JP2017134915A - Slurry composition for nonaqueous secondary battery functional layer, functional layer for nonaqueous secondary battery and nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slurry composition for a nonaqueous secondary battery functional layer, which enables the formation of a nonaqueous secondary battery functional layer small in remaining water content and internal resistance.SOLUTION: A slurry composition for a nonaqueous secondary battery functional layer comprises: non-conductive particles; at least one kind of polymer components selected from a group consisting of a natural polymer and a semi-synthetic polymer; polycarboxylic acid including carboxylic acid group-containing monomer units at a rate of 20-50 mass%, which is water insoluble when pH is 6.5 or less and is water soluble when pH is 8.0 or more; a binding material; and water. The content of the polymer components is 0.1-0.6 pt.mass per 100 pts.mass of the non-conductive particles. The mass ratio of the content of the polymer components to the content of the polycarboxylic acid is 0.01 to 1.35.SELECTED DRAWING: None

Description

  The present invention relates to a slurry composition for a non-aqueous secondary battery functional layer, a functional layer for a non-aqueous secondary battery, and a non-aqueous secondary battery.

  Non-aqueous secondary batteries such as lithium ion secondary batteries (hereinafter sometimes simply referred to as “secondary batteries”) have the characteristics of being small and light, having high energy density, and capable of repeated charge and discharge. Yes, it is used for a wide range of purposes. The non-aqueous secondary battery generally includes a battery member such as a positive electrode, a negative electrode, and a separator that separates the positive electrode and the negative electrode and prevents a short circuit between the positive electrode and the negative electrode.

  Here, in the secondary battery, a battery member provided with a functional layer that imparts desired performance (for example, heat resistance and strength) to the battery member is used. Specifically, for example, a separator in which a functional layer is formed on a separator base material, or an electrode in which a functional layer is formed on an electrode base material in which an electrode mixture layer is provided on a current collector It is used as a battery member. In addition, as a functional layer that can improve the heat resistance and strength of the battery member, a functional layer made of a porous film layer formed by binding non-conductive particles with a binder (binder) is used. For example, this functional layer has a functional layer slurry composition containing non-conductive particles, a binder, and a dispersion medium such as water on the surface of a base material (separator base material, electrode base material, etc.). It is formed by applying and drying the applied functional layer slurry composition.

Therefore, in recent years, for the purpose of further improving the performance of secondary batteries, improvement of slurry compositions for non-aqueous secondary battery functional layers used for the formation of functional layers has been actively carried out (for example, patent documents). 1).
Specifically, for example, in Patent Document 1, a slurry composition used for forming a functional layer composed of a porous membrane layer contains a carboxylic acid group-containing monomer unit in an amount of 20% by mass to 50% by mass, and pH The slurry composition is coated by adding a polycarboxylic acid having a water solubility of 6.5 or less and water-insoluble and having a pH of 8 or more and a water-soluble thickener such as carboxymethylcellulose salt as a thickener. There has been proposed a technique for improving workability and improving high-temperature cycle characteristics of a secondary battery including a porous film layer (functional layer) formed using a slurry composition.

International Publication No. 2015/129408

  However, in the slurry composition described in Patent Document 1, the water content remaining in the functional layer formed using the slurry composition and the internal resistance of the functional layer are reduced, and the rate characteristics of the secondary battery including the functional layer are reduced. In addition, there is room for improvement in terms of improving the high-temperature cycle characteristics.

Then, an object of this invention is to provide the slurry composition for non-aqueous secondary battery functional layers which can form the functional layer for non-aqueous secondary batteries with little residual water content and internal resistance.
Another object of the present invention is to provide a functional layer for a non-aqueous secondary battery that has a small amount of residual moisture and internal resistance and can exhibit excellent rate characteristics and high-temperature cycle characteristics for a non-aqueous secondary battery. To do.
And an object of this invention is to provide the non-aqueous secondary battery which is excellent in a rate characteristic and a high temperature cycling characteristic.

  The present inventor has intensively studied for the purpose of solving the above problems. Then, the present inventor has a polycarboxylic acid containing a carboxylic acid group-containing monomer unit in an amount of 20% by mass to 50% by mass, water-insoluble at pH 6.5 or less, and water-soluble at pH 8 or more. A slurry composition for a non-aqueous secondary battery functional layer containing an acid and a polymer component comprising a natural polymer and / or a semi-synthetic polymer, the content of the polymer component within a predetermined range, and a high content By keeping the ratio of the molecular component content and the polycarboxylic acid content within a predetermined range, the performance required for the functional layer such as heat shrinkage resistance is ensured, while the residual moisture content and the internal resistance are low. The inventors have found that a functional layer for an aqueous secondary battery can be formed, and completed the present invention.

That is, the present invention aims to advantageously solve the above problems, and the slurry composition for a non-aqueous secondary battery functional layer of the present invention comprises non-conductive particles, natural polymers and semi-synthetics. It contains at least one polymer component selected from the group consisting of polymers and carboxylic acid group-containing monomer units in a proportion of 20% by mass or more and 50% by mass or less, and has a pH of 6.5 or less. A slurry composition for a non-aqueous secondary battery functional layer, comprising a water-insoluble polycarboxylic acid having a pH of 8.0 or higher, a water-soluble polycarboxylic acid, a binder, and water. The content is 0.1 parts by mass or more and 0.6 parts by mass or less per 100 parts by mass of the non-conductive particles, and the mass ratio of the content of the polymer component to the content of the polycarboxylic acid is 0.00. It is 01 or more and 1.35 or less. Thus, the mass ratio of the content of the polymer component to the content of the polycarboxylic acid within the predetermined range of the content of the polymer component (the content of the polymer component / the content of the polycarboxylic acid) Is within a predetermined range, it is possible to form a functional layer for a non-aqueous secondary battery with a small amount of residual moisture and low internal resistance while ensuring performance required for the functional layer such as heat shrinkage resistance.
In the present invention, the determination of the water solubility or water insolubility of the polycarboxylic acid at a specific pH is made as follows. That is, an aqueous polycarboxylic acid solution having a concentration of 2% by mass with adjusted pH is prepared and stirred at 25 ° C. for 1 hour to obtain an evaluation solution. Next, the evaluation liquid is transferred to a cell having an optical path length of 30 mm, and the scattered light and the total light transmitted light are measured using a haze meter, and obtained by the formula: haze = (scattered light / total light transmitted light) × 100 (%). Obtain the haze of the evaluation solution. When the haze of the evaluation liquid is 60% or more, it is determined that the polycarboxylic acid is water-insoluble at the pH of the evaluation liquid. When the haze of the evaluation liquid is less than 60% The polycarboxylic acid is determined to be water-soluble at the pH of the evaluation solution.

  Here, in the slurry composition for a non-aqueous secondary battery functional layer of the present invention, the polymer component is preferably carboxymethyl cellulose or a carboxymethyl cellulose salt. When the polymer component is carboxymethyl cellulose or carboxymethyl cellulose salt, the heat shrinkage resistance of the functional layer for non-aqueous secondary battery formed using the slurry composition for non-aqueous secondary battery functional layer can be improved.

  And it is preferable that pH of the slurry composition for non-aqueous secondary battery functional layers of this invention is 6.0 or more and 12.0 or less. If pH is 6.0 or more and 12.0 or less, it formed using the slurry composition for non-aqueous secondary battery functional layers, improving the coating property of the slurry composition for non-aqueous secondary battery functional layers. The amount of residual moisture in the functional layer for a non-aqueous secondary battery can be further reduced. Therefore, it is possible to further improve the rate characteristics and high-temperature cycle characteristics of the non-aqueous secondary battery including the non-aqueous secondary battery functional layer formed using the non-aqueous secondary battery functional layer slurry composition.

  Moreover, this invention aims at solving the said subject advantageously, The functional layer for non-aqueous secondary batteries of this invention is any of the slurry composition for non-aqueous secondary battery functional layers mentioned above. It is characterized by being formed using Thus, if the slurry composition for non-aqueous secondary battery functional layers described above is used, the residual water content and internal resistance of the non-aqueous secondary battery functional layer can be reduced. Accordingly, excellent rate characteristics and high-temperature cycle characteristics can be exhibited in the non-aqueous secondary battery including the non-aqueous secondary battery functional layer.

  Furthermore, this invention aims at solving the said subject advantageously, The non-aqueous secondary battery of this invention is equipped with the functional layer for non-aqueous secondary batteries mentioned above, It is characterized by the above-mentioned. Thus, if the functional layer for non-aqueous secondary batteries described above is used, excellent rate characteristics and high-temperature cycle characteristics can be exhibited in the non-aqueous secondary batteries.

According to the slurry composition for a non-aqueous secondary battery functional layer of the present invention, it is possible to form a functional layer for a non-aqueous secondary battery with a small amount of residual moisture and low internal resistance.
In addition, according to the functional layer for a non-aqueous secondary battery of the present invention, the non-aqueous secondary battery can exhibit excellent rate characteristics and high-temperature cycle characteristics.
And according to this invention, the non-aqueous secondary battery excellent in a rate characteristic and a high temperature cycling characteristic is obtained.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the slurry composition for a non-aqueous secondary battery functional layer of the present invention is used as a material for preparing a functional layer for a non-aqueous secondary battery. And the functional layer for non-aqueous secondary batteries of this invention is formed using the slurry composition for non-aqueous secondary battery functional layers of this invention. Moreover, the nonaqueous secondary battery of this invention is provided with the functional layer for nonaqueous secondary batteries of this invention at least.

(Slurry composition for non-aqueous secondary battery functional layer)
The slurry composition for a non-aqueous secondary battery functional layer according to the present invention includes a non-conductive particle, a polymer component selected from the group consisting of natural polymers and semi-synthetic polymers, and a carboxylic acid group. A binder containing a monomer unit containing 20% by mass or more and 50% by mass or less, a water-insoluble water having a pH of 6.5 or lower, and a water-soluble polycarboxylic acid having a pH of 8.0 or higher; A slurry composition containing water as a dispersion medium, optionally containing additives and the like. The slurry composition for a non-aqueous secondary battery functional layer of the present invention has a polymer component content of 0.1 to 0.6 parts by mass per 100 parts by mass of non-conductive particles, The mass ratio of the content of the polymer component to the acid content is 0.01 or more and 1.35 or less.

The non-aqueous secondary battery functional layer slurry composition of the present invention contains a predetermined amount of a polymer component composed of a natural polymer and / or a semi-synthetic polymer and a polycarboxylic acid having a predetermined composition and properties. Therefore, it is possible to form a functional layer for a non-aqueous secondary battery with a small amount of residual moisture and internal resistance while ensuring performance required for the functional layer, such as heat-resistant shrinkage. Therefore, if the slurry composition for a non-aqueous secondary battery functional layer of the present invention is used, a non-aqueous secondary battery excellent in rate characteristics and high-temperature cycle characteristics can be obtained.
If only the residual moisture content and internal resistance of the functional layer are to be reduced, it is possible to simply reduce the content of the polymer component and polycarboxylic acid in the slurry composition for the functional layer. When the content of polycarboxylic acid is simply reduced, the performance of the functional layer such as heat shrinkage can be impaired. In contrast, in the slurry composition for a non-aqueous secondary battery functional layer of the present invention, not only the content of the polymer component is made relatively small, but also the mass ratio of the polymer component to the polycarboxylic acid (polymer Since the content of the component / the content of the polycarboxylic acid is within a specific range, the residual moisture content and the internal resistance of the functional layer can be efficiently reduced while ensuring heat-resistant shrinkage.

<Non-conductive particles>
Here, the non-conductive particles are particles that do not dissolve in the dispersion medium water and the non-aqueous electrolyte solution of the secondary battery, and the shape thereof is maintained in them. And since a nonelectroconductive particle is electrochemically stable, it exists stably in a functional layer under the use environment of a secondary battery.

As the nonconductive particles, for example, various inorganic fine particles and organic fine particles can be used.
Specifically, as the non-conductive particles, both inorganic fine particles and organic fine particles other than the particulate polymer described later that can be used as a binder can be used, but usually inorganic fine particles are used. . Especially, as a material of nonelectroconductive particle, the material which exists stably in the use environment of a non-aqueous secondary battery and is electrochemically stable is preferable. From this point of view, preferable examples of the non-conductive particles are aluminum oxide (alumina), aluminum oxide hydrate (boehmite (AlOOH), gibbsite (Al (OH) ₃ ), silicon oxide, magnesium oxide (magnesia). ), Oxide particles such as calcium oxide, titanium oxide (titania), barium titanate (BaTiO ₃ ), ZrO, alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; sharing of silicon, diamond, etc. Binding crystal particles: Barium sulfate, calcium fluoride, barium fluoride, calcium carbonate, etc., poorly soluble ion crystal particles, clay fine particles, such as talc, montmorillonite, etc. These particles can be used as needed. Element substitution, surface treatment, solid solution, etc. may be applied. Also, as the non-conductive particles, barium sulfate particles, alumina particles, boehmite particles are preferred.
In addition, the nonelectroconductive particle mentioned above may be used individually by 1 type, and may be used in combination of 2 or more types.

Further, 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. When the volume average particle diameter of the non-conductive particles is 0.1 μm or more, the Gurley value of the functional layer is prevented from increasing (that is, the ionic conductivity is lowered), and the secondary battery including the functional layer is excellent. Rate characteristics can be exhibited. Moreover, if the volume average particle diameter of the non-conductive particles is 5 μm or less, the density of the functional layer can be increased and the heat shrinkage resistance of the functional layer can be increased.
In the present invention, the “volume average particle diameter of non-conductive particles” means the particle diameter at which the cumulative volume calculated from the small diameter side is 50% in the particle diameter distribution (volume basis) measured by the laser diffraction method. (D50).

<Polymer component>
The polymer component can function as a viscosity modifier for adjusting the viscosity of the slurry composition for a non-aqueous secondary battery functional layer of the present invention, and is non-conductive in a functional layer formed using the slurry composition for a functional layer. It can function as a component that enhances the heat shrinkability of the functional layer while binding components such as conductive particles. The polymer component is at least one selected from the group consisting of natural polymers and semi-synthetic polymers.

[Natural polymer]
Here, examples of the natural polymer include polysaccharides and proteins derived from plants or animals. Moreover, the natural polymer by which the fermentation process by the microorganisms etc. and the process by the heat | fever were carried out by the case can be illustrated. These natural polymers can be classified as plant natural polymers, animal natural polymers, microbial natural polymers, and the like.

Examples of plant-based natural polymers include gum arabic, gum tragacanth, galactan, guar gum, carob gum, caraya gum, carrageenan, pectin, cannan, quince seed (malmello), alkeocolloid (gasso extract), starch (rice, corn, potato) , Derived from wheat, etc.), glycyrrhizin and the like.
Examples of animal-based natural polymers include collagen, casein, albumin, gelatin, chitin, and chitosan.
Furthermore, examples of the microbial natural polymer include xanthan gum, dextran, succinoglucan, and bullulan.

[Semi-synthetic polymer]
The semi-synthetic polymer is obtained by modifying a natural polymer using a chemical reaction. Such semi-synthetic polymers can be classified as starch-based semi-synthetic polymers, cellulose-based semi-synthetic polymers, alginic acid-based semi-synthetic polymers, and animal or microbial semi-synthetic polymers.

  Examples of the starch-based semisynthetic polymer include solubilized starch, carboxymethyl starch, methylhydroxypropyl starch, and modified potato starch.

Cellulosic semisynthetic polymers can be classified into nonionic, anionic and cationic.
Nonionic cellulose semisynthetic polymers include, for example, alkylcelluloses such as methylcellulose, methylethylcellulose, ethylcellulose, and microcrystalline cellulose; hydroxyethylcellulose, hydroxybutylmethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxy And hydroxyalkylcelluloses such as propylmethylcellulose stearoxy ether, carboxymethylhydroxyethylcellulose, alkylhydroxyethylcellulose, and nonoxynylhydroxyethylcellulose;
Examples of the anionic cellulose semisynthetic polymer include substitution products obtained by substituting the above nonionic cellulose semisynthetic polymer with various derivative groups and salts thereof (sodium salt, ammonium salt, and the like). Specific examples include sodium cellulose sulfate, carboxymethyl cellulose (CMC) and salts thereof.
Furthermore, examples of the cationic cellulose semisynthetic polymer include, for example, low nitrogen hydroxyethyl cellulose dimethyl diallyl ammonium chloride (polyquaternium-4), chloride O- [2-hydroxy-3- (trimethylammonio) propyl] hydroxyethyl cellulose (polyquaternium). -10) and O- [2-hydroxy-3- (lauryldimethylammonio) propyl] hydroxyethylcellulose (polyquaternium-24) and the like.

  Examples of the alginic acid-based semisynthetic polymer include sodium alginate and propylene glycol alginate.

  Furthermore, examples of the animal-based semi-synthetic polymer include water-soluble chitin derivatives and water-soluble chitosan derivatives, and microbial-based semi-synthetic polymers include chemicals such as xanthan gum, dehydroxanthan gum, dextran, succinoglucan, and bullulan. Examples include modified products.

  Among these, from the viewpoint of improving the heat shrinkability of the functional layer, the polymer component is preferably xanthan gum, water-soluble chitin derivative, water-soluble chitosan derivative, carboxymethyl cellulose or carboxymethyl cellulose salt, carboxymethyl cellulose or carboxymethyl cellulose salt. Is more preferable.

[Content of polymer component]
And content of the high molecular component in the slurry composition for non-aqueous secondary battery functional layers of this invention is 0.1 mass part or more and 0.6 mass part or less per 100 mass parts of nonelectroconductive particle. Is preferably 0.3 parts by mass or more, more preferably 0.35 parts by mass or more, preferably 0.55 parts by mass or less, and 0.45 parts by mass or less. It is more preferable. When the content of the polymer component is less than 0.1 parts by mass per 100 parts by mass of the non-conductive particles, the heat shrinkability of the functional layer cannot be ensured. In addition, when the content of the polymer component is more than 0.6 parts by mass per 100 parts by mass of the non-conductive particles, the residual moisture content and internal resistance of the functional layer formed using the slurry composition for the functional layer are sufficiently reduced. The rate characteristics and high-temperature cycle characteristics of the non-aqueous secondary battery cannot be sufficiently improved.

<Polycarboxylic acid>
Like the polymer component described above, the polycarboxylic acid can function as a viscosity modifier for adjusting the viscosity of the slurry composition for a non-aqueous secondary battery functional layer of the present invention, and uses the functional layer slurry composition. In the functional layer formed in this manner, it can function as a component that enhances the heat shrinkage resistance of the functional layer while binding components such as non-conductive particles.

[Composition of polycarboxylic acid]
Here, the polycarboxylic acid is derived from a carboxylic acid group-containing monomer unit, which is a structural unit derived from a carboxylic acid group-containing monomer, and a monomer copolymerizable with the carboxylic acid group-containing monomer. And a structural unit. The monomer copolymerizable with the carboxylic acid group-containing monomer is not particularly limited, and includes (meth) acrylic acid ester monomers, crosslinkable monomers and other monomers. Can be mentioned. That is, the polycarboxylic acid is at least one selected from the group consisting of a carboxylic acid group-containing monomer unit, a (meth) acrylic acid ester monomer unit, a crosslinkable monomer unit, and other monomer units. Containing monomer units of seeds.
In the present invention, “(meth) acryl” means acryl and / or methacryl.

[[Carboxylic acid group-containing monomer unit]]
Examples of the carboxylic acid group-containing monomer that can form a carboxylic acid group-containing monomer unit include a compound having a —COOH group (carboxylic acid group) and a group capable of undergoing a polymerization reaction. In addition, for example, a compound capable of generating a carboxylic acid group by hydrolysis can also be used as the carboxylic acid group-containing monomer. Specific examples of such carboxylic acid group-containing monomers include acid anhydrides that can generate carboxylic acid groups by hydrolysis.

Examples of the carboxylic acid group-containing monomer include, but are not particularly limited to, ethylenically unsaturated carboxylic acid monomers.
Examples of the ethylenically unsaturated carboxylic acid monomer include ethylenically unsaturated monocarboxylic acid and derivatives thereof, ethylenically unsaturated dicarboxylic acid and acid anhydrides thereof, and derivatives thereof.
Examples of the ethylenically unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid and the like. Examples of ethylenically unsaturated monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid and the like can be mentioned.
Examples of the ethylenically unsaturated dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like. Examples of the acid anhydride of the ethylenically unsaturated dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride and the like. Examples of ethylenically unsaturated dicarboxylic acid derivatives include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid and other maleic acids; methylallyl maleate, maleic acid Examples thereof include maleic acid esters such as diphenyl acid, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate and fluoroalkyl maleate.
Among these, acrylic acid, methacrylic acid and itaconic acid are preferable, and methacrylic acid is more preferable. Further, one type of ethylenically unsaturated carboxylic acid monomer may be used alone, or two or more types may be used in combination at any ratio.

  And polycarboxylic acid needs to contain a carboxylic acid group containing monomer unit in the ratio of 20 mass% or more and 50 mass% or less, and the content rate of a carboxylic acid group containing monomer unit becomes like this. % To 45% by mass. By setting the ratio of the carboxylic acid group-containing monomer unit in the polycarboxylic acid to be the above lower limit or more, the dispersibility of the polycarboxylic acid in the slurry composition for the functional layer and in the functional layer is improved, and the rate of the secondary battery is increased. The characteristics can be further improved. Further, by setting the ratio of the carboxylic acid group-containing monomer unit in the polycarboxylic acid to be equal to or less than the above upper limit, it is possible to further reduce the residual moisture content of the functional layer and further improve the high-temperature cycle characteristics of the secondary battery. it can.

[[(Meth) acrylic acid ester monomer unit]]
The (meth) acrylic acid ester monomer that can form a (meth) acrylic acid ester monomer unit is not particularly limited, and an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms can be used. Can be mentioned. Especially, as alkyl (meth) acrylate, the alkyl (meth) acrylate which has a C1-C10 alkyl group is preferable, and the alkyl (meth) acrylate which has a C1-C6 alkyl group is more preferable.
In the present invention, “(meth) acrylate” means acrylate and / or methacrylate.

  Here, as alkyl (meth) acrylate, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2 -Alkyl acrylates such as ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, Pentyl methacrylate, hexyl methacrylate, heptyl meta Relate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n- tetradecyl methacrylate, and alkyl methacrylates such as stearyl methacrylate. In addition, these may use only 1 type and may use it combining 2 or more types by arbitrary ratios.

  In addition, it is preferable that polycarboxylic acid contains 50 to 80 mass% of (meth) acrylic acid ester monomer units, and it is more preferable to contain 50 to 75 mass%.

The polycarboxylic acid is a (meth) acrylic acid ester monomer unit (U1) having an alkyl group having 1 to 3 carbon atoms as a (meth) acrylic acid ester monomer unit, and 4 to 6 carbon atoms. It is preferable to include a (meth) acrylic acid ester monomer unit (U2) having the following alkyl group, a monomer unit derived from ethyl (meth) acrylate, and a single amount derived from butyl (meth) acrylate It is more preferable to include a body unit.
In addition, when polycarboxylic acid contains (meth) acrylic acid ester monomer unit (U1) and (meth) acrylic acid ester monomer unit (U2), (meth) acrylic acid ester single amount in polycarboxylic acid The mass ratio (U1 / U2) of the content of the (meth) acrylic acid ester monomer unit (U1) to the content of the body unit (U2) is, for example, 1.0 or more and 10 or less, preferably 2.5 or more and 6 0.0 or less.

[[Crosslinkable monomer unit]]
The crosslinkable monomer that can form a crosslinkable monomer unit is not particularly limited, and includes a monomer that can form a crosslinked structure by polymerization. As an example of the crosslinkable monomer, a monomer having heat crosslinkability is usually mentioned. More specifically, a monofunctional monomer having a thermally crosslinkable crosslinkable group and one olefinic double bond per molecule; a multifunctional having two or more olefinic double bonds per molecule Monomer.

  Examples of thermally crosslinkable crosslinkable groups include epoxy groups, N-methylolamide groups, oxetanyl groups, oxazoline groups, and combinations thereof. Among these, an epoxy group is more preferable in terms of easy adjustment of cross-linking and cross-linking density.

  Examples of the crosslinkable monomer having an epoxy group as a thermally crosslinkable group and having an olefinic double bond include vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o- Unsaturated glycidyl ethers such as allylphenyl glycidyl ether; butadiene monoepoxide, chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5,9- Monoepoxides of dienes or polyenes such as cyclododecadiene; 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 croto Glycidyl-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, etc. Examples include glycidyl esters of unsaturated carboxylic acids.

  Examples of the crosslinkable monomer having an N-methylolamide group as a thermally crosslinkable group and having an olefinic double bond include a methylol group such as N-methylol (meth) acrylamide. Examples include (meth) acrylamides.

Furthermore, 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) acryloyl Oxymethyl) -4-trifluoromethyloxetane.
In the present invention, “(meth) acryloyl” means acryloyl and / or methacryloyl.

  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 2-isopropenyl-5-ethyl-2-oxazoline.

  Furthermore, examples of the crosslinkable monomer having two or more olefinic double bonds per molecule 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, tri Methylolpropane-diallyl ether, allyl or vinyl ethers of other polyfunctional alcohols, triallylamine, methylenebisacrylamide and divinylbenzene It is below.

Among the above-mentioned monomers, ethylene dimethacrylate, allyl methacrylate, allyl glycidyl ether and N-methylol acrylamide are preferable as the crosslinkable monomer, and ethylene dimethacrylate is more preferable.
Moreover, a crosslinking | crosslinked monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The polycarboxylic acid preferably contains 0.5% by mass or more of the crosslinkable monomer unit, more preferably 0.7% by mass or more, and preferably 1.5% by mass or less. More preferably, the content is 1.0% by mass or less. By setting the ratio of the crosslinkable monomer unit in the polycarboxylic acid to the above lower limit or more, it is possible to improve the electrolytic solution resistance of the polycarboxylic acid and further improve the rate characteristics and high-temperature cycle characteristics of the secondary battery. . Moreover, the peel strength of a functional layer can be raised by making the ratio of the crosslinkable monomer unit in polycarboxylic acid below the said upper limit.

[[Other monomer units]]
Other monomers that can form other monomer units are not particularly limited, and a polymerizable group and a surface active group (that is, a hydrophilic group and a copolymerizable group that can be copolymerized with other monomers). A reactive surfactant which is a monomer having a hydrophobic group) and a fluorine-containing (meth) acrylic acid ester monomer.

[Properties of polycarboxylic acid]
The polycarboxylic acid must be water-insoluble at pH 6.5 or lower, and water-soluble at pH 8.0 or higher. When the polycarboxylic acid does not have the above properties, the residual moisture content in the functional layer increases, and the rate characteristics and high-temperature cycle characteristics of the secondary battery including the functional layer deteriorate.
In addition, the solubility of polycarboxylic acid can be adjusted by adjusting suitably the kind and ratio of the monomer unit contained in polycarboxylic acid.

[Method for preparing polycarboxylic acid]
In addition, the polycarboxylic acid mentioned above is not specifically limited, For example, the monomer composition containing the monomer mentioned above can be manufactured by superposing | polymerizing in an aqueous solvent. At this time, the ratio of each monomer in the monomer composition is usually the same as the ratio of the monomer units in the polycarboxylic acid.
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 may be used. In addition, as the polymerization reaction, any reaction such as ionic polymerization, radical polymerization, and living radical polymerization may be used.

[Polycarboxylic acid content]
And it is preferable that content of polycarboxylic acid in the slurry composition for non-aqueous secondary battery functional layers of this invention is 0.1 mass part or more per 100 mass parts of nonelectroconductive particle, 0.2 More preferably, it is more preferably 0.4 parts by mass or more, more preferably 10 parts by mass or less, more preferably 4 parts by mass or less, and more preferably 1.5 parts by mass or less. More preferably, it is particularly preferably 0.55 parts by mass or less. By setting the content of polycarboxylic acid to the above lower limit or more, the heat shrinkage resistance of the functional layer can be improved. Further, by setting the polycarboxylic acid content to be equal to or less than the above upper limit, the residual moisture content and internal resistance of the functional layer formed using the functional layer slurry composition can be further reduced, and the rate of the non-aqueous secondary battery can be reduced. Characteristics and high-temperature cycle characteristics can be further improved.

<Mass ratio of polymer component to polycarboxylic acid>
Moreover, in the slurry composition for a non-aqueous secondary battery functional layer of the present invention, the mass ratio of the content of the polymer component to the content of the polycarboxylic acid needs to be 0.01 or more and 1.35 or less. It is preferably 0.1 or more, more preferably 0.7 or more, further preferably 0.75 or more, preferably 1 or less, and 0.95 or less. Is more preferably 0.9 or less. If the content of the polymer component is within the above-described range, and the mass ratio of the content of the polymer component to the content of the polycarboxylic acid is within the above range, the heat resistance shrinkage of the functional layer can be ensured and the function can be ensured. Reduction of the residual moisture content and internal resistance of the layer and improvement of the rate characteristics and high-temperature cycle characteristics of the secondary battery including the functional layer can be satisfactorily arranged.

<Binder>
The binder can function as a component that binds components such as non-conductive particles in the functional layer formed using the slurry composition for a non-aqueous secondary battery functional layer of the present invention. The binder that can be contained in the slurry composition for a non-aqueous secondary battery functional layer of the present invention is not particularly limited, and is present in the form of particles in a known binder, for example, the slurry composition. A particulate polymer. And as a particulate polymer, a conjugated diene polymer and an acrylic polymer are preferable, and an acrylic polymer is more preferable. The particulate polymer may be in the form of particles or any other shape in the functional layer formed using the slurry composition for functional layers.

Here, the conjugated diene polymer refers to a polymer containing a conjugated diene monomer unit. A specific example of the conjugated diene polymer is not particularly limited, and is a copolymer containing an aromatic vinyl monomer unit such as a styrene-butadiene copolymer (SBR) and an aliphatic conjugated diene monomer unit. Examples thereof include a polymer, butadiene rubber (BR), acrylic rubber (NBR) (a copolymer containing acrylonitrile units and butadiene units), and hydrides thereof.
Moreover, an acrylic polymer refers to the polymer containing a (meth) acrylic acid ester monomer unit.
These binders may be used alone or in combination of two or more.

  The acrylic polymer that can be preferably used as the binder is not particularly limited, and is a (meth) acrylic acid ester monomer unit, a crosslinkable monomer unit, and a carboxylic acid group-containing monomer. Examples thereof include a polymer containing a body unit and other monomer units.

Here, as the (meth) acrylic acid ester monomer that can form a (meth) acrylic acid ester monomer unit contained in an acrylic polymer suitable as a binder, the above-mentioned polycarboxylic acid (meth) ) The same thing as the (meth) acrylic acid ester monomer which can form an acrylic acid ester monomer unit is mentioned.
Among them, as the (meth) acrylic acid ester monomer that can form the (meth) acrylic acid ester monomer unit contained in the acrylic polymer, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate are preferable. , Ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate are more preferable, and butyl acrylate and 2-ethylhexyl acrylate are still more preferable.

  In addition, the ratio of the (meth) acrylic acid ester monomer unit in the acrylic polymer is preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably 58% by mass or more, and preferably 98% by mass. % Or less, more preferably 97% by mass or less, and still more preferably 96% by mass or less. The peel strength of the functional layer can be increased by setting the proportion of the (meth) acrylic acid ester monomer unit to be equal to or higher than the lower limit of the above range. Moreover, the high temperature cycling characteristic of a secondary battery provided with a functional layer can be improved by setting it as below an upper limit.

Moreover, as the crosslinkable monomer that can form a crosslinkable monomer unit that can be contained in an acrylic polymer suitable as a binder, the above-mentioned crosslinkable monomer unit of polycarboxylic acid can be formed. The thing similar to a crosslinkable monomer is mentioned.
Among them, as the crosslinkable monomer capable of forming the crosslinkable monomer unit contained in the acrylic polymer, allyl methacrylate, allyl glycidyl ether and N-methylol acrylamide are preferable, and allyl glycidyl ether and N-methylol acrylamide are preferable. More preferred.

  The ratio of the crosslinkable monomer unit in the acrylic polymer is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, preferably 3.0% by mass or less, more preferably 2.5% by mass or less. By setting the ratio of the crosslinkable monomer unit to be equal to or higher than the lower limit of the above range, the rate characteristics of the secondary battery including the functional layer can be enhanced. Moreover, the peeling strength of a functional layer can be made high by making it into an upper limit or less.

Moreover, as the carboxylic acid group-containing monomer that can form a carboxylic acid group-containing monomer unit that can be contained in an acrylic polymer suitable as a binder, the carboxylic acid group-containing monomer of the above-described polycarboxylic acid is used. The thing similar to the carboxylic acid group containing monomer which can form a body unit is mentioned.
Among them, as the carboxylic acid group-containing monomer capable of forming the carboxylic acid group-containing monomer unit contained in the acrylic polymer, acrylic acid, methacrylic acid and itaconic acid are preferable, and acrylic acid and methacrylic acid are more preferable. .

  In addition, the ratio of the carboxylic acid group-containing monomer unit in the acrylic polymer is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and preferably 6.0% by mass or less. Preferably it is 4.0 mass% or less. By making the ratio of the carboxylic acid group-containing monomer unit at least the lower limit of the above range, the dispersibility of the binder in the functional layer slurry composition and in the functional layer is improved, and the secondary battery including the functional layer The rate characteristics can be improved. Moreover, by making it into the upper limit value or less, the residual moisture content of the functional layer can be reduced and the high temperature cycle characteristics of the secondary battery can be improved.

Other monomers that can form other monomer units that can be included in an acrylic polymer suitable as a binder include 1,3-butadiene, 2-methyl-1,3-butadiene, Aliphatic conjugated diene monomers such as 2,3-dimethyl-1,3-butadiene and 2-chloro-1,3-butadiene; styrene, chlorostyrene, vinyltoluene, t-butylstyrene, methyl vinylbenzoate, vinyl Aromatic vinyl monomers such as naphthalene, chloromethylstyrene, hydroxymethylstyrene, α-methylstyrene and divinylbenzene; α, β-unsaturated nitriles such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and α-ethylacrylonitrile Compound monomers; (Meth) acrylamide monomers such as acrylamide and methacrylamide; ethylene, Olefin monomers such as propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate; methyl vinyl ether, ethyl vinyl ether, butyl Vinyl ether monomers such as vinyl ether; vinyl ketone monomers such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone and isopropenyl vinyl ketone; and complex such as N-vinyl pyrrolidone, vinyl pyridine and vinyl imidazole Examples thereof include ring-containing vinyl compound monomers. Among these, as other monomers, acrylonitrile, acrylamide and styrene are preferable, and acrylonitrile and styrene are more preferable.
In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

In addition, the acrylic polymer mentioned above is not specifically limited, For example, it can superpose | polymerize and manufacture the monomer composition containing the monomer mentioned above in an aqueous solvent. At this time, the ratio of each monomer in the monomer composition is usually the same as the ratio of the monomer units in the acrylic polymer.
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 may be used. In addition, as the polymerization reaction, any reaction such as ionic polymerization, radical polymerization, and living radical polymerization may be used.

[Binder content]
And the content of the binder in the slurry composition for a non-aqueous secondary battery functional layer of the present invention is preferably 2 parts by mass or more per 100 parts by mass of non-conductive particles, and 2.5 parts by mass More preferably, it is more preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 6 parts by mass or less. . By making the content of the binder not less than the lower limit, the peel strength of the functional layer can be improved. Further, by making the content of the binder not more than the above upper limit, it is possible to suppress an increase in the internal resistance of the functional layer formed using the slurry composition for the functional layer, and the rate characteristics of the non-aqueous secondary battery Can be further improved.

<Dispersion medium>
The slurry composition for a non-aqueous secondary battery functional layer of the present invention contains water as a dispersion medium. The slurry composition for a non-aqueous secondary battery functional layer may contain a small amount of a medium other than water such as an organic solvent as a dispersion medium.
Here, normally, in the slurry composition for functional layers, the non-conductive particles and the particulate polymer as the binder are dispersed in water. On the other hand, the polycarboxylic acid is dissolved or dispersed in water depending on the pH of the functional layer slurry composition. Furthermore, the polymer component is dissolved in water.

<Additives>
The slurry composition for a non-aqueous secondary battery functional layer may contain any other component in addition to the components described above. The other components are not particularly limited as long as they do not affect the battery reaction, and known components can be used. Moreover, these other components may be used individually by 1 type, and may be used in combination of 2 or more types.
Examples of the other components include a dispersant, a leveling agent, an antioxidant, an antifoaming agent, a wetting agent, a pH adjuster (for example, hydrogen chloride; ammonia; lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. Alkali metal hydroxides; hydroxides of alkaline earth metals such as calcium hydroxide and magnesium hydroxide), and known additives such as electrolyte additives having a function of inhibiting electrolyte decomposition .

<PH of slurry composition for non-aqueous secondary battery functional layer>
The non-aqueous secondary battery functional layer slurry composition of the present invention containing the components described above preferably has a pH of 6.0 or higher, more preferably 6.5 or higher, and 12.0. Or less, more preferably 9.5 or less, and even more preferably 9.0 or less. If the pH of the functional layer slurry composition is at least the above lower limit, the coatability of the functional layer slurry composition can be improved, so that a uniform functional layer can be formed satisfactorily for the non-aqueous secondary battery. The rate characteristics can be further improved. Further, if the pH of the functional layer slurry composition is set to the above upper limit or less, the increase in the residual moisture content of the functional layer formed using the functional layer slurry composition is suppressed, and the nonaqueous secondary battery The high temperature cycle characteristics can be further improved.
In addition, pH of the slurry composition for non-aqueous secondary battery functional layers can be adjusted by adding the pH adjuster mentioned above.

<Method for producing slurry composition for non-aqueous secondary battery functional layer>
The slurry composition for a non-aqueous secondary battery functional layer of the present invention is not particularly limited, and the above-described non-conductive particles, polymer component, polycarboxylic acid, binder, and as necessary. Any additive to be used can be obtained by mixing in the presence of water as a dispersion medium. In addition, when the monomer composition is polymerized in an aqueous solvent to prepare a polycarboxylic acid or a binder, the polycarboxylic acid or the binder is mixed with other components as it is in an aqueous dispersion. can do. Moreover, when mixing polycarboxylic acid and a binder in the state of an aqueous dispersion, you may use the water in an aqueous dispersion as a dispersion medium.

  Here, the mixing method and mixing order of the components described above are not particularly limited, but it is preferable to perform mixing using a disperser as a mixing device in order to disperse each component efficiently. And it is preferable that a disperser is an apparatus which can disperse | distribute and mix the said component uniformly. 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.

(Functional layer for non-aqueous secondary batteries)
The functional layer for a non-aqueous secondary battery of the present invention is formed from the above-described slurry composition for a non-aqueous secondary battery functional layer. For example, the functional layer slurry composition described above is used as a suitable base material. After forming the coating film by coating on the surface, it can be formed by drying the formed coating film. That is, the functional layer for a non-aqueous secondary battery of the present invention is composed of a dried product of the slurry composition for a non-aqueous secondary battery functional layer described above, and is usually non-conductive particles, a polymer component, and a polycarboxylic acid. And a binder and an optional additive. When the above-described polycarboxylic acid and / or binder contains a crosslinkable monomer unit, the polymer containing the crosslinkable monomer unit is a slurry for a non-aqueous secondary battery functional layer. The composition may be crosslinked at the time of drying the composition, or at the time of heat treatment optionally performed after drying (that is, the functional layer for non-aqueous secondary battery is made of the above-described polycarboxylic acid and / or binder). It may contain a cross-linked product).

  And since the functional layer for non-aqueous secondary batteries of the present invention is formed using the slurry composition for non-aqueous secondary battery functional layers described above, the amount of residual moisture and the internal content are ensured while ensuring heat-resistant shrinkage. Resistance can be sufficiently reduced. Therefore, if the non-aqueous secondary battery functional layer formed using the non-aqueous secondary battery functional layer slurry composition described above is used, the rate characteristics and high-temperature cycle characteristics of the non-aqueous secondary battery can be improved. it can.

<Base material>
Here, there is no limitation on the base material on which the functional layer slurry composition is applied. For example, a functional layer slurry composition coating is formed on the surface of the release base, and the coating is dried to form the functional layer. It may be formed and the release substrate is peeled off from the functional layer. Thus, the functional layer peeled off from the release substrate can be used as a self-supporting film for forming a battery member of a secondary battery. Specifically, the functional layer peeled off from the release substrate may be laminated on the separator substrate to form a separator having the functional layer, or the functional layer peeled off from the release substrate may be used as the electrode substrate. An electrode provided with a functional layer may be formed by stacking on the substrate.
However, from the viewpoint of improving the production efficiency of the battery member by omitting the step of peeling off the functional layer, it is preferable to use a separator substrate or an electrode substrate as the substrate. The functional layer provided on the separator substrate and the electrode substrate can be suitably used as a protective layer for improving the heat resistance and strength of the separator and the electrode.

[Separator substrate]
Although it does not specifically limit as a separator base material, Known separator base materials, such as an organic separator base material, are mentioned. The organic separator substrate is a porous member made of an organic material. Examples of the organic separator substrate include a microporous membrane or a nonwoven fabric containing a polyolefin resin such as polyethylene and polypropylene, an aromatic polyamide resin, and the like. From the viewpoint of excellent strength, a polyethylene microporous film or nonwoven fabric is preferred. In addition, the thickness of a separator base material can be made into arbitrary thickness, Preferably they are 5 micrometers or more and 30 micrometers or less, More preferably, they are 5 micrometers or more and 20 micrometers or less, More preferably, they are 5 micrometers or more and 18 micrometers or less. If the thickness of the separator substrate is 5 μm or more, sufficient safety can be obtained. In addition, if the thickness of the separator base material is 30 μm or less, it is possible to suppress the ion conductivity from being lowered, to suppress the rate characteristics of the secondary battery from being lowered, and to heat shrink the separator base material. Heat resistance can be increased by suppressing the increase in force.

[Electrode substrate]
Although it does not specifically limit as an electrode base material (a positive electrode base material and a negative electrode base material), The electrode base material with which the electrode compound-material layer was formed on the electrical power collector is mentioned.
Here, the current collector, the electrode active material in the electrode mixture layer (positive electrode active material, negative electrode active material) and the binder for electrode mixture layer (binder for positive electrode mixture layer, binder for negative electrode mixture layer) For the method of forming the electrode mixture layer on the current collector and the current collector, known ones can be used, for example, as described in JP2013-145663A and International Publication No. 2015/129408. Things can be used.

<Method for forming functional layer for non-aqueous secondary battery>
Examples of the method for forming a functional layer on a substrate such as the separator substrate and electrode substrate described above include the following methods.
1) The slurry composition for a non-aqueous secondary battery functional layer of the present invention is applied to the surface of a separator substrate or an electrode substrate (in the case of an electrode substrate, the surface on the electrode mixture layer side, the same applies hereinafter), and then dried. how to;
2) A method of drying a separator base material or an electrode base material after immersing it in the slurry composition for a non-aqueous secondary battery functional layer of the present invention;
3) The slurry composition for a non-aqueous secondary battery functional layer of the present invention is applied on a release substrate, dried to produce a functional layer, and the resulting functional layer is applied to the surface of a separator substrate or an electrode substrate. To transfer to
Among these, the method 1) is particularly preferable because the layer thickness of the functional layer can be easily controlled. Specifically, the method 1) includes a step of applying the functional layer slurry composition on the substrate (application step), and drying the functional layer slurry composition applied on the substrate to obtain a functional layer. Including a step of forming (functional layer forming step).

[Coating process]
In the coating process, the method for coating the functional layer slurry composition on the substrate is not particularly limited, and examples thereof include a doctor blade method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush method. Examples thereof include a coating method.

[Functional layer formation process]
Moreover, in a functional layer formation process, it does not specifically limit as a method of drying the slurry composition for functional layers on a base material, A well-known method can be used. Examples of the drying method include drying with warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with infrared rays, electron beams, or the like. The drying conditions are not particularly limited, but the drying temperature is preferably 50 to 150 ° C., and the drying time is preferably 5 to 30 minutes.

<Functional layer thickness>
And it is preferable that the thickness of the functional layer formed using the slurry composition for non-aqueous secondary battery functional layers of this invention is 0.3 micrometer or more and 10 micrometers or less. If the thickness of the functional layer is 0.3 μm or more, the heat resistance and strength of the battery member provided with the functional layer can be further improved. Moreover, if the thickness of a functional layer is 10 micrometers or less, the rate characteristic excellent in the secondary battery can be exhibited.

(Battery member having a functional layer)
The battery member (separator and electrode) provided with the functional layer of the present invention is not limited to the separator base or electrode base and the functional layer of the present invention as long as the effects of the present invention are not significantly impaired. You may provide components other than a functional layer.

  Here, the constituent elements other than the functional layer of the present invention are not particularly limited as long as they do not correspond to the functional layer of the present invention, and are provided on the functional layer of the present invention for bonding between battery members. Examples thereof include an adhesive layer used.

(Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention includes the above-described functional layer for a non-aqueous secondary battery of the present invention. More specifically, the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolyte solution, and the functional layer for the non-aqueous secondary battery described above is a battery member of the positive electrode, the negative electrode, and the separator. Included in at least one. And the non-aqueous secondary battery of this invention can exhibit the outstanding rate characteristic and high temperature cycling characteristic.

<Positive electrode, negative electrode and separator>
At least one of the positive electrode, the negative electrode, and the separator used for the secondary battery of the present invention includes the functional layer of the present invention. Specifically, as a positive electrode and a negative electrode having a functional layer, an electrode in which the functional layer of the present invention is provided on an electrode substrate formed by forming an electrode mixture layer on a current collector can be used. . Moreover, as a separator which has a functional layer, the separator which provides the functional layer of this invention on a separator base material can be used. In addition, as an electrode base material and a separator base material, the thing similar to what was mentioned by the term of the "functional layer for non-aqueous secondary batteries" can be used.
Moreover, as a positive electrode, a negative electrode, and a separator which do not have a functional layer, it does not specifically limit, The electrode which consists of an electrode base material mentioned above, and the separator which consists of a separator base material mentioned above can be used.

<Electrolyte>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte, for example, a lithium salt is used in a lithium ion secondary battery. 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. Among these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferable because they are easily dissolved in a solvent and exhibit a high degree of dissociation. In addition, electrolyte may be used individually by 1 type and may be used in combination of 2 or more types. Usually, the lithium ion conductivity tends to increase as the supporting electrolyte having a higher degree of dissociation is used, so that the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, in a lithium ion secondary battery, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC). Carbonates such as propylene carbonate (PC), butylene carbonate (BC), and methyl ethyl carbonate (MEC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane, Sulfur-containing compounds such as dimethyl sulfoxide; are preferably used. Moreover, you may use the liquid mixture of these solvents. Among these, carbonates are preferable because they have a high dielectric constant and a wide stable potential region. Usually, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted depending on the type of solvent.
The concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate. Moreover, you may add a known additive to electrolyte solution.

(Method for producing non-aqueous secondary battery)
In the non-aqueous secondary battery of the present invention described above, for example, a positive electrode and a negative electrode are overlapped via a separator, and this is placed in a battery container by winding or folding as necessary. It can be manufactured by pouring and sealing. Of the positive electrode, the negative electrode, and the separator, at least one member is a member with a functional layer. In addition, an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like may be placed in the battery container to prevent an increase in pressure inside the battery or overcharge / discharge. The shape of the battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, and the like.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%”, “ppm”, and “parts” representing amounts are based on mass unless otherwise specified.
In addition, in a polymer produced by copolymerizing a plurality of types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the polymer is usually unless otherwise specified. This coincides with the ratio (preparation ratio) of the certain monomer in the total monomers used for polymerization of the polymer.
In the examples and comparative examples, the water solubility of the polycarboxylic acid, the pH of the slurry composition, the peel strength of the functional layer, the moisture content and the heat shrinkage resistance, the rate characteristics of the secondary battery and the high temperature cycle characteristics were measured by the following methods. And evaluated.

<Water solubility of polycarboxylic acid>
A polycarboxylic acid aqueous solution (concentration 2%) having a desired pH was prepared using a polycarboxylic acid and a pH adjuster. And it stirred at 25 degreeC for 1 hour, and was set as the evaluation liquid.
The obtained evaluation liquid was transferred to a cell having an optical path length of 30 mm, and the scattered light and the total light transmitted light were measured using a haze meter. The formula: haze = (scattered light / total light transmitted light) × 100 (%) The haze value of the evaluation liquid required was determined. When the haze of the evaluation solution was 60% or more, it was determined that the polycarboxylic acid was water-soluble, and when it was less than 60%, the polycarboxylic acid was determined to be water-insoluble.
<PH>
The pH of the slurry composition was measured using a desktop pH meter (trade name “F-51” manufactured by HORIBA) calibrated with pH standard solutions (pH 4, pH 7 and pH 9).
<Peel strength>
The produced separator was cut into a rectangle having a width of 10 mm and a length of 100 mm to obtain a test piece. And the cellophane tape (what is prescribed | regulated to JISZ1522) was affixed on the surface by the side of the functional layer of a test piece. Next, the cellophane tape was fixed on a horizontal surface of the test table in a flat state, and one end of the separator was peeled off at a pulling rate of 10 mm / min in the direction perpendicular to the cellophane tape, and the stress at that time was measured. The measurement was performed three times, and the average value was obtained as the peel strength and evaluated according to the following criteria. The higher the peel strength, the greater the binding force between the functional layer and the separator substrate, that is, the higher the adhesion strength.
A: Peel strength is 200 N / m or more B: Peel strength is 150 N / m or more and less than 200 N / m C: Peel strength is 100 N / m or more and less than 150 N / m D: Peel strength is less than 100 N / m <water content>
The produced separator was cut out into a size of 10 cm wide × 10 cm long to obtain a test piece. And the obtained test piece was left to stand in the environment of temperature 25 degreeC and dew point temperature -60 degreeC for 24 hours. Then, using a coulometric titration moisture meter, the moisture content of the test piece was measured by the Karl Fischer method (JIS K-0068 (2001), moisture vaporization method, vaporization temperature 150 ° C.) to obtain the moisture content of the functional layer. It was evaluated according to the criteria.
A: Water content is less than 450 ppm B: Water content is 450 ppm or more and less than 550 ppm C: Water content is 550 ppm or more and less than 650 ppm D: Water content is 650 ppm or more <Heat-resistant shrinkage>
The produced separator was cut into a square having a width of 12 cm and a length of 12 cm, and a test piece was obtained by drawing a square having a side of 10 cm inside the cut square piece. And after putting a test piece in a 150 degreeC thermostat and leaving it for 1 hour, the square area change (= {(square area before leaving-square area after leaving)) / square before leaving to stand Of area} × 100%) was determined as the heat shrinkage rate and evaluated according to the following criteria. It shows that the heat contraction rate of the separator which has a functional layer is excellent, so that a heat shrinkage rate is small.
A: Heat shrinkage rate is less than 20% B: Heat shrinkage rate is 20% or more and less than 25% C: Heat shrinkage rate is 25% or more and less than 30% D: Heat shrinkage rate is 30% or more <Rate characteristics>
About the produced lithium ion secondary battery, in a 25 degreeC environment, the charge / discharge cycle which charges to 4.35V with the constant current of 0.2C, and discharges to 3.0V with the constant current of 0.2C, Under the environment, a charge / discharge cycle in which the battery was charged to 4.35 V with a constant current of 0.2 C and discharged to 3.0 V with a constant current of 1.0 C was performed. Then, the ratio of the discharge capacity at 1.0 C to the discharge capacity at 0.2 C (= {(discharge capacity at 1.0 C) / (discharge capacity at 0.2 C)} × 100%) is obtained as the capacity change rate ΔC ′. The evaluation was based on the following criteria. The larger the capacity change rate ΔC ′, the better the rate characteristic.
A: Capacity change rate ΔC ′ is 85% or more B: Capacity change rate ΔC ′ is 80% or more and less than 85% C: Capacity change rate ΔC ′ is 75% or more and less than 80% D: Capacity change rate ΔC ′ is less than 75% <High temperature cycle characteristics>
The prepared lithium ion secondary battery was allowed to stand for 24 hours in an environment at 25 ° C., and then charged at 4.35 V, 0.1 C, and discharged at 2.75 V, 0.1 C at 25 ° C. The charge / discharge operation was performed, and the initial capacity C0 was measured. Furthermore, in an environment of 60 ° C., a charge / discharge cycle with one cycle of 4.35 V, 0.1 C charge and 2.75 V, 0.1 C discharge was repeated, and the capacity C1 after 1000 cycles was measured. And capacity | capacitance maintenance factor (DELTA) C (= (C1 / C0) * 100 (%)) was calculated | required and evaluated by the following reference | standard. It shows that it is excellent in high temperature cycling characteristics, so that capacity | capacitance maintenance factor (DELTA) C is high.
A: Capacity maintenance ratio ΔC is 70% or more B: Capacity maintenance ratio ΔC is 60% or more and less than 70% C: Capacity maintenance ratio ΔC is 50% or more and less than 60% D: Capacity maintenance ratio ΔC is less than 50%

Example 1
<Preparation of polycarboxylic acid>
In a 5 MPa pressure vessel with a stirrer, 30 parts of methacrylic acid as a carboxylic acid group-containing monomer, 57 parts of ethyl acrylate as a (meth) acrylic acid ester monomer having an alkyl group having 1 to 3 carbon atoms, and 4 or more carbon atoms 12.2 parts of butyl acrylate as a (meth) acrylic acid ester monomer having 6 or less alkyl groups, 0.8 part of ethylene dimethacrylate as a crosslinkable monomer, emulsifier (trade name “Latemul PD, manufactured by Kao Corporation” -104 ") 1.0 part, 150 parts of ion-exchanged water, and 1.0 part of potassium persulfate as a polymerization initiator were stirred sufficiently, and then heated to 60 ° C to initiate polymerization. When the polymerization conversion reached 96%, the reaction was stopped by cooling. And sodium hydroxide aqueous solution was added and pH was adjusted to 4.0 and the water dispersion liquid containing polycarboxylic acid was obtained.
About the obtained polycarboxylic acid, the water solubility in each pH was evaluated. The results are shown in Table 1.
<Preparation of binder>
In a 5 MPa pressure vessel with a stirrer, 93 parts of butyl acrylate as a (meth) acrylic acid ester monomer, 2 parts of methacrylic acid as a carboxylic acid group-containing monomer, 2 parts of N-methylolacrylamide as a crosslinkable monomer, After 3 parts of acrylonitrile as a monomer, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water and 0.3 part of potassium persulfate as a polymerization initiator were stirred sufficiently, To initiate polymerization. When the polymerization conversion reached 96%, the reaction was stopped by cooling. And the mixture containing a particulate polymer (acrylic polymer) was obtained. A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate polymer to adjust the pH to 6.5 to obtain an aqueous dispersion containing the particulate polymer as a binder.
<Preparation of slurry composition>
100 parts of alumina particles (volume average particle size: 0.5 μm) as non-conductive particles, 0.4 parts of carboxymethylcellulose sodium salt (product name “Daicel 1220” manufactured by Daicel Corporation) as a polymer component, the above polycarboxylic acid 0.5 parts of an aqueous dispersion containing acid (corresponding to a solid content) and 5 parts of an aqueous dispersion containing the above particulate polymer (corresponding to a solid content) are mixed, and water is further added to obtain a solid content concentration of 40% by mass. It was adjusted to become. Furthermore, a sodium hydroxide aqueous solution was added to prepare a slurry composition for a non-aqueous secondary battery functional layer.
And pH of the obtained slurry composition was measured. The results are shown in Table 1.
<Manufacture of separator>
The thickness after drying the slurry composition with a gravure coater on one surface of a polypropylene / polyethylene / polypropylene separator base material having a multilayer structure (manufactured by Celgard, trade name “Celgard 2325”, thickness: 18 μm) Was applied to a thickness of 4 μm and dried. This drying was performed by conveying the separator base material at a rate of 20 m / min in an oven at 100 ° C. over 1 minute. And the separator formed by forming a functional layer on a separator base material was obtained.
And the obtained separator was used and the peel strength of the functional layer, the moisture content, and the heat shrinkability were evaluated. The results are shown in Table 1.
<Production of positive electrode>
100 parts of LiCoO ₂ (volume average particle diameter (D50): 12 μm) as a positive electrode active material, ₂ parts of acetylene black (trade name “HS-100”, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, positive electrode mixture Polyvinylidene fluoride (trade name “# 7208”, manufactured by Kureha Co., Ltd.) as the binder for the layer is 2 parts in terms of solid content, and N-methylpyrrolidone (NMP) is 70% in total solid content. Thus, it was put into a planetary mixer and mixed to obtain a positive electrode slurry composition.
The obtained positive electrode slurry composition was applied with a comma coater onto an aluminum foil having a thickness of 20 μm, which is a current collector, so that the film thickness after drying was about 150 μm, and dried to be a positive electrode raw material. Got. This drying was performed by transporting the aluminum foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Then, the positive electrode raw material was rolled with a roll press to obtain a positive electrode having a positive electrode mixture layer with a thickness of 95 μm.
<Manufacture of 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, ions After adding 150 parts of exchange water and 0.5 part of potassium peroxodisulfate as a polymerization initiator and stirring sufficiently, the mixture was heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing the binder for negative electrode mixture layer (SBR). A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode mixture layer and adjusted to pH 8, and then the unreacted monomer was removed by heating under reduced pressure. Then, it cooled to 30 degrees C or less, and obtained the water dispersion liquid containing the binder for desired negative mix layers.
2% aqueous solution of artificial graphite (volume average particle diameter (D50): 15.6 μm) 100 parts as negative electrode active material and sodium salt of carboxymethyl cellulose (trade name “MAC350HC” manufactured by Nippon Paper Industries Co., Ltd.) as a thickener Was adjusted to a solid content concentration of 68% with ion-exchanged water and then mixed at 25 ° C. for 60 minutes. Furthermore, after adjusting to 62% of solid content concentration with ion-exchange water, it mixed for 15 minutes at 25 degreeC. The above-mentioned binder for negative electrode mixture layer (SBR) was mixed with 1.5 parts of solid content and ion-exchanged water, adjusted to a final solid content concentration of 52%, and further mixed for 10 minutes. This was defoamed under reduced pressure to prepare a slurry composition for negative electrode having good fluidity.
The obtained negative electrode slurry composition was applied on a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying was about 150 μm, and dried to obtain a negative electrode raw material. Got. 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. Then, the negative electrode original fabric was rolled by a roll press to obtain a negative electrode having a negative electrode mixture layer thickness of 100 μm.
<Manufacture of secondary batteries>
An aluminum packaging exterior was prepared as the battery exterior. The produced positive electrode was cut into a square of 4.6 cm × 4.6 cm to obtain a rectangular positive electrode. The produced separator was cut into a 5.5 cm × 5.5 cm square to obtain a rectangular separator. Further, the produced negative electrode was cut into a 5 cm × 5 cm square to obtain a rectangular negative electrode. A rectangular positive electrode was placed in the aluminum packaging exterior so that the current collector-side surface was in contact with the aluminum packaging exterior. A rectangular separator was disposed on the surface of the rectangular positive electrode on the positive electrode mixture layer side so that the functional layer side surface was in contact with the rectangular positive electrode. Furthermore, the rectangular negative electrode was arrange | positioned so that the surface by the side of the negative electrode compound material layer might face a separator on a separator. Next, an electrolytic solution (solvent: ethylene carbonate / methyl ethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: LiPF ₆ having a concentration of 1 M) was injected so that no air remained. Furthermore, 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 a lithium ion secondary battery was manufactured.
And the rate characteristic and the high temperature cycling characteristic were evaluated about the obtained lithium ion secondary battery. The results are shown in Table 1.

(Examples 2-3)
In the same manner as in Example 1 except that the amount of carboxymethyl cellulose sodium salt was changed to 0.2 part (Example 2) and 0.5 part (Example 3), respectively, during the preparation of the slurry composition. Carboxylic acid, binder, slurry composition, separator, positive electrode, negative electrode, and secondary battery were produced. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In the same manner as in Example 1 except that the amount of the aqueous dispersion containing the polycarboxylic acid was changed to 6 parts (corresponding to the solid content) at the time of preparing the slurry composition, the polycarboxylic acid, the binder, and the slurry composition were used. A separator, a positive electrode, a negative electrode, and a secondary battery were manufactured. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
During the preparation of polycarboxylic acid, the amount of methacrylic acid was changed to 25 parts, and the amount of ethyl acrylate was changed to 62 parts, in the same manner as in Example 1, polycarboxylic acid, binder, slurry composition, A separator, a positive electrode, a negative electrode, and a secondary battery were produced. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
During the preparation of polycarboxylic acid, the amount of methacrylic acid was changed to 45 parts, and the amount of ethyl acrylate was changed to 42 parts, in the same manner as in Example 1, polycarboxylic acid, binder, slurry composition, A separator, a positive electrode, a negative electrode, and a secondary battery were produced. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
During preparation of the binder, 65 parts of 2-ethylhexyl acrylate as the (meth) acrylic acid ester monomer, 3 parts of acrylic acid as the carboxylic acid group-containing monomer, 2 parts of allyl glycidyl ether as the crosslinkable monomer A polycarboxylic acid, a binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced in the same manner as in Example 1 except that 30 parts of styrene was used as the other monomer. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Examples 8 to 9)
When preparing the slurry composition, 100 parts of boehmite particles (volume average particle size: 0.8 μm) (Example 8) and barium sulfate particles (volume average particle size: 0.6 μm) were used as non-conductive particles instead of alumina particles. ) A polycarboxylic acid, a binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced in the same manner as in Example 1 except that 100 parts (Example 9) were used. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
A polycarboxylic acid, a binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a polycarboxylic acid, except that the amount of carboxymethyl cellulose sodium salt was changed to 1.5 parts during the preparation of the slurry composition. A secondary battery was manufactured. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
Example 1 except that the amount of carboxymethylcellulose sodium salt was changed to 1.5 parts and the amount of the aqueous dispersion containing polycarboxylic acid was changed to 2 parts (corresponding to the solid content) during the preparation of the slurry composition. In the same manner as above, a polycarboxylic acid, a binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
A binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced in the same manner as in Example 1 except that an aqueous dispersion containing a polycarboxylic acid was not blended when preparing the slurry composition. . Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
At the time of preparing the slurry composition, 0.5 part (corresponding to solid content) of an aqueous solution of polyacrylic acid (trade name “A-210” manufactured by Toa Gosei Co., Ltd.) was blended in place of the aqueous dispersion containing polycarboxylic acid. Except for the above, a binder, a slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 5)
At the time of preparing the slurry composition, the amount of carboxymethyl cellulose sodium salt was changed to 0.05 part, and the binder was not treated in the same manner as in Example 1 except that the aqueous dispersion containing polycarboxylic acid was not blended. A slurry composition, a separator, a positive electrode, a negative electrode, and a secondary battery were produced. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

In Table 1 shown below,
“CMC-Na” refers to carboxymethylcellulose sodium salt;
“MAA” indicates a methacrylic acid unit;
“AA” indicates an acrylic acid unit;
“EA” indicates an ethyl acrylate unit;
“BA” represents a butyl acrylate unit;
“EDMA” refers to ethylene dimethacrylate units;
“2-EHA” refers to a 2-ethylhexyl acrylate unit;
“NMA” indicates N-methylolacrylamide units;
“AGE” indicates an allyl glycidyl ether unit;
“AN” represents an acrylonitrile unit;
“ST” indicates a styrene unit.

From Table 1, Examples 1 to 9 in which the content of the polymer component is within a predetermined range and the ratio between the content of the polymer component and the content of the predetermined polycarboxylic acid is within the predetermined range. Thus, it can be seen that the rate characteristics and high-temperature cycle characteristics of the secondary battery can be improved by forming a functional layer with a small amount of residual moisture and internal resistance while ensuring the performance required for the functional layer, such as heat shrinkability.
Further, from Table 1, in Comparative Example 1 in which the content of the polymer component is large and the ratio between the content of the polymer component and the content of the predetermined polycarboxylic acid is large, the residual moisture content of the functional layer is increased. Thus, it can be seen that the high-temperature cycle characteristics of the secondary battery deteriorate. Furthermore, from Table 1, in Comparative Example 2 in which the content of the polymer component is large, even if the ratio between the content of the polymer component and the content of the predetermined polycarboxylic acid is within the predetermined range, the functional layer It can be seen that the residual moisture content of the secondary battery increases and the rate characteristics and high-temperature cycle characteristics of the secondary battery deteriorate. Further, from Table 1, it can be seen that in Comparative Examples 3 and 5 in which no polycarboxylic acid was added, it was difficult to ensure heat-resistant shrinkage and the rate characteristics and high-temperature cycle characteristics of the secondary battery were lowered. Furthermore, in Comparative Example 4 in which the predetermined polycarboxylic acid was not used, it can be seen that the residual moisture content of the functional layer increases and the high-temperature cycle characteristics of the secondary battery deteriorate.

According to the slurry composition for a non-aqueous secondary battery functional layer of the present invention, it is possible to form a functional layer for a non-aqueous secondary battery with a small amount of residual moisture and low internal resistance.
In addition, according to the functional layer for a non-aqueous secondary battery of the present invention, the non-aqueous secondary battery can exhibit excellent rate characteristics and high-temperature cycle characteristics.
And according to this invention, the non-aqueous secondary battery excellent in a rate characteristic and a high temperature cycling characteristic is obtained.

Claims (5)

A ratio of 20% by mass or more and 50% by mass or less of non-conductive particles, a polymer component composed of at least one selected from the group consisting of natural polymers and semi-synthetic polymers, and carboxylic acid group-containing monomer units And a non-aqueous secondary battery functional layer containing a polycarboxylic acid having a pH of 6.5 or less and water-insoluble, a pH of 8.0 or more and water-soluble, a binder, and water. A slurry composition comprising:
The content of the polymer component is 0.1 parts by mass or more and 0.6 parts by mass or less per 100 parts by mass of the non-conductive particles,
The slurry composition for non-aqueous secondary battery functional layers whose mass ratio of content of the said high molecular component with respect to content of the said polycarboxylic acid is 0.01-1.35.   The slurry composition for a non-aqueous secondary battery functional layer according to claim 1, wherein the polymer component is carboxymethyl cellulose or carboxymethyl cellulose salt.   The slurry composition for a non-aqueous secondary battery functional layer according to claim 1 or 2, wherein the pH is 6.0 or more and 12.0 or less.   The functional layer for non-aqueous secondary batteries formed using the slurry composition for non-aqueous secondary battery functional layers in any one of Claims 1-3.   A non-aqueous secondary battery comprising the functional layer for a non-aqueous secondary battery according to claim 4.