KR-20260065959-A - Composite coating separator and method of manufacturing the same, lithium-ion battery including the same

KR20260065959AKR 20260065959 AKR20260065959 AKR 20260065959AKR-20260065959-A

Abstract

The present invention discloses a composite coating separator, a method for manufacturing the same, and a lithium-ion battery including the same. The composite coating separator comprises a substrate film and a coating layer formed on at least one surface of the substrate film. The coating layer comprises aramid and an inorganic filler. The inorganic filler is filled within a three-dimensional network structure formed by the aramid. The coating layer fill rate is 80% to 98%, and the coating layer fill rate = 100% × (1 - area of inorganic filler exposed on the surface of the coating layer / area of the coating layer). In the composite coating separator of the present invention, the filling rate of the inorganic filler within the coating layer is appropriate, so the coating layer simultaneously possesses high temperature resistance, air permeability, and powder detachment prevention properties.

Inventors

옌 팅궈
류 가오쥔
바이 야오쭝
정 레이
마 핑촨
가오 페이페이
둥 추춘
성 레이
리 야디

Assignees

시노마 리튬 배터리 세퍼레이터 컴퍼니 리미티드
차이나 내셔널 빌딩 머터리얼 그룹 컴퍼니 리미티드

Dates

Publication Date: 20260511
Application Date: 20240828
Priority Date: 20230921

Claims (10)

A composite coating separator comprising a base film and a coating layer formed on at least one surface of the base film, A composite coating membrane characterized by comprising aramid and an inorganic filler, wherein the inorganic filler is filled within a three-dimensional network structure formed by the aramid, the coating layer filling rate is 80% to 98%, and the coating layer filling rate = 100% × (1 - area of inorganic filler exposed on the surface of the coating layer / area of the coating layer); the increase in air permeability per unit thickness of the coating layer is less than 35 s/100cc/μm; the composite coating membrane has a thermal shrinkage rate in the MD direction of less than 5%, a thermal shrinkage rate in the TD direction of less than 1%, and a powder shedding rate of less than 0.5% under conditions of 120℃ and 1h; and the thickness of the coating layer is 1 to 4μm.
In paragraph 1, A composite coating separator characterized by the thickness of the above-described film being 4 to 20 μm, the air permeability being 50 to 500 s/100 cc, and the porosity being 40 to 55%.
In paragraph 1, A composite coating separation membrane characterized in that the inorganic filler is selected from at least one of a ceramic material, a nanowire material, or a nanotube material; the ceramic material is selected from one or more of Al₂O₃ , SiO₂ , TiO₂ , ZrO₂ , BaTiO₃ , MgO , CaO, AlOOH, and SiC; the nanowire material is selected from one or more of carbon nanowires, attapulgite, silver nanowires, boron carbide nanowires, nanocellulose, copper hydroxide nanowires, silicon monooxide nanowires, and hydroxyapatite nanowires; and the nanotube material is selected from one or more of carbon nanotubes, silver nanotubes, boron carbide nanotubes, copper hydroxide nanotubes, silicon monooxide nanotubes, and hydroxyapatite nanotubes.
In paragraph 1, A composite coating separation membrane characterized in that the inorganic filler is an inorganic particle having a hydroxyl functional group on its surface; and the particle size of the inorganic filler is 0.01 to 0.5 μm.
In paragraph 1, A composite coating separation membrane characterized in that the slurry forming the coating layer comprises an aramid stock solution and an inorganic filler, and the rotational viscosity of the aramid stock solution is 2000 to 4000 mPa·s.
In paragraph 5, A composite coating separator characterized in that the solid content of the slurry forming the coating layer is 4 wt% to 5 wt%; and the aramid stock solution comprises at least one of poly(m-phenylene isophthalamide) and poly(p-phenylene terephthalamide) and a solvent, wherein the solvent is N-methylpyrrolidone.
In paragraph 5, A composite coating separation membrane characterized in that the above aramid stock solution further comprises an auxiliary agent, wherein the auxiliary agent is one or more of CaCl₂ , KOH, LiCl, and pyridine, and the mass content of the auxiliary agent in the above aramid stock solution is ≤10%.
A method for manufacturing a composite coating separation membrane according to claim 1, A slurry forming the coating layer is obtained by performing a first high-speed dispersion by blending an inorganic filler with an organic solvent, and then performing a second high-speed dispersion by mixing with an aramid stock solution; wherein the rotational viscosity of the aramid stock solution is 2000~4000 mPa·s, the solid content of the slurry forming the coating layer is 4 wt%~5 wt%, the rotational speed of the first high-speed dispersion is 6500~10000 r/min, and the time of the first high-speed dispersion is 10~60 min; the rotational speed of the second high-speed dispersion is 6500~10000 r/min, the time of the second high-speed dispersion is 10~60 min, and the rotational speed of the first high-speed dispersion and the rotational speed of the second high-speed dispersion are the same. A method for manufacturing a composite coating separation membrane characterized by including the step of obtaining a composite coating separation membrane by coating the above slurry on one or both sides of a substrate film.
In paragraph 8, A method for manufacturing a composite coating separation membrane characterized in that the above organic solvent is N-methylpyrrolidone.
As a lithium-ion battery, A lithium-ion battery characterized by including a composite coating separator according to claim 1.

Description

Composite coating separator and method of manufacturing the same, lithium-ion battery including the same The present invention relates to the field of lithium-ion batteries, and specifically to a composite coating separator for lithium-ion batteries and a method for manufacturing the same. Separators are a core component of lithium-ion batteries, primarily serving as pathways for lithium ions and as electronic insulators. Polyolefins (e.g., PE and PP) are the main materials currently used in commercially available lithium-ion battery separators. While they offer advantages in terms of chemical stability, mechanical performance, and cost, as lithium-ion batteries continue to be adopted in the electric vehicle sector, the disadvantages of polyolefins—such as high-temperature resistance and wettability with the electrolyte—are becoming increasingly prominent. This seriously degrades the safety performance of lithium-ion batteries and hinders their application, particularly in power batteries. A general method to solve the aforementioned problems is to coat one or both sides of a polyolefin substrate film with a high-temperature resistant and hydrophilic coating layer, and the coating layer material is primarily an inorganic material or an organic polymer. Here, while coating with a mixture of the aforementioned inorganic and organic materials allows the separator to possess both high-temperature resistance and hydrophilic properties simultaneously, the air permeability, high-temperature resistance, and powder shedding of the coating layer directly affect the performance of the separator. Therefore, research on the separator coating layer is particularly important. The main objective of the present invention is to provide a composite coating separator, a method for manufacturing the same, and a lithium-ion battery including the same, in order to overcome the problem of the prior art, which cannot simultaneously possess high temperature resistance, air permeability, and powder detachment prevention properties of the coating layer. The inventors discovered that by mixing aramid fibers with an inorganic filler to form a coating layer, a coating separator possessing high temperature resistance, air permeability, and powder detachment prevention properties simultaneously can be obtained when the coating layer filler ratio is within a specific range. The specific solutions are as follows. A composite coating separator comprising a base film and a coating layer formed on at least one surface of the base film, wherein the coating layer comprises aramid and an inorganic filler, the inorganic filler is filled within a three-dimensional network structure formed by the aramid, the coating layer filling rate is 80% to 98%, and the coating layer filling rate = 100% × (1 - area of inorganic filler exposed on the surface of the coating layer / area of the coating layer). In one embodiment of the composite coating separator according to the present invention, the increase in air permeability per unit thickness of the coating layer is less than 35 s/100 cc/μm; and the composite coating separator has a thermal shrinkage rate in the MD direction of less than 5%, a thermal shrinkage rate in the TD direction of less than 1%, and a powder shedding rate of less than 0.5% under conditions of 120°C and 1h. In one embodiment of the composite coating separator according to the present invention, the thickness of the substrate film is 4 to 20 μm, the air permeability is 50 to 500 s/100 cc, and the porosity is 40 to 55%; and the thickness of the coating layer is 1 to 4 μm. In one embodiment of a composite coating separator according to the present invention, the inorganic filler is selected from at least one of a ceramic material, a nanowire material, or a nanotube material; the ceramic material is selected from one or more of Al₂O₃ , SiO₂ , TiO₂ , ZrO₂ , BaTiO₃ , MgO , CaO, AlOOH, and SiC; the nanowire material is selected from one or more of carbon nanowires, attapulgite, silver nanowires, boron carbide nanowires, nanocellulose, copper hydroxide nanowires, silicon monooxide nanowires, and hydroxyapatite nanowires; and the nanotube material is selected from one or more of carbon nanotubes, silver nanotubes, boron carbide nanotubes, copper hydroxide nanotubes, silicon monooxide nanotubes, and hydroxyapatite nanotubes. In one embodiment of the composite coating separation membrane according to the present invention, the inorganic filler is an inorganic particle having a hydroxyl functional group on its surface; and the particle size of the inorganic filler is 0.01 to 0.5 μm. A composite coating separation membrane comprising a base film and a coating layer formed on at least one surface of the base film, wherein the slurry forming the coating layer comprises an aramid stock solution and an inorganic filler, and the rotational viscosity of the aramid stock solution is 2000 to 4000 mPa·s. In one embodiment of the composite coating separator ac