrode active material is appropriately selected in view of other constituent requirements of the lithium ion secondary battery. From the viewpoint of improving battery characteristics such as initial efficiency, load characteristics, and cycle characteristics, the volume average particle diameter of the negative electrode active material is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. Is 100 μm or less, more preferably 50 μm or less, and still more preferably 20 μm or less.

The specific surface area of the negative electrode active material, the output from the viewpoint of improving the density, preferably ^2m 2 / g or more, more preferably ^3m 2 / g or more, more preferably ^{5 m} 2 / g or more, and preferably ^{20 m} 2 / g or less, more preferably 15 m ² / g or less, and further preferably 10 m ² / g or less. The specific surface area of the negative electrode active material can be measured by, for example, the BET method.

  The ratio of the negative electrode active material in the electrode active material layer is preferably 85% by weight or more, more preferably 88% by weight or more, and preferably 99% by weight or less, more preferably 97% by weight or less. By setting the amount of the negative electrode active material in the above range, it is possible to realize a negative electrode that exhibits excellent flexibility and binding properties while exhibiting high capacity.

  The electrode active material layer preferably contains an electrode binder in addition to the electrode active material. By including the binder for the electrode, the binding property of the electrode active material layer is improved, and the strength against the mechanical force applied in the process of winding the electrode is increased. In addition, since the electrode active material layer is less likely to be peeled off from the current collector and the porous film, the risk of short-circuiting due to the detached desorbed material is reduced.

  As the electrode binder, for example, a polymer can be used. Examples of the polymer that can be used as the electrode binder include the same examples as those exemplified as examples of the particulate polymer in the description of the porous membrane slurry composition of the present invention. Moreover, the binder for electrodes may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the binder for the electrode in the electrode active material layer is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, particularly preferably 0.5 parts by weight or more with respect to 100 parts by weight of the electrode active material. It is preferably 5 parts by weight or less, more preferably 3 parts by weight or less. When the amount of the electrode binder is within the above range, it is possible to prevent the electrode active material from dropping from the electrode without inhibiting the battery reaction.

  The electrode active material layer may contain any component other than the electrode active material and the electrode binder as long as the effects of the present invention are not significantly impaired. Examples thereof include a conductive material and a reinforcing material. Moreover, arbitrary components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Examples of the conductive material include conductive carbon such as acetylene black, ketjen black, carbon black, graphite, vapor-grown carbon fiber, and carbon nanotube; carbon powder such as graphite; fibers and foils of various metals; . By using a conductive material, electrical contact between electrode active materials can be improved, and battery characteristics such as cycle characteristics can be improved.

The specific surface area of the conductive material is preferably 50 m ² / g or more, more preferably 60 m ² / g or more, particularly preferably 70 m ² / g or more, preferably 1500 m ² / g or less, more preferably 1200 m ² / g. Hereinafter, it is particularly preferably 1000 m ² / g or less. By setting the specific surface area of the conductive material to be equal to or higher than the lower limit of the above range, the low temperature output characteristics of the lithium ion secondary battery can be improved. Moreover, the binding property of an electrode active material layer and an electrical power collector can be improved by setting it as an upper limit or less.

  As the reinforcing material, for example, various inorganic and organic spherical, plate-like, rod-like or fibrous fillers can be used. By using the reinforcing material, a tough and flexible electrode can be obtained, and excellent long-term cycle characteristics can be obtained.

  The amount of the conductive material and the reinforcing agent used is usually 0 part by weight or more, preferably 1 part by weight or more, preferably 20 parts by weight or less, more preferably 10 parts by weight, with respect to 100 parts by weight of the electrode active material. It is as follows.

  The thickness of the electrode active material layer is preferably 5 μm or more, more preferably 10 μm or more, preferably 300 μm or less, more preferably 250 μm or less for both the positive electrode and the negative electrode.

  The method for producing the electrode active material layer is not particularly limited. The electrode active material layer can be produced, for example, by applying an electrode active material, a solvent, and, if necessary, an electrode slurry composition containing an electrode binder and optional components onto a current collector and drying it. As the solvent, either water or an organic solvent can be used.

[4.3. (Porous membrane provided in electrode for secondary battery)
The electrode of the present invention includes the porous film described above on the electrode plate. That is, the electrode of the present invention includes an electrode plate and a porous film obtained by applying a porous film slurry composition on the electrode plate and drying it. Such an electrode can be manufactured, for example, by performing the above-described porous film manufacturing method using an electrode plate as a substrate. At this time, the porous film may be provided on only one surface of the electrode plate, or may be provided on both surfaces. However, since the porous film is usually provided on the electrode active material layer, the electrode of the present invention includes a current collector, an electrode active material layer, and a porous film in this order.

[5. Lithium ion secondary battery]
The lithium ion secondary battery of this invention is equipped with a positive electrode, a negative electrode, and electrolyte solution. In addition, the secondary battery of the present invention satisfies the following requirement (A), satisfies the requirement (B), or satisfies both the requirements (A) and (B).
(A) At least one of the positive electrode and the negative electrode of the lithium ion secondary battery of the present invention is the electrode of the present invention.
(B) The lithium ion secondary battery of the present invention includes a separator, and the separator is the separator of the present invention.

  In the lithium ion secondary battery of this invention, generation | occurrence | production of the gas by charging / discharging can be suppressed. The reason why such an effect is obtained is not necessarily clear. According to the study of the present inventor, the water-soluble polymer contained in the porous film can trap halide ions in the electrolytic solution. It is inferred that the generation of the cause gas is suppressed. If halide ions are contained in the battery, the electrolyte and SEI may be decomposed along with charge and discharge, and gas may be generated. On the other hand, in the lithium ion secondary battery of the present invention, since the water-soluble polymer traps halide ions, the amount of halide ions in the electrolytic solution is reduced, so the amount of gas generated can be reduced. It is thought that.

  In addition, the lithium ion secondary battery of the present invention usually has good cycle characteristics. The reason why such a good cycle characteristic can be realized is not necessarily clear, but according to the study of the present inventor, it is presumed as follows. That is, firstly, since the generation of gas is suppressed as described above, it is possible to suppress a decrease in battery capacity due to the gas. Second, since the water-soluble polymer can trap halide ions in the electrolyte, corrosion of the current collector caused by halide ions can be prevented. If corrosion of the current collector can be prevented, an increase in resistance of the electrode due to the progress of corrosion can be suppressed. In addition, since the corrosion of the current collector can be prevented, a decrease in the binding force between the current collector and the electrode active material layer can be suppressed. Thirdly, since the water-soluble polymer according to the present invention is excellent in the ability to bind the porous membrane and the separator substrate or electrode plate, the porous membrane is peeled off from the separator substrate or electrode plate by repeated charge and discharge. hard. Therefore, the increase in the distance between the positive electrode and the negative electrode due to charge / discharge can be suppressed. And it is inferred that excellent cycle characteristics can be realized by combining these factors.

[5.1. electrode〕
In principle, the lithium ion secondary battery of the present invention includes the electrode of the present invention as one or both of a positive electrode and a negative electrode. However, when the lithium ion secondary battery of the present invention includes the separator of the present invention as a separator, an electrode other than the electrode of the present invention may be provided as both the positive electrode and the negative electrode.

[5.2. separator〕
In principle, the lithium ion secondary battery of the present invention includes the separator of the present invention as a separator. However, when the secondary battery of the present invention includes the electrode of the present invention as at least one of a positive electrode and a negative electrode, a separator other than the separator of the present invention may be provided as a separator. Moreover, since the porous film with which the electrode of this invention is provided has a function as a separator, you may abbreviate | omit a separator in the secondary battery provided with the electrode of this invention.

[5.3. Electrolyte)
As the electrolytic solution, for example, a solution obtained by dissolving a lithium salt as a supporting electrolyte in a non-aqueous solvent can be used. Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and the like. In particular, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li that are easily soluble in a solvent and exhibit a high degree of dissociation are preferably used. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  The amount of the supporting electrolyte is preferably 1% by weight or more, more preferably 5% by weight or more, preferably 30% by weight or less, more preferably 20% by weight or less, as the concentration in the electrolytic solution. By keeping the amount of the supporting electrolyte within this range, the ionic conductivity can be increased and the charging characteristics and discharging characteristics of the secondary battery can be improved.

  As a solvent used for the electrolytic solution, a solvent capable of dissolving the supporting electrolyte can be used. Examples of such a solvent include alkyl carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and methyl ethyl carbonate (MEC). Esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; In particular, dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate are preferred because high ion conductivity is easily obtained and the use temperature range is wide. A solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  Moreover, electrolyte solution may contain an additive as needed. As the additive, for example, carbonate compounds such as vinylene carbonate (VC) are preferable. An additive may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

[5.4. Source of halide ions)
As described above, in the lithium ion secondary battery of the present invention, it is considered that the generation of gas is suppressed by trapping halide ions by the water-soluble polymer. Examples of components considered to be a source of such halide ions include the following.

For example, the sources of fluoride ions include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi, ( Examples include supporting electrolytes for electrolytic solutions such as CF ₃ SO ₂ ) ₂ NLi and (C ₂ F ₅ SO ₂ ) NLi; binders for electrodes such as polyvinylidene fluoride.
Further, for example, as a source of chloride ions, there may be mentioned a supporting electrolyte of an electrolytic solution such as LiAlCl ₄ and LiClO ₄ ; an additive such as a carboxymethyl cellulose salt; a residual HCl of an electrode active material, and the like.

  The lithium ion secondary battery of the present invention is significant in that it can suppress deterioration in battery performance due to halide ions, even if it includes a component that can generate halide ions as described above.

[5.5. Method for producing lithium ion secondary battery]
The manufacturing method of the lithium ion secondary battery of the present invention is not particularly limited. For example, the above-described negative electrode and positive electrode may be overlapped via a separator, and this may be wound or folded in accordance with the shape of the battery and placed in the battery container, and the electrolyte may be injected into the battery container and sealed. Furthermore, if necessary, an expanded metal; an overcurrent prevention element such as a fuse or a PTC element; a lead plate or the like may be inserted to prevent an increase in pressure inside the battery or overcharge / discharge. The shape of the battery may be any of, for example, a laminate cell type, a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and can be implemented with any modifications without departing from the scope of the claims of the present invention and the equivalents thereof.
In the following description, “%” and “part” representing amounts are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and normal pressure conditions unless otherwise specified.

[Evaluation method]
(1. Measuring method of cell volume change)
The lithium ion secondary battery of the 800 mAh wound type cell manufactured by the Example and the comparative example was left still for 24 hours in 25 degreeC environment. Thereafter, in an environment of 25 ° C., a charge / discharge operation was performed in which the battery was charged at 0.1 C to 4.35 V and discharged at 0.1 C to 2.75 V. Thereafter, the wound cell was immersed in liquid paraffin, and its volume V0 was measured.

  Furthermore, charging and discharging were repeated 1000 cycles under the same conditions as described above in a 60 ° C. environment. Thereafter, the wound cell was immersed in liquid paraffin, and its volume V1 was measured.

  The volume change ΔV of the wound cell before and after repeating charge and discharge for 1000 cycles was calculated by “ΔV = (V1−V0) / V0 × 100 (%)”. It shows that it is excellent in the capability to suppress generation | occurrence | production of gas, so that the value of this volume variation | change_quantity (DELTA) V is small.

(2. Measuring method of viscosity change rate of porous membrane slurry composition)
About the porous membrane slurry composition manufactured by the Example and the comparative example, the viscosity (eta) 0 in 25 degreeC and rotation speed 60rpm was measured with the B-type viscosity meter.
Then, after leaving the porous membrane slurry composition at 25 ° C. for 7 days, the viscosity η1 was measured again in the same manner as described above.
From the measured viscosity η0 and viscosity η1, viscosity change rate = {(η1−η0) / η0} × 100 (%) was calculated. A smaller viscosity change rate indicates that the porous film slurry composition is less likely to change in viscosity over time, and is excellent in dispersion stability.

(3. Evaluation method of high-temperature cycle characteristics)
The lithium ion secondary battery of the 800 mAh wound type cell manufactured by the Example and the comparative example was left still for 24 hours in 25 degreeC environment. Thereafter, under an environment of 25 ° C., a charge / discharge operation of charging up to 4.35 V at 0.1 C and discharging to 2.75 V at 0.1 C was performed, and the initial capacity C0 was measured.

  Furthermore, in a 60 ° C. environment, the charge / discharge operation was repeated 1000 cycles under the same conditions as described above, and the capacity C1 after 1000 cycles was measured.

  The capacity retention rate ΔC was calculated by “ΔC = C1 / C0 × 100 (%)”. The higher the capacity retention ratio ΔC, the better the high-temperature cycle characteristics of the lithium ion secondary battery, and the longer the battery life.

(4. Method for measuring peel strength between separator substrate and porous film after high-temperature cycle test)
After measuring the capacity retention ratio ΔC described in the above section (3. Evaluation method of high temperature cycle characteristics), lithium ion secondary batteries (Examples 1 to 18, 20 and 21 and comparison) Examples 1-4) were dismantled. The disassembled battery separator was washed with an electrolyte solution solvent (EC / DEC / VC = 68.5 / 30 / 1.5 volume ratio) and dried. The dried separator was cut into a rectangle having a length of 100 mm and a width of 10 mm to obtain a test piece. A cellophane tape was affixed to the surface of the porous membrane with the test piece facing down. At this time, a cellophane tape defined in JIS Z1522 was used. The cellophane tape was fixed on a horizontal test bench. Thereafter, the stress was measured when one end of the separator substrate was pulled vertically upward and pulled at a pulling speed of 50 mm / min. This measurement was performed 3 times, the average value of stress was calculated | required, and the said average value was made into peel strength.

(5. Method for measuring peel strength between electrode plate and porous film after high-temperature cycle test)
After measuring the capacity retention ratio ΔC described in the above section (3. Evaluation method for high temperature cycle characteristics), the lithium ion secondary battery (Example 19) of the wound cell was disassembled. The negative electrode of the disassembled battery was washed with an electrolyte solvent (EC / DEC / VC = 68.5 / 30 / 1.5 volume ratio) and dried. The dried negative electrode was cut into a rectangle having a length of 100 mm and a width of 10 mm to obtain a test piece. A cellophane tape was affixed to the surface of the porous membrane with the test piece facing down. At this time, a cellophane tape defined in JIS Z1522 was used. The cellophane tape was fixed on a horizontal test bench. Then, the stress when one end of the current collector was pulled vertically upward at a pulling speed of 50 mm / min and peeled was measured. This measurement was performed 3 times, the average value of stress was calculated | required, and the said average value was made into peel strength.

[Example 1]
(1-1. Production of water-soluble polymer)
In a 5 MPa pressure vessel with a stirrer, 1 part of acrylamide (carboxylic amide monomer), 35 parts of methacrylic acid (acid group-containing monomer), 2,2,2-trifluoroethyl methacrylate (fluorine-containing (meth) acrylic acid) Ester monomer) 3 parts, ethyl acrylate (arbitrary monomer) 60 parts, ethylene dimethacrylate (crosslinkable monomer) 1 part, t-dodecyl mercaptan 0.6 part, ion-exchanged water 150 parts, and excess After adding 1.0 part of potassium sulfate (polymerization initiator) and stirring sufficiently, the polymerization was started by heating to 60 ° C. When the polymerization conversion reached 96%, the reaction was stopped by cooling to obtain a mixture containing a water-soluble polymer. By adding 10% ammonia water to the mixture containing the water-soluble polymer and adjusting the pH to 8, the water-soluble polymer was dissolved in water to obtain an aqueous solution containing the desired water-soluble polymer.

(1-2. Production of particulate polymer)
In a 5 MPa pressure vessel with a stirrer, 94 parts of butyl acrylate, 2 parts of acrylonitrile, 3 parts of methacrylic acid, 1 part of allyl methacrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water and persulfuric acid as a polymerization initiator After adding 0.5 part of potassium and stirring sufficiently, it heated to 50 degreeC and superposition | polymerization was started. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing particulate polymer (ACL). A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate polymer to adjust the pH to 8. Thereafter, unreacted monomers were removed from the mixture by heating under reduced pressure, and then cooled to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate polymer.

(1-3. Production of non-conductive particles)
In a 5 MPa pressure vessel equipped with a stirrer, 88 parts of styrene, 10 parts of acrylamide, 2 parts of ethylene glycol dimethacrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water and 0.5 parts of potassium persulfate as a polymerization initiator A portion was added and stirred sufficiently, and then heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing non-conductive particles. A 5% aqueous sodium hydroxide solution was added to the mixture containing the non-conductive particles to adjust the pH to 8. Then, after removing unreacted monomer from the mixture by heating under reduced pressure, the mixture was cooled to 30 ° C. or lower to obtain an aqueous dispersion containing desired non-conductive particles.

(1-4. Production of porous membrane slurry composition)
100 parts of the aqueous dispersion containing the non-conductive particles obtained in the step (1-3) corresponding to the solid content and 2% of the aqueous solution containing the water-soluble polymer obtained in the step (1-1) are equivalent to the solid content. Part, 2 parts of carboxymethylcellulose sodium salt ("1220" manufactured by Daicel) and an aqueous dispersion containing the particulate polymer obtained in the step (1-2) so as to be 2 parts equivalent to the solid content. Then, water was further mixed to adjust the solid content concentration to 40% by weight to produce a porous membrane slurry composition.
A part of the porous film slurry composition thus obtained was taken out and the viscosity change rate was measured in the manner described above.

(1-5. Production of separator with porous film)
On a single-layer polypropylene separator substrate (“Celgard 2500” manufactured by Celgard), the porous film slurry composition obtained in the step (1-4) was coated with a gravure coater and the coating amount after drying was 6 mg / kg. the coating is cm ^2, and dried. This drying was performed by conveying the separator base material at a rate of 20 m / min in an oven at 100 ° C. over 1 minute. This obtained the separator provided with a separator base material and a porous membrane.

(1-6. Production of particulate binder for negative electrode)
In a 5 MPa pressure vessel with a stirrer, 33.5 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 62 parts of styrene, 1 part of 2-hydroxyethyl acrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, ion exchange After adding 150 parts of water and 0.5 part of potassium persulfate as a polymerization initiator and stirring sufficiently, the mixture was heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a particulate binder (SBR). A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate binder to adjust the pH to 8. Thereafter, the unreacted monomer was removed from the mixture by distillation under reduced pressure, followed by cooling to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate binder.

(1-7. Production of negative electrode slurry composition)
100 parts of artificial graphite (volume average particle diameter 15.6 μm) and 1 part of a 2% aqueous solution of carboxymethyl cellulose sodium salt (“MAC350HC” manufactured by Nippon Paper Industries Co., Ltd.) as a thickener are mixed in an amount equivalent to the solid content, and ion exchange is further performed. Water was added to adjust the solid content concentration to 68%, and the mixture was mixed at 25 ° C. for 60 minutes. Further, ion exchange water was added to adjust the solid content concentration to 62%, and the mixture was further mixed at 25 ° C. for 15 minutes. To the mixed solution thus obtained, 1.5 parts of the aqueous dispersion containing the particulate binder obtained in the step (1-6) is added in an amount corresponding to the solid content, and ion-exchanged water is further added to obtain a final solid content concentration. The mixture was adjusted to 52% and further mixed for 10 minutes. This was defoamed under reduced pressure to obtain a negative electrode slurry composition having good fluidity.

(1-8. Production of negative electrode)
The negative electrode slurry composition obtained in the step (1-7) was applied on a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying was about 150 μm. Dried. This drying was performed by conveying the copper foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a negative electrode raw material before pressing. The negative electrode raw material before pressing was rolled with a roll press to obtain a negative electrode after pressing with a negative electrode active material layer having a thickness of 80 μm.

(1-9. Production of positive electrode slurry composition)
100 parts of LiCoO ₂ having a volume average particle diameter of 12 μm as the positive electrode active material, ₂ parts of acetylene black (“HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.) as the conductive material, and solid PVDF (manufactured by Kureha Co., # 7208) as the binder 2 parts were mixed in an equivalent amount, and N-methylpyrrolidone was further added to adjust the total solid content concentration to 70%. These were mixed by a planetary mixer to prepare a positive electrode slurry composition.

(1-10. Production of positive electrode)
The positive electrode slurry composition obtained in the step (1-9) was applied onto a 20 μm thick aluminum foil as a current collector with a comma coater so that the film thickness after drying was about 150 μm, Dried. This drying was performed by conveying the aluminum foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Then, it heat-processed for 2 minutes at 120 degreeC, and obtained the positive electrode.

(1-11. Production of lithium ion secondary battery)
An aluminum packaging exterior was prepared as the battery exterior. The positive electrode obtained in the step (1-10) was cut into a square of 4.6 × 4.6 cm ² and arranged so that the surface on the current collector side was in contact with the aluminum packaging exterior.
Then, the separator with the porous film obtained in the step (1-5) is cut into a square of 5 × 5 cm ² , and this is cut on the surface of the positive electrode active material layer of the positive electrode, and the surface on the separator substrate side becomes the positive electrode Arranged to face each other.
Furthermore, the negative electrode after pressing obtained in the step (1-8) was cut into a 5 × 5 cm ² square, and this was arranged on the separator so that the surface on the negative electrode active material layer side faces the separator.

An electrolytic solution (solvent: EC / DEC / VC = 68.5 / 30 / 1.5 volume ratio, electrolyte: LiPF ₆ having a concentration of 1 M) was injected into the aluminum packaging exterior so as not to leave air. Further, in order to seal the opening of the aluminum packaging material, heat sealing at 150 ° C. was performed to close the aluminum exterior, thereby manufacturing a lithium ion secondary battery.
Using the lithium ion secondary battery thus obtained, the cell volume change ΔV, the capacity retention ratio ΔC, and the peel strength after the high-temperature cycle test were measured in the manner described above.

[Example 2]
In the step (1-3), the amount of styrene was changed to 98 parts, and acrylamide was not used.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 3]
In the step (1-3), the amount of styrene was changed to 97.85 parts, and the amount of acrylamide was changed to 0.15 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 4]
In the step (1-3), the amount of styrene was changed to 53 parts, and the amount of acrylamide was changed to 45 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 5]
In the step (1-3), the amount of sodium dodecylbenzenesulfonate was changed to 1.2 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 6]
In the step (1-3), the amount of sodium dodecylbenzenesulfonate was changed to 0.1 part.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 7]
In the step (1-1), the amount of methacrylic acid was changed to 22 parts, and the amount of ethyl acrylate was changed to 73 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 8]
In the step (1-1), the amount of methacrylic acid was changed to 78 parts, and the amount of ethyl acrylate was changed to 17 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 9]
In the step (1-1), vinyl sulfonic acid (VSA) was used instead of methacrylic acid.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 10]
In the step (1-1), instead of using 35 parts of methacrylic acid, 25 parts of methacrylic acid and 10 parts of vinyl sulfonic acid were used in combination.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 11]
In the step (1-1), the amount of acrylamide was changed to 0.2 part, and the amount of ethyl acrylate was changed to 60.8 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 12]
In the step (1-1), the amount of acrylamide was changed to 9 parts, and the amount of ethyl acrylate was changed to 52 parts.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 13]
In the step (1-1), N-methylolacrylamide was used instead of acrylamide.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 14]
In the step (1-1), methacrylamide was used instead of acrylamide.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 15]
In the step (1-1), N, N-dimethylaminoethylacrylamide was used instead of acrylamide.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 16]
In the step (1-1), N, N-dimethylaminopropylacrylamide was used instead of acrylamide.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 17]
In the step (1-3), the amount of styrene was changed to 90 parts, and ethylene glycol dimethacrylate was not used.
In the step (1-2), butyl acrylate, acrylonitrile, methacrylic acid and allyl methacrylate are not used. Instead, 62.5 parts of styrene, 33.0 parts of 1,3-butadiene, 3.5 parts of itaconic acid And 1.0 part of 2-hydroxyethyl acrylate was used in combination.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 18]
In the step (1-4), instead of the aqueous dispersion containing non-conductive particles obtained in the step (1-3), 100 parts of Al ₂ O ₃ particles (volume average particle diameter of 0.5 μm) were added. Using.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 19]
On the negative electrode active material layer of the negative electrode after the press manufactured in the step (1-8), the porous film slurry composition manufactured in the step (1-4) is applied with a gravure coater and the coating amount after drying is 6 mg. / Cm < ² > was applied and dried. This drying was performed by conveying the negative electrode in an oven at 100 ° C. at a speed of 20 m / min for 1 minute. This obtained the negative electrode provided with the electrode plate provided with an electrical power collector and a negative electrode active material layer, and a porous film.

In the step (1-11), a single-layer polypropylene separator base material (“Celguard 2500” manufactured by Celgard) was used in place of the separator with a porous film, and the porous film produced in Example 19 as a negative electrode An attached negative electrode was used.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 20]
In the step (1-1), the amount of methacrylic acid was changed to 22 parts, the amount of acrylamide was changed to 9 parts, ethyl acrylate was changed to 68 parts, and 2,2,2-trifluoroethyl methacrylate was changed to Not used.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Example 21]
In the step (1-1), the amount of methacrylic acid was changed to 78 parts, the amount of acrylamide was changed to 0.5 parts, the ethyl acrylate was changed to 20.5 parts, Fluoroethyl methacrylate was not used.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 1]
In the step (1-4), 100 parts of Al ₂ O ₃ particles (volume average particle diameter 2 μm) were used in place of the aqueous dispersion containing non-conductive particles obtained in the step (1-3). In the step (1-4), 2 parts of polymethacrylic acid was used instead of the aqueous solution containing the water-soluble polymer obtained in the step (1-1).
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 2]
In the step (1-1), the amount of methacrylic acid is changed to 15 parts, the amount of ethyl acrylate is changed to 85 parts, and acrylamide, 2,2,2-trifluoroethyl methacrylate and ethylene dimethacrylate are not used. It was.
In the step (1-4), 100 parts of Al ₂ O ₃ particles (volume average particle diameter 2 μm) are used instead of the aqueous dispersion containing the non-conductive particles obtained in the step (1-3). Using.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 3]
In the step (1-1), the amount of acrylamide was changed to 0.05 part, the amount of ethyl acrylate was changed to 64.95 parts, and 2,2,2-trifluoroethyl methacrylate and ethylene dimethacrylate were used. There wasn't.
In the step (1-4), 100 parts of Al ₂ O ₃ particles (volume average particle diameter 2 μm) are used instead of the aqueous dispersion containing the non-conductive particles obtained in the step (1-3). Using.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 4]
In the step (1-1), the amount of acrylamide was changed to 15 parts, the amount of ethyl acrylate was changed to 50 parts, and 2,2,2-trifluoroethyl methacrylate and ethylene dimethacrylate were not used.
In the step (1-4), 100 parts of Al ₂ O ₃ particles (volume average particle diameter 2 μm) are used instead of the aqueous dispersion containing the non-conductive particles obtained in the step (1-3). Using.
A lithium ion secondary battery was manufactured and evaluated in the same manner as in Example 1 except for the above items.

[result]
The results of Examples and Comparative Examples are shown in Tables 1 to 6 below.
In the following Tables 1 to 6, the meanings of the abbreviations are as follows.
“ST”: Styrene “EGDMA”: Ethylene glycol dimethacrylate “Monomer X”: Amide monomer “AAm”: Acrylamide “Monomer I”: Acid group-containing monomer “MAA”: Methacrylic acid “VSA” ": Vinyl sulfonic acid" PMAA ": polymethacrylic acid" monomer II ": amide monomer" NMA ": N-methylol acrylamide" MAAm ": methacrylamide" DMAEAAm ": N, N-dimethylaminoethyl acrylamide" DMAPAAm ”: N, N-dimethylaminopropylacrylamide“ Monomer III ”: Crosslinkable monomer“ EDMA ”: Ethylene dimethacrylate“ Monomer IV ”: Fluorine-containing (meth) acrylate monomer“ TFEMA ” ": 2,2,2-trifluoroethyl methacrylate" monomer V ": any single amount “EA”: ethyl acrylate “Mw”: weight average molecular weight “BA”: butyl acrylate “AN”: acrylonitrile “AMA”: allyl methacrylate “BD”: 1,3-butadiene “IA”: itaconic acid “β-HEA” : 2-hydroxyethyl acrylate "Sepa": Separator

[Consideration]
As can be seen from Tables 1 to 6, the volume change ΔV of the battery cells is significantly smaller in the example than in the comparative example. From this, it was confirmed that generation of gas in the lithium ion secondary battery can be suppressed by the present invention.

  Moreover, the viscosity change rate of the porous membrane slurry composition is smaller in the example than in the comparative example. From this, it was confirmed that the porous membrane slurry composition according to the present invention is usually excellent in dispersion stability. As described above, the porous membrane produced using the porous membrane slurry composition having excellent dispersion stability has a small compositional bias and a uniform composition even when the porous membrane slurry composition after long-term storage is used. Therefore, there is no local brittle part, and the overall mechanical strength is excellent. Therefore, the safety of the lithium ion secondary battery can be improved.

  In addition, the battery capacity retention rate ΔC is larger in the example than in the comparative example. From this, it was confirmed that a battery excellent in high-temperature cycle characteristics is usually obtained by the present invention. For this reason, it can be expected that the lifetime of the lithium ion secondary battery is extended by the present invention.

  Further, the peel strength after the cycle test is greater in the example than in the comparative example. From this, it was confirmed that the porous film according to the present invention can maintain a high binding force to the separator substrate and the electrode plate even when charging and discharging are repeated. If the porous film is peeled off from the separator substrate or the electrode plate, the distance between the positive electrode and the negative electrode is increased, the resistance is increased, and the battery performance may be lowered. Therefore, the porous film excellent in the binding force to the separator substrate and the electrode plate has an advantage that the battery performance can be prevented from deteriorating.

Claims (11)

A porous membrane slurry composition for a lithium ion secondary battery comprising non-conductive particles, a water-soluble polymer, a particulate polymer and water,
A porous membrane slurry composition for a lithium ion secondary battery, wherein the water-soluble polymer comprises 20 wt% to 80 wt% of acid group-containing monomer units and 0.1 wt% to 10 wt% of amide monomer units.   The porous membrane slurry composition for a lithium ion secondary battery according to claim 1, wherein the non-conductive particles are organic particles.   The porous membrane slurry composition for a lithium ion secondary battery according to claim 2, wherein the non-conductive particles are polymer particles containing 0.1 wt% to 50 wt% of amide monomer units.   The porous membrane slurry composition for a lithium ion secondary battery according to any one of claims 1 to 3, wherein the water-soluble polymer has a weight average molecular weight of 5,000 to 1,000,000.   5. The lithium ion secondary battery according to claim 1, wherein the acid group-containing monomer unit has at least one group selected from the group consisting of a carboxylic acid group and a sulfonic acid group. Porous membrane slurry composition.   The porous membrane slurry composition for a lithium ion secondary battery according to any one of claims 1 to 5, comprising a carboxymethylcellulose salt.   The porous film slurry composition for a lithium ion secondary battery according to any one of claims 1 to 6, wherein the water-soluble polymer contains 0.1% to 2.0% by weight of a crosslinkable monomer. . A separator substrate;
A lithium ion secondary battery comprising: a porous film obtained by applying and drying the porous film slurry composition for a lithium ion secondary battery according to any one of claims 1 to 7 on the separator substrate. separator. An electrode plate,
The electrode for lithium ion secondary batteries provided with the porous film obtained by apply | coating and drying the porous film slurry composition for lithium ion secondary batteries as described in any one of Claims 1-7 on the said electrode plate. . A lithium ion secondary battery comprising a positive electrode, a negative electrode, an electrolyte and a separator,
A lithium ion secondary battery, wherein the separator is a separator for a lithium ion secondary battery according to claim 8. A lithium ion secondary battery comprising a positive electrode, a negative electrode and an electrolyte solution,
A lithium ion secondary battery, wherein at least one of the positive electrode and the negative electrode is an electrode for a lithium ion secondary battery according to claim 9.