JP5926619B2 - Coating liquid for lithium ion battery separator and method for producing lithium ion battery separator - Google Patents

Description

The present invention relates to a coating solution for a lithium ion battery separator and a method for producing a lithium ion battery separator.

  A lithium ion secondary battery, which is one of the electrochemical elements, has a feature of high energy density, and is widely used as a power source for portable electric devices such as mobile phones, portable music players, and notebook personal computers. . In addition, the movement to use lithium ion secondary batteries is spreading in large equipment such as electric bicycles, hybrid cars, and electric cars. For this reason, lithium ion secondary batteries are required to have high capacity and charge / discharge characteristics at a large current. However, since lithium ion secondary batteries are non-aqueous batteries, they emit smoke compared to water-based batteries. It is known that there is a high risk of ignition, rupture, etc., and improvement in safety is also required.

  In a lithium ion secondary battery, the risk of smoking increases due to temperature rise due to external heat, overcharge, internal short circuit, external short circuit, and the like. These can be prevented to some extent by an external protection circuit. In addition, the polyolefin resin porous film used as a lithium ion battery separator melts at around 120 ° C., and the pores are blocked to block the flow of current and ions, thereby suppressing battery temperature rise. . This is called a shutdown function. However, when the temperature rises due to external heat or when a chemical reaction occurs inside the battery due to the temperature rise, the battery temperature further rises even if the shutdown function works, and when the battery temperature reaches 150 ° C or higher, The porous film contracted, causing an internal short circuit, which could cause ignition.

  As described above, it is difficult to suppress the ignition of the battery by the shutdown function of the separator. In addition, with the increase in capacity of batteries, the increase in current during charging and discharging is also progressing, and in order to suppress the Joule heat generated at that time, it is also necessary to lower the resistance value of the separator impregnated with the electrolyte. It has become. For this reason, metal oxide fine particles were used for the purpose of suppressing the ignition of the battery by lowering the resistance value while making it difficult to cause an internal short circuit by raising the heat shrinkage temperature than the porous film of polyolefin resin. Separator has been developed. In this separator, the pore diameter is controlled by the metal oxide fine particles, and it is possible to suppress internal short circuit, improve heat resistance, and lower the resistance value.

  For example, a separator having a microporous pseudoboehmite layer obtained as a porous film by mixing pseudoboehmite and a binder, drying and peeling after coating on a separately prepared film has been proposed (for example, patents) Reference 1). However, although this separator has an improved heat shrink temperature, it tends to cause powder falling and cracking, so that it is difficult to take it out as a rolled-up separator alone, resulting in poor handling during battery production. It was.

  Also proposed is a separator having a porous inorganic coating on and in the nonwoven fabric, the inorganic coating having aluminum (Al), silicon (Si) and / or zirconium (Zr) oxide particles. (For example, refer to Patent Document 2). Although this separator uses non-woven fabric as a base material, handling is improved, but other metal oxides are detected by silica fine particles generated by the sol-gel method. Drops and cracks are likely to occur, which leads to the generation of pinholes and causes internal short circuits, making it difficult to be a useful separator.

  Furthermore, a coating liquid containing insulating fine particles having heat resistance, a thickener, and a dispersion medium, and a separator coated with the coating liquid on a substrate have been proposed (for example, Patent Document 3). reference). Moreover, the coating liquid which further contains a dispersing agent and the coating liquid which further contains a binder are described. Specific examples of thickeners include synthetic polymers such as polyethylene glycol, polyacrylic acid, polyvinyl alcohol, vinyl methyl ether-maleic anhydride copolymer; cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose; xanthan gum Natural polysaccharides such as welan gum, gellan gum, guar gum and carrageenan; starches such as dextrin and pregelatinized starch; clay minerals such as montmorillonite and hectorite; inorganic oxides such as fumed silica, fumed alumina and fumed titania Etc. are mentioned. Dispersants include various anionic, cationic, and nonionic surfactants; polymer systems such as polycarboxylic acid, polyacrylic acid, polymethacrylic acid, polycarboxylate, polyacrylate, and polymethacrylate Dispersants and the like are mentioned. However, in the separator coated with the coating liquid on the base material, the surface of the coating layer is uneven, or the adhesiveness with the base material is not sufficient, so that the insulating fine particles fall off from the base material. There was a case.

JP-T-2001-527274 JP 2005-536658 Gazette International Publication No. 2009/096451 Pamphlet

  The present invention provides a lithium ion battery separator that has less irregularities on the surface of the coating layer containing at least an alumina hydrate and a binder polymer, and has less powder falling when producing a lithium ion battery separator having high heat resistance. There is.

In the present invention, as a result of intensive research to solve the above problems,
(1) In a coating solution for a lithium ion battery separator for coating a nonwoven fabric and drying to produce a lithium ion battery separator, a salt of alumina hydrate, binder polymer and aliphatic olefin-maleic acid copolymer is added. and also contains the medium is water, the aliphatic olefins - salts of maleic acid copolymer is Ri alkali metal salt or amide ammonium salts der, aliphatic olefins - amount of a salt of maleic acid copolymer is , to the alumina hydrate, a coating solution for a lithium ion battery separator, wherein 2.0 wt% or less der Rukoto than 0.05 mass%,
(2) the coating solution coated on the nonwoven fabric, a method of manufacturing a lithium-ion battery separator, characterized by drying,
I found out.

  Lithium ion battery comprising alumina hydrate, binder polymer and aliphatic olefin-maleic acid copolymer salt, wherein the aliphatic olefin-maleic acid copolymer salt is an alkali metal salt or an amido ammonium salt With the separator coating liquid, it is possible to achieve the effect that the unevenness and powder fall off of the surface of the coating layer in the lithium ion battery separator obtained by coating and drying the coating liquid on a nonwoven fabric are reduced.

  The coating liquid of the present invention comprises an alumina hydrate, a binder polymer, and a salt of an aliphatic olefin-maleic acid copolymer, and the salt of the aliphatic olefin-maleic acid copolymer is an alkali metal salt or A coating liquid for a lithium ion battery separator, which is an amido ammonium salt.

  Examples of the alumina hydrate include gibbsite type, boehmite type, pseudoboehmite type, bayerite type, and diaspore type crystal types. In the present invention, synthetic boehmite is preferable from the viewpoint of battery stability. .

  The average particle size of the alumina hydrate of the present invention is preferably 0.01 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less. In addition, the average particle diameter of the said alumina hydrate is an average particle diameter calculated | required from the particle size distribution measurement by a laser diffraction method.

  There is no restriction | limiting in particular about the shape of the alumina hydrate of this invention, Granular shapes, such as substantially spherical shape, rugby ball shape, and cube shape, scale shape, needle shape, plate shape, etc. may be sufficient. In addition, the primary particles of fine particles may be aggregated into secondary particles, or single particles may be used.

  Specific examples include APYRAL (registered trademark) AOH and ACTILOX (registered trademark) manufactured by Nabaltec, Germany, and Cerasur (registered trademark) BMT, BMB, and BMI manufactured by Kawai Lime.

  The binder polymer used in the coating liquid of the present invention is not particularly limited as long as it is electrochemically stable and stable with respect to the nonaqueous electrolytic solution. Specifically, for example, ethylene-vinyl acetate copolymer (EVA), acrylate copolymer, fluorine rubber, styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP). ), And resins such as polyurethane, and a resin in which a crosslinked structure is introduced into some of these resins in order to prevent dissolution in a non-aqueous electrolyte can also be used. These binder polymers may be used individually by 1 type, and may use 2 or more types together. Among these, styrene butadiene rubber (SBR) and acrylate copolymers are particularly preferable.

  The addition amount of the binder polymer used in the coating liquid of the present invention is preferably 3% by mass or more and 25% by mass or less with respect to the alumina hydrate. From the viewpoint of the balance between the powder falling off of the coating layer and the voids in the coating layer, the content is more preferably 5% by mass or more and 20% by mass or less.

  The salt of the aliphatic olefin-maleic acid copolymer used in the coating liquid of the present invention can be easily obtained by neutralizing and hydrolyzing the aliphatic olefin-maleic anhydride copolymer with an aqueous alkali solution.

  Specific examples of the aliphatic olefin include aliphatic groups such as isobutene, 1-butene, 2-butene, 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-hexene. And monoolefins. Isobutene is preferred because it has few irregularities and is difficult to fall off.

  The method for producing the copolymer is not particularly limited, but a monomer mixture of an aliphatic olefin and maleic anhydride is used in an organic solvent such as hydrocarbon, using a radical initiator such as an organic peroxide or an azo compound. And can be easily obtained by copolymerization.

  The salt of the aliphatic olefin-maleic acid copolymer is obtained as an alkali metal salt or amidoammonium salt by reacting the copolymer obtained by the above method with an alkali metal hydroxide or ammonia in water. . The amount of alkali metal hydroxide or ammonia used is appropriately selected according to the amount of copolymer and the amount of maleic anhydride in the copolymer. Usually, alkali metal hydroxide or ammonia is used as maleic anhydride. 30 to 100 mol% based on the acid is used.

  Examples of the salt of the aliphatic olefin-maleic acid copolymer include lithium salt, potassium salt, sodium salt, and amido ammonium salt.

  The mass average molecular weight of the salt of the aliphatic olefin-maleic acid copolymer used in the present invention is preferably 500 to 500,000, more preferably 5,000 to 200,000. The mass average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

  Specifically, Kuraray's Isoban (registered trademark) 04, 06, 10, 18 or the like neutralized and hydrolyzed with alkali metal hydroxide or ammonia in water or Kuraray's Isoban (registered trademark) 110 104, Quinflow (registered trademark) 540, 543 manufactured by Nippon Zeon Co., Ltd., and the like. These may be used alone or in combination of two or more.

  The addition amount of the salt of the aliphatic olefin-maleic acid copolymer used in the coating liquid of the present invention is preferably 0.05% by mass or more and 3.0% by mass or less with respect to the alumina hydrate. From the viewpoint of powder falling off of the coating layer and surface properties of the coating layer, 0.1% by mass or more and 2.0% by mass or less is more preferable.

  The coating liquid of the present invention is preferably applied to a nonwoven fabric. The nonwoven fabric manufactured by a conventionally known method can be used. For example, what was manufactured by methods, such as the spun bond method, the melt blow method, the dry method, the wet method, and the electrospinning method, can be used.

  In the present invention, the nonwoven fabric may be smoothed by calendaring or thermal calendaring for the purpose of controlling the surface and thickness of the nonwoven fabric.

  As the constituent material of the nonwoven fabric, polyethylene terephthalate, polybutylene terephthalate and derivatives thereof, polyester such as aromatic polyester, wholly aromatic polyester, polyolefin, acrylic, polyacetal, polycarbonate, aliphatic polyketone, aromatic polyketone, aliphatic polyamide, Aromatic polyamide, wholly aromatic polyamide, polyimide, polyamideimide, polyphenylene sulfide, polybenzimidazole, polyetheretherketone, polyethersulfone, poly (para-phenylenebenzobisthiazole), poly (para-phenylene-2,6- Benzobisoxazole), polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane and polyvinyl chloride Like Wei and cellulose fibers. The nonwoven fabric may contain two or more of these constituent materials.

The nonwoven fabric used in this onset bright, preferably a basis weight in the range of 5.0~30.0g / ^{m 2.} If the basis weight exceeds 30.0 g / m ² , the nonwoven fabric occupies most of the separator, and the effect of the coating layer may be difficult to obtain. If it is less than 5.0 g / m ² , it may be difficult to obtain uniformity as a nonwoven fabric. As a fabric weight of a nonwoven fabric, 7.0-20.0 g / m < ² > is more preferable. The basis weight means the basis weight based on the method defined in JIS P 8124 (paper and paperboard—basis weight measurement method).

  There is no particular limitation on the method of applying the coating liquid of the present invention to the nonwoven fabric, for example, conventionally known air doctor coater, blade coater, knife coater, rod coater, squeeze coater, impregnation coater, gravure coater, kiss roll coater, Examples include a die coater, a reverse roll coater, a transfer roll coater, and a spray coater.

In the present invention, the adhesion amount of the coating layer is preferably 1.0~20.0g / ^{m 2,} further 4.0~17.5g / ^{m 2} is more preferable. If the amount of the coating layer deposited is less than 1.0 g / m ² , the surface of the nonwoven fabric cannot be sufficiently covered, the pore diameter becomes large, and good battery characteristics such as short circuit may not be exhibited. is there. On the other hand, when the adhesion amount of the coating layer exceeds 20.0 g / m ² , it may be difficult to reduce the thickness of the separator.

  In order to produce a uniform coating layer by the above coating method, a thickener, an antifoaming agent, a wetting agent, and the like can be appropriately added to the coating solution as necessary.

  In the present invention, the method of drying after coating is not particularly limited, and a known drying method can be used. In particular, a method of drying by heating, such as a method of blowing hot air or a method of irradiating infrared rays, is produced. It has good properties and is preferably used.

Oite this onset bright, the basis weight of the separator is preferably ^{10.0~50.0g / m 2, 15.0~40.0g / m} 2 is more preferable. Moreover, 10.0-50.0 micrometers is preferable and, as for the thickness of a separator, 15.0-40.0 micrometers is more preferable. Preferably 0.4~1.2g / cm ³ as the density of the separator, 0.6~1.0g / cm ³ is more preferable.

  In the present invention, after coating and drying, the lithium ion battery separator may be smoothed by calendaring for the purpose of controlling the flatness and thickness of the coating layer surface.

  Examples of the present invention will be described below.

<Production of non-woven fabric>
45 parts by mass of oriented crystallized polyethylene terephthalate (PET) short fibers having a fineness of 0.06 dtex (average fiber diameter of 2.4 μm) and a fiber length of 3 mm, an orientation of fineness of 0.1 dtex (average fiber diameter of 3.0 μm) and a fiber length of 3 mm 15 parts by mass of crystallized PET-based short fibers, a fine component of 0.2 dtex (average fiber diameter 4.3 μm), and a fiber length of 3 mm PET-based short fibers for a single-component binder (softening point 120 ° C., melting point 230 ° C.) 40 parts by mass Were mixed together, disintegrated in water with a pulper, and a uniform papermaking slurry having a concentration of 1% by mass was prepared under stirring by an agitator. Using a circular paper machine, this papermaking slurry is made up by a wet method, and a PET short fiber for a binder is adhered by a cylinder dryer at 120 ° C. to develop a nonwoven fabric strength. The basis weight is 15.2 g / m ² . A non-woven fabric was used. Furthermore, this nonwoven fabric was subjected to heat treatment at a roll temperature of 185 ° C., a linear pressure of 740 N / cm, and a conveying speed of 20 m / min using a 1-nip thermal calendar composed of a metal roll and a metal roll, and a nonwoven fabric having a thickness of 27 μm was obtained. Produced.

<Preparation of salt of aliphatic olefin-maleic acid copolymer>
(Salt A of aliphatic olefin-maleic acid copolymer)
41.5 parts by mass of sodium hydroxide is dissolved in 566 parts by mass of distilled water, and is stirred with an agitator. Isoban (registered trademark) # 10 (manufactured by Kuraray Co., Ltd., isobutylene-maleic anhydride copolymer, mass average molecular weight) 160,000 to 170,000) was added, and the mixture was further dissolved by stirring for 4 hours while heating to 95 ° C. After cooling, distilled water corresponding to the amount reduced by evaporation was added to prepare a 20% by mass aqueous solution of an aliphatic olefin-maleic acid copolymer salt A (neutralization degree 0.8).

(Salt B of aliphatic olefin-maleic acid copolymer)
Dissolve 58.1 parts by weight of potassium hydroxide in 632.4 parts by weight of distilled water and stir with an agitator to obtain Isoban (registered trademark) # 10 (Kuraray Co., Ltd., isobutylene-maleic anhydride copolymer, weight average molecular weight). 160,000 to 170,000) was added, and the mixture was further dissolved by stirring for 4 hours while heating to 95 ° C. After cooling, distilled water corresponding to the amount reduced by evaporation was added to prepare a 20% by mass aqueous solution of an aliphatic olefin-maleic acid copolymer salt B (degree of neutralization 0.8).

(Salt C of aliphatic olefin-maleic acid copolymer)
31.1 parts by mass of lithium hydroxide was dissolved in 524.5 parts by mass of distilled water, and isoban (registered trademark) # 10 (manufactured by Kuraray Co., Ltd., isobutylene-maleic anhydride copolymer, mass average molecular weight) was stirred with an agitator. (160,000 to 170,000) was added and dissolved by stirring for 4 hours while heating to 95 ° C. After cooling, distilled water corresponding to the amount reduced by evaporation was added to prepare a 20% by mass aqueous solution of an aliphatic olefin-maleic acid copolymer salt C (degree of neutralization 0.8).

Example 1
Alumina hydrate A (boehmite, single particle, average particle size 0.9 μm, Navaltech Co., Ltd., trade name: APYRAL (registered trademark) -AOH60) 90.3 parts by mass in terms of solid content, aliphatic olefin-malein 0.5 parts by mass of the acid copolymer salt A in terms of solid content was mixed and stirred with a homogenizer, and then carboxymethylcellulose sodium salt (1% by mass aqueous solution B viscosity 7000 mPa · s, etherification degree 0.7). 0.2 parts by mass in terms of solid content is mixed and stirred, and then 9 parts by mass in terms of solid content of styrene-butadiene latex is mixed and stirred, and ion-exchanged water is further added to obtain a solid content concentration of 25% by mass. A coating liquid A was prepared. The coating solution is uniformly applied to one side of the non-woven fabric so that the dry solid content is 10.2 g / m ² by a gravure coater on the non-woven fabric after the thermal calendar treatment, and lithium ion with a thickness of 30.2 μm A battery separator was obtained.

Example 2
A coating liquid B was prepared in the same manner as in Example 1, except that the salt B of the aliphatic olefin-maleic acid copolymer was used instead of the salt A of the aliphatic olefin-maleic acid copolymer in Example 1. Then, a lithium ion battery separator having a dry solid content of 10.5 g / m ² and a thickness of 31.0 μm was obtained.

Example 3
A coating solution C was prepared in the same manner as in Example 1, except that the salt C of the aliphatic olefin-maleic acid copolymer was used instead of the salt A of the aliphatic olefin-maleic acid copolymer in Example 1. Then, a lithium ion battery separator having a dry solid content of 10.5 g / m ² and a thickness of 31.0 μm was obtained.

Example 4
90.3 parts by mass of alumina hydrate A in terms of solid content, salt of aliphatic olefin-maleic acid copolymer, Isoban (registered trademark) # 104 (manufactured by Kuraray Co., Ltd., amidoammonium of isobutylene-maleic acid copolymer) 0.5 parts by mass of a salt and a mass average molecular weight of 55,000 to 65,000) in terms of solid content are mixed and stirred with a homogenizer, and then carboxymethylcellulose sodium salt (1% by mass aqueous solution B viscosity 7000 mPa · s, etherification) Degree 0.7) is mixed with 0.2 parts by mass in terms of solid content and stirred, and then 9 parts by mass of styrene-butadiene latex in terms of solid content is mixed and stirred, and then ion-exchanged water is added to form a solid. A coating liquid D having a partial concentration of 25% by mass was produced. The coating solution is uniformly applied to one side of the non-woven fabric so that the dry solid content is 10.5 g / m ² by a gravure coater on the non-woven fabric after the heat calendering treatment, and lithium ion having a thickness of 30.8 μm A battery separator was obtained.

Example 5
In Example 4, instead of Isoban (registered trademark) # 104, Isoban (registered trademark) # 110 (manufactured by Kuraray Co., Ltd., amidoammonium salt of isobutylene-maleic acid copolymer, mass average molecular weight 160,000 to 170,000) was used. A coating solution E was prepared and applied in the same manner as in Example 1 except that it was used, and a lithium ion battery separator having a dry solid content of 10.5 g / m ² and a thickness of 31.0 μm was obtained.

Example 6
In Example 1, instead of Isovan (registered trademark) # 104, Quinnflow (registered trademark) 543 (manufactured by Nippon Zeon Co., Ltd., amido ammonium salt of 2-methyl-2-butene-maleic acid copolymer, weight average molecular weight 8, The coating solution F was prepared and coated in the same manner as in Example 1 except that a dry ion solid content of 10.5 g / m ² and a thickness of 31.0 μm was used. Obtained.

Example 7
In Example 5, alumina hydrate I (pseudo boehmite, aggregated particles, average particle size 0.4 μm, manufactured by Sasol Corporation, trade name: DISPERAL (registered trademark) 80) was used instead of alumina hydrate A. A coating liquid G was prepared and applied in the same manner as in Example 5 to obtain a lithium ion battery separator having a dry solid content of 10.2 g / m ² and a thickness of 28.9 μm.

(Comparative Example 1)
A coating liquid H was prepared and applied in the same manner as in Example 1 except that the salt A of the aliphatic olefin-maleic acid copolymer was not used in Example 1, and the dry solid content of the coating layer was 10 A lithium ion battery separator having a thickness of 1 g / m ² and a thickness of 29.7 μm was obtained.

(Comparative Example 2)
Example 1 except that Aaron (registered trademark) T-50 (manufactured by Toa Gosei Co., Ltd., polyacrylic acid sodium salt, mass average molecular weight 6,000) was used in place of Isoban (registered trademark) # 104 in Example 1. Coating liquid I was prepared and coated in the same manner as described above to obtain a lithium ion battery separator having a dry solid content of 10.1 g / m ² and a thickness of 30.8 μm.

(Comparative Example 3)
A coating solution was used in the same manner as in Example 1 except that Alaster (registered trademark) 703S (Arakawa Chemical Co., Ltd., styrene-maleic acid copolymer) was used instead of Isoban (registered trademark) # 104 in Example 1. J was prepared and coated to obtain a lithium ion battery separator having a dry solid content of 10.4 g / m ² and a thickness of 31.6 μm.

<Evaluation>
The following evaluation was performed about the coating liquid and lithium ion battery separator which were obtained by the Example and the comparative example, and the result was shown in Table 1.

[Surface property]
About the produced separator, cut the surface of the separator into a strip of 50 mm width × 200 mm, fix the upper end with tape, slide a black cloth with a 50 g weight on it, The cloth and the separator were visually confirmed and evaluated according to the following degree.
A: Roughness of the coating layer surface, adhesion of the coating layer to the black cloth, and peeling of the coating layer are not observed.
○: There is a slight roughness of the surface, and the coating layer is attached to the surface of the black cloth, but no peeling is seen in the coating layer.
Δ: Some roughness of the surface, a coating layer is attached to the surface of the black cloth, and peeling is seen in the coating layer.
X: Roughness of the surface is seen, a large amount of coating layer is attached to the surface of the black cloth, and peeling is seen in the coating layer.

  The alumina hydrate of Examples 1-7, a binder polymer, and a salt of an aliphatic olefin-maleic acid copolymer, wherein the salt of the aliphatic olefin-maleic acid copolymer is an alkali metal salt or amide Since it was an ammonium salt, in a separator produced by coating and drying this, good results were obtained that there was little powder fall off or peeling off of the coating layer, and there were few irregularities on the surface of the coating layer.

  In Comparative Example 1, since a salt of an aliphatic olefin-maleic acid copolymer was not contained, in the separator produced by coating and drying this on a nonwoven fabric, the surface property tended to deteriorate.

  In Comparative Example 2, since the salt of polyacrylic acid is used instead of the salt of the aliphatic olefin-maleic acid copolymer, the surface property tends to be deteriorated in the separator prepared by coating and drying the non-woven fabric. It was seen.

  In Comparative Example 3, since a styrene-maleic acid copolymer is used instead of the salt of the aliphatic olefin-maleic acid copolymer, the surface property is deteriorated in the separator produced by coating and drying the nonwoven fabric. The tendency to do was seen.

The coating liquid for lithium ion battery separator and the method for producing lithium ion battery separator of the present invention are not limited to lithium ion secondary battery applications, but include manganese dry batteries, alkaline manganese batteries, silver oxide batteries, lithium primary batteries, lead storage batteries, nickel -Cadmium battery, nickel-hydrogen battery, nickel-zinc battery, silver oxide-zinc battery, lithium polymer battery, various gel electrolyte batteries, zinc-air battery, iron-air battery, aluminum-air battery, fuel cell, solar battery , Sodium sulfur battery, polyacene battery, electrolytic capacitor, electric double layer capacitor, lithium ion capacitor, etc.

Claims (2)

A coating solution for a lithium ion battery separator for coating a nonwoven fabric and drying to produce a lithium ion battery separator, containing alumina hydrate, a binder polymer, and a salt of an aliphatic olefin-maleic acid copolymer. becomes, the medium is water, the aliphatic olefins - salts of maleic acid copolymer is Ri alkali metal salt or amide ammonium salts der, aliphatic olefins - amount of a salt of maleic acid copolymer is alumina water to hydrate, lithium ion battery separator coating solution, wherein 2.0 wt% or less der Rukoto than 0.05 mass%. Applying a coating solution of claim 1 in nonwoven manufacturing method of a lithium ion battery separator, characterized by drying.