KR20210093691A - Method for producing a secondary battery separator coating material, a separator comprising the coating material, and a secondary battery comprising the separator - Google Patents

Abstract

Provided is a method for manufacturing a secondary battery separator coating material. The method for manufacturing a secondary battery separator coating material may comprise: a step of manufacturing a functional structure comprising a bed type carrier having pores therein, and an additive carried in the pores of the bed type carrier; and a step of manufacturing a functional coating material by mixing the functional structure, a binder, and a solvent. According to the present invention, performance and reliability of the secondary battery can be improved.

Description

Method for producing a secondary battery separator coating material, a separator comprising the coating material, and a secondary battery comprising the separator, a separator comprising the coating material, and a secondary battery comprising the separator }

The present invention relates to a method for manufacturing a secondary battery separator coating material, a separator including the coating material, and a secondary battery including the separator, and more specifically, a functional structure provided with an additive to a carrier having a plurality of pores. It relates to a method of manufacturing a secondary battery separator coating material comprising a separator, a separator comprising the coating material, and a secondary battery comprising the separator.

Recently, interest in portable electronic devices such as smart phones and electric vehicles has increased, and the demand for lithium secondary batteries used as energy sources is increasing. In particular, in the case of an electric vehicle, high output and high energy density are required to improve the drivable distance compared to the prior art.

However, as the cycle progresses in the lithium secondary battery, a side reaction between the electrode and the electrolyte participating in the electrochemical reaction occurs, and accordingly, the performance of the lithium secondary battery, such as capacity maintenance rate and lifespan, may be deteriorated.

Therefore, a method of forming a solid electrolyte interface on the surface of the anode to suppress such side reactions is being studied. When a carbon-based material is mainly included as the negative electrode of a lithium secondary battery _{, a solid electrolyte interface such as Li 2} CO ₃ , Li ₂ O, LiOH, etc. may be formed by a reaction between lithium and a carbon-based material due to the high reactivity of lithium ions. . However, it may not be easy to control the solid electrolyte interface.

Accordingly, a method for preparing a solid electrolyte interface by introducing a functional additive is being studied. For example, in Korean Patent Laid-Open Publication No. 10-2018-0106973, a borate-based lithium compound and a non-lithium-type additive are included, and the non-lithium-type additive is selected from the group consisting of a vinyl silane-based compound and a sulfate-based compound. As described above, an electrolyte additive composition characterized in that it does not contain a phosphate-based compound is disclosed.

Korean Patent Publication No. 10-2018-0106973

One technical problem to be solved by the present invention is a method for manufacturing a secondary battery separator coating material that improves properties such as spreadability, breathability, heat resistance, wettability, etc., a separator including the coating material, and a secondary battery including the separator is to provide

Another technical problem to be solved by the present invention is a method for producing a secondary battery separator coating material in which the performance degradation problem due to long-term use of a secondary battery is solved, a separator including the coating material, and a secondary battery including the separator is to provide

Another technical problem to be solved by the present invention is to provide a method for manufacturing a secondary battery separator coating material for improving reliability and performance of a secondary battery, a separator including the coating material, and a secondary battery including the separator there is.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above-described technical problems, the present invention provides a method of manufacturing a secondary battery separator coating material.

According to an embodiment, the method for manufacturing the secondary battery separator coating material includes preparing a functional structure comprising a needle-shaped carrier having pores therein, and an additive supported in the pores of the needle-shaped carrier, and Comprising the step of preparing a functional coating material by mixing the functional structure, the binder, and the solvent, the sum of the content of the functional structure and the content of the binder in the functional coating material is 15 relative to the total weight of the functional coating material greater than wt % and less than 25 wt %.

According to an embodiment, the manufacturing of the functional structure includes the steps of providing the acicular carrier to the additive to prepare a first mixed solution, and decompressing the first mixed solution in a vacuum environment, the acicular carrier Supporting the additive in the pores of the, and drying the needle-shaped carrier on which the additive is supported, may include the step of manufacturing the functional structure.

According to an embodiment, the method of manufacturing the secondary battery separator coating material may further include, after the manufacturing of the functional structure, the step of forming a polymer coating layer on the surface of the functional structure.

According to an embodiment, the forming of the polymer coating layer comprises the steps of preparing a second mixed solution containing any one of a polymer or a monomer of the polymer, in the needle-shaped carrier on which the additive is supported, the second It may include providing a mixed solution.

According to one embodiment, the binder, polyimide (polyimide), polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-cohexafluoropropylene), polyvinylidene fluoride-trichlorethylene (polyvinylidene fluoride-cotrichlorethylene), poly Methyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer (polyethylene-co- vinyl acetate), polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylflurane (cyanoethylpullulan), cyanoethylpolyvinylalcohol (cyanoethylpolyvinylalcohol), cyanoethylcellulose (cyanoethylcellulose), cyanoethylsucrose (cyanoethylsucrose), pullulan (pullulan) and any one of carboxyl methyl cellulose can do.

According to an embodiment, the solvent may include at least one of N-methyl-2-pyrrolidone (NMP) and ethanol (Ethanol).

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

According to one embodiment, the secondary battery is disposed between the negative electrode and the positive electrode, and a functional structure is coated separator, and comprising an electrolyte disposed between the negative electrode and the separator and between the positive electrode and the separator, the functional structure is, including an acicular carrier having pores therein, and an additive supported in the pores of the acicular carrier, wherein the additive is released from the acicular carrier.

According to an embodiment, the needle-shaped carrier may include any one of halloysite, alumina, silica, zirconia, zinc oxide, and titanium oxide.

According to an embodiment, the additive may include any one of a solid electrolyte interface (SEI) forming material, a battery side reaction inhibiting material, a thermal stability improving material, and an overcharge inhibiting material.

According to an embodiment, the solid electrolyte interface (SEI) forming material may include any one of vinylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone.

According to an embodiment, the separator may include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylenepolyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal. (polyacetal), polyamide (polyamide), polycarbonate (polycarbonate), polyimide (polyimide), polyetheretherketone (polyetheretherketone), polyethersulfone (polyethersulfone), polyphenyleneoxide (polyphenyleneoxide), polyphenylenesulfide (polyphenylenesulfidro) and may include any one of polyethylenenaphthalene (polyethylenenaphthalene).

A secondary battery according to an embodiment of the present invention includes a separator disposed between a negative electrode and a positive electrode and coated with a functional coating material including a functional structure, and disposed between the negative electrode and the separator and between the positive electrode and the separator Including an electrolyte, wherein the functional structure includes a needle-shaped carrier having pores therein, and an additive supported inside the pores of the needle-shaped carrier, wherein the additive is released from the needle-shaped carrier can Accordingly, since the additive is continuously supplied to the electrolyte, the negative electrode, and the positive electrode, the problem of deterioration in performance of the secondary battery caused by deterioration due to repeated charging and discharging can be solved.

In addition, the functional coating material to be coated on the separator, the acicular carrier having pores therein, and the step of preparing the functional structure comprising the additive supported in the pores of the acicular carrier, and the It is prepared through the step of mixing the functional structure, the binder, and the solvent, wherein the sum of the content of the functional structure and the content of the binder in the functional coating material exceeds 15 wt% of the total weight of the functional coating material by 25 wt% % can be controlled. Accordingly, since the separator coated with the functional coating material has improved spreadability, breathability, heat resistance, and wettability, the performance and reliability of the secondary battery may be improved.

1 and 2 are flowcharts illustrating a method of manufacturing a secondary battery separator coating material according to an embodiment of the present invention.
3 and 4 are views showing a secondary battery separator coating material according to an embodiment of the present invention.
5 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
6 is a photograph showing the shrinkage rate of a separator included in a secondary battery according to an embodiment of the present invention.
7 is a photograph showing the wettability of a separator included in a secondary battery according to an embodiment of the present invention.
8 is a graph showing the release characteristics of the functional structure according to the experimental example of the present invention.
9 is a graph showing the performance of 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 and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

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

In addition, in various embodiments of the present specification, terms such as first, second, third, etc. are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Accordingly, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes a complementary embodiment thereof. In addition, in the present specification, 'and/or' is used to mean including at least one of the elements listed before and after.

In the specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to designate that a feature, number, step, element, or a combination thereof described in the specification is present, and one or more other features, numbers, steps, configuration It should not be construed as excluding the possibility of the presence or addition of elements or combinations thereof. Also, in the present specification, the term “connection” is used to include both indirectly connecting a plurality of components and directly connecting a plurality of components.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 and 2 are flowcharts illustrating a method of manufacturing a secondary battery separator coating material according to an embodiment of the present invention, and FIGS. 3 and 4 are views showing a secondary battery separator coating material according to an embodiment of the present invention.

1 to 4 , a functional structure 100 may be manufactured ( S100 ). According to an embodiment, the manufacturing of the functional structure includes the steps of providing a acicular carrier to an additive to prepare a first mixed solution (S110), and supporting the additive in the pores of the acicular carrier (S120). ), and drying the needle-shaped carrier on which the additive is supported (S130). Hereinafter, each step will be described in detail.

In the step S110, the needle-shaped carrier 110 is provided in a solution containing the additive 120, a first mixed solution may be prepared. According to one embodiment, the needle-shaped carrier 110 may be a material insoluble in the electrolyte of the secondary battery. For example, the needle-shaped carrier 110 may include any one of halloysite, alumina, silica, zirconia, zinc oxide, and titanium oxide.

For example, the needle-shaped carrier 110 may be manufactured by any one process selected from a self-assembly process using a surfactant, an anodization process, an electrochemical etching process, and the like. Accordingly, the needle-shaped carrier 110 may include a plurality of pores 115 therein. Alternatively, the needle-shaped carrier 110 may be obtained directly from volcanic ash or a weathering product of rock. Accordingly, in the needle-shaped carrier 110 , the pores 115 may be formed therein without a separate process for forming the pores 115 .

According to an embodiment, the additive 120 may include any one of a solid electrolyte interface (SEI) forming material, a battery side reaction inhibiting material, a thermal stability improving material, and an overcharge inhibiting material.

For example, the solid electrolyte interface (SEI) forming material may include any one of vinylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone. The solid electrolyte interface (SEI) forming material may form and restore a solid electrolyte interface on the surface of the negative electrode of the secondary battery.

For example, the battery side reaction inhibitory material is ethylenediaminetetraacetic acid, tetramethylethylenediamine, pyridine, dipyridyl, ethylbis(diphenylphosphine), butyronitrile, succinonitrile, iodine, and ammonium halide. The battery side reaction inhibiting material may suppress side reactions at the interface between the negative electrode and the electrolyte of the secondary battery.

For example, the thermal stability improving material may include any one of hexamethyldisiloxane, hexamethoxycyclotriphosphazene, hexamethylphosphoramide, cyclohexylbenzene, biphenyl, dimethylpyrrole, and trimethylphosphate. The thermal stability improving material may improve the thermal stability of the secondary battery electrolyte.

For example, the overcharge inhibitor may include any one of n-butylferrocene, a halogen-substituted benzene derivative, cyclohexylbenzene, and biphenyl. The overcharge inhibiting material may prevent overcharge of the secondary battery.

In step S120, the first mixed pressure solution may be decompressed in the vacuum chamber. Accordingly, the additive 120 may be loaded in the pores 115 of the needle-shaped carrier 110 .

In the step S130 , the needle-shaped carrier 110 on which the additive 120 is supported may be dried through a decompression process. Accordingly, the solvent is evaporated from the first mixed pressure solution, and the functional structure 100 may be manufactured.

According to an embodiment, after the step S130 , the polymer coating layer 130 may be formed on the surface of the functional structure 100 . More specifically, the step of forming the polymer coating layer 130 includes preparing a second mixed solution containing any one of a polymer or a monomer of the polymer, providing the functional structure to the second mixed solution, and It may include depressurizing the second mixed solution provided with the functional structure.

For example, the polymer is polyethyleneimine, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer (poly(fluoride-co-hexafluoropropylene)), polyurethane ), polyethylene oxide, or polydimethylsiloxane.

The functional structure, the binder, and the solvent may be mixed to prepare a functional coating material (S200). The functional coating material may be coated on a separator of a secondary battery to be described later. In this case, the additive may be released from the separator. A more detailed description will be given later.

For example, the binder is polyimide, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-cotrichlorethylene, polymethylmethacrylic Rate (polymethylmethacrylate), polybutylacrylate (polybutylacrylate), polyacrylonitrile (polyacrylonitrile), polyvinylpyrrolidone (polyvinylpyrrolidone), polyvinylacetate (polyvinylacetate), ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate) , polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan , cyanoethylpolyvinylalcohol (cyanoethylpolyvinylalcohol), cyanoethylcellulose (cyanoethylcellulose), cyanoethylsucrose (cyanoethylsucrose), pullulan (pullulan) and carboxyl methyl cellulose (carboxyl methyl cellulose) may include any one .

For example, the solvent may include at least one of N-methyl-2-pyrrolidone (NMP) and ethanol (Ethanol).

According to an embodiment, the content of the functional structure and the content of the binder in the functional coating material may be controlled. For example, the sum of the content of the functional structure and the content of the binder in the functional coating material may be controlled to be more than 15 wt% and less than 25 wt% based on the total weight of the functional coating material. Accordingly, the separator coated with the functional coating material may have improved spreadability, breathability, heat resistance, and wettability. As a result, the performance and reliability of the secondary battery including the separator coated with the functional coating material may be improved.

Above, a method for manufacturing a secondary battery separator coating material according to an embodiment of the present invention has been described. Hereinafter, a secondary battery according to an embodiment of the present invention including a separator coated with the secondary battery separator coating material will be described.

5 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 5 , the secondary battery according to an embodiment of the present invention may include a negative electrode 210 , a positive electrode 220 , a separator 230 , and electrolytes 240a and 240b . According to one embodiment, the negative electrode 210 is a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping / dedoping lithium, or It may include any one of transition metal oxides. For example, the material capable of reversibly intercalating/deintercalating lithium ions may be any one of crystalline carbon or non-hard carbon, and the crystalline carbon may be amorphous, plate-like, flaky, spherical, or fibrous. may be any one of natural graphite or artificial graphite, and the amorphous carbon may be any one of soft carbon, hard carbon, mesophase pitch carbide, or calcined coke. The lithium metal alloy is sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) , silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), gallium (Ge), aluminum (Al) or tin (Sn) ) may include at least one metal element. The material capable of doping/undoping lithium may be at least one of silicon oxide, a silicon metal alloy, a silicon-carbon composite, tin oxide, a tin metal alloy, or a tin-carbon composite. The transition metal oxide may be lithium titanium oxide. In this case, the negative electrode 210 may further include a conductive material. More specifically, the negative electrode 210 may include a carbon active material, conductive carbon, and PVdF binder mixed in an NMP solvent in a ratio of 92:3:5, coated on a copper current collector, and dried at 80°C.

Alternatively, the positive electrode 220 may be a compound capable of reversibly intercalating/deintercalating lithium ions. For example, the positive electrode 220 may be a composite oxide of at least one of aluminum, cobalt, manganese, and nickel, and lithium. More specifically, the positive electrode 220 is, Li(N _0.6 M _0.2 C _0.2 )O ₂ , PVdF, and conductive carbon are mixed in an NMP solvent in a ratio of 90:5:5, coated on an aluminum current collector, and 80° C. may be dried in

According to one embodiment, the negative electrode 210 and the positive electrode 220 may be disposed to face each other and spaced apart. The separator 230 may be disposed between the cathode 210 and the anode 220 .

For example, the separator 230 may include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene polyethylene terephthalate, polybutyleneterephthalate, polyester, polyacetal. (polyacetal), polyamide (polyamide), polycarbonate (polycarbonate), polyimide (polyimide), polyetheretherketone (polyetheretherketone), polyethersulfone (polyethersulfone), polyphenyleneoxide (polyphenyleneoxide), polyphenylenesulfide (polyphenylenesulfidro) and may include any one of polyethylenenaphthalene (polyethylenenaphthalene).

A functional coating layer 230a may be formed on the surface of the separator 230 . The functional coating layer 230a may be formed of a functional coating material. The functional coating material may be the same as the functional coating material described in the method for manufacturing the secondary battery separator coating material described with reference to FIGS. 1 to 4 . That is, the functional structure 100 may be coated on the surface of the separator 230 .

The functional structure 100 coated on the surface of the separator 230 may release the additive 120 . In other words, the additive 120 supported in the acicular carrier 110 may be released from the acicular carrier 110 . The released additive 120 may move toward the negative electrode 210 and the positive electrode 220 through the electrolytes 240a and 240b. According to an embodiment, the additive 120 may be released at a substantially constant rate. For example, the additive 120 may be released at a rate of 2-4%/day. Accordingly, the additive 120 may be continuously supplied to the electrolytes 240a and 240b , the negative electrode 210 , and the positive electrode 220 . As a result, the problem of performance degradation of the secondary battery caused by deterioration due to repeated charging and discharging can be solved.

According to an embodiment, the polymer coating layer 130 coated on the surface of the functional structure 100 may control the speed of the additive 120 emitted from the needle-shaped carrier 110 . For example, as the thickness of the polymer coating layer 130 increases, the release rate of the additive 120 may be relatively slow. In contrast, as the thickness of the polymer coating layer 130 decreases, the release rate of the additive 120 may be relatively increased.

According to an embodiment, the functional coating layer 230a may include a first functional structure and a second functional structure. That is, the surface of the separator 230 may be coated with a functional coating material including the first functional structure and the second functional structure. The first functional structure and the second functional structure may have different thicknesses of the polymer coating layer coated on the surface. For example, the thickness of the polymer coating layer coated on the surface of the first functional structure may be thicker than the thickness of the polymer coating layer coated on the surface of the second functional structure.

Accordingly, the release rate of the additive released from the first functional structure and the second functional structure may be different from each other. Specifically, as described above, the additive release rate of the second functional structure having a relatively thin polymer coating layer may be faster than the additive release rate of the first functional structure having a relatively thick polymer coating layer.

As a result, in the separation membrane 230 coated with the first functional structure and the second functional structure, the plurality of functional structures may release the additive at different rates, respectively.

The electrolytes 240a and 240b may be disposed between the negative electrode 210 and the separator 230 and between the positive electrode 220 and the separator 230 . According to an embodiment, the electrolytes 240a and 240b may include a lithium salt. For example, the electrolytes 240a and 240b may include 1M LiPF ₆ ethylene carbonate (EC)/ethyl methyl carbonate (EMC).

The secondary battery according to an embodiment of the present invention is disposed between the negative electrode 210 and the positive electrode 220, the separator 230 coated with the functional coating material, and the negative electrode 210 and the separator ( 230) and the electrolyte (240a, 240b) disposed between the positive electrode 220 and the separator 230, the functional structure 100, the needle-shaped having the pores 115 therein It includes the carrier 110, and the additive 120 supported inside the pores 115 of the needle-shaped carrier 110, and the additive 120 is released from the needle-shaped carrier 110. may include Accordingly, since the additive 120 is continuously supplied to the electrolytes 240a and 240b, the negative electrode 210, and the positive electrode 220, the performance of the secondary battery is generated due to deterioration due to repeated charging and discharging. The degradation problem can be solved.

In addition, the functional coating material coated on the separator 230 includes the acicular carrier 110 having pores therein, and the additive supported in the pores 115 of the acicular carrier 110 ( 120) is prepared through the step of preparing the functional structure 100 including, and mixing the functional structure, the binder, and the solvent, the content of the functional structure in the functional coating material and the amount of the binder The sum of the content may be controlled to be more than 15 wt% and less than 25 wt% based on the total weight of the functional coating material. Accordingly, since the separator 230 coated with the functional coating material has improved spreadability, breathability, heat resistance, and wettability, the performance and reliability of the secondary battery may be improved.

Above, the secondary battery according to the embodiment of the present invention has been described. Hereinafter, a method for manufacturing a secondary battery separator coating material according to an embodiment of the present invention and specific experimental examples and characteristic evaluation results of the secondary battery are described.

Manufacturing of functional structures according to experimental examples

0.5 g of halloysite, an inorganic porous carrier, was placed in 400 μL vinylene carbonate (VC), and vinylene carbonate was supported in the pores of halloysite through a decompression process in a vacuum chamber. Thereafter, the vinylene carbonate-supported halloysite was dried through a reduced pressure process to prepare a functional structure.

Preparation of functional coating materials according to Experimental Examples 1 to 8

The functional structure, the binder, and the solvent were mixed and dispersed to prepare a functional coating material according to the experimental example. More specifically, as a binder, polyimide (PI) was used, and as a solvent, a solution in which N-methyl-2-pyrrolidone (NMP) and ethanol were mixed was used.

In addition, functional coating materials according to Experimental Examples 1 to 8 were prepared by different ratios of the functional structure, binder, and solvent, and the specific content of the functional coating material according to Experimental Examples 1 to 8 is shown in <Table 1> below. is arranged through

division Functional structure: binder (wt%) (functional structure + binder): solvent (wt%) Experimental Example 1 9:1 1:9 Experimental Example 2 9:1 1.5:8.5 Experimental Example 3 9:1 2:8 Experimental Example 4 9:1 2.5:7.5 Experimental Example 5 9:1 3:7 Experimental Example 6 8:2 2:8 Experimental Example 7 7:3 2:8 Experimental Example 8 6:4 2:8

Preparation of functional coating material according to Experimental Example 9

A functional coating material according to Experimental Example 9 was prepared by mixing and dispersing the functional structure, binder, initiator, and surfactant. More specifically, as a binder, butyl acrylate (BA) 53.7 wt%, methyl methacrylate (MMA) 11.8 wt%, acrylonitrile (AN) 6.5 wt%, 2-ethylhexyl acrylate (2-EHA) 23.7 A material in which wt% and 0.6 wt% of methacrylic acid (MAA) was polymerized at 80° C. for about 3 hours, tert-butyl hydroperoxide was used as an initiator, and sodium lauryl sulfate 3.5 wt. % solution was used. In addition, the functional structure and the binder were mixed in a ratio of 34.4: 75.6 wt%.

Secondary battery manufacturing according to the embodiment

A negative electrode prepared by mixing a carbon active material, conductive carbon, and PVdF binder in a NMP (N-methyl-2-pyrrolidone) solvent in a ratio of 92:3:5, coating it on a copper current collector and drying at 80°C, and Li (N _0.6 M _0.2 C _0.2 )O ₂ , PVdF, and conductive carbon are mixed in an NMP solvent in a ratio of 90:5:5, coated on an aluminum current collector, and dried at 80° C. to prepare a prepared positive electrode.

A coin-type secondary battery was prepared by disposing a PE separator coated with a functional coating material according to Experimental Examples 1 to 9 and a 1M LiPF ₆ EC (ethylene carbonate)/EMC (ethyl methyl carbonate) electrolyte between the negative electrode and the positive electrode did.

The interest batteries including the separator coated with the coating material according to Experimental Examples 1 to 9 are defined as the secondary batteries according to Examples 1 to 9, respectively.

Preparation of secondary batteries according to comparative examples

A secondary battery including a polyethylene (PE) separator is prepared.

6 is a photograph showing the shrinkage rate of a separator included in a secondary battery according to an embodiment of the present invention.

Referring to FIG. 6 , after preparing a polyethylene separator (PE) according to a comparative example and a separator (HNTs coated) including a secondary battery according to Example 9, each separator was left at 130°C for 30 minutes, The area to be contracted was taken and shown.

As can be seen in FIG. 6 , in the case of the polyethylene separator (PE) according to the comparative example, it was confirmed that the area was contracted by about 25% over time. However, in the case of the separator (HNTs coated) included in the secondary battery according to Example 9, it was confirmed that the area was maintained constant despite the passage of time.

7 is a photograph showing the wettability of a separator included in a secondary battery according to an embodiment of the present invention.

Referring to FIG. 7 , after preparing a polyethylene separator (PE) according to a comparative example and a separator (HNTs coated) including a secondary battery according to Example 9, an electrolyte is dropped on each separator, and a wet area is measured at 5 second intervals It was photographed and shown.

As can be seen in FIG. 7 , in the case of the polyethylene separator (PE) according to the comparative example, the wet area is maintained substantially constant over time, but the separator (HNTs coated) included in the secondary battery according to Example 9 is used. In the case of the case, it was confirmed that the wet area gradually increased with time. Accordingly, it was found that the separator included in the secondary battery according to the embodiment of the present invention has high wettability.

8 is a graph showing the release characteristics of the functional structure according to the experimental example of the present invention.

Referring to FIG. 8 , the functional structure according to the experimental example was put into a solution in which Ethylene Carbonate (EC): Ethyl Methyl Carbonate (EMC) was mixed in a ratio of 3: 7, and then the emission amount of VC was measured. More specifically, the release amount of VC was expressed as a release percentage (%) according to release time (days) using gas chromatography. As can be seen in FIG. 8 , it was confirmed that the functional structure according to the experimental example continuously released VC at a constant level.

9 is a graph showing the performance of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 9 , after preparing the secondary battery (HNTs coated) according to Example 9 and the secondary battery (PE separator) according to the comparative example, each battery was charged and discharged at 25° C. at 0.5 C-rate. After the cycle, the specific capacity (capacity retention, %) according to the number of cycles was measured and shown.

As can be seen in FIG. 9 , in the secondary battery according to the comparative example, it was confirmed that the specific capacity was significantly reduced as the number of cycles increased. However, in the secondary battery according to Example 9, it was confirmed that the specific capacity was maintained substantially constant despite the increase in the number of cycles. Accordingly, it can be seen that, in the secondary battery according to the embodiment, the problem of performance degradation due to long-term use of the secondary battery is solved by the additive (VC) released from the separator.

In addition, after preparing the separators included in the secondary batteries according to Examples 1 to 8, spreadability, air permeability, heat resistance, and wettability of each separator were measured. The measured progress is summarized in <Table 2> below.

division spreadability breathable heat resistance wettability Example 1 under award under award Example 2 middle award middle award Example 3 award middle award award Example 4 middle middle award middle Example 5 middle under middle middle Example 6 middle under middle under Example 7 under under middle under Example 8 under under under under

As can be seen from <Table 2>, the separators included in the secondary batteries according to Examples 1 to 5 have more spreadability, air permeability, and heat resistance than the separators included in the secondary batteries according to Examples 6 to 8. , it was confirmed that the wettability characteristics were high. That is, it can be seen that when the ratio of the functional structure: binder (wt%) is controlled to 9:1 in the manufacturing process of the functional coating material, the properties of the separator are effectively improved.

In addition, the separator included in the secondary battery according to Example 3 has characteristics of spreadability, air permeability, heat resistance, and wettability than the separators included in the secondary batteries according to Examples 1, 2, 4, and 5. This high was confirmed.

That is, (functional structure + binder): solvent (wt%) in the ratio of 1:9, 1.5:8.5, 2:8, 2.5:7.5, 3:7 of the functional coating material-coated separator, (functional Structure + binder): It was found that the characteristics of the separation membrane coated with a functional coating material in which the ratio of solvent (wt%) was controlled to 2:8 was the highest.

Accordingly, when the sum of the content of the functional structure and the content of the binder in the functional coating material in the manufacturing process of the functional coating material is controlled to be more than 15 wt% and less than 25 wt% based on the total weight of the functional coating material, the characteristics of the separator are It can be seen that the improvement is effective.

As mentioned above, although the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to specific embodiments and should be construed according to the appended claims. In addition, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the present invention.

100: functional structure
110: bed carrier
115: Qigong
120: additive

Claims (11)

Preparing a functional structure comprising an acicular carrier having pores therein, and an additive supported in the pores of the acicular carrier; and
Including the step of preparing a functional coating material by mixing the functional structure, binder, and solvent,
The method of manufacturing a secondary battery separator coating material comprising the sum of the content of the functional structure and the content of the binder in the functional coating material is more than 15 wt% and less than 25 wt% based on the total weight of the functional coating material.
According to claim 1,
The step of preparing the functional structure,
providing the acicular carrier to the additive to prepare a first mixed solution;
supporting the additive in the pores of the needle-shaped carrier by decompressing the first mixed solution in a vacuum environment; and
Drying the needle-shaped carrier on which the additive is supported, a method of manufacturing a secondary battery separator coating material comprising the step of manufacturing the functional structure.
3. The method of claim 2,
After the step of preparing the functional structure,
Method for producing a secondary battery separator coating material further comprising the step of forming a polymer coating layer on the surface of the functional structure.
4. The method of claim 3,
The step of forming the polymer coating layer,
preparing a second mixed solution containing any one of a polymer or a monomer of the polymer; and
Method for producing a secondary battery separator coating material comprising the step of providing the functional structure to the second mixed solution.
According to claim 1,
The binder is polyimide, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate ), polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide (polyethylene oxide), polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyano Secondary battery separator coating material comprising any one of ethyl polyvinyl alcohol (cyanoethylpolyvinylalcohol), cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose manufacturing method.
According to claim 1,
The solvent is a method of manufacturing a secondary battery separator coating material comprising at least one of N-methyl-2-pyrrolidone (NMP) and ethanol (Ethanol).
a separator disposed between the negative electrode and the positive electrode and coated with a functional structure; and
An electrolyte disposed between the negative electrode and the separator and between the positive electrode and the separator,
The functional structure includes an acicular carrier having pores therein, and an additive supported in the pores of the acicular carrier,
The additive is a secondary battery comprising that released from the needle-shaped carrier.
8. The method of claim 7,
The acicular carrier is a secondary battery comprising any one of halloysite, alumina, silica, zirconia, zinc oxide, and titanium oxide.
8. The method of claim 7,
The additive may include any one of a solid electrolyte interface (SEI) forming material, a battery side reaction inhibiting material, a thermal stability improving material, and an overcharge inhibiting material.
10. The method of claim 9,
The solid electrolyte interface (SEI) forming material may include any one of vinylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone.
8. The method of claim 7,
The separator includes high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene polyethylene terephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide (polyamide), polycarbonate (polycarbonate), polyimide (polyimide), polyetheretherketone, polyethersulfone (polyethersulfone), polyphenyleneoxide (polyphenyleneoxide), polyphenylenesulfidro (polyphenylenesulfidro) and polyethylenenaphthalene A secondary battery comprising any one of (polyethylenenaphthalene).

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