CN-122029682-A - Separator for electrochemical device and method for manufacturing same

Abstract

The separator according to the present invention includes a porous polymer substrate, an adhesive layer, and a heat-resistant layer, wherein the adhesive layer includes an acrylic adhesive polymer having a swelling ratio of 50% or more. The separator can ensure sufficient peel strength while being thin.

Inventors

• LI ZHAOYONG
• Cui Renrong
• Pu Bingzan
• Pei Gengxi
• Pei Yuanzhi

Assignees

• 株式会社LG新能源

Dates

Publication Date

20260512

Application Date

20250710

Priority Date

20240710

Claims (13)

1. 1. A separator, comprising: A porous polymer substrate, and a porous coating layer, Wherein the porous coating layer includes an adhesive layer on at least one surface of the porous polymer substrate, and a heat-resistant layer on one surface of the adhesive layer, Wherein the adhesive layer comprises a first adhesive polymer, Wherein the heat resistant layer comprises inorganic particles and a second binder polymer, Wherein the first binder polymer comprises an acrylic polymer, and Wherein the swelling ratio (swelling ratio) of the acrylic polymer is 50% or more.
2. 2. The separator plate according to claim 1, Wherein the swelling ratio of the acrylic polymer is 60% or more.
3. 3. The separator plate according to claim 1, Wherein the swelling ratio of the acrylic polymer is measured by the following formula 1: (1) Wherein in formula 1, W 0 represents an initial mass of a film made of the binder polymer when measured at 25 ℃, and W 1 represents a mass of the binder polymer film measured at 25 ℃ after the film has been put into dimethyl carbonate and stored at 60 ℃ for 48 hours.
4. 4. A separator plate according to claim 3, Wherein the carbonate-based solvent comprises dimethyl carbonate.
5. 5. The separator plate according to claim 1, Wherein the acrylic polymer is crosslinked and has a degree of crosslinking of 0.01% to 80%.
6. 6. The separator plate according to claim 1, Wherein the acrylic polymer comprises poly (methyl methacrylate) (poly (methylmethacrylate)), poly (ethylhexyl acrylate) (poly (ethylhexyl acrylate)), poly (butyl acrylate) (poly (butylacrylate)), poly (acrylonitrile) (poly (acrylonitrile)), a copolymer of ethylhexyl acrylate (ethylhexyl acrylate) and methyl methacrylate (METHYL METHACRYLATE), a copolymer of butyl acrylate and methyl methacrylate, an ethyl acrylate-N, N-dimethylacrylamide copolymer, an ethyl acrylate-2- (dimethylamino) ethyl acrylate copolymer, an ethyl acrylate-N, N-diethylacrylamide copolymer, an ethyl acrylate-2- (diethylamino) ethyl acrylate copolymer, or a mixture of two or more thereof.
7. 7. The separator plate according to claim 1, Wherein the peel strength (PEEL STRENGTH) between the porous polymeric substrate and the porous coating is 50 gf/15mm or greater.
8. 8. The separator plate according to claim 1, Wherein the adhesive layer does not include inorganic particles.
9. 9. An electrochemical device comprising: A positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, Wherein the separator is a separator according to any one of claims 1 to 8.
10. 10. A method for manufacturing a separator, the method comprising: preparing a porous polymer substrate; Preparing a slurry for forming an adhesive layer including a first adhesive polymer and a first aqueous solvent, applying the slurry for forming an adhesive layer to at least one surface of the porous polymer substrate and drying the slurry to form an adhesive layer, and Preparing a slurry for forming a heat-resistant layer including inorganic particles, a second binder polymer, a second aqueous solvent, and an organic solvent, applying the slurry for forming a heat-resistant layer to one surface of the binder layer and drying the slurry to form a heat-resistant layer, Wherein the first binder polymer comprises an acrylic polymer, and Wherein the swelling ratio (swelling ratio) of the acrylic polymer is 50% or more.
11. 11. The method for manufacturing a separator according to claim 10, Wherein the organic solvent comprises a carbonate solvent.
12. 12. The method for manufacturing a separator according to claim 10, Wherein the organic solvent comprises dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or mixtures thereof.
13. 13. The method for manufacturing a separator according to claim 10, Wherein the second aqueous solvent and the organic solvent are mixed in a volume ratio of 95:5 to 80:20.

Description

Separator for electrochemical device and method for manufacturing same Technical Field The present disclosure relates to a separator for an electrochemical device and a method of manufacturing the same. The present application is based on and claims priority from korean patent application No. 10-2024-0091290 filed on 10 7/10 of 2024 to korean intellectual property office, the disclosure of which is incorporated herein by reference in its entirety. Background Recently, there is an increasing interest in energy storage technology. As the range of applications as energy sources for mobile phones, video cameras, and laptop computers, and electric vehicles expands, more efforts are being made in research and development of electrochemical devices. In this regard, in the field of electrochemical devices attracting the greatest attention, development of rechargeable secondary batteries has become a focus of attention. Recently, in the development of secondary batteries, research and development have focused on new electrode and battery designs to improve capacity density and specific energy. An electrochemical device includes an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, and a battery case that accommodates the electrode assembly, and the separator prevents a short circuit caused by contact between the positive and negative electrodes and provides a path for movement of an electrolyte between the positive and negative electrodes. Therefore, it is important to maintain an electrode assembly structure including a positive electrode, a separator, and a negative electrode in a stacked configuration after electrolyte wetting. In order to improve the safety of electrochemical devices, separators having a ceramic-containing heat-resistant layer on at least one surface of a porous polymer substrate have been attempted. However, when the heat-resistant layer having a smaller thickness is formed to reduce the thickness of the separator, peeling occurs due to lower adhesive strength between the porous polymer substrate and the heat-resistant layer. Disclosure of Invention Technical problem The present disclosure relates to providing separators having a smaller thickness and improved peel strength. Technical proposal One aspect of the present disclosure provides a separator, an electrochemical device, and a method for manufacturing a separator of the following embodiments. The separator according to the first embodiment includes: A porous polymer substrate, and a porous coating layer, Wherein the porous coating layer includes an adhesive layer on at least one surface of the porous polymer substrate, and a heat-resistant layer on one surface of the adhesive layer, Wherein the adhesive layer comprises a first adhesive polymer, Wherein the heat resistant layer comprises inorganic particles and a second binder polymer, Wherein the first binder polymer comprises an acrylic polymer, and Wherein the swelling ratio (swelling ratio) of the acrylic polymer is 50% or more. According to a second embodiment, in the first embodiment, The swelling ratio of the acrylic polymer may be 60% or more. According to a third embodiment, in the first or second embodiment, The swelling ratio of the acrylic polymer can be measured by the following formula 1: (1) In formula 1, W 0 represents the initial mass of the film made of the adhesive polymer when measured at 25 ℃, and W 1 represents the mass of the adhesive polymer film measured at 25 ℃ after the film has been put into dimethyl carbonate and stored at 60 ℃ for 48 hours. According to a fourth embodiment, in any one of the first to third embodiments, The carbonate-based solvent may include dimethyl carbonate. According to a fifth embodiment, in any one of the first to fourth embodiments, The acrylic polymer may be crosslinked and have a degree of crosslinking of 0.01% to 80%. According to a sixth embodiment, in any one of the first to fifth embodiments, The acrylic polymer may include poly (methyl methacrylate) (poly (methylmethacrylate)), poly (ethylhexyl acrylate) (poly (ethylhexyl acrylate)), poly (butyl acrylate) (poly (butylacrylate)), poly (acrylonitrile) (poly (acrylonitrile)), a copolymer of ethylhexyl acrylate (ethylhexyl acrylate) and methyl methacrylate (METHYL METHACRYLATE), a copolymer of butyl acrylate and methyl methacrylate, an ethyl acrylate-N, N-dimethylacrylamide copolymer, an ethyl acrylate-2- (dimethylamino) ethyl acrylate copolymer, an ethyl acrylate-N, N-diethylacrylamide copolymer, an ethyl acrylate-2- (diethylamino) ethyl acrylate copolymer, or a mixture of two or more thereof. According to a seventh embodiment, in any one of the first to sixth embodiments, The peel strength (PEEL STRENGTH) between the porous polymer substrate and the porous coating may be 50 gf/15mm or greater. According to an eighth embodiment, in any one of the first to seventh embodiments, The adhesive