# US 12,183,949 B2 · Separator for secondary battery, manufacturing method thereof, method for manufacturing secondary battery comprising the separator and secondary battery manufactured by the method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,183,949 B2 - Document ID: US12183949B2 - Status: Granted - Kind: B2 - Application number: 17/914,126 - Filed: 2021-07-15 - Published: 2024-02-01 - Granted: 2024-12-31 - Earliest claimed: 2020-07-20 - Assignees: LG Energy Solution, Ltd. - Applicants: LG Energy Solution, Ltd. - Inventors: Kyung-Ryun Ka; Hye-Jin Kwon; Seung-Hyun Lee; Je-An Lee - Web page: https://patentgrep.com/patent/US12183949B2 ## CPC - H01M 50/417: Polyolefins - H01M 50/449: having a layered structure - H01M 10/052: Li-accumulators - H01M 10/0585: of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators - H01M 10/0587: of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators - H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)} - H01M 50/42: Acrylic resins - H01M 50/434: Ceramics - H01M 50/443: Particulate material - H01M 50/446: Composite material consisting of a mixture of organic and inorganic materials - H01M 50/451: comprising layers of only organic material and layers containing inorganic material - H01M 50/457: comprising three or more layers - H01M 50/461: {with adhesive layers between electrodes and separators} - H01M 50/491: Porosity - H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries - Y02E 60/10: Energy storage using batteries - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A separator for a secondary battery comprising a porous polymer substrate; a first layer on at least one surface of the porous polymer substrate, wherein the first layer includes inorganic particles and a nonparticulate acrylic polymer having a glass transition temperature of 15° C. or less, wherein the nonparticulate acrylic polymer connects and fixes the inorganic particles; and a second layer on an upper surface of the first layer, wherein the second layer includes a particulate acrylic polymer having a glass transition temperature of 20° C. to 50° C. The separator for a secondary battery has good adhesion with the electrode and can solve the resistance problem in the presence of the inorganic particles. ## Claims ### Claim 1 A separator for a secondary battery, comprising: a porous polymer substrate; a first layer on at least one surface of the porous polymer substrate, wherein the first layer comprises inorganic particles and a nonparticulate acrylic polymer having a glass transition temperature of 15° C. or less, wherein the nonparticulate acrylic polymer connects and fixes the inorganic particles; and a second layer on an upper surface of the first layer, wherein the second layer comprises a uniform particulate acrylic polymer, wherein the uniform particulate acrylic polymer has a glass transition temperature in a range of 20° C. to 50° C., wherein in the first layer and the second layer, a slurry containing the inorganic particles, the nonparticulate acrylic polymer, and the uniform particulate acrylic polymer is coated on at least one surface of the porous polymer substrate, and the uniform particulate acrylic polymer has a lower density than the inorganic particles to move to an upper part of the inorganic particles so that the second layer is formed on the upper surface of the first layer. ### Claim 2 (depends on 1) The separator for the secondary battery according to claim 1, wherein the glass transition temperature of the nonparticulate acrylic polymer is 0° C. or less. ### Claim 3 (depends on 1) The separator for the secondary battery according to claim 1, wherein the nonparticulate acrylic polymer comprises a repeating unit comprising a first monomer and a repeating unit comprising a second monomer, and wherein a glass transition temperature of the first monomer is higher than a glass transition temperature of the second monomer. ### Claim 4 (depends on 3) The separator for the secondary battery according to claim 3, wherein the first monomer comprises at least one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, or t-butyl methacrylate. ### Claim 5 (depends on 3) The separator for the secondary battery according to claim 3, wherein the second monomer comprises at least one of 2-ethyl hexyl methacrylate, lauryl methacrylate or octadecyl methacrylate. ### Claim 6 (depends on 3) The separator for the secondary battery according to claim 3, wherein the repeating unit comprising the second monomer is present in an amount of 60 weight % or more based on 100 weight % of the nonparticulate acrylic polymer. ### Claim 7 (depends on 1) The separator for the secondary battery according to claim 1, wherein the uniform particulate acrylic polymer comprises a repeating unit comprising a third monomer and a repeating unit comprising a fourth monomer, and wherein a glass transition temperature of the third monomer is higher than a glass transition temperature of the fourth monomer. ### Claim 8 (depends on 7) The separator for the secondary battery according to claim 7, wherein the third monomer comprises at least one of styrene, vinyl acetate or acrylonitrile. ### Claim 9 (depends on 7) The separator for the secondary battery according to claim 7, wherein the fourth monomer comprises at least one of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethyl hexyl acrylate or ethylene. ### Claim 10 (depends on 7) The separator for the secondary battery according to claim 7, wherein a weight ratio of the repeating unit comprising the third monomer to the repeating unit comprising the fourth monomer is 1.5:8.5 to 4:6. ### Claim 11 (depends on 1) The separator for the secondary battery according to claim 1, wherein an average particle size of the uniform particulate acrylic polymer is in a range of 200 nm to 800 nm. ### Claim 12 (depends on 1) The separator for the secondary battery according to claim 1, wherein a ratio of a density of the uniform particulate acrylic polymer to a density of the inorganic particles is 0.5 or less. ### Claim 13 (depends on 1) The separator for the secondary battery according to claim 1, wherein a density of the uniform particulate acrylic polymer is 1.5 g/m3 or less. ### Claim 14 (depends on 1) The separator for the secondary battery according to claim 1, wherein a density of the inorganic particles is 2.0 g/m3 or more. ### Claim 15 (depends on 1) The separator for the secondary battery according to claim 1, wherein the separator for the secondary battery has an adhesion strength with an electrode of 30 gf/25 mm to 200 gf/25 mm. ### Claim 16 (depends on 1) The separator for the secondary battery according to claim 1, wherein an air permeability of the separator for the secondary battery is in a range of 10 sec/100 cc to 300 sec/100 cc. ### Claim 17 (depends on 1) The separator for the secondary battery according to claim 1, wherein an adhesion strength between the porous polymer substrate and the first layer is 10 gf/15 mm to 300 gf/15 mm. ### Claim 18 (depends on 1) A secondary battery, comprising: a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the separator is the separator for the secondary battery according to claim 1. ### Claim 19 A method for manufacturing a secondary battery comprising: (S1) preparing a porous polymer substrate; (S2) preparing an aqueous slurry comprising inorganic particles, a nonparticulate acrylic polymer having a glass transition temperature of 15° C. or less, and a uniform particulate acrylic polymer, wherein the uniform particulate acrylic polymer has a glass transition temperature in a range of 20° C. to 50° C.; (S3) coating the aqueous slurry on at least one surface of the porous polymer substrate; and (S4) drying the result of the (S3), wherein the nonparticulate acrylic polymer adheres the inorganic particles to each other to keep the inorganic particles held together, and wherein the uniform particulate acrylic polymer has a lower density than the inorganic particles to move to an upper part of the inorganic particles so that a second layer is formed on an upper surface of a first layer including the inorganic particles. ### Claim 20 (depends on 19) The method for manufacturing a secondary battery according to claim 19, wherein a ratio of a density of the uniform particulate acrylic polymer to a density of the inorganic particles is 0.5 or less.