JP6337900B2 - Porous membrane slurry composition for secondary battery, separator for secondary battery, electrode for secondary battery, and secondary battery - Google Patents

Description

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

  In recent years, portable terminals such as notebook computers, mobile phones, and PDAs (Personal Digital Assistants) have been widely used. As a power source used as a power source for these portable terminals, a secondary battery such as a lithium ion secondary battery is frequently used.

In secondary batteries, a separator is generally provided to prevent a short circuit between the positive electrode and the negative electrode. Further, the separator may be provided with a porous film as necessary. By providing a porous film on the separator, the separator can be prevented from being damaged by a foreign substance, and 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 (refer patent document 1).

International Publication No. 2012/011555

For secondary batteries such as lithium ion secondary batteries, development of technology capable of improving cycle characteristics and rate characteristics is required in order to improve battery performance.
The present invention was devised in view of the above problems, and can provide a secondary battery porous membrane slurry composition, a secondary battery separator, and a secondary battery capable of producing a secondary battery excellent in both cycle characteristics and rate characteristics. An object of the present invention is to provide a battery electrode and a secondary battery excellent in both cycle characteristics and rate characteristics.

As a result of intensive studies to solve the above problems, the present inventor has found that non-conductive particles, a particulate polymer containing carboxylic acid primary amide monomer units at a predetermined ratio, and one molecule of functional group capable of capturing heavy metals. A secondary battery comprising a porous film formed using a slurry composition containing a compound having a predetermined number or more per unit and an SP value in a predetermined range and water, is excellent in both cycle characteristics and rate characteristics. The inventors have found that battery characteristics are exhibited, and completed the present invention.
That is, the present invention is as follows.

[1] Non-conductive particles, a particulate polymer containing 0.1% to 10% by weight of a carboxylic acid primary amide monomer unit, 3 or more functional groups capable of capturing heavy metals per molecule, and A porous membrane slurry composition for a secondary battery, comprising a compound having an SP value of 12 (cal / cm ³ ) ^1/2 to 15 (cal / cm ³ ) ^1/2 and water.
[2] The porous membrane slurry composition for a secondary battery according to [1], wherein the amount of the compound with respect to 100 parts by weight of the particulate polymer is 0.1 to 10 parts by weight.
[3] The porous membrane slurry composition for a secondary battery according to [1] or [2], wherein the functional group is at least one group selected from the group consisting of an amino group and an acidic group.
[4] The porous membrane slurry composition for a secondary battery according to [3], wherein the acidic group is a carboxylic acid group or a phosphonic acid group.
[5] The porous membrane for a secondary battery according to any one of [1] to [4], further comprising a water-soluble polymer containing 20% by weight to 80% by weight of the acidic group-containing monomer unit. Slurry composition.
[6] a separator substrate;
The separator for secondary batteries provided with the porous film obtained by apply | coating and drying the porous film slurry composition for secondary batteries as described in any one of [1]-[5] on the said separator base material.
[7] An electrode plate;
An electrode for a secondary battery, comprising: a porous film obtained by applying and drying the porous film slurry composition for a secondary battery according to any one of [1] to [5] on the electrode plate.
[8] A secondary battery comprising a positive electrode, a negative electrode, an electrolytic solution and a separator,
The secondary battery whose said separator is a separator for secondary batteries as described in [6].
[9] A secondary battery comprising a positive electrode, a negative electrode and an electrolyte solution,
A secondary battery, wherein at least one of the positive electrode and the negative electrode is a secondary battery electrode according to [7].

According to the porous membrane slurry composition for a secondary battery, the separator for a secondary battery, and the electrode for a secondary battery of the present invention, a secondary battery excellent in both cycle characteristics and rate characteristics can be produced.
The secondary battery of the present invention is excellent in both cycle characteristics and rate characteristics.

  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 its equivalents.

  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 when 0.5 g of the substance is dissolved in 100 g of water at 25 ° C., the insoluble content is 0 wt% or more and less than 0.5 wt%. 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 membrane slurry composition for secondary battery]
The porous membrane slurry composition for secondary batteries of the present invention (hereinafter sometimes referred to as “porous membrane slurry composition” as appropriate) has 1 functional group capable of capturing non-conductive particles, particulate polymers, and heavy metals. A compound having a predetermined number or more per molecule and having an SP value in a predetermined range (hereinafter sometimes referred to as “capturing agent” as appropriate) and water are included.

[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. For this reason, even when a stress that causes the separator base material to shrink due to heat is generated, the porous film can withstand 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). More preferred are aluminum oxide hydrate, magnesium oxide and magnesium hydroxide, more preferred are aluminum oxide, aluminum oxide hydrate, magnesium oxide and magnesium hydroxide, and particularly preferred is aluminum oxide.

  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.

  When organic particles are used as non-conductive particles, the organic particles may not have a glass transition temperature, but when the polymer forming the organic particles has a glass transition temperature, the glass transition temperature is preferably It is 150 ° C. or higher, more preferably 200 ° C. or higher, particularly preferably 250 ° C. or higher. The upper limit of the glass transition temperature of the polymer forming the organic particles is arbitrary, but is usually 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, from the viewpoint of increasing the porosity of the porous film and suppressing the decrease in ionic conductivity due to the porous film, a tetrapod (registered trademark) shape, a plate shape, and a scale shape are preferable.

  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 of the particles represents a 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, the intensity | strength of a porous film can be improved and the short circuit of a secondary battery can be prevented stably by keeping the quantity of nonelectroconductive particle in the said range.

[1.2. (Particulate polymer)
The particulate polymer is a polymer particle. This particulate polymer contains carboxylic acid primary amide monomer units in a predetermined ratio. Here, the carboxylic acid primary amide monomer unit refers to a structural unit having a structure formed by polymerizing a carboxylic acid primary amide monomer. Further, the carboxylic acid primary amide monomer means a compound having a structure formed by condensation of carboxylic acid and primary amide. In the secondary battery including the porous film formed using the porous film slurry composition of the present invention, the particulate polymer contains a carboxylic acid primary amide monomer unit at a predetermined ratio. Can be suppressed.

Thus, although the reason which can suppress generation | occurrence | production of gas is not necessarily certain, according to examination of this inventor, it estimates as follows. However, this invention is not restrict | limited by the reason demonstrated below.
In general, when halide ions are contained in a secondary battery, the electrolyte solution and SEI (interlayer solid electrolyte interface) may be decomposed along with charge and discharge, and gas may be generated. On the other hand, the porous film containing the particulate polymer can trap halide ions in the electrolytic solution. For this reason, it is presumed that the generation of gas due to halide ions is suppressed.

  Moreover, when the porous membrane slurry composition of this invention contains a particulate polymer, the following advantages are usually obtained. That is, the binding property of the porous membrane is improved, and the secondary battery separator of the present invention (hereinafter sometimes referred to as “separator”) or the secondary battery electrode (hereinafter also referred to as “separator” as appropriate) during handling such as winding and transportation. Hereinafter, the strength against the mechanical force applied to the electrode may 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 secondary battery can be made small.

Examples of the carboxylic acid primary amide monomer include unsaturated carboxylic acid primary amide compounds such as (meth) acrylamide, α-chloroacrylamide, crotonic acid amide, maleic acid diamide, and fumaric acid diamide. Of these, (meth) acrylamide is preferred.
Moreover, a carboxylic acid primary amide monomer and a carboxylic acid primary amide 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 carboxylic acid primary amide monomer unit in the particulate polymer is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1.0% by weight or more, and usually 10% by weight. % Or less, preferably 7% by weight or less, more preferably 5% by weight or less. By setting the ratio of the carboxylic acid primary amide monomer unit in the particulate polymer to be equal to or higher than the lower limit of the above range, halide ions in the electrolytic solution can be effectively captured by the particulate polymer. Moreover, the rate characteristic of a secondary battery can be improved by making it below an upper limit.

  Further, the particulate polymer can contain an acidic group-containing monomer unit. Here, the acidic group-containing monomer unit refers to a structural unit having a structure formed by polymerizing an acidic group-containing monomer. Moreover, an acidic group containing monomer shows the monomer containing an acidic group. Therefore, the particulate polymer having an acidic group-containing monomer unit contains an acidic group. Since the binding property of the particulate polymer is high because it has an acidic group having a large polarity, it is possible to improve the binding property between the porous membrane and the separator substrate and the binding property between the porous membrane and the electrode plate. it can.

As the acidic 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 represents a hydrocarbon group) Phosphonic acid groups; and the like. Therefore, as an acidic group containing monomer, the monomer which has these acidic groups is mentioned, for example. Further, for example, a monomer capable of generating the acidic group by hydrolysis is also exemplified as the acidic group-containing monomer. Specific examples of such acidic 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 phosphonic acid group (phosphonic 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 acidic group containing monomer. Examples of such a salt include a sodium salt of styrene sulfonic acid such as p-styrene sulfonic acid.
Moreover, an acidic group containing monomer and an acidic 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 acidic group-containing monomer unit in the particulate polymer 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 50%. % By weight or less, more preferably 45% by weight or less, particularly preferably 40% by weight or less. By making the ratio of the acidic group-containing monomer unit in the particulate polymer at least the lower limit of the above range, the binding property between the porous membrane and the separator substrate and the binding property between the porous membrane and the electrode plate are effective. Can be enhanced. Moreover, durability of a porous film can be improved by making it into an upper limit or less.

  The particulate polymer may contain a crosslinkable 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 particulate polymer can be crosslinked, so that the strength and stability of the porous film can be increased. Thereby, it becomes possible to exhibit the effect | action by a particulate polymer stably. In addition, since the degree of swelling of the particulate polymer by the electrolytic solution can be prevented from becoming excessively high, normally the output characteristics of the secondary battery can be 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 N-methylolamide group, an epoxy group, an oxetanyl group, an oxazoline group, and combinations 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 N-methylolamide group as a thermally crosslinkable group and having an olefinic double bond have a methylol group such as N-methylol (meth) acrylamide (meta ) Acrylamides.

  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 ester compounds; 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.

Among these, as the crosslinkable monomer, N-methylol acrylamide, allyl methacrylate, ethylene dimethacrylate, allyl glycidyl ether, glycidyl methacrylate, and ethylene glycol dimethacrylate are preferable, and N-methylol acrylamide, allyl methacrylate, ethylene dimethacrylate, Allyl glycidyl ether and glycidyl methacrylate are more preferred.
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 particulate 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. By making the ratio of the crosslinkable monomer unit in the particulate polymer at least the lower limit of the above range, the mechanical strength of the particulate polymer can be increased, so that the binding property between the porous membrane and the separator substrate and The binding property between the porous membrane and the electrode plate can be enhanced. Moreover, durability of a porous film can be improved by making it into an upper limit or less.

  The particulate coalescence may 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. Since the (meth) acrylic acid ester monomer unit has high strength, the molecules of the particulate polymer can be stabilized.

  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 particulate polymer is preferably 50% by weight or more, more preferably 55% by weight or more, particularly preferably 58% by weight or more, and preferably 98% by weight or less. More preferably, it is 97% by weight or less, particularly preferably 96% by weight or less. By setting the ratio of the (meth) acrylic acid ester monomer unit in the particulate polymer 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 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.

  Furthermore, the particulate polymer may contain an arbitrary structural unit in addition to the above-described structural unit. Examples of arbitrary structural units that can be included in the particulate polymer include structural units having a structure formed by polymerizing the following monomers. That is, aliphatic conjugated diene monomers such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene; styrene Aromatic vinyl monomers such as chlorostyrene, vinyl toluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, hydroxymethyl styrene, α-methyl styrene, divinyl benzene; Α, β-unsaturated nitrile compound monomers such as methacrylonitrile; olefin monomers such as ethylene and propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl acetate, vinyl propionate and vinyl butyrate , Vinyl ester monomers such as vinyl benzoate; methyl vinyl ether, ethyl vinyl Vinyl ether monomers such as ether and butyl vinyl ether; vinyl ketone monomers such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone and isopropenyl vinyl ketone; and N-vinyl pyrrolidone, vinyl pyridine and vinyl imidazole And a structural unit having a structure formed by polymerizing one or more of the following heterocyclic ring-containing vinyl compound monomers. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  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, the properties such as the flexibility and winding property of the separator and the electrode provided with the porous membrane, and the binding property of the porous membrane are highly balanced. is there. Here, the binding property of the porous film includes the binding property between the porous film and the separator substrate, and the binding property between the porous film and the electrode plate. Moreover, the glass transition temperature of a particulate polymer can be adjusted by combining various monomers, for example.

  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. 8 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 secondary battery can be made favorable by making it below an upper limit. In addition, the amount of the particulate polymer within the above range usually means the binding property between the non-conductive particles, the binding property between the porous film and the separator substrate, and between the porous film and the electrode plate. It is also significant in that the binding property can be increased, the flexibility of the porous membrane can be increased, and the ion conductivity of the porous membrane can be increased.

  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.

[1.3. (Capturing agent)
The scavenger has a functional group capable of capturing heavy metals. Here, the heavy metal refers to a metal having a specific gravity of 4.0 g / cm ³ or more. The upper limit of the specific gravity of the heavy metal is arbitrary, but is usually 23 g / cm ³ or less. In addition, as the functional group, a group capable of capturing an atom or ion of at least one kind of metal among heavy metals can be used. When the porous film contains the scavenger, the porous film can capture the heavy metal in the electrolytic solution, so that it is possible to suppress the precipitation of the heavy metal on the negative electrode accompanying the charge / discharge of the secondary battery.

  Among the heavy metals, the functional group is preferably capable of capturing a metal that easily precipitates in the secondary battery. Specifically, it is preferable that the functional group can capture at least one kind of metal selected from the group consisting of Co, Mn, Ni and Fe. Thereby, it is possible to effectively suppress the metal deposition in the negative electrode.

  In addition, when the functional group captures a heavy metal, the functional group and the heavy metal are usually bonded to each other by, for example, a chemical or electrical action between the functional group and the heavy metal atom or ion. . An example of such a bond is a coordination bond. In this case, the scavenger containing the functional group can be a ligand capable of coordinating with a heavy metal.

  The capturing agent has 3 or more of the above functional groups per molecule of the capturing agent. By having three or more functional groups per molecule as described above, the ability of the capture agent to capture heavy metals can be enhanced, so that it is possible to effectively capture heavy metals in the electrolytic solution. For example, when the functional group can form a coordination bond with a heavy metal, usually, a plurality of functional groups coordinate to one heavy metal atom or heavy metal ion to effectively capture the heavy metal. it can. In this case, the scavenger can function as a multidentate ligand. The upper limit of the number of functional groups per molecule of scavenger is arbitrary, but is usually 10 or less.

  Preferable examples of the functional group include an amino group and an acidic group. Therefore, as the scavenger, it is preferable to use a compound having three or more groups per molecule selected from the group consisting of an amino group and an acidic group. Moreover, as a suitable example among the said acidic groups, a carboxylic acid group and a phosphonic acid group are mentioned. Therefore, the scavenger preferably has a carboxylic acid group or a phosphonic acid group as an acidic group. By using these suitable groups as functional groups, the dispersibility of the scavenger can be improved, so that the scavenger can be stably present in the porous membrane slurry composition. Among these, from the viewpoint of effectively increasing the dispersibility of the scavenger, it is particularly preferable that the scavenger contains both an amino group and an acidic group as functional groups. Here, one kind of the functional group may be used alone, or two or more kinds may be used in combination at any ratio.

The SP value of the scavenger is usually 12 (cal / cm ³ ) ^1/2 or more, usually 15 (cal / cm ³ ) ^1/2 or less, preferably 14.5 (cal / cm ³ ) ^{1/2. 2} or less, more preferably 14 (cal / cm ³ ) ^1/2 or less. By making the SP value of the scavenger greater than or equal to the lower limit of the above range, it is possible to prevent the scavenger from being excessively dissolved in the electrolytic solution, so that the rate characteristics of the secondary battery can be improved. Moreover, by making it below the upper limit value, the scavenger can be hardly dissolved in water in the porous membrane slurry composition, so that the destabilization of the particulate polymer can be prevented and the binding force can be kept high. Therefore, the binding property between the porous membrane and the separator substrate and the binding property between the porous membrane and the electrode plate can be increased.

  Here, the SP value means a solubility parameter. The SP value can be calculated using the method introduced in Hansen Solubility Parameters A User's Handbook, 2ndEd (CRCPless). The SP value of an organic compound can be estimated from the molecular structure of the organic compound. Specifically, it can be calculated using simulation software (for example, “HSPiP” (http://www.hansen-solubility.com)) that can calculate the SP value from the SMILE equation. The simulation software also includes Hansen SOLUBILITY PARAMETERS A User's Handbook Second Edition, Charles M. Based on the theory described in Hansen.

  Examples of the scavenger include ethylenediaminetetraacetic acid, glycol etherdiaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid and nitrotris (methylenephosphonic acid), nitrilotriacetic acid, trans-1,2-diaminocyclohexanetetra Examples include acetic acid, diethylene-triaminepentaacetic acid, and chelating agents such as salts thereof. Moreover, a capture | acquisition agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the scavenger is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, preferably 10 parts by weight or less, more preferably 5 parts by weight with respect to 100 parts by weight of the particulate polymer. Part or less, particularly preferably 3 parts by weight or less. By making the amount of the scavenger greater than or equal to the lower limit of the above range, the scavenger can effectively capture the heavy metal in the electrolytic solution, so that the cycle characteristics of the secondary battery can be improved. Moreover, the rate characteristic of a secondary battery can be made favorable by making it below an upper limit.

[1.4. Water-soluble polymer)
The porous membrane slurry composition of the present invention preferably 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 acts to bind the non-conductive particles by interposing between the non-conductive particles in the porous film, and by interposing between the non-conductive particles and the separator substrate. An effect of binding the porous film and the separator substrate and an effect of binding the porous film and the electrode plate by interposing between the non-conductive particles and the electrode plate can be achieved.

  The water-soluble polymer preferably includes an acidic group-containing monomer unit. The water-soluble polymer having an acidic group-containing monomer unit contains an acidic group. Since the affinity of the water-soluble polymer to water is increased by the action of the acidic group, the water-soluble polymer can be made soluble in water. In addition, since the water-soluble polymer has a high adsorptivity to non-conductive particles because it has a highly polar acidic 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.

Examples of the acidic group, the acidic group-containing monomer unit, and the acidic group-containing monomer include the same examples as those exemplified in the section of the particulate polymer. Especially, it is preferable that an acidic group containing monomer unit has at least 1 type of group chosen from the group which consists 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 acidic group containing monomer and an acidic 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 acidic group-containing monomer unit in the water-soluble polymer is preferably 20% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less, and particularly preferably 40% by weight or less. By increasing the ratio of the acidic group-containing monomer unit in 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 and the binding property between the porous membrane and the electrode plate are improved be able to. Moreover, it can prevent that the viscosity of a porous membrane slurry composition becomes high too much by setting it as an upper limit or less. Therefore, since the applicability | paintability of a porous film slurry composition can be made favorable, the rate characteristic of a secondary battery can be made favorable.

  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 can be increased to reduce the internal resistance of the 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 monomers include 2,2,2-trifluoroethyl (meth) acrylate, β- (perfluorooctyl) ethyl (meth) acrylate, 2,2, (meth) acrylic acid. 3,3-tetrafluoropropyl, (meth) acrylic acid 2,2,3,4,4,4-hexafluorobutyl, (meth) acrylic acid 1H, 1H, 9H-perfluoro-1-nonyl, (meth) 1H, 1H, 11H-perfluoroundecyl acrylate, perfluorooctyl (meth) acrylate, perfluoroethyl (meth) acrylate, trifluoromethyl (meth) acrylate, (meth) acrylic acid 3 [4 [1 -Trifluoromethyl-2,2-bis [bis (trifluoromethyl) fluoromethyl] ethynyloxy] benzooxy] 2-hydroxypropyl 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 in the water-soluble polymer to be equal to or higher than the lower limit of the above range, the cycle characteristics of the secondary battery can be improved. Moreover, by making it into below an upper limit, the binding property of a porous film and a separator base material and the binding property of a porous film and an electrode plate can be improved.

  The water-soluble polymer can contain a crosslinkable monomer unit. 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. In addition, since the degree of swelling of the water-soluble polymer by the electrolytic solution can be prevented from becoming excessively high, normally, the low-temperature output characteristics of the secondary battery can be improved.

Examples of the crosslinkable monomer include the same examples as those exemplified in the section of the particulate polymer.
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. By making the ratio of the crosslinkable monomer unit in the water-soluble polymer more than the lower limit of the above range, the mechanical strength of the water-soluble polymer can be increased, so that the binding property between the porous membrane and the separator substrate and The binding property between the porous membrane and the electrode plate can be enhanced. Moreover, durability of a porous film can be improved by making it into an upper limit or less.

  The water-soluble polymer can contain reactive surfactant units. The reactive surfactant unit is a structural unit having a structure formed by polymerizing a reactive surfactant. The reactive surfactant unit forms part of the water-soluble polymer and can function as a surfactant.

  The reactive surfactant is a monomer having a polymerizable group that can be copolymerized with another monomer and having a surface active group (hydrophilic group and hydrophobic group). Usually, the reactive surfactant has a polymerizable unsaturated group, and this group also acts as a hydrophobic group after polymerization. Examples of the polymerizable unsaturated group that the reactive surfactant has include a vinyl group, an allyl group, a vinylidene group, a propenyl group, an isopropenyl group, and an isobutylidene group. One kind of the polymerizable unsaturated group may be used alone, or two or more kinds may be used in combination at any ratio.

  The reactive surfactant usually has a hydrophilic group as a portion that exhibits hydrophilicity. Reactive surfactants are classified into anionic, cationic and nonionic surfactants depending on the type of hydrophilic group.

Examples of the anionic hydrophilic group include —SO ₃ M, —COOM, and —PO (OM) ₂ . Here, M represents a hydrogen atom or a cation. Examples of cations include alkali metal ions such as lithium, sodium and potassium; alkaline earth metal ions such as calcium and magnesium; ammonium ions; ammonium ions of alkylamines such as monomethylamine, dimethylamine, monoethylamine and triethylamine; and And ammonium ions of alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.
Examples of cationic hydrophilic groups include primary amine salts such as —NH ₂ HX, secondary amine salts such as —NHCH ₃ HX, tertiary amine salts such as —N (CH ₃ ) ₂ HX, A quaternary amine salt such as —N ⁺ (CH ₃ ) ₃ X ^— ; Here, X represents a halogen group.
-OH is mentioned as an example of a nonionic hydrophilic group.

  Examples of suitable reactive surfactants include compounds represented by the following formula (II).

In the formula (II), R represents a divalent linking group. Examples of R include -Si-O- group, methylene group and phenylene group.
In the formula (II), R ³ represents a hydrophilic group. An example of R ³ includes —SO ₃ NH ₄ .
In the formula (II), n represents an integer of 1 to 100.

Another example of a suitable reactive surfactant has a structural unit having a structure formed by polymerizing ethylene oxide and a structural unit having a structure formed by polymerizing butylene oxide. Mention may be made of compounds having an alkenyl group having a terminal double bond and —SO ₃ NH ₄ . Specific examples of such reactive surfactants include trade names “Latemul PD-104” and “Latemul PD-105” manufactured by Kao Corporation.
As the reactive surfactant and the reactive surfactant unit, one type may be used alone, or two or more types may be used in combination at any ratio.

  The ratio of the reactive surfactant unit in the water-soluble polymer is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, particularly preferably 0.5% by weight or more, and preferably It is 5% by weight or less, more preferably 4% by weight or less, and particularly preferably 2% by weight or less. The dispersibility of the porous membrane slurry composition can be improved by setting the ratio of the reactive surfactant unit in the water-soluble polymer to be equal to or higher than the lower limit of the above range. Moreover, durability of a porous film can be improved by setting it as an upper limit or less.

  The water-soluble polymer can contain a (meth) acrylic acid ester monomer unit. Examples of the (meth) acrylic acid ester monomer include the same examples as those exemplified in the section of the particulate polymer. 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 making the amount of the (meth) acrylic acid ester monomer unit in the water-soluble polymer equal to or higher than the lower limit of the above range, the binding property between the porous membrane and the separator substrate and the binding between the porous membrane and the electrode plate Sexuality can be increased. Moreover, the softness | flexibility of a porous film can be improved by making it into an upper limit or less.

  The water-soluble polymer can contain any structural unit in addition to the structural units described above. Examples of arbitrary structural units that can be contained in the water-soluble polymer include the same examples as those exemplified as the structural units that can be contained in the particulate polymer. 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. Hereinafter, it is particularly preferably 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 and the binding property between the porous membrane and the electrode plate can be improved. Moreover, the cycle characteristic of a secondary battery can be improved by making it 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 weight ratio of the particulate polymer to the water-soluble polymer is particulate polymer / water-soluble polymer, preferably 50/50 or more, more preferably 70/30 or more, and particularly preferably 90/10 or more. , Preferably 99/1 or less. By setting the weight ratio of the particulate polymer to the water-soluble polymer to be equal to or higher than the lower limit of the above range, the binding property of the porous film can be enhanced. Moreover, by making it below an upper limit, stability of a porous membrane slurry composition can be made high, and uniform application | coating becomes possible at the time of application | coating of a porous membrane slurry composition. Therefore, the rate characteristic of the secondary battery can be improved.

  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); ketone compounds such as diacetone alcohol (169) and γ-butyrolactone (204); ethyl alcohol (78), isopropyl alcohol (82), normal propyl alcohol (97) and the like. Alcohol compounds; 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 ( 88) glycol ether compounds and the like; and 1,3-dioxolane (75), 1,4-dioxolane (101) include ether compounds such as tetrahydrofuran (66). 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.

  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.

[1.5. 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 particulate polymer and the scavenger are dispersed in water, and the water-soluble polymer is dissolved in water.

  Further, as the solvent, a solvent other than water may be used in combination with water. Examples of solvents that can be used in combination with water include cycloaliphatic hydrocarbon compounds such as cyclopentane and cyclohexane; aromatic hydrocarbon compounds such as toluene and xylene; ketone compounds such as ethyl methyl ketone and cyclohexanone; ethyl acetate and acetic acid Ester compounds such as butyl, γ-butyrolactone, ε-caprolactone; nitrile compounds such as acetonitrile and propionitrile; ether compounds such as tetrahydrofuran and ethylene glycol diethyl ether: methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, and the like And alcohol compounds; amide compounds such as N-methylpyrrolidone (NMP) and N, N-dimethylformamide; 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, the solid content of the composition means a substance remaining after the composition is dried.

[1.6. (Optional ingredients)
The porous membrane slurry composition may contain an optional component in addition to the non-conductive particles, the particulate polymer, the scavenger, the water-soluble polymer and water described above. 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 usually increases the dispersion stability of the non-conductive particles in the porous membrane slurry composition, improves the binding property between the porous membrane and the separator substrate, or between the porous membrane and the electrode plate. The binding property can be increased. 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, the 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.

  In addition, the porous membrane slurry composition includes, for example, an isothiazoline compound, a pyrithione compound, a dispersant, a leveling agent, an antioxidant, a thickener, an antifoaming agent, a wetting agent, and an electrolyte having a function of suppressing decomposition of an electrolytic solution. It may contain a liquid additive.

[1.7. 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.

[1.8. 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 of the disperser 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]
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 and metal deposition in a 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.

Further, the weight of the porous membrane per unit area is preferably 0.3 mg / cm ² or more, more preferably 0.45 mg / cm ² or more, particularly preferably 0.6 mg / cm ² or more, preferably 0. It is 95 mg / cm ² or less, more preferably 0.8 mg / cm ² or less, and particularly preferably 0.7 mg / cm ² or less. By setting the weight of the porous membrane per unit area to be equal to or higher than the lower limit of the above range, the heat resistance of the porous membrane 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 film. In the separator of the present invention, by providing the porous film, it is 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 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 manufactured using the porous film slurry composition of this invention, generation | occurrence | production of gas and metal precipitation can be suppressed in a secondary battery provided with the said separator.

[3.1. (Separator substrate)
As the separator substrate, for example, a porous substrate having fine pores can be used. By using such a separator base material, a short circuit can be prevented in the secondary battery without hindering charging / discharging of the battery. Specific examples of the separator substrate include a microporous film or a nonwoven fabric containing a polyolefin resin such as polyethylene resin and polypropylene resin, an aromatic polyamide resin, and the like.

  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 with 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 membrane obtained by apply | coating the porous membrane slurry composition of this invention on the said separator base material, and drying. Such a separator can be manufactured, for example, by performing the porous film manufacturing method described above using a separator base material as a base material. At this time, the porous film may be provided only on one side of the separator base material, or may be provided on both sides.

[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 manufactured using the porous film slurry composition of this invention, generation | occurrence | production of gas and metal precipitation can be suppressed in a 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. There are various types of electrode active materials depending on the types of secondary batteries. Here, electrode active materials for lithium ion secondary batteries will be described in particular. However, the electrode active material is not limited to those listed below.

  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 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 diameter 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 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 consideration of other constituent requirements of the 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 an electrode binder include polyethylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid derivatives, poly An acrylonitrile 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. These soft polymers may have a cross-linked structure or may have a functional group introduced by modification.
The polymer may be in the form of particles or non-particulates.
Furthermore, the binder for electrodes may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Among these polymers, it is preferable to use a binder that can be a source of halide ions because the advantage of the present invention that gas generation can be suppressed can be effectively utilized. For example, it is preferable to use polyvinylidene fluoride as a binder, and it is more preferable to use latex-like polyvinylidene fluoride dispersed in water (hereinafter sometimes referred to as “aqueous PVdF” as appropriate).
In order to reduce environmental burden, it is desired to produce an electrode using an electrode slurry composition containing water as a solvent. Therefore, when using polyvinylidene fluoride as a binder for electrodes, it is required to use water-based PVdF as the polyvinylidene fluoride. However, water-based PVdF can be a source of fluoride ions in the secondary battery. Conventionally, it has been difficult to use water-based PVdF because gas is generated when fluoride ions are generated in the secondary battery. On the other hand, even when water-based PVdF is used as the electrode binder in the electrode of the present invention, gas generation can be suppressed in the secondary battery, and deterioration of battery characteristics can be prevented.

  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 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 by, for example, applying an electrode active material and 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 and drying the porous film slurry composition of the present invention on the electrode plate. 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. Secondary battery]
The 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 secondary battery of the present invention is the electrode of the present invention.
(B) The secondary battery of the present invention includes a separator, and the separator is the separator of the present invention.

The secondary battery of the present invention is excellent in both cycle characteristics and rate characteristics. The reason why such an effect is obtained is not necessarily clear, and according to the study of the present inventor, it is assumed as follows. However, this invention is not restrict | limited for the reason demonstrated below.
The secondary battery of the present invention includes the electrode or separator of the present invention. These electrode and separator of this invention are equipped with the porous membrane manufactured using the composition for porous membrane slurries of this invention. Since the porous film is provided, generation of gas and metal deposition can be suppressed in the secondary battery of the present invention. The gas and the deposited metal can cause, for example, the destruction of the electrode and the movement of ions in the electrolytic solution. On the other hand, the secondary battery of the present invention can suppress gas generation and metal deposition as described above, and thus is presumed to be excellent in both cycle characteristics and rate characteristics.

[5.1. electrode〕
In principle, the 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 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 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 ion 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 carbonate compounds such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and methyl ethyl carbonate (MEC). Ester compounds such as γ-butyrolactone and methyl formate; ether compounds 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.

  In the electrolytic solution, the capture agent may be eluted from the porous membrane. Even in this case, the concentration of the scavenger in the electrolytic solution is preferably small. The specific concentration of the scavenger in the electrolytic solution is preferably 0.1% by weight or less, more preferably 0.07% by weight or less, and particularly preferably 0.05% by weight or less. By keeping the concentration of the scavenger in the electrolytic solution within the above range, the precipitation of the scavenger can be prevented and the rate characteristics of the secondary battery can be improved. Moreover, there is no restriction | limiting in the lower limit of the density | concentration of the scavenger in electrolyte solution, For example, 0.01 weight% or more may be sufficient.

[5.3. Source of halide ions)
As described above, in the secondary battery of the present invention, it is considered that the generation of gas is suppressed by trapping halide ions by the particulate 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.

  Even if the secondary battery of the present invention is configured to include a component capable of generating halide ions as described above, it is possible to suppress deterioration in battery performance due to the halide ions. Therefore, the secondary battery of the present invention is significant in that the above-described components that are considered to cause a decrease in battery performance can be applied to the secondary battery.

[5.4. Secondary battery manufacturing method)
The manufacturing method of the 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 according to 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]
[Method for measuring peel strength between separator substrate and porous membrane]
The separator was cut into a rectangle with a length of 100 mm and a width of 10 mm to obtain a test piece. A cellophane tape (as defined in JIS Z1522) was affixed to the surface of the porous membrane with the test piece facing down. At this time, the cellophane tape was fixed upward on a horizontal test bench. Thereafter, the stress was measured when one end of the separator substrate was pulled upward in the direction of gravity 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. The measured peel strength was evaluated according to the following criteria. The higher the peel strength, the greater the binding property between the porous membrane and the separator substrate, that is, the higher the adhesion strength.

(Evaluation criteria)
A: The peel strength is 150 N / m or more.
B: The peel strength is 100 N / m or more and less than 150 N / m.
C: The peel strength is 50 N / m or more and less than 100 N / m.
D: The peel strength is less than 50 N / m.

[Method of evaluating rate characteristics of secondary battery]
The 800 mAh wound type lithium ion secondary battery manufactured in Examples and Comparative Examples was allowed to stand in an environment of 25 ° C. for 24 hours. Then, the charge / discharge rate of 0.1 C was charged to 4.35 V, and the first charge / discharge operation for discharging to a discharge voltage of 2.75 V was performed.

  After the first charging / discharging operation, the second charging / discharging operation is performed at 25 ° C., charging to 4.35 V at a charging rate of 0.1 C, and discharging to 3.0 V at a discharging rate of 1.0 C. It was. In the second charging / discharging operation, the battery capacity (hereinafter sometimes referred to as “battery capacity at 1.0 C” as appropriate) was obtained.

  Further, after the first charge / discharge operation, the battery is charged to 4.35 V at a charge rate of 0.1 C at 25 ° C. and 2.30 at a discharge rate of 3.0 C, separately from the second charge / discharge operation. A third charging / discharging operation for discharging to 75 V was performed. In this third charging / discharging operation, the battery capacity (hereinafter sometimes referred to as “battery capacity at 3.0 C” as appropriate) was determined.

  The ratio of the battery capacity at 3.0 C to the battery capacity at 1.0 C was calculated as a percentage, and the charge / discharge rate characteristic (= “battery capacity at 3.0 C” / “battery capacity at 1.0 C”) was obtained. The charge / discharge rate characteristics were evaluated according to the following criteria. The higher the value of the charge / discharge rate characteristic, the smaller the internal resistance of the secondary battery, indicating that high-speed charge / discharge is possible.

(Evaluation criteria)
A: The charge / discharge rate characteristic is 80% or more.
B: The charge / discharge rate characteristics are 70% or more and less than 80%.
C: The charge / discharge rate characteristics are 60% or more and less than 70%.
D: Charge / discharge rate characteristics are less than 60%.

[Evaluation test of high-temperature cycle characteristics of secondary batteries]
The 800 mAh wound type lithium ion secondary battery manufactured in Examples and Comparative Examples was allowed to stand in an environment of 25 ° C. for 24 hours. Thereafter, under an environment of 25 ° C., a charge / discharge operation of charging to 4.35 V at a charge rate of 0.1 C and discharging to 2.75 V at a 0.1 C discharge rate was performed, and an initial capacity C0 was measured.

Thereafter, in an environment of 60 ° C., a charge / discharge operation of charging to 4.35 V at a charge rate of 0.1 C and discharging to 2.75 V at a 0.1 C discharge rate was repeated 1000 times (1000 cycles), and after 1000 cycles The capacity C1 was measured.
The capacity retention ratio ΔC was calculated by “ΔC = C1 / C0 × 100 (%)”. This capacity retention rate ΔC was evaluated according to the following criteria. The higher the capacity retention ratio ΔC, the better the high-temperature cycle characteristics of the secondary battery and the longer the battery life.
(Evaluation criteria)
A: The capacity maintenance ratio ΔC is 70% or more.
B: The capacity maintenance ratio ΔC is 60% or more and less than 70%.
C: The capacity retention ratio ΔC is 50% or more and less than 60%.
D: The capacity maintenance ratio ΔC is less than 50%.

[Measurement method of cell volume change rate]
The 800 mAh wound type lithium ion secondary batteries manufactured in the examples and comparative examples were allowed to stand in an environment at 25 ° C. for 24 hours. Thereafter, in a 25 ° C. environment, a charge / discharge operation was performed in which the battery was charged to 4.35V at a charge rate of 0.1C and discharged to 2.75V at a discharge rate of 0.1C. Then, the battery cell was immersed in liquid paraffin, and the volume V0 was measured.

  Furthermore, in a 60 ° C. environment, a charging / discharging operation of charging to 4.35 V at a charging rate of 0.1 C and discharging to 2.75 V at a discharging rate of 0.1 C was repeated 1000 cycles. The battery cell after 1000 cycles of charge and discharge was immersed in liquid paraffin, and its volume V1 was measured.

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

(Evaluation criteria)
A: Volume change rate ΔV is less than 20%.
B: Volume change rate ΔV is 20% or more and less than 30%.
C: Volume change rate ΔV is 30% or more and less than 40%.
D: Volume change rate ΔV is 40% or more.

[Measurement method of concentration of scavenger in electrolyte]
The 800 mAh wound type lithium ion secondary batteries manufactured in the examples and comparative examples were allowed to stand in an environment at 25 ° C. for 24 hours.
Thereafter, in a 25 ° C. environment, a charge / discharge operation was performed in which the battery was charged to 4.35V at a charge rate of 0.1C and discharged to 2.75V at a discharge rate of 0.1C.
Thereafter, in a 60 ° C. environment, a charge / discharge operation of charging to 4.35 V at a charge rate of 0.1 C and discharging to 2.75 V at a discharge rate of 0.1 C was repeated 1000 cycles.
Thereafter, the battery cells were disassembled to take out the electrolytic solution, and the taken-out electrolytic solution was analyzed by gas chromatography mass spectrometry (GC / MS analysis). From the chromatogram obtained as a result of GC / MS analysis, the amount of the capture agent eluted in the electrolyte was quantified from the peak area ratio of the electrolyte component and the capture agent, and the concentration of the capture agent in the electrolyte was measured. . The lower the concentration of the scavenger in the electrolytic solution, the smoother the movement of lithium ions in the electrolytic solution can be, so the rate characteristics of the secondary battery can be improved.

[Example 1]
(1-1. Production of water-soluble polymer)
In a 5 MPa pressure vessel with a stirrer, 32.5 parts of methacrylic acid (acidic group-containing monomer), 7.5 parts of 2,2,2-trifluoroethyl methacrylate (fluorine-containing (meth) acrylic acid ester monomer), 58 parts of ethyl acrylate (arbitrary monomer), 1.0 part of ethylene dimethacrylate (crosslinkable monomer), 1.0 part of polyoxyalkylene alkenyl ether ammonium sulfate (reactive surfactant), 0 t-dodecyl mercaptan .6 parts, 150 parts of ion-exchanged water, and 1.0 part of potassium persulfate (polymerization initiator) were added and sufficiently stirred, and then heated to 60 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the mixture was cooled and the reaction was stopped to obtain a mixture containing a water-soluble polymer. 10% aqueous ammonia was added to the mixture containing the water-soluble polymer to adjust the pH to 8 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, 93.8 parts of butyl acrylate, 2 parts of acrylonitrile, 2 parts of methacrylic acid, 0.2 part of allyl methacrylate, 2 parts of acrylamide, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 ion-exchanged water After adding 0.3 part of potassium persulfate as a part and a polymerization initiator, and stirring sufficiently, it heated at 50 degreeC and started superposition | polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a particulate polymer. A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate polymer to adjust the pH to 7. Thereafter, unreacted monomers were removed from the mixture by distillation under reduced pressure, and then the mixture was cooled to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate polymer.

(1-3. Production of porous membrane slurry composition)
100 parts of alumina particles (volume average particle diameter of 0.5 μm, BET specific surface area of 5.0 m ² / g) as non-conductive particles, ² parts of carboxymethyl cellulose sodium salt (“1220” manufactured by Daicel) as non-conductive particles. 0.06 part by weight of ethylenediaminetetraacetic acid, 0.32 part of an aqueous solution containing the water-soluble polymer prepared above, corresponding to the solid content, and the particulate polymer produced above 6 parts of the aqueous dispersion containing the mixture was added and mixed, and water was further mixed to adjust the solid content concentration to 40% by weight to produce a porous membrane slurry composition.

(1-4. Manufacture of separator with porous membrane)
The porous membrane slurry composition prepared above is applied to one side of a polyethylene separator substrate (thickness 16 μm, Gurley value 210 s / 100 cc) with a gravure coater so that the coating amount after drying is 6 mg / cm ^2. It was applied and dried at 50 ° C. for 1 minute. Thereby, a separator provided with a separator base material and a porous film having a thickness of 4 μm was obtained.
About this separator, the peeling strength of a separator base material and a porous membrane was measured by the method mentioned above.

(1-5. 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 150 parts of water and 0.5 part of potassium persulfate as a polymerization initiator were added and sufficiently stirred, 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 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, unreacted monomers were removed from the mixture by distillation under reduced pressure under heating, and then cooled to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate binder.

(1-6. Production of negative electrode slurry composition)
To a planetary mixer, 100 parts of artificial graphite (volume average particle diameter 15.6 μm) and 1 part of a 2% aqueous solution of carboxymethylcellulose sodium salt (“MAC350HC” manufactured by Nippon Paper Industries Co., Ltd.) as a thickener are added. The mixture was further mixed with ion exchange water to adjust the solid content concentration to 68%, and then 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 resulting mixture, 1.5 parts of the aqueous dispersion containing the particulate binder produced above is added in an amount corresponding to the solid content, and ion exchange water is further added to adjust the final solid content concentration to 52%. For an additional 10 minutes. This was defoamed under reduced pressure to obtain a negative electrode slurry composition having good fluidity.

(1-7. Production of negative electrode)
The negative electrode slurry composition was applied on a copper foil having a thickness of 20 μm as a current collector by a comma coater so that the film thickness after drying was about 150 μm and 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 having a negative electrode active material layer thickness of 80 μm.

(1-8. Production of positive electrode slurry composition)
100 parts of LiCoO ₂ having a volume average particle size of 12 μm as a positive electrode active material, ₂ parts of acetylene black (“HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and carboxymethyl cellulose (manufactured by Nippon Paper Chemical Co., Ltd. “ MAC-350HC ") was mixed with 1 part of solid content, and 2 parts of a polyvinylidene fluoride aqueous dispersion as a binder was mixed with solid content, and further water was added to adjust the total solid content concentration to 65%. These were mixed by a planetary mixer to prepare a positive electrode slurry composition.

(1-9. Production of positive electrode)
The positive electrode slurry composition was applied with a comma coater onto an aluminum foil having a thickness of 20 μm as a current collector so that the film thickness after drying was about 150 μm and 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. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a positive electrode raw material before pressing. The positive electrode raw material before pressing was rolled by a roll press to obtain a positive electrode having a positive electrode active material layer thickness of 80 μm.

(1-10. Lithium ion secondary battery)
The separator provided with the porous membrane manufactured as described above was cut out to 55 × 5.5 cm ² , the negative electrode was cut to 50 × 5.2 cm ² , and the positive electrode was cut to 49 × 5 cm ² . The cut out positive electrode, separator, and negative electrode were stacked and wound with a winding machine to obtain a wound body. At this time, the positive electrode active material layer of the positive electrode and the porous film of the separator face each other, and the negative electrode active material layer of the negative electrode and the separator base material of the separator face each other.

The obtained wound body was pressed at 60 ° C. and 0.5 MPa to obtain a flat body. This flat body is wrapped with an aluminum packaging material exterior as a battery exterior, and an electrolytic solution (solvent: EC / DEC / VC = 68.5 / 30 / 1.5 volume ratio, electrolyte: concentration 1M) is coated on the aluminum packaging exterior. LiPF ₆ ) was injected so that no air remained. Further, in order to seal the opening of the aluminum packaging material exterior, heat sealing at 150 ° C. was performed to close the aluminum packaging material exterior, and an 800 mAh wound type lithium ion secondary battery was manufactured.
With respect to this lithium ion secondary battery, the charge / discharge rate characteristics, the capacity retention rate ΔC, the cell volume change rate ΔV, and the concentration of the scavenger in the electrolytic solution were measured by the methods described above.

[Example 2]
In the step (1-2), the amount of butyl acrylate was changed to 95.6 parts, and the amount of acrylamide was changed to 0.2 parts.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 3]
In the step (1-2), the amount of butyl acrylate was changed to 86.3 parts, and the amount of acrylamide was changed to 9.5 parts.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 4]
In a 5 MPa pressure vessel with a stirrer, 62 parts of styrene, 31.5 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 1 part of 2-hydroxyethyl acrylate, 2 parts of acrylamide, and sodium dodecylbenzenesulfonate 0.4 as an emulsifier Part, 150 parts of ion-exchanged water and 0.5 part of potassium persulfate as a polymerization initiator were 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 a particulate polymer. 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 distillation under reduced pressure, and then the mixture was cooled to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate polymer.

In the step (1-3), as the aqueous dispersion containing the particulate polymer, the one prepared in Example 4 was used instead of the one prepared in Example 1.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 5]
In the step (1-2), methacrylamide was used instead of acrylamide.
A lithium ion secondary battery was produced 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 ethylenediaminetetraacetic acid with respect to 100 parts of alumina particles was changed to 0.0018 part (the amount of ethylenediaminetetraacetic acid with respect to 100 parts of particulate polymer was 0.03 part).
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 7]
In the step (1-3), the amount of ethylenediaminetetraacetic acid relative to 100 parts of alumina particles was changed to 0.48 parts (the amount of ethylenediaminetetraacetic acid relative to 100 parts of the particulate polymer was 8 parts).
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 8]
In the step (1-3), glycol ether diamine tetraacetic acid was used instead of ethylenediaminetetraacetic acid.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 9]
In the step (1-3), 1,3-diamino-2-hydroxypropane tetraacetic acid was used instead of ethylenediaminetetraacetic acid.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 10]
In the step (1-3), nitrotris (methylenephosphonic acid) (Nitrilotis (Methylene Phosphonic Acid)) was used instead of ethylenediaminetetraacetic acid.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 11]
On the positive electrode active material layer of the positive electrode after the press produced in the step (1-9), the porous film slurry composition obtained in the step (1-3) is applied with a gravure coater and the coating amount after drying is 6 mg. / Cm ^2, and applied at 50 ° C. for 1 minute. This obtained the positive electrode provided with the electrode plate provided with an electrical power collector and a positive electrode active material layer, and the porous film of thickness 4 micrometers.

In the step (1-10), a polyethylene separator (thickness 16 μm, Gurley value 210 s / 100 cc) not having a porous film was used instead of the separator having a porous film, and the electrode plate produced in Example 11 as a positive electrode And the positive electrode provided with a porous film was used. At this time, the positive electrode porous film and the separator were opposed to each other.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Example 12]
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 polyvinylidene fluoride (manufactured by Kureha Co., # 7208) as the binder The N-methylpyrrolidone solution was mixed with 2 parts corresponding to the solid content, 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.

In the said process (1-9), what was manufactured in Example 12 was used instead of what was manufactured in Example 1 as a positive electrode slurry composition.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 1]
In the step (1-3), ethylenediaminetetraacetic acid was not used.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 2]
In the step (1-3), hydroxyethylidene diphosphonic acid was used instead of ethylenediaminetetraacetic acid.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 3]
In the step (1-3), citric acid was used instead of ethylenediaminetetraacetic acid.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 4]
In the step (1-2), the amount of butyl acrylate was changed to 95.8 parts, and acrylamide was not used.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 5]
In the step (1-2), the amount of butyl acrylate was changed to 80.8 parts, and the amount of acrylamide was changed to 15 parts.
A lithium ion secondary battery was produced and evaluated in the same manner as in Example 1 except for the above items.

[Comparative Example 6]
In the step (1-2), N-methylolacrylamide was used instead of acrylamide.
A lithium ion secondary battery was produced 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 the following table. In the table below, the numerical value next to the abbreviation indicating a monomer in the monomer column indicates the amount of the monomer in all the monomers.
In the table below, the meanings of the abbreviations are as follows.
“BA”: butyl acrylate “AN”: acrylonitrile “MAA”: methacrylic acid “AMA”: allyl methacrylate “ST”: styrene “BD”: 1,3-butadiene “IA”: itaconic acid “β-HEA”: 2 -Hydroxyethyl acrylate "AAm": Acrylamide "MAAm": Methacrylamide "NMA": N-methylolacrylamide "Classification of amide": Classification of amide monomer "Primary": Carboxylic acid primary amide monomer " “Secondary”: secondary amide monomer of carboxylic acid “EA”: ethyl acrylate “F-ACL”: 2,2,2-trifluoroethyl methacrylate “EDMA”: ethylene dimethacrylate “PD-104”: polyoxy Ammonium alkenyl ether ammonium sulfate “grain: water”: particulate polymer Weight ratio with water-soluble polymer “EDTA”: ethylenediaminetetraacetic acid “GEDTA”: glycol etherdiaminetetraacetic acid “DPDA-OH”: 1,3-diamino-2-hydroxypropanetetraacetic acid “NTMP”: nitrotris (methylenephosphone) acid)
“HEDP”: hydroxyethylidene diphosphonic acid “number of functional groups”: number of functional groups capable of capturing heavy metal possessed by one molecule of scavenger “amount relative to particulate polymer”: scavenger for 100 parts by weight of particulate polymer “Concentration in electrolytic solution”: Concentration of scavenger in electrolytic solution “CMC salt”: Salt of carboxymethyl cellulose “Sepa”: Separator substrate “LCO”: LiCoO ₂
“Water-based PVdF”: Polyvinylidene fluoride dispersed in water “PVdF”: Polyvinylidene fluoride

[Consideration]
As described above, in the examples, excellent results are obtained in both cycle characteristics and rate characteristics. In the examples, the volume change rate is small. From these facts, it was confirmed that the present invention can suppress the generation of gas due to charge and discharge and realize a secondary battery excellent in both cycle characteristics and rate characteristics.

Claims (9)

Non-conductive particles, particulate polymer containing 0.1% to 10% by weight of carboxylic acid primary amide monomer unit, 3 or more functional groups capable of capturing heavy metals per molecule, and SP value ^{12 (cal / cm 3) 1/2} ~15 (cal / cm 3) compound is ^1/2, and a water porous film slurry composition for a secondary battery.   The porous membrane slurry composition for a secondary battery according to claim 1, wherein the amount of the compound with respect to 100 parts by weight of the particulate polymer is 0.1 to 10 parts by weight.   The porous membrane slurry composition for a secondary battery according to claim 1 or 2, wherein the functional group is at least one group selected from the group consisting of an amino group and an acidic group.   The porous membrane slurry composition for a secondary battery according to claim 3, wherein the acidic group is a carboxylic acid group or a phosphonic acid group.   Furthermore, the porous film slurry composition for secondary batteries as described in any one of Claims 1-4 containing the water-soluble polymer which contains 20 to 80weight% of acidic group containing monomer units. A separator substrate;
The separator for secondary batteries provided with the porous film obtained by apply | coating and drying the porous film slurry composition for secondary batteries as described in any one of Claims 1-5 on the said separator base material. An electrode plate,
An electrode for a secondary battery, comprising: a porous film obtained by applying and drying the porous film slurry composition for a secondary battery according to any one of claims 1 to 5 on the electrode plate. A secondary battery comprising a positive electrode, a negative electrode, an electrolyte and a separator,
A secondary battery, wherein the separator is a secondary battery separator according to claim 6. A secondary battery comprising a positive electrode, a negative electrode and an electrolyte solution,
A secondary battery, wherein at least one of the positive electrode and the negative electrode is an electrode for a secondary battery according to claim 7.