# US 12,119,512 B2 · Method for preparing composite separator including controlling amount of non-solvent supplied during hot-air drying, composite separator including porous substrate with fluorine-based resin porous layer with more small-diameter pores than large-diameter pores, and lithium battery comprising composite separator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,119,512 B2 - Document ID: US12119512B2 - Status: Granted - Kind: B2 - Application number: 17/195,437 - Filed: 2021-03-08 - Published: 2021-09-09 - Granted: 2024-10-15 - Earliest claimed: 2020-03-09 - Assignees: Samsung SDI Co., Ltd. - Applicants: Samsung SDI Co., Ltd. - Inventors: Daehyun Hong - Web page: https://patentgrep.com/patent/US12119512B2 ## CPC - H01M 50/403: Manufacturing processes of separators, membranes or diaphragms - H01M 10/052: Li-accumulators - H01M 50/417: Polyolefins - H01M 50/426: Fluorocarbon polymers - H01M 50/434: Ceramics - H01M 50/446: Composite material consisting of a mixture of organic and inorganic materials - H01M 50/449: having a layered structure - 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 method of preparing a composite separator for a lithium battery includes: coating a binder composition on one side or both sides of a porous substrate; hot-air drying the porous substrate coated with the binder composition; and supplying a non-solvent during the hot-air drying, such that a porous layer is on one side or both sides of the porous substrate, wherein the binder composition includes a good-solvent, a binder, and inorganic particles, an amount of the non-solvent supplied during the hot-air drying is from 12 g/m3 to 17 g/m3, and a ratio (e) of the hot-air supply speed to the moving speed of the porous substrate per unit transit time in the hot-air dryer is from 2.2 to 5.0. ## Claims ### Claim 1 A composite separator, the composite separator comprising: a porous substrate; and a porous layer formed on one side or both sides of the porous substrate, wherein a coating amount of the porous layer is in a range from 3.5 g/m2 to 4.5 g/m2, wherein the porous layer comprises a fluorine-based binder having a polar functional group and inorganic particles, wherein the porous layer has a surface morphology in which a plurality of pores are discontinuously arranged in the form of island on a polymer film, wherein a ratio (a/b) of the number of pores having a diameter of 500 nm to 1000 nm per 1 μm2 of the porous layer (a) to the number of pores having a diameter less than 500 mm per 1 μm2 of the porous layer (b) is from 0.25 to 0.85, wherein the porous layer has a peel strength of 0.3 N/m or more with respect to the porous substrate, and wherein an area covered by the plurality of pores is smaller than an area covered by the polymer film. ### Claim 2 (depends on 1) The composite separator of claim 1, wherein the peel strength is from 0.3 N/m to 0.95 N/m. ### Claim 3 (depends on 1) The composite separator of claim 1, wherein the porous layer comprises 0.3 to 0.4 pores having a diameter of 500 nm to 1000 nm per 1 μm2, and 0.5 to 1.5 pores having a diameter less than 500 nm per 1 μm2. ### Claim 4 (depends on 1) The composite separator of claim 1, wherein each of the plurality of pores has a diameter of 500 nm to 1000 nm or a diameter less than 500 nm. ### Claim 5 (depends on 1) The composite separator of claim 1, wherein the inorganic particles comprise at least one selected from alumina, titania, boehmite, and barium sulfate. ### Claim 6 (depends on 1) The composite separator of claim 1, wherein an amount of the inorganic particles is 90 wt % or less based on a total weight of the porous layer. ### Claim 7 (depends on 1) The composite separator of claim 1, wherein the fluorine-based binder comprises a vinylidene fluoride-hexafluoropropylene copolymer, and the vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of −10° C. or lower and a melting point of 150° C. or higher. ### Claim 8 (depends on 7) The composite separator of claim 7, wherein the vinylidene fluoride-hexafluoropropylene copolymer has a weight average molecular weight of 700,000 Dalton to 1,200,000 Dalton. ### Claim 9 An electrode assembly comprising: a positive electrode; a negative electrode; and a composite separator interposed between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the composite separator are wound in a jelly roll shape, wherein the electrode assembly is configured to have a bending strength of 460 N or more, the bending strength being an amount of force needed to bend the jelly roll shaped electrode in a downward direction, and wherein the composite separator comprises: a porous substrate; and a porous layer formed on one side or both sides of the porous substrate, wherein a coating amount of the porous layer is in a range from 3.5 g/m2 to 4.5 g/m2, wherein the porous layer comprises a fluorine-based binder having a polar functional group and inorganic particles, wherein the porous layer has a surface morphology in which a plurality of pores are discontinuously arranged in the form of island on a polymer film, wherein a ratio (a/b) of the number of pores having a diameter of 500 nm to 1000 nm per 1 μm2 of the porous layer (a) to the number of pores having a diameter less than 500 mm per 1 μm2 of the porous layer (b) is from 0.25 to 0.85, and wherein the porous layer has a peel strength of 0.3 N/m or more with respect to the porous substrate. ### Claim 10 (depends on 9) The composite separator electrode assembly of claim 9, wherein the bending strength is from 460 N to 550 N. ### Claim 11 (depends on 1) An electrode assembly comprising: a positive electrode; a negative electrode; and the composite separator of claim 1 interposed between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the composite separator are wound in a jelly roll shape, and wherein the electrode assembly is configured to have a bending strength of 460 N or more, the bending strength being an amount of force needed to bend the jelly roll shaped electrode in a downward direction. ### Claim 12 (depends on 11) The electrode assembly of claim 11, wherein the bending strength is from 460 N to 550 N. ### Claim 13 (depends on 1) A lithium battery, the lithium battery comprising: an electrode assembly comprising: a positive electrode; a negative electrode; and the composite separator according to claim 1 interposed between the positive electrode and the negative electrode, wherein the electrode assembly is wound in a jelly roll shape.