KR101670802B1 - Porous membrane for secondary battery - Google Patents

Porous membrane for secondary battery Download PDF

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KR101670802B1
KR101670802B1 KR1020140170038A KR20140170038A KR101670802B1 KR 101670802 B1 KR101670802 B1 KR 101670802B1 KR 1020140170038 A KR1020140170038 A KR 1020140170038A KR 20140170038 A KR20140170038 A KR 20140170038A KR 101670802 B1 KR101670802 B1 KR 101670802B1
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South Korea
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slurry
particles
porous
polypropylene
inorganic
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KR1020140170038A
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Korean (ko)
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KR20160065692A (en
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이진우
김수희
임동진
주재석
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에스케이씨 주식회사
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/16Separators; Membranes; Diaphragms; Spacing elements characterised by the material
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/145Manufacturing processes
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/16Separators; Membranes; Diaphragms; Spacing elements characterised by the material
    • H01M2/1606Separators; Membranes; Diaphragms; Spacing elements characterised by the material comprising fibrous material
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/16Separators; Membranes; Diaphragms; Spacing elements characterised by the material
    • H01M2/164Separators; Membranes; Diaphragms; Spacing elements characterised by the material comprising non-fibrous material
    • H01M2/1653Organic non-fibrous material
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/16Separators; Membranes; Diaphragms; Spacing elements characterised by the material
    • H01M2/164Separators; Membranes; Diaphragms; Spacing elements characterised by the material comprising non-fibrous material
    • H01M2/166Mixtures of inorganic and organic non-fibrous material
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2/00Constructional details or processes of manufacture of the non-active parts
    • H01M2/14Separators; Membranes; Diaphragms; Spacing elements
    • H01M2/16Separators; Membranes; Diaphragms; Spacing elements characterised by the material
    • H01M2/1686Separators having two or more layers of either fibrous or non-fibrous materials
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00Electrolytes
    • H01M2300/0017Non-aqueous electrolytes
    • H01M2300/0025Organic electrolyte
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00Electrolytes
    • H01M2300/0088Composites
    • H01M2300/0091Composites in the form of mixtures

Abstract

The present invention relates to a porous separator for a secondary battery, and more particularly, to a porous separator for a secondary battery capable of improving the quality of a secondary battery by applying a mixture of inorganic particles and polyethylene particles to the surface of the porous substrate film, will be.

Description

TECHNICAL FIELD [0001] The present invention relates to a porous separator for a secondary battery,

The present invention relates to a porous separator for a secondary battery, and more particularly, to a porous separator for a secondary battery capable of improving the quality of a secondary battery by applying a mixture of inorganic particles and polyethylene particles to the surface of the porous substrate film, will be.

In recent years, in order to cope with high capacity and high output of a lithium secondary battery, safety of a battery has become a very important issue. However, the safety of such a battery is also related to the performance of the battery.

Conventionally, in order to improve the safety, a method of coating an inorganic material on a separation membrane is used, but the water content of the separation membrane is a problem. The moisture present in the separator causes a deterioration in performance and safety of the battery.

Korean Patent Registration No. 10-727247 discloses an organic / inorganic material including a porous substrate having pores and a porous active layer coated on at least one surface of the porous substrate and containing a mixture of inorganic particles and a binder polymer, Composite separator. Here, polyethylene terephthalate, polyester, polyethylene, polypropylene, and the like can be used as the substrate, various inorganic oxide particles are used as the inorganic particles, and a carboxyl group, a maleic anhydride group, A hydroxyl group and at least one functional group selected from the group consisting of a cyano group and an acrylate group at the same time.

In addition, Korean Patent Registration No. 10-1147602 discloses an organic / inorganic composite porous separator comprising an active layer coated with a mixture of inorganic particles and a binder polymer, wherein at least one region selected from the group consisting of a substrate surface and a pore portion existing in the substrate is coated with a mixture of inorganic particles and a binder polymer Has been proposed.

Korean Patent Laid-Open Publication No. 2013-99543 discloses a polyvinylidene fluoride homopolymer having a weight average molecular weight of 1,000,000 g / mol or more, a polyvinylidene fluoride-hexafluoropropylene copolymer having a weight average molecular weight of 800,000 g / mol or less, A separation membrane coated with an organic and inorganic mixture containing particles has been proposed.

Korean Patent Registration No. 10-1341196 discloses a polymer compound binder comprising a first organic binder which is an emulsion or suspension in which inorganic particles and water-insoluble polymer compound are dispersed in water, and a second organic binder which is a water-soluble polymer compound Wherein the weight ratio of the water to the inorganic particles is in the range of 95: 5 to 20:80, and the weight ratio of the inorganic particles to the inorganic particles is at least one selected from the group consisting of one surface, Inorganic composite porous separator characterized in that the weight ratio of the particles to the first organic binder is 4: 1 to 140: 1, and the weight ratio of the inorganic particles to the second organic binder is 10: 1 to 200: .

However, such conventional separators are coated with inorganic particles and binder polymers on their surfaces, but they can not achieve satisfactory safety due to low heat shrinkage, shutdown characteristics and low moisture content at the same time. The problem of defects such as penetration is not solved.

Korea Patent No. 10-727247 Korea Patent No. 10-1147602 Korean Patent Laid-Open Publication No. 2013-99543 Korean Patent No. 10-1341196

The present invention solves the problem of safety by coating an organic / inorganic compound on a conventional separation membrane as described above, and selectively using a specific component.

Accordingly, it is an object of the present invention to provide a porous separator for a secondary battery in which safety of a separator is enhanced by coating inorganic particles and polymer particles on a surface of a porous substrate film.

Another object of the present invention is to provide a method for producing a porous separator for a secondary battery by coating a mixture of inorganic particles and polyethylene particles on the surface of a polypropylene porous substrate film.

In order to solve the above problems, the present invention provides a polypropylene porous base film and a coating layer comprising a mixture of inorganic particles and polyethylene particles on both sides of the base film, wherein the shutdown temperature is 90 ° C to 125 ° C, Lt; 0 > C for 1 hour, and a moisture content of 800 ppm or less. The present invention also provides a porous separator for a secondary battery.

The present invention also relates to a process for producing a polypropylene porous substrate film, Dispersing the inorganic particles in a polymer binder and water to prepare an inorganic slurry; Preparing a polyethylene slurry using a solution containing polyethylene particles; Mixing the inorganic slurry and the polyethylene slurry to prepare a composite slurry; And coating the composite slurry on the polypropylene-based film to form a coating layer in which inorganic particles and polyethylene particles are mixed with each other to form a porous separator for a secondary battery.

The porous separator produced according to the present invention comprises polyethylene particles as a specific polymer component in mixing inorganic particles and polymer particles coated on a polypropylene porous base film, It is possible to realize heat resistance and low heat shrinkage due to particle introduction, and the stability of the separator can be greatly improved due to the simultaneous implementation of fast shutdown characteristics and low water content due to the polyethylene particles in the surface layer.

Particularly, the water content can be minimized by controlling the particle size of the inorganic particles and the polymer particles, and thus the problem of inhibiting the safety due to the water content of the separator can be greatly improved.

In addition, since the safety of the separation membrane is enhanced and improved, it is possible to prevent deterioration in performance of the secondary battery.

1 is a view conceptually showing a cross-sectional structure of a porous separator for a secondary battery according to the present invention.

Hereinafter, the present invention will be described in more detail as an embodiment.

The present invention relates to a porous separator improved in safety of a separator by forming a separator by coating a mixture of inorganic particles and polyethylene particles on the surface of a polypropylene base film.

According to another preferred embodiment of the present invention, the polypropylene porous substrate film may be made of a polypropylene resin having an MI of 2 to 8 g / 10 min. The polypropylene porous base film may preferably have a thickness of 5 to 10 mu m.

According to another preferred embodiment of the present invention, the inorganic particles are preferably Al 2 O 3 . The inorganic particles of Al 2 O 3 preferably have a maximum diameter of 0.9 to 1.3 μm.

According to the present invention, the inorganic particles exhibit stable characteristics in terms of performance after battery assembly, unlike other inorganic particles. Therefore, when applied as inorganic particles in the present invention, heat resistance and low heat shrinkage can be realized, .

According to another preferred embodiment of the present invention, the polyethylene particles having a maximum diameter of 0.9 to 1.3 mu m can be preferably used.

According to the present invention, unlike other polymer components, polyethylene particles as polymer particles to be mixed together with inorganic particles have a melting temperature at 90 ° C to 125 ° C and polyethylene particles having hydrophobicity are dispersed among the inorganic particles to lower the water content When mixed with inorganic particles, when applied to a polypropylene porous base film, the phenomenon of polymer melt occurs at the corresponding temperature to block pores between the inorganic particles, and when a high temperature phenomenon occurs due to an abnormality in the battery, A fast shutdown function can be implemented to ensure safety, and a side reaction in the battery due to a low moisture content can be minimized, thereby preventing performance deterioration.

According to another preferred embodiment of the present invention, it is preferable that the inorganic particles and the polyethylene particles contained in the coating layer are contained in a weight ratio of 70:30 to 90:10.

According to another preferred embodiment of the present invention, the thickness of the coating layer in which the inorganic particles and the polyethylene particles are mixed is 1 to 5 탆, more preferably 2 to 4 탆. If the thickness is too thick, the heat shrinkage rate and the heat resistance tend to decrease. If the thickness is too thin, the heat shrinkage rate and the shutdown function may be difficult to realize.

A method of manufacturing a porous separator for a secondary battery according to the present invention will now be described as an embodiment.

According to the present invention, the porous separation membrane can be formed by a process of producing a polypropylene porous base film, producing an inorganic slurry, preparing a polypropylene slurry, and preparing a composite slurry, and coating the polypropylene porous base film with the polypropylene porous base film. This will be described step by step as an example.

(1) Production method of PP porous substrate film

0.1 to 2 parts by weight of a beta -crystalline nucleating agent is mixed with 100 parts by weight of a polypropylene resin (MI: 2 to 8 g / 10 min), melt-mixed at 220 to 230 DEG C using a twin-screw extruder, To prepare blended resin pellets. The produced resin pellets are extruded into a sheet at a resin temperature of 220 to 240 ° C using, for example, a T-die extruder and cooled on a cooling roll having a surface temperature of 120 to 130 ° C and a diameter of 800 to 1200 mm for 20 to 60 seconds And solidified to prepare a beta-crystallized polypropylene undrawn sheet.

The prepared beta-crystallized polypropylene unstretched sheet is stretched 4 to 6 times in the longitudinal direction by a longitudinal stretching apparatus having a roll surface temperature of 100 to 120 DEG C, stretched 4 to 7 times in the transverse direction by a transverse stretching apparatus at 120 to 140 DEG C Followed by heat setting at 150 to 160 ° C, followed by relaxation of 5 to 15% to prepare a porous polypropylene film as a base film.

(2) Production method of inorganic slurry

The inorganic slurry disperses the inorganic particles together with the polymeric binder in water to prepare a slurry. The kind of the inorganic material used is preferably Al 2 O 3 , and the particle size thereof is preferably 0.9 to 1.3 μm. As the binder used, PVA or acrylic polymer may be preferably used, and the content thereof is preferably, for example, 92 to 98 parts by weight of inorganic particles and 2 to 8 parts by weight of binders, wherein the total solid content is 30 to 50% Is preferable.

(3) Production method of polyethylene slurry

A polyethylene slurry is prepared using a solution containing polyethylene particles. At this time, it is preferable to prepare a solution containing 30 to 50 wt% of solid content in the polyethylene slurry. The solution used herein can be prepared as a slurry using, for example, a solution of the polyethylene particle component and PVA. In this case, the polyethylene particles and the PVA content ratio are preferably 92 to 98: 2 to 8 weight ratio.

(4) Manufacturing method of composite slurry

The inorganic slurry and the polyethylene slurry are mixed so that the composition of the inorganic particles and the polyethylene factor is in a weight ratio of 70:30 to 90:10.

According to the present invention, if the inorganic slurry is mixed too little, the heat shrinkage rate is lowered, and if the inorganic slurry is mixed in too much amount, the shutdown function is deteriorated.

In addition, according to the present invention, if the size of the inorganic filler or the polyethylene particles is too small, the moisture content increases due to the increase of the surface area of the solid content. If the particle size is too large, do.

(5) Coating method of composite slurry

According to the present invention, the prepared composite slurry is coated on the surface of the prepared polypropylene porous base film, and both sides thereof can be coated by the same method.

The coating of the composite slurry can be performed using, for example, a baker or gravure coating. After the coating, the coating is dried at 60 to 80 ° C. for about 3 to 10 minutes to form inorganic particles and polyethylene particles on both surfaces of the polypropylene porous base film Can be produced.

FIG. 1 is a view typically showing a cross-sectional structure of a porous membrane sample thus prepared. Here, the structure is shown in which the coating layers 40a and 40b are formed in a state where the inorganic particles 20 and the polyethylene particles 30 are mixed on both sides of the polypropylene porous base film 10.

The porous separator according to the present invention has a shutdown temperature of 90 to 125 ° C, preferably 95 to 110 ° C, a heat shrinkage of 20% or less, preferably 5 to 18% at 150 ° C and 1 hour, , And a water content of 800 ppm or less, preferably 200 to 700 ppm.

According to the present invention, in introducing ceramic particles for heat resistance enhancement and polymer particles for low shutdown implementation, the moisture content can be minimized by controlling the particle size. Accordingly, the separator according to the present invention can improve safety when applied to various electric appliances, energy storage systems, and secondary batteries such as electric vehicles and hybrid vehicles.

Accordingly, the present invention includes a secondary battery including the above-described porous separator. Such a secondary battery can be suitably applied to a lithium secondary battery.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

Example 1

0.2 part by weight of a beta crystal nucleating agent (N, N'-dicyclohexyl-2,6-naphthalenedicarboxamide) was added to 100 parts by weight of a polypropylene resin (Mitsui, F144H, MI: 4 g / 10 min) , Melt-mixed at 230 DEG C using a twin-screw extruder, and cooled and cut to prepare a resin pellet blended with a beta-crystal nucleating agent. The resin pellets thus prepared were extruded into a sheet at a resin temperature of 230 DEG C using a T-die extruder and cooled and solidified on a cooling roll having a diameter of 1000 mm maintained at a surface temperature of 125 DEG C for 40 seconds to obtain a sheet having a width of 400 mm and a thickness of 140 mu m To obtain a beta-crystallized polypropylene undrawn sheet.

The prepared beta-crystallized polypropylene unstretched sheet was stretched four times in the longitudinal direction by a longitudinal stretching apparatus at a roll surface temperature of 110 DEG C, stretched seven times in the transverse direction by a transverse stretching apparatus at 135 DEG C, and then heat- Followed by 10% relaxation to prepare a porous polypropylene film having a thickness of 6 탆.

For the production of the Al 2 O 3 slurry, 96 parts by weight of Al 2 O 3 particles having a particle diameter of 1 μm, 4 parts by weight of PVA and 150 parts by weight of water were added into the vessel and dispersed by stirring for 4 hours to prepare an Al 2 O 3 slurry .

To prepare a PE slurry, a solution (W401, manufactured by Mitsui) containing 40 wt% of PE particles having a particle size of 1 mu m having a particle size of 1 mu m was added in an amount of 96 parts by weight of PE particles alone. And 65 parts by weight of water were added thereto, followed by stirring and dispersing for 1 hour to prepare a polyethylene (PE) slurry.

For the preparation of the composite slurry, 70 parts by weight and 30 parts by weight of the Al 2 O 3 slurry and the PE slurry were respectively mixed.

The composite slurry was coated on one surface of the prepared PP porous substrate film of A4 size size using a bar coater and then dried at 70 DEG C for 5 minutes to obtain a sample on which a coating layer was formed on one surface. Thereafter, the composite slurry was coated on the other surface by the same method to prepare a porous membrane sample having a coating layer structure on both sides.

Example 2

A porous separator was prepared in the same manner as in Example 1 except that the composition in the composite slurry was used under the conditions shown in Table 1 below.

Example 3

A porous separator was prepared in the same manner as in Example 1 except that the composition in the composite slurry was used under the conditions shown in Table 1 below.

Example 4

A porous separator was prepared in the same manner as in Example 1, except that the particle size of Al 2 O 3 was used in the conditions shown in Table 1 below.

Example 5

Al 2 O 3 A porous coating film was prepared in the same manner as in Example 1 except that the particle size and the composite slurry composition were used under the conditions shown in Table 1 below.

Example 6

Al 2 O 3 A porous separator was prepared in the same manner as in Example 1 except that an acrylic binder roll was used in preparing the slurry and the PE slurry.

Comparative Example 1

A porous separator was prepared in the same manner as in Example 1 except that only the Al 2 O 3 slurry was applied to the coating slurry applied to the PP porous substrate film.

Comparative Example 2

A porous separator was prepared in the same manner as in Example 1 except that the composition in the composite slurry was used under the conditions shown in Table 1 below.

Comparative Example 3

A porous separator was prepared in the same manner as in Example 1 except that the composition in the composite slurry was used under the conditions shown in Table 1 below.

Comparative Example 4

A porous separator was prepared in the same manner as in Example 1 except that the thickness of the PP porous substrate film was 20 mu m.

Comparative Example 5

The porous separator was prepared in the same manner as in Example 1 except that the particle size and the slurry composition were used under the conditions shown in Table 1 below.

Comparative Example 6

The porous separator was prepared in the same manner as in Example 1 except that the particle size was used in the conditions shown in Table 1 below.

Comparative Example 7

The porous separator was prepared in the same manner as in Example 1 except that the particle size was used as the condition of Table 1.

Comparative Example 8

A porous separator was prepared in the same manner as in Comparative Example 2 except that an acrylic binder was used in the preparation of the Al 2 O 3 slurry and the PE slurry.

Comparative Example 9

A porous separator was prepared in the same manner as in Comparative Example 3 except that an acrylic binder was used in the preparation of the Al 2 O 3 slurry and the PE slurry

Experimental Example

The porous membrane samples prepared in the examples and comparative examples were subjected to Gurley measurement after 5 minutes of treatment for each temperature, and physical properties were evaluated by considering the temperature which was not measured even after 10 minutes of Gurley value as Shutdown temperature. The results are shown in Table 1 below. The heat shrinkage was measured by a method of calculating the degree of shrinkage after treating a specimen of 10 cm × 10 cm at 150 ° C. and 1 hour.

materials Slurry Al 2 O 3 Size
(탆)
PEsize
(탆)
Al 2 O 3 : PE
(Parts by weight)
Shutdown temperature
(° C)
Heat Shrinkage (%)
MD TD Example 1 PP Composite slurry One One 70:30 100 8 15 Example 2 PP Composite slurry One One 80:20 100 7 12 Example 3 PP Composite slurry One One 90:10 100 6 11 Example 4 PP Composite slurry 1.3 One 70:30 100 8 18 Example 5 PP Composite slurry 1.3 One 90:10 100 7 13 Example 6 PP Composite slurry One One 70:30 100 6 13 Comparative Example 1 PP Al 2 O 3 slurry One - - 180 5 6 Comparative Example 2 PP Composite slurry One One 60:40 100 15 25 Comparative Example 3 PP Composite slurry One One 95: 5 180 7 13 Comparative Example 4 PP Composite slurry 0.5 0.5 70:30 100 8 14 Comparative Example 5 PP Composite slurry 0.5 0.5 90:10 100 7 12 Comparative Example 6 PP Composite slurry 1.5 One 70:30 100 21 28 Comparative Example 7 PP Composite slurry 1.5 0.5 70:30 100 14 24 Comparative Example 8 PP Composite slurry One One 60:40 100 14 24 Comparative Example 9 PP Composite slurry One One 95: 5 180 6 12

The results of moisture content measurement for the above Examples and Comparative Examples are shown in Table 2 below.

materials Slurry Al 2 O 3 Size
(탆)
PEsize
(탆)
Al 2 O 3 : PE
(Parts by weight)
Moisture Content (ppm)
Example 1 PP Composite slurry One One 70:30 600 Example 2 PP Composite slurry One One 80:20 610 Example 3 PP Composite slurry One One 90:10 620 Example 4 PP Composite slurry 1.3 One 70:30 580 Example 5 PP Composite slurry 1.3 One 90:10 590 Example 6 PP Composite slurry One One 70:30 570 Comparative Example 1 PP Al 2 O 3 slurry One - - 1300 Comparative Example 2 PP Composite slurry One One 60:40 605 Comparative Example 3 PP Composite slurry One One 95: 5 650 Comparative Example 4 PP Composite slurry 0.5 0.5 70:30 1000 Comparative Example 5 PP Composite slurry 0.5 0.5 90:10 1050 Comparative Example 6 PP Composite slurry 1.5 One 70:30 600 Comparative Example 7 PP Composite slurry 1.5 0.5 70:30 620 Comparative Example 8 PP Composite slurry One One 60:40 590 Comparative Example 9 PP Composite slurry One One 95: 5 600

The porous separator according to the present invention can be suitably applied to various electric appliances, energy storage systems, and secondary batteries such as electric vehicles and hybrid automobiles, as compared with the prior art.

10-polypropylene porous substrate film
20 - inorganic particles
30 - Polypropylene particles
40a, 40b - Coating layer

Claims (16)

  1. A polypropylene porous base material film and a coating layer in which inorganic particles and polyethylene particles are mixed in a weight ratio of 70:30 to 90:10 on both sides of the base material film and have a shutdown temperature of 90 ° C to 125 ° C, , A heat shrinkage rate of 20% or less and a water content of 800 ppm or less,
    Wherein the inorganic particles and the polyethylene particles have a maximum diameter of 0.9 to 1.3 mu m, respectively.
  2. The porous separator according to claim 1, wherein the polypropylene porous base film is made of a polypropylene resin having an MI of 2 to 8 g / 10 min.
  3. The porous separator according to claim 1, wherein the polypropylene porous base film has a thickness of 5 to 10 탆.
  4. The porous separator according to claim 1, wherein the inorganic particles are Al 2 O 3 .
  5. delete
  6. delete
  7. delete
  8. The porous separator according to claim 1, wherein the coating layer has a thickness of 1 to 5 μm.
  9. Preparing a polypropylene porous substrate film;
    Dispersing inorganic particles having a maximum diameter of 0.9 to 1.3 탆 into a polymeric binder and water to prepare an inorganic slurry;
    Preparing a polyethylene slurry using a solution containing polyethylene particles having a maximum diameter of 0.9 to 1.3 mu m;
    Mixing the inorganic slurry and the polyethylene slurry to prepare a composite slurry; And
    Coating the composite slurry on the polypropylene base film to form a coating layer in which inorganic particles and polyethylene particles are mixed at a weight ratio of 70:30 to 90:10;
    The method of claim 1, wherein the porous separator is a porous separator.
  10. [12] The method of claim 9, wherein the polypropylene porous substrate film is formed to a thickness of 5 to 10 [mu] m using a polypropylene resin having an MI of 2 to 8 g / 10 min.
  11. [Claim 11] The method according to claim 9, wherein the inorganic slurry is formed into a slurry state using Al 2 O 3 particles.
  12. delete
  13. delete
  14. [Claim 11] The method of claim 9, wherein the coating of the composite slurry is performed such that the coating layer has a thickness of 1 to 5 mu m after drying.
  15. The secondary battery according to any one of claims 1 to 4, further comprising a porous separator.
  16. 16. The secondary battery according to claim 15, wherein the secondary battery is lithium secondary battery.
KR1020140170038A 2014-12-01 2014-12-01 Porous membrane for secondary battery KR101670802B1 (en)

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WO2018187255A1 (en) * 2017-04-06 2018-10-11 Asahi Kasei Kabushiki Kaisha Separator for lithium-ion secondary battery
CN110521021A (en) * 2017-11-24 2019-11-29 株式会社Lg化学 Method of manufacturing separator, thus obtained partition and the electrochemical appliance including the partition
KR20200045790A (en) * 2018-10-23 2020-05-06 에스케이아이이테크놀로지주식회사 Separator for secondary battery and electrochemical device using the same

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