KR20150083944A - Organic/inorganic composite separator for secondary battery, method of manufacturing the same, and secondary battery using the same - Google Patents

Abstract

The present invention relates to an organic/inorganic composite separator for a secondary battery, a method for manufacturing the same, and a secondary battery using the same. The method includes: a step of preparing a coating solution including gelatin and inorganic particles; a step of coating a base film with the coating solution; and a step of forming a coating film coated on the base film by drying the base film on which the coating solution is coated.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic / inorganic composite separator for a secondary battery, a manufacturing method thereof, and a secondary battery using the same,

The present invention relates to an organic-inorganic hybrid membrane for a secondary battery, a production method thereof, and a secondary battery using the same, and more particularly, to an organic-inorganic hybrid membrane for a secondary battery including gelatin, a method for producing the same, and a secondary battery using the same will be.

With the development of portable mobile electronic devices such as smart phones, MP3 players, and tablet PCs and electric vehicles, the demand for secondary batteries capable of storing electrical energy is increasing explosively.

Research and development of a lithium secondary battery having a high energy density and a long life span as compared with a nickel-cadmium battery or a nickel-hydrogen battery which has heretofore been used as a secondary battery are under development.

In the lithium secondary battery, the separator prevents direct contact between the negative electrode and the positive electrode to prevent internal short-circuiting of the battery, and provides a passage for lithium ion during charging and discharging. Such a separator is a key component of a secondary battery that directly affects the safety and performance of the secondary battery.

Conventionally, a polyolefin-based separator such as polyethylene or polypropylene has been used as a separator for a lithium secondary battery. However, in order to solve the problem of low wettability to an electrolyte and low safety due to heat shrinkage, a separator coated with an inorganic material Research and development is under way.

For example, in Korean Patent Laid-Open Publication No. 10-2009-0056811 (Application No. 10-2008-0097364), inorganic particles coated on a porous substrate having porous pores are used to improve heat resistance and insolubility and impregnability with an electrolyte Discloses a technique for producing a separation membrane for a secondary battery having a porous coating layer using an organic solvent.

However, when a separator for a secondary battery is manufactured using an organic solvent, the cost of using and recovering the organic solvent is increased, resulting in an increase in the manufacturing cost, and various regulations may be applied depending on the use of the toxic chemical.

An object of the present invention is to provide an environmentally friendly organic / inorganic composite membrane for a secondary battery, a method for manufacturing the same, and a secondary battery including the same.

It is another object of the present invention to provide an organic-inorganic hybrid membrane for a secondary battery having a reduced manufacturing cost, a method for manufacturing the same, and a secondary battery including the same.

It is another object of the present invention to provide an organic-inorganic hybrid membrane for a secondary battery having improved mechanical strength, a method for producing the same, and a secondary battery including the same.

It is another object of the present invention to provide an organic-inorganic hybrid membrane for a secondary battery having improved thermal stability, a method for producing the same, and a secondary battery including the same.

In order to solve the above-described technical problems, the present invention provides a method for manufacturing an organic / inorganic composite separator for a secondary battery.

The method for producing an organic / inorganic composite separator for a secondary battery includes the steps of preparing a coating solution containing gelatin and inorganic particles, coating the coating solution on a base layer, Followed by drying to form a coating film coated on the base film.

The step of preparing the coating solution may include preparing a solvent, and dissolving the gelatin in the solvent.

The step of preparing the coating solution may further include adding a nonsolvent to the solvent.

The solvent may comprise water.

The weight ratio of the gelatin to the total weight of the gelatin and the inorganic particles may be 10 wt% to 50 wt%.

The coating solution may further comprise a water-soluble polymer.

The water-soluble polymer may include at least one of an acrylate-based polymer, a carboxyl-based polymer, an acetate-based polymer, a vinyl alcohol-based polymer, a cellulose-based polymer, a pullulan-based polymer, or a sucrose-based polymer.

The gelatin may comprise a gelatin derivative.

The gelatin derivative may include at least one of phthalated gelatin, esterified gelatin, amidated gelatin, or formylated gelatin.

In order to solve the above technical problems, the present invention provides an organic-inorganic hybrid membrane for a secondary battery.

The organic / inorganic hybrid composite membrane for a secondary battery includes a base film and a coating film coated on the base film, wherein the coating film includes gelatin and inorganic particles.

The weight ratio of the gelatin to the total weight of the gelatin and the inorganic particles may be 10 wt% to 50 wt%.

In the coating film, the weight of the gelatin may be at least lower than the weight of the inorganic particles.

The thickness of the coating layer may be 0.1 to 10 mu m.

In order to solve the above technical problems, the present invention provides a secondary battery.

The secondary battery includes an anode-anode composite separator for a secondary battery according to an embodiment of the present invention and an anode and a cathode spaced apart from each other with the organic-inorganic hybrid membrane separated therebetween.

According to an embodiment of the present invention, an organic-inorganic hybrid membrane for a secondary battery in which inorganic particles are coated using gelatin having environment-friendly and hydrophilic properties can be provided. The use of an organic solvent is minimized, the manufacturing cost is reduced, and an environmentally friendly organic / inorganic hybrid membrane for a secondary battery and a manufacturing method thereof can be provided.

In addition, due to the hydrophilicity of the gelatin contained in the separation membrane, the impregnation rate and ion conductivity of the electrolyte are improved, thermal / mechanical / chemical stability of the separation membrane is improved, and a long-life secondary battery having excellent charge- .

1 is a flow chart for explaining a method of manufacturing an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.
2 is a view for explaining an organic-inorganic hybrid membrane for a secondary battery and a secondary battery including the same according to an embodiment of the present invention.
FIG. 3 and FIG. 4 are electron micrographs for explaining an organic / inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention.
FIG. 5 is a photograph for explaining electrolyte wettability of an organic-inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention. FIG.
6 is a view for explaining the heat shrinkage ratio of the organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.
7 is a graph illustrating charge / discharge characteristics of a secondary battery including an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a flow chart for explaining a method of manufacturing an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.

Referring to Figure 1, a coating solution containing gelatin and inorganic particles is prepared (S110). The step of preparing the coating solution includes preparing a solvent, dissolving the gelatin in the solvent , And dispersing the inorganic particles. For example, water may be used as the solvent. A non-solvent (for example, butanol) may be further added to the solvent.

The weight ratio of the gelatin to the total weight of the gelatin and the inorganic particles may be 10 wt% to 50 wt%. If the weight ratio of the gelatin to the sum of the weights of the gelatin and the inorganic particles is less than 10% by weight, the dispersibility of the inorganic particles by the gelatin decreases, The impregnation rate and the ion conductivity of the organic / inorganic composite membrane can be reduced. On the other hand, when the weight ratio of the gelatin to the sum of the weights of the gelatin and the inorganic particles is higher than 50% by weight, the gelatin which is excessively charged causes porosity of the organic / inorganic composite membrane for a secondary battery The impregnation rate and the ionic conductivity of the electrolyte solution can be reduced. Therefore, the weight ratio of the gelatin to the sum of the weights of the gelatin and the inorganic particles according to an embodiment of the present invention may be preferably 10 wt% to 50 wt%.

The gelatin may contain, in addition to pure gelatin, a gelatin derivative. For example, the gelatin derivative may include at least one of phthalated gelatin, esterified gelatin, amidated gelatin, or formylated gelatin.

The coating solution may further comprise a water-soluble polymer in addition to the gelatin and the inorganic particles. For example, the water-soluble polymer may include at least one of an acrylate polymer, a carboxyl polymer, an acetate polymer, a vinyl alcohol polymer, a cellulose polymer, a pullulan polymer, or a sucrose polymer have.

The inorganic particles may be selected from the group consisting of Si, Al, Sn, Ge, Cr, Mn, Ni, Zn, (C), indium (In), cadmium (Cd), bismuth (Bi), lead (Pb), or vanadium (V), or a complex fluoride or oxide of two or more .

The coating solution may be coated on a base layer (S120). The step of coating the coating solution on the base film may include coating one surface of the base film with the coating solution, Drying at a room temperature, and coating the other surface opposite to the one surface of the base film with the coating solution.

The base film may include at least one selected from the group consisting of a polyolefin resin, a fluorine resin, a polyester resin, a polyacrylonitrile resin, and a microporous membrane made of a cellulose-based material. For example, the polyolefin-based resin may include polyethylene, polypropylene, and the like. The fluororesin may include polyvinylidene fluoride, flitetrafluoroethylene, and the polyester-based resin may include polyethylene terephthalate , Polybutylene terephthalate, and the like.

After the base film is coated with the coating solution, the base film may be dried to form a coating film coated on the base film. (S130) The base film may be dried in a vacuum oven. According to one embodiment, the base film may be dried at a temperature of about 80 DEG C for at least 12 hours using a vacuum oven.

According to the method for manufacturing an organic / inorganic composite membrane for a secondary battery according to an embodiment of the present invention, an organic-inorganic hybrid membrane for a secondary battery coated with inorganic particles can be produced using gelatin having environmental and hydrophilic properties. Thus, the use of the organic solvent is minimized, and the cost for using and recovering the organic solvent can be reduced. Accordingly, a manufacturing method of an organic / inorganic composite separator for a secondary battery which is reduced in manufacturing cost and is environmentally friendly can be provided.

The organic / inorganic composite separator for a secondary battery manufactured according to the method for producing an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention includes the base film and the coating film formed by drying the coating solution containing the gelatin . Hereinafter, an organic-inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention and a secondary battery including the same will be described with reference to FIG.

2 is a view for explaining an organic-inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention, and a secondary battery including the same.

Referring to FIG. 2, a secondary battery according to an embodiment of the present invention includes an anode 110 and a cathode 120 facing each other, a separator 130 between the anode 110 and the cathode 120, .

The anode 110 may include a cathode active material. For example, the cathode active material may be LiMO ₂ (M = V, Cr, Co, Ni), LiM ₂ O ₄ (M = Mn, Ti, V), LiMPO ₄ at least it may include any of the substances from the _{LiNi 1-x Co x O 2} (0 <x <1), LiNi 2-x Mn x O 4 (0 <x <2), or Li [NiMnCo] O ₂ . The cathode active material may have a layered structure, a spinel structure, or an olivine structure depending on the kind of the active material used.

The cathode 120 may include a negative electrode active material. For example, the negative electrode active material may be a carbon material such as graphite or hard carbon, a metal material such as Li, Na, Mg, Al, Si, In, Ti, Pb, Ga, Ge, Sn, Bi, Sb, , Silicon, or silicon oxide, or a Ti-based oxide such as Li ₄ Ti ₅ O ₁₂ .

The electrolyte may be impregnated in the separator 130, the anode 110, or the cathode 120. The electrolyte may be a gel polymer electrolyte or a liquid electrolyte. For example, the electrolyte is prepared by dissolving dimethyl carbonate (DC), ethylmethyl carbonate (EMC), or the like in a basic solvent containing ethylene carbonate (EC), propylene carbonate May be added, and the lithium salt may be dissolved.

For example, the lithium salt may be at least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroacetate (LiAsF ₆ ) Sala Sat borate (LiBOB), lithium trifluoromethyl sulfonate (LiCF ₃ SO _3), lithium or trifluoro-methanesulfonyl this may include at least one selected document imide (LiTFSI) Middle Ages.

The separation membrane 130 may include a base film 132 and a coating film 134 or 136 coated on the base film 132. The thickness of the separation membrane 130 having the base film 132 and the coating films 134 and 136 may be 5 to 30 μm and the separation ratio of the separation membrane 130 may be at least 30%.

The base film 132 may be formed of a material selected from among a polyolefin resin, a fluororesin, a polyester resin, a polyacrylonitrile resin, or a microporous film made of a cellulose-based material, for example, And may include at least any one of them.

The coating layers 134 and 136 may include gelatin and inorganic particles. When the weight of the gelatin in the coating films 134 and 136 is larger than the weight of the inorganic particles, the pores of the separation membrane 130 are reduced by the excessively applied gelatin, so that the impregnation rate and ion conductivity Can be reduced. Therefore, the weight of the gelatin in the coating layers 134 and 136 may be at least less than the weight of the inorganic particles. On the other hand, when the weight of the gelatin is significantly smaller than the weight of the inorganic particles, the dispersibility of the inorganic particles by the gelatin is decreased, so that the impregnation rate and ion conductivity of the separator 130 are decreased . Accordingly, the weight ratio of the gelatin and the inorganic particles constituting the coating layers 134 and 136 may be 5: 5 to 1: 9 according to an embodiment of the present invention.

The coating layers 134 and 136 may include a first coating layer 134 coated on one surface of the base layer 132 and a second coating layer 136 coated on the other surface of the base layer 132, . &Lt; / RTI &gt; The first coating layer 134 and the second coating layer 136 may have substantially the same thickness. For example, the thickness of the first coating layer 134 and the second coating layer 136 may be 0.1 μm to 10 μm. Alternatively, the thicknesses of the first coating layer 134 and the second coating layer 136 may be different from each other.

According to the non-organic composite membrane for a secondary battery and the secondary battery including the same according to an embodiment of the present invention, inorganic and organic composite membranes coated with inorganic particles using gelatin having hydrophilic properties can be provided. Accordingly, the impregnation rate and ion conductivity of the organic / inorganic composite separator for a secondary battery can be improved, and the thermal / mechanical / chemical stability of the organic / inorganic composite separator for a secondary battery can be improved. As a result, a long-life secondary battery having excellent charge / discharge characteristics can be provided.

Hereinafter, the physical / chemical characteristics of the organic / inorganic hybrid membrane for a secondary battery manufactured using gelatin and the secondary battery comprising the same will be described with reference to FIG. 3 to FIG.

Preparation of membranes according to Examples and Comparative Examples

<Preparation of separation membrane according to the embodiments>

Aluminum oxide and gelatin were added to 8.1 mL of water as a solvent and 1.1 mL of butanol as a non-solvent, and the mixture was dispersed for about 12 hours to prepare a coating solution. Using the polyethylene membrane as the base membrane, the coating solution was coated on one side of the polyethylene membrane, dried at room temperature, and then coated on the other side of the polyethylene membrane. The polyethylene membrane coated with the coating solution was dried in a vacuum oven at 80 캜 for about 12 hours or more to prepare an organic / inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention.

The separation membrane according to Example 1 was made to have a thickness of 17 mu m by coating a polyethylene membrane with a coating solution containing aluminum oxide and gelatin of the same weight.

The separation membrane according to Example 2 was made to have a thickness of 15 탆 by coating a polyethylene membrane with a coating solution containing aluminum oxide and gelatin at a weight ratio of 7: 3.

The separation membrane according to Example 3 was made to have a thickness of 15 탆 by coating a polyethylene membrane with a coating solution containing aluminum oxide and gelatin at a weight ratio of 8: 2.

The separation membrane according to Example 4 was formed to have a thickness of 17 탆 by coating a polyethylene membrane with a coating solution containing aluminum oxide and gelatin at a weight ratio of 9: 1.

&Lt; Preparation of separation membrane according to comparative example &

A 9 micrometer thick polyethylene film not coated with the separator according to the comparative example was used.

FIG. 3 and FIG. 4 are electron micrographs for explaining an organic / inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention.

FIG. 3 (a) is an electron micrograph of a polyethylene separator according to a comparative example, and FIGS. 3 (b) and 3 (c) are electron micrographs of the separator according to Examples 2 and 3, respectively. 4 (a) to 4 (d) are electron micrographs of the separation membrane according to Examples 1 to 4, respectively.

3 and 4, when the weight ratio of aluminum oxide to gelatin is 5: 5 according to Example 1, it can be seen that the pores of the separation membrane according to Example 1 are almost clogged by the excessive amount of gelatin. In addition, when the weight ratio of aluminum oxide to gelatin was 9: 1 according to Example 4, it was confirmed that the gelatin was not sufficiently supplied and the dispersibility of aluminum oxide was reduced.

On the other hand, according to Examples 2 and 3, when the weight ratio of gelatin to aluminum oxide is 7: 3 or 8: 2, it can be confirmed that aluminum oxide is uniformly dispersed in gelatin.

Measurements of electrolytic solution impregnation rate and ion conductivity of separators according to Examples and Comparative Examples

Table 1 below shows measurements of electrolyte impregnation rates and ionic conductivities of the membranes prepared according to Examples 1 to 4 and Comparative Examples described above. In order to measure the electrolyte impregnation rate and ionic conductivity of the separator in Table 1, a mixed solution of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 30:50:20 was added to 5 wt% of FEC Was used as the electrolyte.

division Electrolyte impregnation rate (%) Ion conductivity (S / cm) Comparative Example (Polyethylene film) 160 1.5 X 10 ^-4 Example 1 (aluminum oxide: gelatin = 5: 5) 57.4 - Example 2 (aluminum oxide: gelatin = 7: 3) 201.6 3.0 X 10 ^-4 Example 3 (aluminum oxide: gelatin = 8: 2) 233.3 3.8 X 10 ^-4 Example 4 (aluminum oxide: gelatin = 9: 1) 187.5 2.7 X 10 ^-4

According to Table 1, when aluminum oxide is added at a relatively higher weight than gelatin according to Examples 2 to 3 to prepare a separation membrane, affinity to electrolyte increases due to hydrophilicity of gelatin, It is confirmed that the electrolytic solution impregnation rate and ion conductivity are improved as compared with the polyethylene film according to the comparative example.

On the other hand, when the weight ratio of aluminum oxide to gelatin is 9: 1 as in Example 4, gelatin is not sufficiently supplied as described above, and the dispersibility of aluminum oxide is reduced. Accordingly, in the case of the separation membrane according to Example 4, it is confirmed that the impregnation rate and the ion conductivity of the electrolyte are reduced as compared with the separation membranes according to Examples 2 and 3.

Also, as described above, when the weight ratio of aluminum oxide to gelatin is 5: 5 according to Example 1, the pores of the separation membrane are blocked due to excessive gelatin introduction, the impregnation rate of the electrolyte is greatly reduced, Problems have occurred.

Therefore, it is understood that setting the weight ratio of gelatin to the sum of the weight of aluminum oxide and gelatin to be added to the coating solution to be 10 wt% to 50 wt% is a method of maximizing the electrolyte impregnation rate and ion conductivity of the separation membrane have.

FIG. 5 is a photograph for explaining electrolyte wettability of an organic-inorganic hybrid membrane for a secondary battery according to an embodiment of the present invention. FIG.

5 (a) to 5 (c) show the electrolyte wettability of the separators according to Comparative Examples, Examples 2 and 3, respectively. As described with reference to Table 1, the electrolyte wettability of the separators coated with the coating film containing aluminum oxide and gelatin of 7: 3 or 8: 2 in weight ratio according to Examples 2 and 3, Compared with the membrane, it can be confirmed that it is excellent.

Measurement of Heat Shrinkage of Separators According to Examples and Comparative Example

6 is a view for explaining the thermal stability of an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.

Referring to FIG. 6, the separators according to Example 2, Example 3, and Comparative Example were cut to a size of 5 cm x 5 cm and left at 130 ° C for 30 minutes. Then, the sizes of the separators were measured, Respectively. 6 (a) to 6 (c) show the separators according to Comparative Example, Example 2, and Example 3, respectively, after being left at 130 캜 for 30 minutes.

The heat shrinkage of the separator according to the comparative example was measured to be 10.4%, the heat shrinkage of the separator according to Example 2 was measured to be 2.6%, and the heat shrinkage of the separator according to Example 3 was less than 2% . The separation membranes according to Example 2 and Example 3 were reduced by about 4 to 5 times as compared with the separation membranes according to the Comparative Example. Compared with the polyethylene separator according to the comparative example, it can be confirmed that the separators coated with a coating film containing aluminum oxide and gelatin having a weight ratio of 7: 3 or 8: 2 according to Examples 2 and 3 have excellent thermal stability.

Comparison of charging and discharging characteristics of secondary batteries using separators according to Examples and Comparative Examples

7 is a graph illustrating charge / discharge characteristics of a secondary battery including an organic / inorganic composite separator for a secondary battery according to an embodiment of the present invention.

&Lt; Preparation of Secondary Battery Using Separation Membrane According to Examples &

In order to evaluate the electrochemical properties of the separator according to Examples 2 and 3, it was confirmed that the separator according to Examples 2 and 3 was used as a negative electrode for a lithium secondary battery, using a natural graphite anode, LiFePO ₄ anode, electrolyte described with reference to Table 1, A battery was prepared.

&Lt; Preparation of Secondary Battery Using Separation Membrane According to Comparative Example &

A lithium secondary battery was fabricated using a natural graphite anode, LiFePO ₄ anode, the electrolyte described with reference to Table 1, and a polyethylene separator according to a comparative example.

Referring to FIG. 7, charge and discharge tests were performed on the lithium secondary batteries manufactured using the separators according to Examples 2, 3, and Comparative Examples. The charge-discharge test was conducted at a current density of 0.5 C at a room temperature of 2.0 to 3.7V.

Compared to the lithium secondary batteries prepared using the separator according to the comparative example in which the coating film having aluminum oxide and gelatin was not coated, the aluminum oxide and gelatin having a weight ratio of 7: 3 or 8: 2 according to Examples 2 and 3 In the case of a lithium secondary battery manufactured using a separation membrane coated with a coating film, gelatin having a high affinity for an electrolyte increases the electrolyte impregnation rate and ion conductivity of the separation membrane. Thus, it can be confirmed that the lithium secondary battery having the separator according to Examples 2 and 3 has high capacity and excellent charge / discharge characteristics.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

110: anode
120: cathode
130: separator
132: base membrane
134, 136: coating film

Claims (14)

Preparing a coating solution containing gelatin and inorganic particles;
Coating the coating solution on a base layer; And
And drying the base film coated with the coating solution to form a coating film coated on the base film.
The method according to claim 1,
Wherein the step of preparing the coating solution comprises:
Preparing a solvent; And
And dissolving the gelatin in the solvent.
3. The method of claim 2,
Wherein the step of preparing the coating solution comprises:
And adding a nonsolvent to the solvent. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
3. The method of claim 2,
Wherein the solvent comprises water.
The method according to claim 1,
Wherein the weight ratio of the gelatin to the total weight of the gelatin and the inorganic particles is 10 wt% to 50 wt%.
The method according to claim 1,
Wherein the coating solution further comprises a water-soluble polymer.
The method according to claim 6,
The water-soluble polymer may be at least one selected from the group consisting of an acrylate polymer, a carboxyl polymer, an acetate polymer, a vinyl alcohol polymer, a cellulosic polymer, a pullulan polymer or a sucrose polymer, (2).
The method according to claim 1,
Wherein the gelatin comprises a gelatin derivative.
9. The method of claim 8,
Wherein the gelatin derivative comprises at least one of phthalated gelatin, esterified gelatin, amidated gelatin, or formalized gelatin.
A base film; And
And a coating film coated on the base film,
Wherein the coating layer comprises gelatin and inorganic particles.
11. The method of claim 10,
Wherein the weight ratio of the gelatin to the sum of the weights of the gelatin and the inorganic particles is 10 wt% to 50 wt%.
11. The method of claim 10,
Wherein the weight of the gelatin in the coating layer is lower than the weight of the inorganic particles.
11. The method of claim 10,
Wherein the thickness of the coating layer is 0.1 to 10 占 퐉.
An organic / inorganic composite separator for a secondary battery according to any one of claims 10 to 13. And
And a positive electrode and a negative electrode spaced apart from each other with the non-organic composite separator for the secondary battery interposed therebetween.

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