WO2021193444A1 - Separator for non-aqueous electrolyte battery - Google Patents

Abstract

This separator for a non-aqueous electrolyte battery includes a non-woven fabric and a porous film formed of a polyvinyl alcohol-based resin, wherein: at least a part of the porous film exists between fibers constituting the non-woven fabric; a contact angle of at least one surface of the separator is at least 35°; and a film thickness is 1-15 μm.

Description

Separator for non-aqueous electrolyte batteries

The present invention relates to a separator for a non-aqueous electrolyte battery and a non-aqueous electrolyte battery including the separator for the non-aqueous electrolyte battery.

In recent years, various non-aqueous electrolyte batteries have been developed with the spread of mobile terminals such as mobile phones, notebook personal computers, pad-type information terminal devices, electric vehicles, hybrid vehicles, and the like. Non-aqueous electrolyte batteries such as lithium ion secondary batteries differ in form, capacity, performance, etc. depending on their application, but in general, a positive electrode and a negative electrode are installed via a separator (separation film), and LiPF ₆ , LiPF 6, A structure in which a lithium salt such as LiBF ₄ , LiTFSI [lithium (bistrifluoromethylsulfonylimide)], or LiFSI [lithium (bisfluorosulfonylimide)] is stored in a container together with an electrolytic solution dissolved in an organic liquid such as ethylene carbonate. have.

Compared to aqueous batteries, non-aqueous electrolyte batteries having the above structure are more likely to have a risk of temperature rise due to external heat, overcharging, smoke generation due to internal short circuit or external short circuit, ignition, explosion, etc., and are highly safe. Sex is required. Therefore, most of the separators constituting the non-aqueous electrolyte battery are composed of a heat-resistant porous film (porous film) or the like. For example, an affinity porous sheet in which a porous sheet such as a non-woven fabric is coated with a heat-resistant resin. Has been proposed (Patent Document 1).

On the other hand, if the thickness of the separator made of a porous membrane is reduced, the amount of active material can be increased and the battery capacity can be increased. For this reason, the need for thinner separators has been increasing in recent years.

Patent No. 5944808

However, according to the study of the present inventor, when a battery containing a separator obtained by thinning an affinity porous sheet as in Patent Document 1 is repeatedly charged and discharged, a minute short circuit is likely to occur, and the battery capacity is likely to decrease, which is sufficient. It was found that a large capacity retention rate could not be obtained.

Therefore, an object of the present invention is to provide a separator for a non-aqueous electrolyte battery capable of forming a non-aqueous electrolyte battery having an excellent capacity retention rate even if the film thickness is thin, and the non-aqueous electrolyte battery.

As a result of diligent studies to solve the above problems, the present inventor has made a porous film in a separator for a non-aqueous electrolyte battery having a thickness of 1 to 15 μm, which comprises a non-woven fabric and a porous film made of a polyvinyl alcohol-based resin. The present invention has been completed by finding that the above problems can be solved by allowing at least a part of the above to exist between the fibers constituting the non-woven fabric and adjusting the contact angle of at least one surface of the separator to 35 ° or more.

[1] A separator for a non-aqueous electrolyte battery containing a non-woven fabric and a porous film made of a polyvinyl alcohol-based resin, at least a part of the porous film exists between fibers constituting the non-woven fabric, and at least one of the separators. A separator for a non-aqueous electrolyte battery having a contact angle of 35 ° or more and a film thickness of 1 to 15 μm.
[2] The separator for a non-aqueous electrolyte battery according to [1], which has an air permeability of 50 to 500 seconds.
[3] 25 ° C., a linear pressure of 40 kg / cm under conditions of natural graphite, the SBR and CMC 98: 1: a negative electrode comprising a ratio of 1, and the peel strength _{P a} at the time obtained by crimping the separator, NCM, ketjen black, 92 carbon black and PVDF: 2.5: 2.5: the positive electrode comprising a ratio of 3, which is the ratio of the peel strength _{P b} when obtained by crimping the separator _{P a} / _{P b} is 0.9 to 40, and the _{P a} and _{P b} exceeds 0N / m, [1] or [2] a separator for a nonaqueous electrolyte battery according to.
[4] Under the conditions of 25 ° C. and a press pressure of 5 MPa, the peel strength when one surface of the separator and the other surface are overlapped and pressure-bonded for 8 hours is 2 N / m or less, [1] to [ 3] The separator for a non-aqueous electrolyte battery according to any one of.
[5] Any of [1] to [4], wherein the separator has a long shape, and the lower tensile strength of the longitudinal tensile strength and the lateral tensile strength is 100 kgf / cm ^{2 or more.} Separator for non-aqueous electrolyte battery described in Crab.
[6] The separator for a non-aqueous electrolyte battery according to any one of [1] to [5], wherein the water content after drying the separator at 100 ° C. for 1 hour is 1% or less.
[7] The non-aqueous electrolyte battery according to any one of [1] to [6], wherein the polyvinyl alcohol-based resin is at least one selected from the group consisting of an ethylene-vinyl alcohol resin and a polyvinyl acetal resin. Separator.
[8] The separator for a non-aqueous electrolyte battery according to any one of [1] to [7], wherein the membrane shrinkage rate at 150 ° C. is 2% or less.
[9] The separator for a non-aqueous electrolyte battery according to any one of [1] to [8], wherein the non-woven fabric has a melting point of 300 ° C. or higher.
[10] The separator for a non-aqueous electrolyte battery according to any one of [1] to [9], wherein the nonwoven fabric contains a molten liquid crystal forming polyester fiber.
[11] A non-aqueous electrolyte battery comprising the separator for a non-aqueous electrolyte battery according to any one of [1] to [10].

The separator for a non-aqueous electrolyte battery of the present invention can form a non-aqueous electrolyte battery having an excellent capacity retention rate even if the film thickness is thin. Therefore, the separator for a non-aqueous electrolyte battery of the present invention can be suitably used for a non-aqueous electrolyte battery.

It is an image which photographed the surface of the separator obtained in Example 2 by SEM. It is an image of the surface of the separator obtained in Comparative Example 2 taken by SEM.

[Separator for non-aqueous electrolyte batteries]
The separator for a non-aqueous electrolyte battery of the present invention contains a non-woven fabric and a porous membrane made of a polyvinyl alcohol-based resin, and at least a part of the porous membrane exists between fibers constituting the non-woven fabric. Further, the separator for a non-aqueous electrolyte battery of the present invention has a thin film thickness of 1 to 15 μm, and the contact angle of at least one surface of the separator is 35 ° or more. In the present specification, the "separator for a non-aqueous electrolyte battery" may be simply referred to as a "separator", and the "porous membrane made of a polyvinyl alcohol-based resin" may be referred to as a "resin porous membrane".

Even when the separator is thinned, the present inventor is surprised if a resin porous film is present between the fibers of the non-woven fabric and the contact angle of at least one surface of the separator is adjusted to 35 ° or more. It has been found that a decrease in battery capacity due to repeated charging and discharging of a battery containing the separator can be effectively suppressed. It is presumed that this is due to the following reasons. That is, since the non-woven fabric or the separator having low air permeability tends to have through holes and minute short-circuits, short-circuits and Liden dried are likely to occur when the battery is repeatedly charged and discharged. The phenomenon is also likely to be accelerated by expansion and contraction of the active material during charging and discharging. However, if the contact angle of at least one surface of the separator is 35 ° or more, the non-woven fabric and the resin porous film are present as a composite from the surface portion of the separator to the inside. Since some of the constituent fibers are present on the surface of the separator and the resin porous film is present between the fibers of the non-woven fabric from the surface to the inside, the strength is high and the formation of micropores is effectively suppressed. It is presumed to be. Therefore, the separator of the present invention can form a non-aqueous electrolyte battery having an excellent capacity retention rate even if the film thickness is thin.

<Non-woven fabric>
The fiber material constituting the non-woven fabric in the present invention is not particularly limited, and for example, polyolefin fiber, cellulose fiber, (meth) acrylic fiber, polyvinyl alcohol fiber, vinyl chloride fiber, styrene fiber, polyester fiber. , Polyamide fiber, polycarbonate fiber, urethane fiber and the like. Among these fibers, polyester fibers such as polyethylene terephthalate fiber, polybutylene terephthalate fiber, polytrimethylene terephthalate fiber, and molten liquid crystal forming polyester fiber; polyethylene fiber, polypropylene fiber, etc. from the viewpoint of easily increasing the capacity retention rate of the battery. Polyethylene-based fibers; polyamide-based fibers are preferable. In particular, from the viewpoint of easily increasing the strength of the separator and the capacity retention rate of the battery, the non-woven fabric contains at least one selected from the group consisting of polyamide fibers, molten liquid crystal-forming polyester fibers, and polyethylene terephthalate fibers. It is more preferable that it contains a polyamide fiber and / or a molten liquid crystal forming polyester fiber, and it is further preferable that it contains a molten liquid crystal forming polyester fiber.

Examples of the type of non-woven fabric include non-woven fabrics formed by a wet method or a dry method, melt blown non-woven fabrics, spunlace non-woven fabrics, thermal bond non-woven fabrics, non-woven fabrics formed by a needle punch method, and the like. Examples of the structure of the base cloth of the non-woven fabric include plain weave and twill weave.

If necessary, commonly used additives such as colorants, inorganic fillers, antioxidants, and ultraviolet absorbers and / or thermoplastic elastomers may be added to the non-woven fabric as long as the effects of the present invention are not impaired.

The molten liquid crystal forming polyester constituting the molten liquid crystal forming polyester fiber is a resin having excellent heat resistance and chemical resistance. In the present specification, the molten liquid crystal forming property shows a property of exhibiting optical anisotropy (liquid crystal property) in the molten phase, and the molten liquid crystal forming polyester means a polyester exhibiting a molten liquid crystal forming property. The "molten liquid crystal forming property" can be determined by, for example, placing the sample on a hot stage, heating it in a nitrogen atmosphere, and observing the transmitted light of the sample. The molten liquid crystal forming polyester is composed of a repeating structural unit derived from, for example, an aromatic diol, an aromatic dicarboxylic acid, an aromatic hydroxycarboxylic acid, etc., and the aromatic diol, the aromatic dicarboxylic acid, etc., as long as the effects of the present invention are not impaired. The structural unit derived from the aromatic hydroxycarboxylic acid is not particularly limited in terms of its chemical composition. Further, the molten liquid crystal forming polyester may contain a structural unit derived from an aromatic diamine, an aromatic hydroxyamine or an aromatic aminocarboxylic acid as long as the effect of the present invention is not impaired. For example, as a preferable structural unit, examples shown in Table 1 can be mentioned.

Y is a substituent that can be independently substituted in the range of the maximum number that can be substituted in 1 to the aromatic ring or the cyclo ring, and specifically, each independently has a hydrogen atom and a halogen atom (for example, for example). , Fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl group (for example, alkyl group having 1 to 4 carbon atoms such as methyl group, ethyl group, isopropyl group, t-butyl group, etc.), alkoxy group (for example, , Methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), aralkyl group [benzyl group (phenylmethyl group), phenethyl group (phenylethyl group), etc. ], An aryloxy group (eg, phenoxy group, etc.), and an aralkyloxy group (eg, benzyloxy group, etc.).

More preferable structural units include the structural units described in Examples (1) to (18) shown in Tables 2, 3 and 4 below. When the structural unit in the formula is a structural unit capable of exhibiting a plurality of structures, two or more such structural units may be combined and used as the structural unit constituting the polymer.

Further, as Z, a substituent represented by the following formula can be mentioned.

Among these, the molten liquid crystal forming polyester used in the present invention has a constitution in which parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are the main components, or parahydroxybenzoic acid and 6-hydroxy-2. -It is preferable that the main components are naphthoic acid, terephthalic acid and biphenol.

The non-woven fabric containing the molten liquid crystal forming polyester is preferably a melt blown non-woven fabric obtained by the melt blow method. A known method can be adopted as the melt blow method. For example, a molten liquid crystal forming polyester is discharged as a molten polymer from a plurality of nozzle holes arranged in a row, and an injection gas port installed adjacent to an orifice die. This is a method of producing a non-woven fabric by injecting high-temperature and high-speed air from the woven fabric into fine fibers of the discharged molten polymer, and then collecting the fiber flow on a conveyor net or the like which is a collector.

In the separator of the present invention, the fiber diameter of the non-woven fabric is preferably 0.1 μm or more, more preferably 0.3 μm or more, still more preferably 0.8 μm or more, preferably 15 μm or less, more preferably 13 μm or less, still more preferably. Is 9 μm or less. When the fiber diameter of the non-woven fabric is at least the above lower limit, the mechanical properties of the obtained separator can be easily enhanced, and when the fiber diameter of the non-woven fabric is at least the above upper limit, the thin film and the internal short circuit of the obtained battery are suppressed. , It is easy to increase the capacity retention rate of the battery.

In the separator of the present invention, the texture of the non-woven fabric is preferably 1 g / m ² or more, more preferably 2 g / m ² or more, still more preferably 3 g / m ² or more, preferably 45 g / m ² or less, more preferably. It is 40 g / m ² or less, more preferably 30 g / m ² or less. When the basis weight of the non-woven fabric is at least the above lower limit, the strength of the separator is increased, and the capacity retention rate of the battery is likely to be increased. Further, when the basis weight of the non-woven fabric is not more than the above upper limit, the internal resistance can be easily reduced.

In the separator of the present invention, the melting point of the non-woven fabric is preferably 140 ° C. or higher, more preferably 200 ° C. or higher, still more preferably 250 ° C. or higher, even more preferably 300 ° C. or higher, particularly preferably 330 ° C. or higher, preferably 330 ° C. or higher. It is 650 ° C. or lower, more preferably 600 ° C. or lower, still more preferably 550 ° C. or lower. When the melting point of the non-woven fabric is at least the above lower limit, the heat resistance of the separator can be easily increased, and when the melting point of the non-woven fabric is at least the above upper limit, the moldability can be easily improved.

In the separator of the present invention, the thickness of the non-woven fabric is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, preferably 20 μm or less, more preferably 17 μm or less, still more preferably 15 μm or less, still more preferably. Is 13 μm or less, particularly preferably 11 μm or less. When the thickness of the non-woven fabric is at least the above lower limit, it is easy to increase the capacity retention rate and the electrolyte holding capacity of the battery, and when the thickness of the non-woven fabric is at least the above upper limit, the amount of active material in the battery can be increased. It is possible to increase the battery capacity easily. The thickness of the non-woven fabric can be measured by a thickness measuring device, for example, by the method described in Examples.

The non-woven fabric may be subjected to calendar treatment or press treatment as necessary in order to improve the accuracy of thickness and homogeneity, and graft polymerization, plasma treatment, corona treatment or the like may be performed depending on the purpose.

<Perforated membrane>
The separator of the present invention contains a porous membrane made of a polyvinyl alcohol-based resin. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, ethylene-vinyl alcohol resin, and polyvinyl acetal resin. These polyvinyl alcohol-based resins can be used alone or in combination of two or more. The porous membrane refers to a membrane having a large number of pores inside and outside the membrane.

Examples of the ethylene-vinyl alcohol resin include those obtained by saponifying an ethylene-vinyl ester copolymer such as an ethylene-vinyl acetate copolymer. The ethylene content (ethylene modification amount) of the ethylene-vinyl alcohol resin is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 25 mol% or more, preferably 60 mol% or less, more preferably. Is 55 mol% or less, more preferably 50 mol% or less. When the ethylene content is at least the above lower limit, the strength and water resistance of the separator and the capacity retention rate of the battery are likely to be improved, and when the ethylene content is at least the above upper limit, the ethylene-vinyl alcohol resin is appropriate. Since it can have hydrophilicity, it becomes easy to process the separator.

In one embodiment of the present invention, the ethylene-vinyl alcohol resin contained in the separator of the present invention has an ethylene content of 5 to 60 from the viewpoint of easily increasing the affinity with the electrolytic solution, the strength, and the capacity retention rate of the battery. It is preferably mol% and the degree of saponification is 80 mol% or more.

The copolymerization form of the ethylene-vinyl alcohol resin is not particularly limited, and may be any of a random copolymer, an alternating copolymer, a block copolymer, a graft copolymer and the like.

As the ethylene-vinyl alcohol resin in the present invention, a commercially available product may be used, or a resin prepared by a conventionally known method may be used.

Examples of polyvinyl alcohol include those obtained by saponifying vinyl alcohol and, if necessary, a resin obtained by polymerizing another monomer. For example, it can be produced by a method of saponifying the resin in a state of being dissolved in a solvent such as alcohol. Examples of the solvent used in this method include lower alcohols such as methanol and ethanol, and methanol can be preferably used. The alcohol used in the saponification reaction may contain a solvent such as acetone, methyl acetate, ethyl acetate, or benzene as long as the amount thereof is, for example, 40% by mass or less. As the catalyst used in the saponification reaction, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methoxyde, or an acid catalyst such as mineral acid is used. The temperature of the saponification reaction is not particularly limited, but is preferably in the range of 20 to 60 ° C. The polyvinyl alcohol obtained by the saponification reaction is washed and then dried.

The polyvinyl acetal resin can be produced, for example, by acetalizing the polyvinyl alcohol with an aldehyde, and the acetalization method is not particularly limited, and examples thereof include a precipitation method and a solid-liquid reaction method. In the precipitation method, for example, water or acetone is used as a solvent, polyvinyl alcohol as a raw material is dissolved in water or acetone, a catalyst such as an acid is added to carry out an acetalization reaction, and the produced polyvinyl acetal resin is precipitated. , A method of neutralizing the acid used as a catalyst to obtain a solid powder. The solid-liquid reaction method is a method in which the reaction can be carried out in the same manner as the precipitation method, except that a solvent in which the raw material polyvinyl alcohol is not dissolved is used. Regardless of which method is used, the obtained polyvinyl acetal resin powder contains impurities such as unreacted aldehydes and salts generated by neutralization. Therefore, the impurities are soluble in order to remove these impurities. A high-purity polyvinyl acetal resin can be obtained by extraction or evaporative removal using a solvent.

Examples of the aldehyde used for acetalization include aliphatic aldehydes such as formaldehyde, acetaldehyde, propyl aldehyde, n-butyl aldehyde (1-butanal), sec-butyl aldehyde, octyl aldehyde, and dodecyl aldehyde; cyclohexanecarbaldehyde and cyclooctane. Alicyclic aldehydes such as carboaldehyde, trimethylcyclohexanecarbaldehyde, cyclopentylaldehyde, dimethylcyclohexanecarbaldehyde, methylcyclohexanecarbaldehyde, methylcyclopentylaldehyde; α-campolene aldehyde, ferlandral, cyclocitral, trimethyltetrahydrobenzaldehyde, Terpen-based aldehydes such as α-pyronenaldehyde, myrtenal, dihydromirtenal, and camphenylanaldehyde; aromatic aldehydes such as benzaldehyde, naphthoaldehyde, anthralaldehyde, phenylacetaldehyde, tolualdehyde, dimethylbenzaldehyde, cuminaldehyde, and benzylaldehyde; Unsaturated aldehydes such as cyclohexene aldehyde, dimethylcyclohexene aldehyde, and achlorein; aldehydes having a heterocycle such as furfural and 5-methylfurfural; hemiacetals such as glucose and glucosamine; aldehydes having an amino group such as 4-aminobutylaldehyde Can be mentioned. These aldehydes can be used alone or in combination of two or more. Among these, aliphatic aldehydes such as n-butyraldehyde (1-butaraldehyde) are preferable from the viewpoint of easily increasing the capacity retention rate of the battery. Also, instead of aldehyde or in combination with aldehyde, aliphatic ketones such as 2-propanone, methyl ethyl ketone, 3-pentanone and 2-hexanone; aliphatic alicyclic ketones such as cyclopentanone and cyclohexanone; aromatics such as acetophenone and benzophenone. Group ketones and the like can also be used.

A known acid can be used as the acid catalyst, and examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as paratoluenesulfonic acid. The acid catalyst is usually used in an amount such that the acid concentration in the final system of the acetal reaction is 0.5 to 5.0% by mass, but the acid catalyst is not limited to this concentration. A predetermined amount of these acid catalysts may be added at one time, but in the case of the precipitation method, the polyvinyl acetal resin having relatively fine particles is added in an appropriate number of times in order to precipitate and precipitate. preferable. On the other hand, in the case of the solid-liquid reaction method, it is preferable to add a predetermined amount at the beginning of the reaction from the viewpoint of reaction efficiency.

Among the polyvinyl alcohol-based resins, at least one selected from the group consisting of ethylene-vinyl alcohol resin and polyvinyl acetal resin is preferable from the viewpoint of easily increasing the capacity retention rate of the battery containing the separator and easily reducing the water content. ..

The polyvinyl alcohol-based resin may be a monomer (also referred to as another monomer) that can be copolymerized with these units in addition to the ethylene unit, acetal unit and vinyl alcohol unit, as long as the effects of the present invention are not impaired. The structural unit from which it is derived may be included. Other monomers include α-olefins such as propylene, 1-butene, isobutene, 1-hexene; allyl, methacrylic acid, crotonic acid, phthalic acid, phthalic anhydride, maleic acid, maleic anhydride, etc. Unsaturated acids such as itaconic acid and itaconic anhydride and salts thereof or alkyl esters having 1 to 18 carbon atoms thereof; acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms, N, N-dimethylacrylamide, 2-acrylamide propane. Acrylamides such as sulfonic acid and salts thereof, acrylamide propyldimethylamine and acid salts thereof or quaternary salts thereof; methallylamide, N-alkylmetharylamide having 1 to 18 carbon atoms, N, N-dimethylmetharylamide, 2-methylamide. Methalamides such as amide propanesulfonic acid and its salts, methacrylicamide propyldimethylamine and its acid salts or quaternary salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide; acrylonitrile , Vinyl cyanide such as methacrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether; allyl acetate; propyl allyl ether, butyl allyl ether, hexyl allyl ether Allyl ethers such as; vinyl halides such as vinyl chloride, vinyl fluoride, vinyl bromide; vinylidene halides such as vinylidene chloride and vinylidene fluoride; vinylsilanes such as trimethoxyvinylsilane; polyoxyalkylene allyl ethers and the like. Oxyalkylene group-containing compounds; isopropenyl acetate; 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decene-1-ol Hydroxy group-containing α-olefins such as oar and 3-methyl-3-buten-1-ol; sulfone such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamide-2-methylpropan sulfonic acid. Acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamidemethyltrimethylammonium chloride, N-acrylamideethyltrimethyl. Examples thereof include compounds having a cationic group derived from ammonium chloride, N-acrylamide dimethylamine, allyltrimethylammonium chloride, metaallyltrimethylammonium chloride, dimethylallylamine, allylethylamine and the like. These monomers can be used alone or in combination of two or more.

The content of structural units derived from other monomers is usually 20 mol% or less, preferably 10 mol% or less, and 5 mol% or less, based on the total molar amount of the structural units constituting the polyvinyl alcohol-based resin. Is more preferable.

The amount of hydroxyl groups in the polyvinyl alcohol-based resin is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 20 mol% or more, still more preferably 30 mol, based on the vinyl group unit of the polyvinyl alcohol-based resin. % Or more, preferably 100 mol% or less, more preferably 90 mol% or less, still more preferably 80 mol% or less. When the amount of hydroxyl groups is within the above range, it is easy to increase the affinity with the electrolytic solution and the capacity retention rate of the battery, and it is easy to reduce the air permeability. The amount of hydroxyl groups ^{can be measured by, for example, 1 1} H-NMR. Note that the vinyl unit of the formula _{- (CH 2 -C (R)} H) - shows the structural unit represented by, R represents represents H or a substituent.

The saponification degree of the polyvinyl alcohol-based resin is preferably 50 mol% or more, more preferably 55 mol% or more, further preferably 60 mol% or more, and preferably 100 mol% or less. When the saponification degree is within the above range, the affinity with the electrolytic solution and the capacity retention rate of the battery can be easily increased, and the air permeability can be easily reduced. The degree of saponification can be measured according to JIS-K6726.

In one embodiment of the present invention, the degree of saponification when polyvinyl alcohol is used as the polyvinyl alcohol-based resin is preferably 50 mol% or more, more preferably 55 mol% or more, still more preferably 60 mol% or more, particularly preferably. Is 65 mol% or more, preferably 100 mol% or less, more preferably 99 mol% or less, still more preferably 98 mol% or less. When the degree of saponification is within the above range, the swelling property with respect to the electrolytic solution is high, the capacity retention rate of the battery is likely to be increased, and the apparent air permeability is likely to be reduced.

In one embodiment of the present invention, the degree of saponification when an ethylene-vinyl alcohol resin and / or a polyvinyl acetal resin is used as the polyvinyl alcohol-based resin is preferably 70 mol% or more, more preferably 80 mol% or more, and further. It is preferably 90 mol% or more, particularly preferably 95 mol% or more, and preferably 100 mol% or less. When the saponification degree is within the above range, the affinity with the electrolytic solution and the capacity retention rate of the battery can be easily increased, and the air permeability can be easily reduced. The degree of saponification can be measured according to JIS-K6726. In the present specification, the saponification degree of the polyvinyl acetal resin means the saponification degree of the polyvinyl alcohol-based resin before acetalization.

In one embodiment of the present invention, the viscosity average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 or more, more preferably 300 or more, still more preferably 400 or more, preferably 5000 or less, more preferably 3000 or less, and further. It is preferably 2500 or less. When the viscosity average degree of polymerization is at least the above lower limit, the strength of the separator is likely to be increased, and the capacity retention rate of the battery is likely to be increased. Further, when the viscosity average degree of polymerization is not more than the above upper limit, the film forming property is likely to be improved. The viscosity average degree of polymerization of the polyvinyl alcohol-based resin can be measured according to JIS-K6726, for example, by the method described in Examples.

The resin porous membrane may contain other additives in addition to the polyvinyl alcohol-based resin and the surfactant. Examples of other additives include polymer compounds other than polyvinyl alcohol-based resins, cross-linking agents, antioxidants, ultraviolet absorbers, lubricants, antifoaming agents, anti-blocking agents, and other inorganic fine powders and organic substances. The content of the other additive is usually 10% by mass or less, preferably 5% by mass or less, based on the mass of the resin porous membrane.

The content of the resin porous film in the separator of the present invention is preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass with respect to the mass of the separator. % Or less, more preferably 45% by mass or less, still more preferably 40% by mass or less. When the content of the resin porous membrane in the separator is at least the above lower limit, it is easy to improve the strength of the separator and the capacity retention rate of the obtained battery, and it is easy to improve the adhesiveness to the electrode and the liquid absorption property. When the content of the resin porous membrane in the separator is not more than the above upper limit, the air permeability can be easily reduced. The content of the porous resin membrane may be calculated by subtracting the mass of the non-woven fabric alone from the mass of the separator; a dissolution test, eg, a solvent in which the porous resin membrane dissolves from the separator but the non-woven fabric does not dissolve (eg, dimethyl). It may be calculated by dissolving the resin porous membrane with sulfoxide, etc. and subtracting the mass after dissolution from the mass before dissolution; by thermal analysis, for example, by weight change using a thermal weight measuring device (TG). It may be calculated. The content of the resin porous membrane can be calculated by, for example, the method described in Examples.

<Separator for non-aqueous electrolyte batteries>
The separator of the present invention contains the non-woven fabric and the porous film made of the polyvinyl alcohol-based resin, at least a part of the porous film exists between the fibers constituting the non-woven fabric, and the contact angle of one surface is 35. Adjusted above °. In such a separator, an optimum amount of resin porous film can be present in the voids of the non-woven fabric from the surface portion of the separator to the inside from the viewpoint of strength, so that even a thin film of 1 to 15 μm has an excellent capacity retention rate. Can form a new battery. In the present specification, compounding does not mean that the surface of the non-woven fabric is coated (or coated) with the porous resin film, but that the porous resin film exists (or penetrates) between the fibers constituting the non-woven fabric (or voids). Indicates the state of

FIG. 1 is an image of one surface of a separator (corresponding to Example 2) according to an embodiment of the present invention taken with a scanning electron microscope (SEM). As shown in the SEM image, in the separator of the present invention, since some fibers of the non-woven fabric are also present on the surface portion and a resin porous film is present between the fibers, the contact angle of the surface is 35 ° or more. Can be. The separator of the present invention may have a resin porous film partially present on the surface of the non-woven fabric as long as the contact angle is within the range of the present invention.

On the other hand, when the contact angle of the separator surface is less than 35 °, the resin porous film tends to cover the entire surface or many surfaces of the non-woven fabric, so that the strength of the surface portion is low, particularly the film thickness. When it is thin, the battery capacity tends to decrease due to repeated charging and discharging.

The contact angle of at least one surface of the separator of the present invention is preferably 36 ° or more, more preferably 37 ° or more, still more preferably 38 ° or more, still more preferably 39 ° or more, and particularly preferably 40 ° or more. .. When the contact angle is at least the above lower limit, the resin porous film and the non-woven fabric tend to be sufficiently composited from the surface portion, so that the capacity retention rate of the obtained battery can be easily improved. The contact angle of at least one surface of the separator of the present invention is preferably 70 ° or less, more preferably 65 ° or less, still more preferably 60 ° or less, and particularly preferably 55 ° or less. When the contact angle is not more than the above upper limit, the affinity with the electrolytic solution is high and the adhesiveness with the electrode is also enhanced, so that the capacity retention rate can be easily increased and the productivity of the battery is also excellent. Further, from the viewpoint of film homogeneity, it is more preferable that the contact angles of both sides of the separator are in the above range. The contact angle in the present specification is a contact angle with respect to propylene carbonate. Specifically, after dividing a 6 cm × 15 cm separator into 10 equal parts, the contact angles at each location are averaged by the sessile drop method using a contact angle meter. For example, the method described in Examples. Can be measured by. For the contact angle, the separator may be manufactured by the method described in the section [Manufacturing method of separator for non-aqueous electrolyte battery], particularly by a method including a liquid removal step, or the type of non-woven fabric or polyvinyl alcohol-based resin may be changed (for example, this book. It can be adjusted by adopting the preferred one of the invention).

The film thickness of the separator of the present invention is 1 to 15 μm. Since the contact angle of at least one surface of the separator of the present invention is adjusted to the above range, even a thin film having a film thickness of 1 to 15 μm can have an excellent capacitance retention rate. The film thickness of the separator of the present invention is preferably 14 μm or less, more preferably 13 μm or less, still more preferably 12 μm or less, still more preferably 11 μm or less, particularly preferably 10 μm or less, and particularly preferably 9 μm or less. It is 2 μm or more, more preferably 3 μm or more. When the film thickness of the separator is equal to or more than the above lower limit, the capacity retention rate of the battery including the separator can be easily increased, and when the film thickness of the separator is equal to or less than the above upper limit, the amount of active material in the battery can be increased. It is possible to increase the battery capacity easily. The film thickness of the separator can be measured by a thickness measuring device, for example, by the method described in Examples. The film thickness of the separator can be adjusted by, for example, changing the film thickness of the non-woven fabric as appropriate.

The separator of the present invention has a specific air permeability because a polyvinyl alcohol-based resin is present between the fibers constituting the non-woven fabric. The air permeability of the separator of the present invention is preferably 50 seconds or longer, more preferably 80 seconds or longer, further preferably 100 seconds or longer, even more preferably 110 seconds or longer, particularly preferably 120 seconds or longer, and preferably 500 seconds or longer. Seconds or less, more preferably 400 seconds or less, still more preferably 300 seconds or less. When the air permeability is at least the above lower limit, it is easy to improve the capacity retention rate of the obtained battery and the liquid absorbency of the electrolytic solution even if the film thickness is thin. Further, since the adhesiveness between the separator and the electrode is easily improved, the positional deviation between the separator and the electrode is unlikely to occur in the battery manufacturing process. On the other hand, when the air permeability is not more than the above upper limit, the liquid permeability of the electrolytic solution tends to be improved. In the present specification, the air permeability indicates the air permeability resistance, and the lower the value, the easier it is for air to pass through. The air permeability can be measured according to JIS P8117, for example, by the method described in Examples. The air permeability can be adjusted by appropriately changing the size (or basis weight) of the voids of the non-woven fabric, the content of the resin porous membrane, the pore diameter of the resin porous film, and the like.

In one embodiment of the present invention, the ratio of the contact angle of one surface of the separator of the present invention and (a contact angle C _x), the contact angle of the other surface (the a contact angle C _y) C _x / _Cy is preferably 0.8 or more, more preferably 0.85 or more, still more preferably 0.90 or more, particularly preferably 0.95 or more, preferably 1.2 or less, and more preferably 1. It is 15 or less, more preferably 1.1 or less, and particularly preferably 1.05 or less. When the contact angle ratio C _x / _Cy is in the above range, it is easy to increase the capacity retention rate of the obtained battery. The contact angle of the separator surface can be measured by the method described above, for example, by the method described in Examples.

In one embodiment of the present invention, a negative electrode comprising natural graphite, SBR (styrene butadiene rubber) and CMC (carboxymethyl cellulose) at a ratio of 98: 1: 1 under the conditions of 25 ° C. and a linear pressure of 40 kg / cm. a peel strength _{P a} at the time of the separator is crimped to the present invention, NCM (nickel - cobalt - ternary material manganese), Ketjen black, carbon black and PVDF (the polyvinylidene fluoride) 92: 2.5: Pa / P _b , which is _{a ratio of the peel strength P b} when the separator of the present invention is pressure-bonded to the positive electrode contained in a ratio of 2.5: 3, is preferably 0.9 or more, more preferably 0.9 or more. It is 1.0 or more, more preferably 1.5 or more, preferably 40 or less, more preferably 30 or less, still more preferably 20 or less, and particularly preferably 14 or less. However, P _a and P _b exceed 0 N / m. When the peel strength ratio P _a / P _b is in the above range, it is easy to increase the capacity retention rate of the battery including the separator, and it is easy to reduce the water content of the separator. For the peel strength P _a and P _b , the electrode surface of the crimped separator and the stainless plate are bonded together using double-sided tape, and a load cell of 50 N is used to obtain 180 ° peel strength, a peel width of 10 mm, and a peel speed of 100 mm /. It can be obtained by measuring under the condition of min, and can be measured by, for example, the method described in Examples. The peel strength ratio P _a / P _b can be adjusted by appropriately changing the amount of hydroxyl groups of the resin constituting the resin porous film.

_{In one embodiment of the present invention, the peel strength Pc} when one surface of the separator of the present invention and the other surface are overlapped and pressure-bonded for 8 hours under the conditions of 25 ° C. and a press pressure of 5 MPa is preferable. 2 N / m or less, more preferably 1.0 N / m or less, still more preferably 0.5 N / m or less, even more preferably 0.3 N / m or less, particularly preferably 0.1 N / m or less, particularly more preferably. It is 0.01 N / m or less. When the peel strength P _c is not more than the above upper limit, the surface of the separator is easily peeled off when the roll-shaped separator wound with the separator is unwound, and the battery characteristics and productivity are easily improved. Peel strength P _c is a single-sided and the stainless steel plate of the two separators were pressed under the above conditions was stuck with double-sided tape, can be measured by the same method as P _a and P _b, for example described in Example It can be measured by the method of. The peel strength P _c can be adjusted by appropriately changing the amount of hydroxyl groups of the resin constituting the non-woven fabric or the resin porous film.

In one embodiment of the present invention, the water content of the separator of the present invention after drying at 100 ° C. for 1 hour is preferably 1% (10,000 ppm) or less, more preferably 0.8% (8,000 ppm or less). , More preferably 0.5% (5,000 ppm) or less, even more preferably 0.3% (3000 ppm) or less, and particularly preferably 0.11% or less (1100 ppm) or less. When the water content of the separator is not more than the above upper limit, it is easy to suppress the decomposition of the resin in the electrolytic solution, and it is easy to increase the capacity retention rate of the battery. The lower limit of the water content is 0% or more. The water content can be measured by drying the separator at 100 ° C. for 1 hour and then using a moisture measuring device at a temperature of 120 ° C., for example, by the method described in Examples. The water content of the separator can be adjusted by appropriately changing the amount of hydroxyl groups of the non-woven fabric or the polyvinyl alcohol-based resin, and tends to decrease as the amount of hydroxyl groups of the polyvinyl alcohol-based resin decreases, for example.

In one embodiment of the present invention, the film shrinkage rate of the separator of the present invention at 150 ° C. is preferably 90% or less, more preferably 50% or less, still more preferably 2% or less, still more preferably 1.5% or less. , Especially preferably 1.0% or less, particularly more preferably 0.5% or less, and most preferably 0.1% or less. When the film shrinkage rate is not more than the above upper limit, the heat resistance is likely to be increased. The film shrinkage rate is the film shrinkage rate when heated at 150 ° C. for 1 hour, and can be calculated by, for example, the method described in Examples. The film shrinkage rate may be adjusted by appropriately changing the type of the non-woven fabric, and for example, the higher the heat resistance of the non-woven fabric, the more it tends to decrease.

In one embodiment of the present invention, the separator of the present invention has a long shape, and the lower tensile strength of the longitudinal tensile strength and the lateral tensile strength is preferably 100 kgf / cm ² or more. preferably 500 kgf / cm ² or more, more preferably 600 kgf / cm ² or more, even more preferably 800 kgf / cm ² or more, and particularly preferably 1,000 kgf / cm ² or more. When the lower tensile strength is at least the above lower limit, the durability is likely to be improved. Further, the lower limit of the tensile strength of usually 10,000kgf / cm ² or less, preferably 5,000 kgf / cm ² or less. In the present specification, the longitudinal direction indicates the MD direction, which is the machine flow direction during separator manufacturing, and the short direction indicates the TD direction, which is the direction perpendicular to the machine flow direction during separator manufacturing. The tensile strength can be measured with a test piece of JIS K 7162-1B using a tensile tester, for example, by the method described in Examples. The tensile strength may be adjusted by appropriately changing, for example, the type of the non-woven fabric, the content of the resin porous film, the film thickness of the separator, the contact angle of the surface, and the like.

In one embodiment of the present invention, the puncture strength of the separator of the present invention is preferably 100 g / mm ² or more, more preferably 200 g / mm ² or more, still more preferably 300 g / mm ² or more, still more preferably 350 g / mm. ² or more, particularly preferably 400 g / mm ² or more. When the piercing strength is equal to or higher than the above lower limit, the strength of the separator is likely to be increased, and the capacity retention rate of the battery is likely to be increased. The upper limit of the piercing strength is usually 5,000 g / mm ² or less, preferably 3,000 g / mm ² or less. The piercing strength can be measured at a temperature of 25 ° C. using a texture analyzer, for example, by the method described in Examples. The piercing strength may be adjusted by appropriately changing, for example, the type of the non-woven fabric, the content of the resin porous film, the film thickness of the separator, the contact angle of the surface, and the like.

The separator of the present invention can have an excellent capacity retention rate of the obtained battery even if it is a thin film. The capacity retention rate (also referred to as discharge capacity retention rate) of the battery containing the separator of the present invention is preferably 81% or more, more preferably 83% or more, still more preferably 85% or more, still more preferably 87% or more. , Especially preferably 88% or more, and particularly more preferably 89% or more. The capacity retention rate can be measured, for example, by the method described in Examples.

In the separator of the present invention, one non-woven fabric may be used, or two or more non-woven fabrics may be used to form a laminated body. For example, it may be a separator containing a laminate in which a plurality of non-woven fabrics are laminated and a porous film made of a polyvinyl alcohol-based resin, and preferably a separator in which the laminate and the resin porous film are composited. .. Further, as long as the contact angle of at least one surface of the separator satisfies 35 ° or more and the effect of the present invention is not impaired, another layer such as a functional layer may be laminated on the separator.

[Manufacturing method of separator for non-aqueous electrolyte battery]
The method for producing the separator of the present invention is not particularly limited, but the step (I) of dissolving the polyvinyl alcohol-based resin in a water-containing solvent to obtain a porous film-forming solution; A method including a step of impregnating the non-woven fabric (II); a step of deliquessing the resin-impregnated non-woven fabric (III); and a step of coagulating the polyvinyl alcohol-based resin in the de-liquidated resin-impregnated non-woven fabric with a coagulating liquid (IV). Is preferable.

In step (I), the water-containing solvent indicates water or a mixed solvent of water and an organic solvent. The organic solvent is not particularly limited as long as it is a solvent that can be mixed with water to dissolve the polyvinyl alcohol-based resin, and for example, alcohols such as methanol, ethanol, butanol, isopropanol, 1-propanol, 1-butanol, and ethylene glycol. System solvent; Cyclic amide solvent such as N-alkylpyrrolidone such as N-methylpyrrolidone, N-ethylpyrrolidone, N-methyl-α-methylpyrrolidone, N-ethyl-α-methylpyrrolidone; N, N-dimethylformamide, Examples thereof include amide solvents such as N and N-dimethylacetamide; cyclic ether solvents such as tetrahydrofuran, dioxane, morpholine and N-methylmorpholin; sulfoxide solvents such as dimethyl sulfoxide; and sulfone solvents such as sulfolane. Among these, from the viewpoint of the solubility of the polyvinyl alcohol-based resin, the organic solvent used is preferably an alcohol-based solvent or a sulfoxide-based solvent. These organic solvents can be used alone or in combination of two or more.

In the mixed solvent containing water and an organic solvent, the mixing ratio of water and the organic solvent (water / organic solvent) is preferably 3/97 to 70/30 in terms of volume ratio, and more preferably 5/95 to 65. / 35. By using a mixed solvent containing water and an organic solvent in a ratio within the above range, a solution for forming a porous membrane containing a polyvinyl alcohol-based resin having a solid content concentration suitable for forming a separator can be easily prepared.

The solid content concentration of the polyvinyl alcohol-based resin in the solution for forming a porous film is preferably 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass. When the solid content concentration of the polyvinyl alcohol-based resin is in the above range, the handleability of the solution for forming a porous film is good, and it is easy to form a separator.

In step (I), the solution for forming a porous film is obtained by mixing a polyvinyl alcohol-based resin and water, and optionally an organic solvent and other additives, and preferably stirring and mixing to dissolve the polyvinyl alcohol-based resin. Be done. The mixing temperature may be, for example, about 20 to 100 ° C., preferably about 25 to 95 ° C., although it depends on the boiling point and solubility of the solvent.

Step (II) is a step of impregnating the non-woven fabric with the solution for forming a porous film. Examples of the impregnation method include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, a brush coating method, and the like. The dipping method is preferable from the viewpoint of easily penetrating between them. The solution temperature at the time of impregnation is preferably 20 to 100 ° C, more preferably 25 to 80 ° C. By including the impregnation step, at least a part of the resin porous film can be present between the fibers (or voids) constituting the non-woven fabric of the obtained separator.

Step (III) is a step of draining the resin-impregnated non-woven fabric obtained by impregnation. In the liquid removal step, the solution for forming a porous film existing (or adhering) on the surface of the non-woven fabric is removed. The liquid removal method uses, for example, a device such as a knife coater, a bar coater, an applicator, a roll coater, a squeeze roll, or a nip roll, and at least a clearance is provided between the coated portion or the liquid removal portion of the device and the surface of the non-woven fabric. Instead, preferably, the liquid is removed along the surface of the non-woven fabric (or along the direction perpendicular to the film thickness direction of the non-woven fabric) while bringing the coated part or the liquid-removing part of the device into contact with the surface of the non-woven fabric. preferable. By removing the liquid in this way, it is easy to adjust the contact angle within the above range of the present invention. The solution temperature at the time of liquid removal is preferably 0 to 70 ° C, more preferably 5 to 60 ° C. By including such a liquid removal step, after the step (IV), the fibers constituting the non-woven fabric and the resin porous film are composited from the surface portion to the inside without covering the entire surface of the non-woven fabric with the resin porous film. A separator is obtained, and the contact angle of the separator surface can be adjusted within the above range of the present invention. In the present invention, at least one surface of the separator may be deliquesed, but it is more preferable to deliquesce both sides.

In one embodiment of the present invention, the resin-impregnated non-woven fabric is placed on the base material, preferably on a base material placed on a horizontal table, and the surface of the resin-impregnated non-woven fabric opposite to the base material is deliquesed as described above. You may. The base material is not particularly limited, and a base material containing a known resin may be used, or a glass substrate may be used. With such a method, the solution for forming a porous film existing (or adhering) on the surface of the non-woven fabric can be easily removed, and in particular, by removing the liquid on one surface, the contact angle can be adjusted on both surfaces of the separator according to the present invention. Easy to adjust to the above range. More specifically, in the embodiment, in order to carry out the liquid removal without providing at least a clearance between the device and the surface of the resin-impregnated non-woven fabric, the clearance between the device and the surface of the base material (base material). It is preferable to perform the liquid removal along the direction perpendicular to the film thickness direction at a position where the clearance with respect to the surface) is equal to or less than the film thickness of the resin-impregnated nonwoven fabric. The clearance with respect to the surface of the base material is not particularly limited as long as it is equal to or less than the film thickness of the resin-impregnated nonwoven fabric, and can be appropriately selected depending on the film thickness of the resin-impregnated nonwoven fabric, preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm. It is as follows. When the clearance is not more than the above upper limit, the contact angle can be easily adjusted to the above range of the present invention, and the smaller the clearance, the larger the contact angle tends to be.

In another embodiment of the present invention, the conveyed resin-impregnated non-woven fabric may be deliquesed by, for example, a squeeze roll. In the liquid removal using a squeeze roll or the like, the liquid can be removed while the rolls are in contact with both surfaces of the resin-impregnated non-woven fabric, so that the contact angle of the obtained separator surface can be easily adjusted to the above range of the present invention. Further, the contact angle and the content of the resin porous film to be supported can be adjusted by adjusting the distance between the rolls, the pressure sandwiched between the rolls, the angle of the rolls, and the like. By using such a liquid removal method, it is possible to manufacture by a roll-to-roll method, and productivity can be improved. Moreover, it is not necessary to use a base material, and the contact angles of both sides of the separator can be efficiently adjusted within the range of the present invention. Specifically, as a roll-to-roll method, for example, the non-woven fabric conveyed to the roll is conveyed and wound through the porous film forming solution, the squeeze roll, the coagulation liquid described later, and a dry region. The method etc. can be mentioned.

Step (IV) is a step of coagulating the polyvinyl alcohol-based resin in the resin-impregnated non-woven fabric that has been deflated with a coagulating liquid. Examples of the method of coagulating include a method of immersing the deflated resin-impregnated non-woven fabric in the coagulating liquid. In one embodiment of the present invention, it is preferable that the resin-impregnated non-woven fabric placed on the substrate is immersed in a coagulating liquid, and after coagulation, the substrate is peeled off. Further, in the roll-to-roll method, a method in which the resin-impregnated non-woven fabric conveyed by the roll is conveyed through the coagulating liquid is preferable.

The coagulating liquid is not particularly limited as long as it is a solvent capable of coagulating the solution for forming a porous membrane, for example, a solvent poor for polyvinyl alcohol-based resin. Examples of the coagulating liquid include water and a mixed solvent of water and an organic solvent. Examples of the organic solvent that can be mixed with water include alcohol solvents such as methanol, ethanol, isopropanol and 1-propanol, and ketone solvents such as acetone and methyl ethyl ketone. These can be used alone or in combination of two or more.

The temperature of the coagulating liquid is preferably 0 to 70 ° C, more preferably 3 to 60 ° C, and even more preferably 5 to 50 ° C. When the temperature of the coagulating liquid is within the above range, a porous membrane made of a polyvinyl alcohol-based resin can be easily obtained, and the air permeability can be easily adjusted to the above range of the present invention.

In the production method of the present invention, the immersion time of the solution for forming a porous membrane in the coagulating liquid is, for example, 0.1 seconds to 30 minutes, preferably 1 second or longer, more preferably 3 seconds or longer, preferably 3 seconds or longer. It is 25 minutes or less, more preferably 20 minutes or less. When the immersion time is equal to or longer than the above lower limit, the polyvinyl alcohol-based resin is likely to be sufficiently solidified, and pores having a desired pore diameter are likely to be obtained. Further, when the immersion time is not more than the above upper limit, excessive swelling in the coagulating liquid can be suppressed.

By step (IV), a non-woven fabric containing a wet film of a polyvinyl alcohol-based resin can be obtained. The obtained wet film may be subjected to a drying treatment for removing the solvent. The method of the drying treatment is not particularly limited, and for example, natural drying; aeration drying with warm air, hot air, and low humidity air; heat drying; decompression / vacuum drying; irradiation ray drying such as infrared rays, far infrared rays, and electron beams, and It may be done by a combination of these. From the viewpoint of improving production efficiency without disturbing the pores and voids formed in the solidification step, aeration drying is preferable. The drying conditions are such that the solvent can be removed as soon as possible according to the type of solvent used, the amount of solvent contained in the wet film, etc., as long as the obtained porous film is not damaged (for example, cracks are generated due to stress concentration). It may be decided as appropriate. For example, the drying temperature is usually 10 to 150 ° C., preferably 25 to 110 ° C., and the drying time is usually about 1 to 90 minutes.

Further, in order to improve the smoothness of the separator, the separator from which the solvent has been removed may be rolled. Examples of the rolling method include a mold press and a roll press.

[Non-aqueous electrolyte battery]
The present invention includes a non-aqueous electrolyte battery including the separator for the non-aqueous electrolyte battery of the present invention. Examples of the non-aqueous electrolyte battery include a lithium ion battery, a sodium ion battery, a lithium sulfur battery, an all-solid-state battery, a lithium ion capacitor, and a lithium battery. The non-aqueous electrolyte battery may be, for example, a non-aqueous electrolyte primary battery or a non-aqueous electrolyte secondary battery, and is preferably a non-aqueous electrolyte secondary battery. Since the non-aqueous electrolyte battery of the present invention contains the separator of the present invention, the capacity retention rate (or discharge capacity retention rate) is excellent even if the film thickness of the separator is thin. Further, since the film thickness of the separator is thin, the amount of active material in the battery can be increased, and the battery capacity can be easily increased. Therefore, the non-aqueous electrolyte battery of the present invention can achieve both an excellent capacity retention rate and a high battery capacity.

In one embodiment of the present invention, the non-aqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, and an electrolytic solution in addition to the separator of the present invention. The non-aqueous electrolyte battery of the present invention can be manufactured using known materials and techniques.

The non-aqueous electrolyte battery of the present invention (sometimes referred to simply as a "battery") includes at least a separator, electrodes (negative electrode and positive electrode), and an electrolytic solution of the present invention. Examples of the non-aqueous electrolyte battery of the present invention include a lithium ion battery, a lithium metal battery, a sodium ion battery, a potassium ion battery, a magnesium battery, a lithium sulfur battery, an all-solid-state lithium battery, a metal air battery, and a lithium ion capacitor. Can be mentioned.

The positive electrode and the negative electrode contained in the non-aqueous electrolyte battery include a cured body and a current collector of the positive electrode or the negative electrode active material, respectively. The cured product may contain a binder (for example, a binder resin) if necessary.

As the negative electrode active material, a material conventionally used as a negative electrode active material of a non-aqueous electrolyte battery can be used, and examples thereof include amorphous carbon, artificial graphite, natural graphite (graphite), and mesocarbon microbeads ( MCMB), pitch-based carbon fibers, carbon black, activated carbon, carbon fibers, hard carbon, soft carbon, mesoporous carbon, carbonaceous materials such as conductive polymers such as polyacene, represented by _{SiO x} , SnO _x , LiTIO _x. Composite metal oxides and other metal oxides, lithium metals, lithium-based metals such as lithium alloys _{, metal compounds such as TiS 2} and LiTiS ₂ , composite materials of metal oxides and carbonaceous materials, magnesium, iron, zinc , Metals such as aluminum and the like.

As the positive electrode active material, for example, a material conventionally used as a positive electrode active material of a non-aqueous electrolyte battery can be used, and examples thereof include TiS ₂ , TiS ₃ , amorphous MoS ₃ , and Cu _2. Transition metal oxides such as V ₂ O ₃ , amorphous V ₂ O-P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ and LiCo O ₂ , LiNiO ₂ , LiMnO ₂ , LiMn _{2 O 4} , lithium-containing composite metal oxides such as _{LiNiCoMnO 2, P 2 -Na 2/3 Ni} 1/3 Mn 2/3 O 2, NaCrO 2, Na 2/3 [Fe 1/2 Mn 1/2] O 2, NaMnO , Na _x CoO ₂ and other sodium-containing composite metal oxides, K ₂ Mn [Fe (CN) ₆ ], K _x MnO ₂ , K _x Fe _0.5 Mn _0.5 O ₂ , _{K FeSO 4} F and other potassium-containing composites. Examples thereof include metal oxides, Mo ₃ S, MgTi ₂ S ₄ , V ₂ O ₅ , NVO, MgFeSiO ₄ , carbon paper, carbon materials, sulfur-based materials and the like. These positive electrode active materials can be used alone or in combination of two or more.

The positive electrode and the negative electrode contained in the non-aqueous electrolyte battery may further contain a conductive auxiliary agent. The conductive auxiliary agent is used to increase the output of the non-aqueous electrolyte battery, and can be appropriately selected depending on the case where it is used for the positive electrode or the negative electrode. Examples thereof include graphite, acetylene black, and carbon black. , Ketjen black, vapor-grown carbon fiber and the like. From the viewpoint that the obtained non-aqueous electrolyte battery can easily increase the output, it is preferable that acetylene black is contained among these.

When the positive electrode and / or the negative electrode contains a conductive auxiliary agent, the content of the conductive auxiliary agent is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the active material. More preferably, it is 3 to 10 parts by mass. When the content of the conductive auxiliary agent is in the above range, there is a sufficient conductive auxiliary effect without lowering the battery capacity.

As the binder, a material conventionally used as a negative electrode active material of a non-aqueous electrolyte battery can be used, and examples thereof include SBR, NBR, acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose (CMC), and polyvinylidene fluoride. (PVDF), acrylic type, polyamide-imide type, polyvinylidene type and the like can be mentioned.

As the binder used for the negative electrode and the positive electrode, it is one of the preferable embodiments to use an SBR emulsion from the viewpoint of the balance between availability and productivity improvement.

In addition to the binder, the active material, and the conductive additive, the positive electrode and / or the negative electrode may be added with a flame retardant aid, a thickener, a defoaming agent, a leveling agent, an adhesion imparting agent, etc., if necessary. Can include agents.

For the electrode, a composition containing a positive electrode or negative electrode active material, a binder resin, and one or more solvents (hereinafter, also referred to as a slurry composition) is applied to a current collector, and the solvent is removed by drying or the like. Obtainable. Further, the electrode may be rolled after drying.

The current collector is not particularly limited as long as it is made of a conductive material, and examples thereof include metal materials such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, and platinum. These current collectors can be used alone or in combination of two or more. Among the current collectors, aluminum is preferable as the positive electrode current collector, and copper is preferable as the negative electrode current collector from the viewpoint of the adhesiveness of the active material and the discharge capacity.

The method of applying the slurry composition to the current collector is not particularly limited, and examples thereof include an extrusion coater, a reverse roller, a doctor blade, and an applicator. The coating amount of the slurry composition is appropriately selected according to the desired thickness of the cured product derived from the slurry composition.

Examples of the electrode rolling method include a mold press and a roll press. The press pressure is preferably 1 to 40 MPa from the viewpoint of easily increasing the battery capacity.

The thickness of the current collector is preferably 1 to 20 μm, more preferably 2 to 15 μm. The thickness of the cured product is preferably 10 to 400 μm, more preferably 20 to 300 μm. The thickness of the electrode is preferably 20 to 200 μm.

The electrolyte solution contained in the non-aqueous electrolyte battery of the present invention may contain an electrolyte salt, an organic solvent and / or an additive, or may be a solid electrolyte, an ionic liquid, or an ionic liquid containing an electrolyte salt. The electrolyte salt may be solid, liquid, or gel as long as it is used in a normal non-aqueous electrolyte battery, and exhibits a function as a battery depending on the type of the negative electrode active material and the positive electrode active material. You can select the one as appropriate. Specific electrolyte salt, for _{example, LiClO 4, LiBF 6, LiPF} 6, LiTFSA, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlC l4, LiCl, LiBr, LiB (C ₂ H ₅ ) ₄ , CF ₃ SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, lower aliphatic lithium carboxylate, NaPF ₆ , NaTFSA, NaFSI, KFSI, KPF ₆ , Mg (TFSA) ₂ , Mg (TFSA) ₂ , Mg [N (CF ₃ SO ₂ ) ₂ ] _{2, and the} like.

The solvent contained in the electrolytic solution is not particularly limited, and specific examples thereof include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate and vinylene carbonate; γ-butyl lactone and the like. Lactones; ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, diethylene glycol diethyl ether; sulfoxides such as dimethyl sulfoxide; 1,3-dioxolane Oxoranes such as 4-methyl-1,3-dioxolane; Nitrogen-containing compounds such as acetonitrile and nitromethane; Organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate and the like. Inorganic acid esters such as triethyl phosphate, dimethyl carbonate, diethyl carbonate; diglimes; triglimes; sulfolanes; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propanesulton, 1,4-butanesulton , Nafta sulton and the like, and these can be used alone or in combination of two or more. When a gel-like electrolytic solution is used, a nitrile-based polymer, an acrylic-based polymer, a fluorine-based polymer, an alkylene oxide-based polymer, or the like can be added as a gelling agent.

The additive contained in the electrolytic solution is not particularly limited, and examples thereof include VC, VEC, FEC, and LiFSI.

The solid electrolyte is not particularly limited _{, and is sulfide-based such as Li 2 SP 2} S ₅ , LGPS, LSiPSCl, LSiSnPS, oxide-based such as LLTO, LATP, LLZO, LAGP, LIPON, and polymer such as PEO-LiTFSI. Examples thereof include complex systems such as LiBH ₄ , LiBH _{4- LiI, LiBH 4-} LiNH ₂ , LiBH _4- P ₂ S _5, and hydride systems such as crosoborane and carboran.

The ionic liquid used as the electrolytic solution is not particularly limited, and is, for example, ammonium-based, pyrrolidinium-based, pyridinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridadinium-based, phosphonium-based, sulfonium-based, triazolium-based, and and one or more cations selected from among the mixture _{^{BF 4 -, PF 6 -,}} AsF 6 -, SbF 6 -, AlCl 4 -, HSO 4 -, ClO 4 -, CH 3 SO 3 -, (F _{5 O2)} 2 ^N - is selected from among ^{_{-, (C 2 F 5 SO}} 2) 2 N -, (C 2 F 5 SO 2) (CF 3 SO 2) N - and _{(CF 3} SO ₂₎ 2 N Examples thereof include compounds containing one or more types of anions selected from at least one.

In the present invention, the shape of the non-aqueous electrolyte battery may be any of known coin type, button type, sheet type, cylindrical type, square type, flat type and the like. The non-aqueous electrolyte battery of the present invention containing the separator of the present invention as a constituent member has high safety, is unlikely to cause an increase in internal resistance, has an excellent capacity retention rate, and is an excellent battery such as a high battery capacity. Has characteristics. The non-aqueous electrolyte battery of the present invention can be suitably used for various purposes, for example, in a mobile terminal requiring miniaturization, thinning, weight reduction and high performance, and in high capacity and large current. It is useful as a battery used in large equipment such as electric vehicles that require performance such as charge / discharge characteristics.

Hereinafter, the present invention will be specifically described with reference to Examples, but these do not limit the scope of the present invention.

The methods for measuring the physical characteristics of the separators (porous membranes) obtained in Examples and Comparative Examples described later are shown below.

[Film thickness]
The film thickness of the separators obtained in Examples and Comparative Examples was measured using a thickness measuring device (constant pressure thickness measuring device PG-02J, manufactured by Teflock Co., Ltd.).

The film thickness of the non-woven fabric used in Examples and Comparative Examples was measured using a thickness measuring device (Thickness meter B-1, Toyo Seiki Seisakusho).

[Viscosity average degree of polymerization]
The viscosity average degree of polymerization of the polyvinyl alcohol-based resin was measured according to JIS K 6726.

[SEM image]
The SEM was photographed using the following devices.
Device KEYENCE VE-8800
Acceleration voltage 8kV
Magnification 1000 times

[Content of porous membrane]
The content of the porous membrane was calculated by subtracting the mass of the non-woven fabric alone from the mass of the separators obtained in Examples and Comparative Examples.

[Measurement of saponification degree and viscosity average degree of polymerization]
The saponification degree of the polyvinyl alcohol-based resin was measured according to JIS-K6726.

[Air permeability]
The air permeability of the separators obtained in Examples and Comparative Examples was determined from the following conditions in accordance with JIS P8117. The air permeability was evaluated 5 times at different locations for each sample, and the average value was taken as the air permeability.
(Measurement condition)
Measuring device: Oken type air permeability smoothness tester (manufactured by Asahi Seiko Co., Ltd.)
Measurement time: 2 minutes

[Contact angle]
The separators obtained in Examples and Comparative Examples were cut into 6 cm × 15 cm, the cut separator was divided into 10 equal parts, and then the contact angle of one surface of the separator with respect to propylene carbonate was contacted at each of the 10 equal parts. The measurement was performed under the following conditions by the sessile drop method using an angle meter. The average value of the values obtained by measuring at each location was evaluated as the contact angle of the separator.
(Measurement condition)
Measuring device: DM700, manufactured by Kyowa Interface Science Co., Ltd. Temperature: 25 ° C
Solvent: Propylene carbonate (PC)
Droplet volume: 1.5 μl
Measurement time: 1000 msec later

[Puncture strength]
The separators obtained in Examples and Comparative Examples were cut into 2 cm squares and measured with a texture analyzer (XT Plus, manufactured by EKO Instruments) using a cylinder probe having a temperature of 25 ° C., a piercing speed of 2 mm / s, and a diameter of 1 mm. Was done.

[Peeling strength]
Under the conditions of 25 ° C. and a linear pressure of 40 kg / cm, a negative electrode containing natural graphite, SBR and CMC in a ratio of 98: 1: 1 and NCM, Ketjen black, carbon rack and PVDF at 92: 2.5: The separators obtained in Examples and Comparative Examples were pressure-bonded to the positive electrodes contained in a ratio of 2.5: 3, respectively. Next, the electrode surface of the crimped sample and the stainless steel plate are bonded together using double-sided tape (double-sided tape made by Nichiban), and 180 ° peel strength (peeling width 10 mm, peeling speed) by a 50 N load cell (manufactured by Imada Co., Ltd.). 100 mm / min) was measured. The peel strength with the negative electrode was P _a , the peel strength with the positive electrode was P _b , and the peel strength ratio P _a / P _b was calculated.
Further, under the conditions of 25 ° C. and a press pressure of 5 MPa, peeling when two separators obtained in Examples and Comparative Examples were used and one surface of the separator and the other surface were overlapped and pressure-bonded for 8 hours. The strength P _c was also carried out in the same manner as described above. In that case, one of the separator surfaces and the stainless steel plate were bonded together using double-sided tape (double-sided tape made by Nichiban).

[Tensile strength]
The tensile strength of the separators obtained in Examples and Comparative Examples was calculated with a test piece of JIS K 7162-1B using a tensile tester under the following conditions. The tensile strength was measured in both the MD direction and the TD direction of the separator.
(Measurement condition)
Measuring device: Autograph AG5000B, manufactured by Shimadzu Corporation Temperature: 25 ° C
Distance between chucks: 70 mm
Test speed: 500 mm / min Test piece: Dumbbell type (test part width 10 mm), test piece thickness 10 μm

[Water content]
The separators obtained in Examples and Comparative Examples were dried at 100 ° C. for 1 hour, and the water content was measured under the following conditions.
(Measurement condition)
Measuring device: Karl Fischer Moisture measuring device, manufactured by Mitsubishi Chemical Analytech Temperature: 120 ° C

[Membrane contraction rate]
The separators obtained in Examples and Comparative Examples were punched to φ17 mm and heated at 150 ° C. for 1 hour. The membrane contraction rate was calculated according to the following formula.
Membrane shrinkage rate = (diameter before heating-diameter after heating) / diameter before heating x 100

[Battery capacity retention rate]
The separators obtained in Examples and Comparative Examples were cut out to a size of 5.1 × 5.0 cm. Next, a positive electrode equivalent to that used in the peel strength test was cut out to a size of 4.8 x 4.5 cm, and a negative electrode equivalent to that used in the peel strength test was cut out to a size of 4.9 x 4.7 cm, and a lead tab was attached. rice field. A separator cut out to the above size was sandwiched between these electrodes. The separator sandwiched between the electrodes was installed in the aluminum laminate pack so that the lead tabs came out of the aluminum laminate pack. Next, 570 μl of an electrolytic solution (ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) = 1/1/1, 1.0M LiPF ₆ ) was sealed in the aluminum laminate pack under reduced pressure, and the volume was increased. A laminated cell (non-aqueous electrolyte battery) for measuring the retention rate was produced.
The above-mentioned laminated cell was tested using a commercially available charge / discharge tester (TOSCAT3100, manufactured by Toyo System). In charging, a constant current charge of 0.2 C was performed up to 0.01 V with respect to the lithium potential, and a constant voltage charge of 0.01 V with respect to the lithium potential was further performed until a current of 0.02 mA was reached. In the discharge, a constant current discharge of 0.2 C was performed up to 1.5 V with respect to the lithium potential. The laminated cell was placed in a constant temperature bath at 25 ° C., and charging / discharging was repeated 100 times under the above conditions, and the capacity retention rate was calculated according to the following formula.
Capacity retention rate = 100th cycle discharge capacity / 1st cycle discharge capacity x 100

[Example 1]
(1) Preparation of solution for forming a porous film Ethethylene-vinyl alcohol resin powder (manufactured by Kuraray, "E105B", ethylene modification amount 44 mol%, saponification degree 100 mol%, viscosity average degree of polymerization 960, hydroxyl group amount 56 mol%) Was dissolved in a mixed solvent of water and 1-propanol (water / 1-propanol = 40/60 volume ratio) at 70 ° C. for 3 hours to prepare a solution for forming a porous film having a solid content concentration of 8% by mass.
(2) Preparation of porous film The above-mentioned solution for forming a porous film sensitive to 50 ° C. was placed in a bat, and a molten liquid crystal-forming polyester non-woven fabric (manufactured by Kuraray, with a grain of 4.1 g / m ² , thickness 10 μm, The non-woven fabric is impregnated with an average fiber diameter of 2.5 μm to 3 μm and a melting point of 350 ° C. by impregnating the non-woven fabric with a solution. The excess liquid was removed using an applicator (T101, manufactured by Matsuo Sangyo Co., Ltd.). The liquid removal is performed by setting the clearance between the coated portion of the applicator and the surface of the glass plate (also referred to as the clearance with respect to the surface of the glass plate) to 5 μm, so that the coated portion of the applicator is in contact with the surface of the resin-impregnated non-woven fabric. It was carried out along the surface. Next, the glass plate base material was immersed in a water bath at 40 ° C. for 10 minutes to solidify. Next, the non-woven fabric containing the wet film of ethylene-vinyl alcohol resin was taken out from the water tank, peeled from the base material, air-dried, and dried at 100 ° C. for 1 hour.
(3) Rolling The obtained separator was rolled using a roll press (manufactured by Hosen Co., Ltd.) under the conditions of 25 ° C. and a linear pressure of 40 kg / cm. In this way, a separator for a non-aqueous electrolyte battery containing a non-woven fabric and a porous membrane made of an ethylene-vinyl alcohol resin was obtained. The content of the resin porous membrane in the separator was 35% by mass with respect to the mass of the separator.

[Example 2]
The melted liquid crystal forming polyester non- ^{woven fabric was changed to a molten liquid crystal forming polyester non-woven fabric made by Kuraray, having a grain size of 8.0 g / m 2} , a thickness of 15 μm, an average fiber diameter of 2.5 μm to 3 μm, and a melting point of 350 ° C. A separator was obtained in the same manner as in Example 1 except that the clearance with respect to the surface of the glass plate was set to 10 μm. The content of the resin porous membrane in the separator was 27% by mass with respect to the mass of the separator.
FIG. 1 shows an SEM image of the surface of the obtained separator for a non-aqueous electrolyte battery. As shown in the SEM image, it was confirmed that the fibers constituting the non-woven fabric were present on the surface of the separator, and that a porous film made of ethylene-vinyl alcohol resin was present between the fibers.

[Example 3]
The melted liquid crystal forming polyester non- ^{woven fabric was changed to a molten liquid crystal forming polyester non-woven fabric made by Kuraray, having a grain size of 8.0 g / m 2} , a thickness of 19 μm, an average fiber diameter of 2.5 μm to 3 μm, and a melting point of 350 ° C. A separator was obtained in the same manner as in Example 1 except that the clearance with respect to the surface of the glass plate was set to 10 μm. The content of the resin porous membrane in the separator was 37% by mass with respect to the mass of the separator.

[Example 4]
(1) Preparation of solution for forming a porous film Polyvinyl butyral resin powder (manufactured by Kuraray, "Mobile B60T", saponification degree 96-99 mol%, hydroxyl group amount 24-27 mol%) was added to dimethylsulfoxide at 70 ° C. for 3 hours. To prepare a solution for forming a porous film having a solid content concentration of 8% by mass.
(2) Preparation of porous film The solution for forming a porous film at 25 ° C. obtained above was placed in a bat, and a molten liquid crystal-forming polyester non-woven fabric (manufactured by Kuraray, with a grain of 4.1 g / m ² , thickness 10 μm, average fiber diameter) was placed. (2.5 μm to 3 μm, melting point 350 ° C.) is impregnated by impregnating the non-woven fabric with the solution, and then the resin-impregnated non-woven fabric is placed on a glass plate placed on a horizontal table, and excess liquid from the resin-impregnated non-woven fabric is placed. Was deflated using an applicator (T101, manufactured by Matsuo Sangyo Co., Ltd.). The liquid removal was carried out along the surface of the resin-impregnated non-woven fabric while bringing the coated portion of the applicator into contact with the surface of the resin-impregnated non-woven fabric by setting the clearance to the surface of the glass plate to 5 μm. Next, the glass plate base material was immersed in a water bath at 25 ° C. for 10 minutes to solidify. Next, the non-woven fabric containing the wet film of polyvinyl butyral resin was taken out from the water tank, peeled from the substrate, air-dried, and dried at 100 ° C. for 1 hour.
After that, rolling was carried out in the same manner as in Example 1 to obtain a separator. The content of the resin porous membrane in the separator was 26% by mass with respect to the mass of the separator.

[Example 5]
The melted liquid crystal forming polyester non- ^{woven fabric was changed to a molten liquid crystal forming polyester non-woven fabric made by Kuraray, having a grain size of 8.0 g / m 2} , a thickness of 15 μm, an average fiber diameter of 2.5 μm to 3 μm, and a melting point of 350 ° C. A separator was obtained in the same manner as in Example 4 except that the clearance with respect to the surface of the glass plate was set to 10 μm. The content of the resin porous membrane in the separator was 25% by mass with respect to the mass of the separator.

[Example 6]
A separator was obtained in the same manner as in Example 5 except that the non-woven fabric was changed to polyethylene terephthalate (basis weight 6.2 g / m ^{2, thickness 9 μm, melting point 255 ° C.).} The content of the resin porous membrane in the separator was 29% by mass with respect to the mass of the separator.

[Example 7]
A separator was obtained in the same manner as in Example 2 except that the non-woven fabric was changed to polyethylene terephthalate (basis weight 6.2 g / m ^{2, thickness 9 μm, melting point 255 ° C.).} The content of the resin porous membrane in the separator was 31% by mass with respect to the mass of the separator.

[Example 8]
A separator was obtained in the same manner as in Example 2 except that the non-woven fabric was changed to polypropylene (basis weight 5.0 g / m ^{2, thickness 13 μm, melting point 168 ° C.).} The content of the resin porous membrane in the separator was 36% by mass with respect to the mass of the separator.

[Comparative Example 1]
The melted liquid crystal forming polyester non- ^{woven fabric was changed to a molten liquid crystal forming polyester non-woven fabric made by Kuraray, having a grain size of 8.0 g / m 2} , a thickness of 15 μm, an average fiber diameter of 2.5 μm to 3 μm, and a melting point of 350 ° C. By setting the clearance to the surface of the glass plate to 20 μm, a separator is provided in the same manner as in Example 1 except that a clearance is provided between the coated portion of the applicator and the surface of the resin-impregnated non-woven fabric so that they do not come into contact with each other. Got The content of the resin porous membrane in the separator was 30% by mass with respect to the mass of the separator.

[Comparative Example 2]
Same as in Example 1 except that the clearance to the surface of the glass plate at the time of liquid removal is set to 20 μm so that a clearance is provided between the coated portion of the applicator and the surface of the resin-impregnated non-woven fabric so that they do not come into contact with each other. A separator was obtained by the method of. The content of the resin porous membrane in the separator was 36% by mass with respect to the mass of the separator. FIG. 2 shows an SEM image of the surface of the obtained separator for a non-aqueous electrolyte battery. As shown in the SEM image, it was confirmed that only a porous film made of ethylene-vinyl alcohol resin was present on the surface of the separator. That is, it was found that in the separator obtained in Comparative Example 2, the surface of the non-woven fabric was covered with the porous film.

[Comparative Example 3]
(1) Preparation of solution for forming a porous film Polyvinyl alcohol-based aqueous solution (manufactured by Kuraray, crustomer, saponification degree 97 to 98 mol%, hydroxyl group content 24-85 mol%, solid content concentration 10% by mass) and polyethylene glycol (molecular weight) A solution for forming a porous film was prepared by adding 42 parts by mass of 1000 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) to a polyvinyl alcohol resin.
(2) Preparation of porous film The solution for forming a porous film at 50 ° C. obtained above was placed in a bat, and a molten liquid crystal-forming polyester non-woven fabric (manufactured by Kuraray, with a grain of 4.1 g / m ² , thickness 10 μm, average fiber diameter) was placed. (2.5 μm to 3 μm, melting point 350 ° C.) is impregnated by impregnating the non-woven fabric with the solution, and then the resin-impregnated non-woven fabric is placed on a glass plate placed on a horizontal table, and excess liquid from the resin-impregnated non-woven fabric is placed. Was deflated using an applicator (T101, manufactured by Matsuo Sangyo Co., Ltd.). In the liquid removal, the clearance with respect to the surface of the glass plate was set to 20 μm, so that a clearance was provided between the coated portion of the applicator and the surface of the resin-impregnated non-woven fabric so that they would not come into contact with each other. Next, the glass plate base material was immersed in an isopropyl alcohol bath at 20 ° C. for 20 minutes to solidify. Next, the non-woven fabric containing the wet film was taken out from the water tank, peeled from the substrate, air-dried, and then dried at 100 ° C. for 1 hour.
After that, rolling was carried out in the same manner as in Example 1 to obtain a separator. The content of the resin porous membrane in the separator was 25% by mass with respect to the mass of the separator.

[Comparative Example 4]
A separator was obtained in the same manner as in Example 1 except that the molten liquid crystal forming polyester non-woven fabric was not used.

[Comparative Example 5]
Same as in Example 7 except that the clearance to the surface of the glass plate at the time of liquid removal is set to 20 μm so that a clearance is provided between the coated portion of the applicator and the surface of the resin-impregnated non-woven fabric so that they do not come into contact with each other. A separator was obtained by the method of. The content of the resin porous membrane in the separator was 35% by mass with respect to the mass of the separator.

[Comparative Example 6]
A separator was obtained in the same manner as in Comparative Example 3 except that the molten liquid crystal forming polyester non-woven fabric was not used.

[Comparative Example 7]
A commercially available PE separator (9 μm) is placed on a glass plate placed on a horizontal table, and alumina is coated with an applicator (T101, manufactured by Matsuo Sangyo Co., Ltd., clearance 5 μm for the PE separator) and hot at 50 ° C. After drying on the plate for 1 hour, the surface opposite to the coated surface was similarly coated with alumina to prepare a heat-resistant coated separator.

[Comparative Example 8]
Using the commercially available PE separator used in Comparative Example 7, alumina was applied to only one side with an applicator (T101, manufactured by Matsuo Sangyo Co., Ltd., clearance 100 μm for the PE separator), and then placed on a hot plate at 50 ° C. for 3 hours. It was dried to prepare a heat-resistant coated separator.

The film thickness, contact angle, air permeability, peel strength ratio Pa / Pb, peel strength P _c , piercing strength, and tensile strength (MD direction and TD direction) of the separators obtained in Examples 1 to 8 and Comparative Examples 1 to 8 ), Water content, film shrinkage rate, and battery capacity retention rate are shown in Table 5. Table 5 also shows the types of resins and non-woven fabrics that make up the porous membrane. In Table 5, EVOH indicates ethylene-vinyl alcohol resin (copolymer), PVB indicates polyvinyl butyral, and PVA indicates polyvinyl alcohol. Heat-resistant PE indicates polyethylene coated with a heat-resistant resin. Further, PL represents a molten liquid crystal forming polyester.

As shown in Table 5, it was confirmed that the separators for non-aqueous electrolyte batteries obtained in Examples 1 to 8 had a significantly higher battery capacity retention rate than those in Comparative Examples 1 to 8.
Therefore, the separator for a non-aqueous electrolyte battery of the present invention can form a non-aqueous electrolyte battery having an excellent battery capacity retention rate even if the film thickness is thin.

Claims (11)

A separator for a non-aqueous electrolyte battery containing a non-woven fabric and a porous film made of a polyvinyl alcohol-based resin, at least a part of the porous film exists between fibers constituting the non-woven fabric, and on at least one surface of the separator. A separator for a non-aqueous electrolyte battery having a contact angle of 35 ° or more and a film thickness of 1 to 15 μm. The separator for a non-aqueous electrolyte battery according to claim 1, which has an air permeability of 50 to 500 seconds. 25 ° C., a linear pressure of 40 kg / cm under conditions of natural graphite, the SBR and CMC 98: 1: a negative electrode comprising a ratio of 1, and the peel strength _{P a} at the time obtained by crimping the separator, NCM, Kek _{P a} / P _b, which is the ratio of _{the peel strength P b} when the separator is crimped to a positive electrode containing chain black, carbon black and PVDF in a ratio of 92: 2.5: 2.5: 3. is 0.9 ~ 40, _{P a} and _{P b} is greater than 0N / m, the non-aqueous electrolyte cell separator according to claim 1 or 2. Any of claims 1 to 3, wherein the peel strength when one surface of the separator and the other surface are overlapped and pressure-bonded for 8 hours under the conditions of 25 ° C. and a press pressure of 5 MPa is 2 N / m or less. Separator for non-aqueous electrolyte battery described in. The separator is elongated, among the tensile strength in the longitudinal direction of the tensile strength and the lateral direction, the lower the tensile strength is 100 kgf / cm ² or more, non according to any one of claims 1 to 4, Separator for water electrolyte batteries. The separator for a non-aqueous electrolyte battery according to any one of claims 1 to 5, wherein the water content after drying the separator at 100 ° C. for 1 hour is 1% or less. The separator for a non-aqueous electrolyte battery according to any one of claims 1 to 6, wherein the polyvinyl alcohol-based resin is at least one selected from the group consisting of an ethylene-vinyl alcohol resin and a polyvinyl acetal resin. The separator for a non-aqueous electrolyte battery according to any one of claims 1 to 7, wherein the membrane shrinkage rate at 150 ° C. is 2% or less. The separator for a non-aqueous electrolyte battery according to any one of claims 1 to 8, wherein the non-woven fabric has a melting point of 300 ° C. or higher. The separator for a non-aqueous electrolyte battery according to any one of claims 1 to 9, wherein the non-woven fabric contains a molten liquid crystal forming polyester fiber. A non-aqueous electrolyte battery comprising the separator for a non-aqueous electrolyte battery according to any one of claims 1 to 10.

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