# US 5,700,600 A · Long life battery separator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,600 A - Document ID: US5700600A - Status: Granted - Kind: A - Application number: 08/585,555 - Filed: 1996-01-12 - Granted: 1997-12-23 - Earliest claimed: 1996-01-12 - Inventors: Thomas Danko; Myron Donald Nicholson - Web page: https://patentgrep.com/patent/US5700600A ## CPC - 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 - H01M 50/414: Synthetic resins, e.g. thermoplastics or thermosetting resins - H01M 50/417: Polyolefins - H01M 50/423: Polyamide resins - H01M 50/429: Natural polymers - H01M 50/454: comprising a non-fibrous layer and a fibrous layer superimposed on one another - H01M 50/494: Tensile strength - H01M 2300/0014: Alkaline electrolytes - 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 A battery separator of a noncellulosic nonwoven substrate extrusion coated on at least one surface with a cellulose film and process for making such separator by contacting a nonwoven noncellulosic textile substrate with a cellulose or cellulose derivative solution on at least one side of said substrate; converting the solution to a solid cellulose or cellulose derivative, preferably having a degree of polymerization of at least 350, more preferably at least 600, to form a coated substrate; washing and drying the coated substrate to provide a battery separator, preferably having a absorption rate of at least 6 mm/5 min. and a 30% KOH absorption of at least 200 g/m.sup.2. ## Claims ### Claim 1 A delamination resistant, battery separator comprising: a nonwoven substrate comprising noncellulosic fibers, said substrate having on at least one surface an extrusion coated cellulosic film having a degree of polymerization of at least about 350, said separator having at least 20% by weight of cellulose added to said substrate based on a bone dry gauge weight of said nonwoven substrate, and said separator having an absorption rate of at least 6 mm/5 min. of an aqueous 30 wt. % KOH solution, and a 30 wt. % KOH solution absorption capacity of at least 200 g/m.sup.2 and a retained wet tensile strength of at least 70% after 41 days in an aqueous solution of 40 weight % KOH. ### Claim 2 (depends on 1) A battery separator, as defined in claim 1, wherein said noncellulosic fibers comprise at least 50 weight % of said nonwoven substrate. ### Claim 3 (depends on 1) A battery separator, as defined in claim 1, wherein said noncellulosic fibers comprise at least 95 weight % of said nonwoven substrate. ### Claim 4 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven noncellulosic substrate comprises polyolefin fibers, polyamide fibers, polyester fibers, or poly(vinyl alcohol) fibers, or blends thereof. ### Claim 5 (depends on 4) A battery separator, as defined in claim 4, wherein said nonwoven substrate further comprises natural cellulose fibers, synthetic cellulose fibers, or blends thereof. ### Claim 6 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises at least 95 weight % polyamide fibers held together by a binding means. ### Claim 7 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises nylon 6, nylon 66, nylon 11, nylon 12, nylon 6,12, nylon 6/12 copolymer, nylon 6/66 copolymer or blends thereof. ### Claim 8 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises polypropylene fibers. ### Claim 9 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises poly(vinyl alcohol) fibers. ### Claim 10 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises polyester fibers. ### Claim 11 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate comprises acrylonitrile-vinyl chloride copolymer fibers. ### Claim 12 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating has a degree of polymerization of at least 600. ### Claim 13 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating comprises regenerated cellulose. ### Claim 14 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating is cellulose, regenerated cellulose, deacetylated cellulose acetate, or viscose having a degree of polymerization of at least about 600. ### Claim 15 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating is deacetylated cellulose acetate. ### Claim 16 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating is derived from a cellulose material comprising at least 90% .alpha.-cellulose. ### Claim 17 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating is derived from a cellulose material comprising at least 95% .alpha.-cellulose. ### Claim 18 (depends on 1) A battery separator, as defined in claim 1, wherein said cellulosic coating is derived from a cellulose material comprising at least 98% .alpha.-cellulose. ### Claim 19 A process for making a delamination resistant battery separator comprising: contacting a nonwoven noncellulosic textile substrate with a liquid cellulose or cellulose derivative solution on at least one side of said substrate; converting said solution to a solid cellulose or cellulose derivative film having a degree of polymerization of at least 350 to form a coated substrate; washing and drying said coated substrate to provide a battery separator having an absorption rate of at least 6 mm/5 min. of an aqueous 30 wt. % KOH solution and a 30% KOH absorption capacity of at least 200 g/m.sup.2, said separator having at least 20% by weight of cellulose added to said substrate based on a bone dry gauge weight of said nonwoven substrate, and wherein said separator has a retained wet strength of at least 70% after 41 days in an aqueous solution of 40% KOH. ### Claim 20 (depends on 19) A process, as defined in claim 19, wherein said degree of polymerization is at least 600. ### Claim 21 (depends on 19) A process, as defined in claim 19, wherein said substrate is in the shape of a tube as said solution is solidified. ### Claim 22 (depends on 1) A battery separator, as defined in claim 1, wherein said nonwoven substrate fibers are held together by a binding means. ### Claim 23 (depends on 22) A battery separator, as defined in claim 22, wherein said binding means comprises 0-5% of regenerated cellulose, an alkyl ketene dimer, a solvated cellulose, or blends thereof, or hydrogen bonds. ### Claim 24 (depends on 1) A battery separator, as defined in claim 1, wherein said separator has a retained wet tensile strength after 83 days of at least 70%. ### Claim 25 (depends on 1) A battery separator, as defined in claim 1, wherein said separator has a retained wet tensile strength after 83 days of at least 90%. ### Claim 26 (depends on 21) A process, as defined in claim 21, wherein said cellulose solution is a solution of cellulose in N-methyl-morpholine-n-oxide. ### Claim 27 A process for making a battery separator comprising: contacting a nonwoven noncellulosic substrate web with a solution of cellulose having at least 95% .alpha.-cellulose in a solvent of N-methyl-morpholine-n-oxide while forming said substrate into a tube; converting said solution to a solid cellulose having a degree of polymerization of at least 350 by removing said solvent to form a cellulose coated tubular substrate; washing and drying said tubular coated substrate to provide a glycerine-free battery separator having a coated substrate thickness of 10 mils or less; wherein penetration of said cellulose coating into said nonwoven substrate is controlled to provide a delamination resistant battery separator having an absorption rate of at least 6 mm/5 min of an aqueous 30 wt. % KOH solution and a 30% KOH absorption capacity of at least 200 g/m.sup.2 and a retained wet tensile strength of at least 70% after 41 days in an aqueous solution of 40% KOH. ### Claim 28 (depends on 27) A process, as defined in claim 27, wherein said cellulose coating is applied at a level of from 100 to 300% bone dry gauge of said nonwoven substrate. ### Claim 29 (depends on 28) A process, as defined in claim 28, wherein said coating application level is from 100 to 150% bone dry gauge of said nonwoven substrate. ### Claim 30 (depends on 1) A film, as defined in claim 1, wherein said separator has between about 150 to 300% by weight of cellulose added to said substrate based on a bone dry gauge weight of said nonwoven substrate.