JP2013186958A - Method for manufacturing metal ion secondary battery separator, and metal ion secondary battery separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a metal ion secondary battery separator having a nonwoven fabric base material with pigment supported thereon, and high initial charge and discharge efficiencies and a good discharge capacity-keeping ratio; and a method for manufacturing the separator superior in stable production.SOLUTION: The method for manufacturing a metal ion secondary battery separator includes the step of coating a nonwoven fabric base material with a pigment-containing coating liquid, followed by drying; in the step a film is used. The method preferably includes the steps of: coating one side of the film with no less than 30 g/mof the pigment-containing coating liquid in terms of the mass before drying; putting together the coated side of the film and the nonwoven fabric base material; drying a sheet having a structure of the film/the pigment-containing coating liquid/the nonwoven fabric base material; and peeling off the film from the sheet.

Description

  TECHNICAL FIELD The present invention relates to a secondary battery separator having a high initial charge / discharge efficiency and an excellent discharge capacity retention rate, which is formed by supporting a pigment on a nonwoven fabric substrate, and a method for producing the secondary battery separator capable of stable production. Is.

  2. Description of the Related Art In recent years, various information terminal devices typified by notebook personal computers and mobile phones are rapidly becoming smaller, lighter, and thinner, and widely used. In addition, hybrid vehicles, electric vehicles, household storage batteries, and the like are becoming popular. Due to such a background, the demand for high energy density secondary batteries (storage batteries) as these power supplies or power storage units is increasing, among them, lithium ion secondary batteries as batteries having high operating voltage and high energy density, Those using metal ions such as sodium ion secondary batteries have attracted attention.

  The secondary battery generally accommodates an electrode group having a separator having electrical insulation and liquid retention between a positive electrode and a negative electrode together with a nonaqueous electric field liquid such as an organic electric field liquid, It is formed by sealing. Conventionally, a polyolefin microporous membrane has been generally used as a secondary battery separator. Polyolefin microporous membrane has a function (shutdown function) that melts and closes the microporous membrane when the temperature inside the battery reaches around 130 ° C, thus improving battery safety in the event of a short circuit. Can do. However, it has been suggested that if the temperature of the polyolefin microporous membrane further increases due to some circumstances, the polyolefin itself may melt and short-circuit, causing thermal runaway. Therefore, a heat-resistant separator that does not melt and shrink even at around 200 ° C. has been developed at present.

  As a heat-resistant separator, a nonwoven fabric composed of polyester fibers and a nonwoven fabric obtained by blending polyester fibers with aramid fibers that are heat-resistant fibers are disclosed (for example, see Patent Documents 1 to 3). However, these have a large hole diameter and an internal short circuit occurs, and this internal short circuit deteriorates the initial charge / discharge efficiency of the battery. In the present invention, the initial charge / discharge efficiency refers to the value obtained by dividing the discharge capacity by the charge capacity. When an internal short circuit occurs in the separator, the charge capacity mainly increases and the initial charge / discharge efficiency deteriorates. . The deterioration of the initial charge / discharge efficiency induces excessive decomposition of the electrolysis solution on the negative electrode, leading to depletion of the electrolysis solution and the deposition of decomposition products on the negative electrode surface and the pores of the separator. This causes problems in efficiency and capacity reduction.

  Moreover, the example which laminates | stacks the nonwoven fabric comprised with the polyester-type fiber on the polyolefin microporous film, and is compounded is described (for example, refer patent document 4). Furthermore, examples in which a nonwoven fabric or a woven fabric is supported by applying a pigment or a resin to impart heat resistance are disclosed (for example, Patent Documents 5 to 7). However, since the nonwoven fabric used as the base material has large pores and low surface smoothness, the coating has a large surface variation and the coating layer becomes non-uniform. When the coating layer becomes non-uniform, the current density in the separator As a result, unevenness is generated and a load is locally applied, so that the discharge capacity maintenance rate of the battery tends to deteriorate. In the present invention, the discharge capacity retention rate refers to a value obtained by dividing the charge capacity by the discharge capacity. When a load is locally applied to the separator, the charge capacity mainly decreases and the discharge capacity maintenance rate decreases. The discharge capacity maintenance rate suggests the life of the battery, and a low one is problematic because the life of the battery is short.

  Moreover, as a method for applying a pigment or the like to a nonwoven fabric substrate, Patent Document 5 describes printing, compression, press-fitting, roller coating, blade coating, brush coating, dip coating, spray coating, and casting coating. . Patent Document 6 describes a method of coating by applying or impregnating such as pulling application, applicator application, die coater application and the like. Patent Document 7 describes a coating method using a coating machine such as a die coater, a gravure coater, a reverse roll coater, a squeeze roll coater, a curtain coater, a blade coater, or a knife coater. Coating to the nonwoven fabric substrate is likely to cause a coating defect called pinhole after coating due to the large pores of the nonwoven fabric, and this coating defect causes the initial charge / discharge efficiency of the battery to deteriorate as well as internal short circuit Furthermore, there is a problem that pigments, resins, and the like are easily dropped during coating.

JP 2003-123728 A JP 2007-317675 A JP 2006-19191 A JP 2005-293891 A JP 2005-536857 A JP 2007-157723 A Republished WO2009 / 096451

  An object of the present invention is to provide a separator for a secondary battery using metal ions, which has a high initial charge / discharge efficiency and an excellent discharge capacity maintenance rate, and is particularly stable by supporting a pigment on a nonwoven fabric substrate. It is providing the manufacturing method of the separator for possible metal ion secondary batteries.

As a result of intensive studies, the present inventors have invented a method for producing a separator for a metal ion secondary battery and a separator for a metal ion secondary battery that can solve the problem. That is,
(1) In the manufacturing method of the separator for metal ion secondary batteries including the process of apply | coating and drying the coating liquid containing a pigment on a nonwoven fabric base material, a metal ion secondary battery using a film in this process Separator manufacturing method,
(2) A step of applying a coating liquid containing a pigment on one surface of the film, a step of bonding a non-woven fabric base material to the coated surface of the film, and a sheet comprising a coating liquid containing a film / pigment / nonwoven fabric base material A method for producing a separator for a metal ion secondary battery according to the above (1), comprising a step of drying, and a step of peeling the film from the sheet;
(3) For the metal ion secondary battery according to the above (1) or (2), comprising applying a coating liquid containing a pigment to a surface of one side of the film by 30 g / m ² or more by mass before drying. Manufacturing method of separator,
(4) A metal ion secondary battery separator produced by the method for producing a metal ion secondary battery separator according to any one of (1) to (3) above,
It is.

  According to the present invention, it is possible to provide a separator for a secondary battery using a metal ion having a high initial charge / discharge efficiency and an excellent discharge capacity maintenance rate, which is achieved by supporting a pigment on a nonwoven fabric base material, and stable production. The manufacturing method of this possible separator for secondary batteries can be provided.

It is a schematic block diagram of the coating machine concerning one Embodiment in the manufacturing method of the separator for metal ion secondary batteries.

  Hereinafter, the content of the present invention will be described more specifically.

  In the present invention, a separator for a metal ion secondary battery (hereinafter sometimes abbreviated as “separator”) is obtained by supporting a pigment on a nonwoven fabric substrate, and a coating containing the pigment on one surface of the film. From the step of coating the liquid, the step of bonding the nonwoven fabric substrate to the coated surface of the film, the step of drying the sheet comprising the coating solution / nonwoven fabric substrate containing the film / pigment, and the step of peeling the film from the sheet Obtained by the manufacturing method.

  FIG. 1 shows a schematic configuration of a coating machine according to an embodiment for carrying out a method for producing a separator for a metal ion secondary battery according to the present invention (hereinafter sometimes abbreviated as “manufacturing method”). Although it is a figure, this invention is not restrict | limited at all by this figure.

  In FIG. 1, the original fabric of the strip-shaped film 1 is mounted as a wound body 2 wound in a roll shape. The film unwound from the wound body 2 is sequentially transported by the transport rolls 11 to 23 constituting the transport system, and is wound as the wound body 3. Arrow 25 represents the traveling direction of the film.

  In FIG. 1, a die coater 24 is installed toward the film 1 traveling between the transport roll 13 and the transport roll 14, and a coating liquid containing a pigment is applied on the film 1 by the die coater 24. The

  In FIG. 1, the raw material of the strip-shaped nonwoven fabric base material 4 is mounted as a wound body 5 wound in a roll shape. The nonwoven fabric base material unwound from the wound body 5 is pressure-bonded on the film 1 to which the coating liquid containing the pigment is applied by the touch roll 9 between the transport rolls 16 to 17. After the nonwoven fabric substrate 4 is pressure-bonded, the sheet 6 is formed of a coating liquid / nonwoven fabric substrate containing a film / pigment, and is then sequentially conveyed by conveyance rollers 17 to 21. By passing through the dryer 10 in this process, the coating liquid is heated and dried to form a coating film, and then the separator 1 is formed by peeling the film 1 from the sheet 6 with the transport roll 22, and the wound body 8. Rolled up as The arrow 26 represents the traveling direction of the nonwoven fabric 4.

  By using the production method of the present invention, the surface of the nonwoven fabric substrate can be uniformly coated with a pigment, so that a positive electrode and a negative electrode can be satisfactorily separated and a separator having excellent metal ion conductivity can be obtained. . In the present invention, the metal ion is not limited as long as it is used as a secondary battery. For example, Co, Mn, Ni, Al, Li, Ti, Fe, Nb, Na, V, Examples include ions of Mo, Mg, Ca, K, etc. Among them, Li is preferable in terms of performance and cost when a secondary battery is used.

In the present invention, the method of coating the pigment-containing coating liquid on one side of the film is not limited at all, blade coater, bar coater, roll coater, air knife coater, die coater, curtain coater, Various systems represented by a gravure coater, a micro gravure coater, a lip coater, a comma coater and the like can be freely selected. Direct coating on the nonwoven fabric substrate is not preferable because the coating method and the coating amount that can be selected are limited due to dropping of the coating liquid due to large holes existing in the nonwoven fabric or insufficient strength of the nonwoven fabric substrate. On the other hand, in this invention, it can apply | coat even if it is a coating amount impossible by the direct coating to a nonwoven fabric base material, and the freedom degree of a compounding design can also be improved. Although the absolute dry coating amount in this invention is not specifically limited, 3-30 g / m < ² > is preferable, More preferably, it is 10-20 g / m < ² >. If it is less than 3 g / m ² , the surface of the nonwoven fabric cannot be covered and pinholes are likely to occur, and if it exceeds 30 g / m ² , the internal resistance value of the separator may become too high.

In the present invention, the coating amount when the pigment-containing coating liquid is applied to one surface of the film is preferably 30 g / m ² or more, more preferably 30 g / m ² or more, 100 g in terms of the mass before drying. / M ^{2 or} less. If it is less than 30 g / m ² , it is difficult to form a uniform coating film on the film, and unevenness and coating defects are likely to occur when the nonwoven fabric substrate is bonded to the coating surface of the film. Moreover, since the coating film formed on a film will become thick too much when it becomes 100 g / m < ² > or more, a non-woven fabric base material is bonded together, and a coating liquid flows easily until it finishes drying, and it becomes easy to produce a nonuniformity.

  The type of film used in the present invention is not limited in any way, but a polyester resin film, a polyolefin resin film such as a polyethylene resin film, a synthetic resin film such as a polyvinyl chloride resin film, a metal foil, and a fine quality Paper such as paper, neutral paper, art paper, coated paper, synthetic paper, non-woven fabric and the like can be freely selected, and the thickness thereof is not particularly limited. Among them, a synthetic resin film is preferable, and a polyethylene terephthalate (PET) film that has heat resistance and is inexpensive is more preferable. Moreover, not only a single layer film but a laminated film can also be used. Further, the mold release treatment is not particularly limited, and a general treatment method using a fluorine type mold release agent or a silicone type mold release agent can be employed.

  Although the coating liquid containing the pigment used for this invention is not restrict | limited at all, It is preferable that it is a liquid mixture of a pigment, a binder, a thickener, etc. from the point of coating property. Further, since it is necessary to uniformly coat the surface of the nonwoven fabric substrate, it is preferable that 70% by mass or more of the coating liquid is the pigment, and the increase in the binder component in the coating liquid is generally a separator. In order to increase the internal resistance of the coating liquid, the binder is preferably 30% by mass or less of the coating liquid, more preferably 90% by mass or more of the coating liquid and 10% by mass or less of the binder of the coating liquid. It is.

  Pigments used in the present invention include potassium titanate, barium titanate, aluminum borate, magnesium sulfate, silicon nitride, silicon carbide, calcium silicate, wollastonite, fiber gypsum, alumina, boehmite, calcium carbonate, zinc oxide, etc. One or more kinds can be freely selected from inorganic pigments and organic pigments such as melamine resin, urea-formalin resin, polyethylene, nylon, styrene plastic pigment, acrylic plastic pigment, and hydrocarbon plastic pigment.

  The binder used in the present invention is an ethylene-acrylic acid copolymer such as an ethylene-vinyl acetate copolymer or an ethylene-ethylene acrylate copolymer, a fluorine-based rubber, a styrene-butadiene rubber, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, One or more kinds can be freely selected from poly-N-vinylacetamide, crosslinked acrylic resin, polyurethane, epoxy resin and the like.

  The thickener used in the present invention includes synthetic polymers such as polyethylene glycol, polyacrylic acid, polyvinyl alcohol, vinyl methyl ether-maleic anhydride copolymer, xanthan gum, welan gum, gellan gum, guar gum, carrageenan, cellulose derivative, dextrin. , Natural polysaccharides such as starches such as pregelatinized starch, viscosity minerals such as montmorillonite and hectorite, inorganic oxides such as fumed silica, fumed alumina, and fumed titania . Furthermore, a wetting agent, an antifoaming agent, etc. can be freely added as needed.

  In this invention, the initial charging / discharging efficiency and discharge capacity maintenance factor of a separator can be improved by passing the process which bonds a nonwoven fabric base material to the coating surface of a film at the time of manufacture of a separator. After coating on the film, the non-woven fabric base material is pasted together, so that the coating liquid can be uniformly attached to the non-woven fabric base material with low surface smoothness, and the surface of the non-woven fabric base material can be coated satisfactorily. And a separator with few pinholes can be manufactured. When coating unevenness occurs, the uniformity of the separator is lowered, and in the metal ion secondary battery, the ionic conductivity in the separator is uneven, and defects such as local metal deposition when charging and discharging are repeated. When the deposited metal becomes a dendrite-like crystal, an internal short circuit occurs, and the battery capacity decreases, so that the discharge capacity maintenance rate of the battery deteriorates. In addition, if there is a pinhole in the separator, the positive electrode and the negative electrode cannot be separated inside the metal ion secondary battery, and the initial charge / discharge efficiency is remarkably lowered, which causes a problem. Moreover, the distance until the nonwoven fabric base material is pasted after coating on the film is not limited at all, but it is within 10 m because the flow of coating liquid on the film and unnecessary drying can be suppressed. It is preferable that

  The nonwoven fabric substrate used in the present invention has an average diameter of 0.5 to 10 μm, vinylon; polyamide such as nylon and aramid; cellulose such as rayon, lyocell and pulp; polyethylene terephthalate, polybutylene terephthalate, aromatic polyester Polyester such as polyethylene, polyolefin such as polypropylene, acrylic, etc. Among ultrafine yarns formed using glass or the like, one or more kinds are used in combination or in combination, and the long diameter of the pore is 0.1 to 70 μm. It is desirable to contain 50% or more of the pores based on the total number of pores, and the thickness of the nonwoven fabric substrate is desirably 9 to 30 μm, but is not limited by these.

  In the present invention, pressure may be applied when the nonwoven fabric substrate is bonded to the coated surface of the film. By adjusting the pressure at the time of bonding, the amount of the coating liquid penetrating into the nonwoven fabric when bonded can be adjusted, and the internal resistance and strength of the separator can be adjusted. When the pressure is increased, the penetration of the coating liquid into the nonwoven fabric can be increased, and the strength of the separator can be improved. When the pressure is weakened, the penetration can be reduced and the internal resistance of the separator can be reduced. Therefore, the separator can be designed according to the purpose by controlling the pressure. In addition, the method of laminating the nonwoven fabric substrate to the coated surface of the film is not limited in any way, but the coated surface of the film is directed vertically upward and the nonwoven fabric substrate is covered from above on the surface. By laminating, the flow of the coating liquid can be suppressed, and pressure control at the time of laminating the non-woven fabric substrate is facilitated, which is more preferable.

  In the present invention, in the drying process, the discharge capacity maintenance rate and the initial charge / discharge efficiency of the separator can be improved by drying the sheet comprising the coating liquid / nonwoven fabric substrate containing the film / pigment, and the drying method. The degree of freedom of selection can be improved. By drying in the state of the sheet, it is possible to suppress the occurrence of repelling due to changes in the concentration of the coating liquid during the drying process, and the occurrence of coating unevenness due to liquid surface flow caused by mechanical vibration during drying. Repelling at the time of drying causes pinholes and significantly reduces the initial charge / discharge efficiency. In addition, when uneven coating occurs, uneven ion conductivity in the separator occurs in the metal ion secondary battery, which deteriorates the discharge capacity retention rate. The drying method of the sheet is not particularly limited, but drying methods represented by convective heat transfer drying such as fluidized bed drying, airflow drying, superheated steam drying, conduction heat transfer drying, radiation heat transfer drying, etc. You can choose freely. In the case of only a coating liquid / nonwoven fabric substrate containing a pigment, a drying method in which hot air or the like hits the coating liquid surface side at the time of drying tends to induce the flow of the coating liquid during the drying process, and uneven coating tends to occur. It is not preferable because it is limited.

  In the present invention, by separating the film from the dried sheet, it is possible to produce a separator with little coating unevenness, minimal pinholes, and high surface smoothness. When this separator is used in a metal ion secondary battery, it has a high discharge capacity maintenance rate due to less coating unevenness, pinholes are minimized, and short-circuiting is suppressed, so that metal ions with high initial charge / discharge efficiency are obtained. A secondary battery can be obtained. In addition, the discharge capacity maintenance ratio can be further improved due to the high smoothness of the separator. Although the effect of the smoothness is not clear, since the smoothness of the surface is high, the separator adheres more uniformly to the electrode, and the ion conductivity becomes more uniform in the metal ion secondary battery. When the discharge is repeated, defects such as metal deposition are less likely to occur, and as a result, the occurrence of a short circuit can be further suppressed. Therefore, it is considered that the discharge capacity maintenance rate of the battery is further improved.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In Examples,% and parts are all based on mass. The coating amount is an absolutely dry coating amount.

Example 1
(1) Preparation of separator coating liquid 100 parts of granular boehmite (trade name: C-20, manufactured by Daimei Chemical Co., Ltd.) was dispersed in 100 parts of a 2% aqueous solution of carboxymethyl cellulose to prepare a boehmite dispersion. To this dispersion, 10 parts of 45% styrene butadiene latex was added and stirred vigorously to prepare a separator coating solution.

(2) Production of separator On the PET film having a thickness of 25 μm, the separator coating liquid was applied so that the dry coating amount was 10 g / m ^2, and thereafter the basis weight was 10 g / m ² and the thickness was 18 μm. A PET nonwoven fabric substrate was bonded to the coated surface and dried as it was, and after drying, the PET film was peeled off to produce a separator having the nonwoven fabric substrate supported with a pigment.

Example 2
50% modified styrene butadiene particles (trade name: V1004 latex) instead of 100 parts of granular boehmite (trade name: C-20, manufactured by Daimei Chemical Co., Ltd.) In the same manner as in Example 1, except that 200 parts of Zeon Co., Ltd.) was used and 150 parts of 1.5% aqueous carboxymethylcellulose solution was used instead of 100 parts of 2% aqueous carboxymethylcellulose solution. A separator carrying a pigment was prepared.

Example 3
In the production of the separator of Example 1 (2), a separator having a nonwoven fabric substrate carrying a pigment was produced in the same manner as in Example 1 except that a process paper having a thickness of 100 μm was used instead of the 25 μm PET film. As the process paper, glassine paper coated with a silicone release agent was used.

Example 4
In the preparation of the coating liquid for separator of Example 1 (1), a non-woven fabric base was prepared in the same manner as in Example 1, except that 230 parts of carboxymethylcellulose 0.8% aqueous solution was used instead of 100 parts of carboxymethylcellulose 2% aqueous solution. A separator having a pigment supported on the material was produced.

Example 5
In the production of the separator coating liquid of Example 1 (1), a nonwoven fabric base was prepared in the same manner as in Example 1 except that 550 parts of a 0.3% aqueous solution of carboxymethylcellulose was used instead of 100 parts of a 2% aqueous solution of carboxymethylcellulose. A separator having a pigment supported on the material was produced.

Example 6
In the production of the separator coating liquid of Example 1 (1), a nonwoven fabric base was prepared in the same manner as in Example 1 except that 900 parts of carboxymethylcellulose 0.2% aqueous solution was used instead of 100 parts of carboxymethylcellulose 2% aqueous solution. A separator having a pigment supported on the material was produced.

Example 7
In the production of the separator coating liquid of Example 1 (1), a nonwoven fabric base was prepared in the same manner as in Example 1 except that 950 parts of a 0.2% aqueous solution of carboxymethylcellulose was used instead of 100 parts of a 2% aqueous solution of carboxymethylcellulose. A separator having a pigment supported on the material was produced.

Comparative Example 1
In the production of the separator of Example 1 (2), without using a PET film having a thickness of 25 μm, an absolutely dry coating amount is 10 g / m ² on a PET nonwoven fabric having a basis weight of 10 g / m ² and a thickness of 18 μm. A separator having a non-woven fabric substrate carrying a pigment was produced in the same manner as in Example 1 except that the separator coating liquid was directly applied and dried.

Comparative Example 2
In the preparation of the coating liquid for separator (1) of Example 1, 50% modified styrene butadiene particles (trade name: V1004 latex) instead of 100 parts of granular boehmite (trade name: C-20, manufactured by Daimei Chemical Co., Ltd.) (2) In the production of the separator, without using a PET film with a thickness of 25 μm, a dry coating amount on a PET nonwoven fabric with a basis weight of 10 g / m ² and a thickness of 18 μm was used. A separator having a non-woven fabric substrate carrying a pigment was produced in the same manner as in Example 1 except that the separator coating liquid was directly applied so as to be 10 g / m ² and dried.

<Preparation of positive electrode>
80 parts of lithium cobaltate as a positive electrode active material, 10 parts of acetylene black as a conductive additive, and 5 parts of polyvinylidene fluoride (PVDF) as a binder are uniformly mixed in N-methyl-2-pyrrolidone (NMP). A positive electrode paste was prepared. This paste was applied onto an aluminum foil having a thickness of 20 μm, dried and calendered to produce a positive electrode having a thickness of 100 μm. Further, the exposed portion of the aluminum foil of the positive electrode was tabbed.

<Production of negative electrode>
90 parts of graphite as a negative electrode active material and 5 parts of PVDF as a binder were uniformly mixed in NMP to prepare a negative electrode agent paste. This paste was applied onto a copper foil having a thickness of 20 μm, dried and calendered to prepare a negative electrode having a thickness of 90 μm. Further, a tab was attached to the exposed portion of the copper foil of the negative electrode.

<Battery assembly>
The positive electrode and the negative electrode obtained as described above were superposed through the separators produced in Examples 1 to 7 and Comparative Examples 1 and 2, to prepare an electrode separator laminate. The electrode separator laminate was loaded into the laminate film exterior material, and an ethylene carbonate / diethyl carbonate (volume ratio 1/1) solution in which 1 mol / l LiPF ₆ was dissolved as an electrolyte was injected, and vacuum sealing was performed. A lithium ion secondary battery having a rated capacity of 30 mAh was produced.

[Initial charge / discharge efficiency]
The produced lithium ion secondary battery is subjected to constant current charging at 1 C up to 4.2 V and constant voltage charging at 4.2 V, and then constant current discharging at 1 C up to 2.8 V, and then discharge capacity / charge The volume ratio was calculated.

[Discharge capacity maintenance rate]
The produced lithium ion secondary battery was subjected to constant current charging at 1 C up to 4.2 V and constant voltage charging at 4.2 V, and then repeated constant current discharging at 1 C up to 2.8 V, with respect to the first time The ratio of charge capacity / discharge capacity at the 100th time was calculated.

As is clear from Table 1, the separators of Examples 1 to 7 are excellent in the initial charge / discharge efficiency and excellent in the discharge capacity maintenance rate as compared with the separators of Comparative Examples 1 and 2. Further, when Examples 1, 2, 4 to 7 are compared, Examples 2 and 4 to 7 have a coating amount (mass before drying) of 30 g / m ² or more, so compared to Example 1, Excellent initial charge / discharge efficiency. Moreover, when Example 2, 4-7 is compared, since the coating amount (mass before drying) of Examples 2, 4-6 is less than 100 g / m < ² >, compared with Example 7, it is initial charge. Excellent discharge efficiency.

1 Film 2 Film roll (unwinding side)
3 Film roll (winding side)
4 Nonwoven fabric base material 5 Nonwoven fabric wound body (unwinding side)
6 Film / pigment containing coating liquid / sheet made of non-woven fabric substrate 7 Separator 8 Separator roll (winding side)
9 touch roll 10 dryer 11 transport roll 12 transport roll 13 transport roll 14 transport roll 15 transport roll 16 transport roll 17 transport roll 18 transport roll 19 transport roll 20 transport roll 21 transport roll 22 transport roll 23 transport roll 24 die coater 25 film Arrow 26 representing the traveling direction of the arrow Arrow representing the traveling direction of the nonwoven fabric substrate

Claims (4)

  In a method for producing a separator for a metal ion secondary battery comprising a step of applying a coating liquid containing a pigment to a nonwoven fabric substrate and drying, a metal ion secondary battery separator characterized by using a film in the step Production method.   A step of applying a coating liquid containing a pigment on one side of the film, a step of bonding a non-woven fabric base material to the coating surface of the film, and a step of drying a sheet made of a coating solution containing a film / pigment / non-woven fabric base material The manufacturing method of the separator for metal ion secondary batteries of Claim 1 including the process of peeling a film from this sheet | seat. The manufacturing method of the separator for metal ion secondary batteries of Claim 1 or 2 including apply | coating the coating liquid containing a pigment by 30g / m < ² > or more by the mass before drying to the surface of one side of a film.   The separator for metal ion secondary batteries manufactured by the manufacturing method of the separator for metal ion secondary batteries in any one of Claims 1-3.