# US 12,113,238 B2 · Separator for lithium secondary battery, method of producing the same, and electrochemical device including the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,238 B2 - Document ID: US12113238B2 - Status: Granted - Kind: B2 - Application number: 17/463,907 - Filed: 2021-09-01 - Published: 2022-03-10 - Granted: 2024-10-08 - Earliest claimed: 2020-09-10 - Assignees: SK Innovation Co., Ltd.; SK ie technology Co., Ltd. - Applicants: SK Innovation Co., Ltd.; SK ie technology Co., Ltd. - Inventors: Tae Wook Kwon; Heung Taek Bae; Dong Yeon Lee; Yun Bong Kim - Web page: https://patentgrep.com/patent/US12113238B2 ## CPC - H01M 50/446: Composite material consisting of a mixture of organic and inorganic materials - H01M 10/052: Li-accumulators - H01M 50/403: Manufacturing processes of separators, membranes or diaphragms - H01M 50/42: Acrylic resins - H01M 50/449: having a layered structure - H01M 50/489: Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties - Y02E 60/10: Energy storage using batteries - 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 ## Abstract Provided is a separator for a lithium secondary battery including a porous substrate and a coating layer including a binder and inorganic particles formed on one surface or both surfaces of the porous substrate. The binder is a binder including: (a) a (meth)acrylamide-based monomer polymerization unit, (b) a (meth)acryl-based monomer polymerization unit containing a hydroxyl group, and (c) a polyfunctional (meth)acrylamide-based monomer polymerization unit. The separator according to the present invention provides a separator for a lithium secondary battery having improved adhesive strength between the inorganic particles and the separator, showing a decreased interfacial resistance characteristic, and showing an improved air permeability. ## Claims ### Claim 1 A separator for a lithium secondary battery comprising: a porous substrate; and a coating layer comprising a binder and inorganic particles formed on one surface or both surfaces of the porous substrate, wherein the binder is a binder comprising: (a) 68 to 93 mol % of a (meth)acrylamide-based monomer polymerization unit, (b) 6 to 31 mol % of a (meth)acryl-based monomer polymerization unit containing a hydroxyl group, and (c) 0.005 to 0.041 mol % of a polyfunctional (meth)acrylamide-based monomer polymerization unit, wherein (b) the (meth)acryl-based monomer polymerization unit containing a hydroxyl group is represented by the following Chemical Formula 2: wherein R2 is hydrogen or a C1 to C6 alkyl group, and L1 is a linear or branched C1 to C6 alkylene group. ### Claim 2 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein (c) the polyfunctional (meth)acrylamide-based monomer polymerization unit is produced by polymerizing a polyfunctional monomer represented by the following Chemical Formula 3: wherein R1 and R2 are independently of each other hydrogen or a C1 to C6 alkyl group, R is a linear or branched C1 to C10 hydrocarbon group, and a is an integer of 2 to 6. ### Claim 3 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein the binder has a weight average molecular weight of 100,000 to 2,000,000 g/mol. ### Claim 4 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein the coating layer comprises 50 to 99.9 wt % of the inorganic particles and 0.1 to 50 wt % of the binder based on a total weight of the coating layer. ### Claim 5 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein the separator for a lithium secondary battery has a shrinkage rate both in a machine direction (MD) and a transverse direction (TD) of 5% or less after being allowed to stand at 150° C. for 60 minutes. ### Claim 6 (depends on 5) The separator for a lithium secondary battery of claim 5, wherein the separator for a lithium secondary battery has a shrinkage rate both in the machine direction (MD) and the transverse direction (TD) of 3% or less after being allowed to stand at 150° for 60 minutes. ### Claim 7 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein the separator for a lithium secondary battery has a change amount of air permeability (ΔG) satisfying the following Equation 1: ΔG=G1−G2≤70 [Equation 1] wherein G1 is a Gurley permeability of the separator comprising the coating layer, G2 is a Gurley permeability of the porous substrate itself, and the Gurley permeability is measured in accordance with ASTM D726 and has a unit of sec/100 cc. ### Claim 8 (depends on 1) The separator for a lithium secondary battery of claim 1, wherein the coating layer has a thickness of 0.3 to 10 μm. ### Claim 9 (depends on 1) A lithium secondary battery comprising the separator for a lithium secondary battery of claim 1. ### Claim 10 A method of producing a separator for a lithium secondary battery, the method comprising: (s1) preparing a slurry composition comprising a binder and inorganic particles; and (s2) applying the slurry composition on one surface or both surfaces of a porous substrate to form a coating layer, wherein the binder is a binder comprising: (a) 66 to 93 mol % of a (meth)acrylamide-based monomer polymerization unit, (b) 6 to 31 mol % of a (meth)acryl-based monomer polymerization unit containing a hydroxyl group, and (c) 0.005 to 0.041 mol % of a polyfunctional (meth)acrylamide-based monomer polymerization unit, wherein (b) the (meth)acryl-based monomer polymerization unit containing a hydroxyl group is represented by the following Chemical Formula 2: wherein R2 is hydrogen or a C1 to C6 alkyl group, and L1 is a linear or branched C1 to C6 alkylene group.