Electric separator comprising a shut-down mechanism, method for the production thereof and its use in lithium batteries
(19)AUSTRALIAN PATENT OFFICE(54) Title Electric separator comprising a shut-down mechanism, method for the production thereof and itsuse in lithium batteries(51)G International Patent Classification(s) H01M 002/16(21) Application No: 2003250909 (22) Application Date: 2003 .07.08(87) WIPO No: WO04/021469(30) Priority Data (31) Number (32) Date 102 38 945.4 2002 .08.24 (33) Country DE 200511037(43)Publication Date : 2004.03.19(43)Publication Journal Date : 2004 .05.06(71) Applicant(s) CREAVIS GESELLSCHAFT FUR TECHNOLOGIE UND INNOVATION MBH(72) Inventor(s) Horpel, Gerhard; Henniqe, Volker;Hying, Christian(-1-1) Application NoAU2003250909 A8(19)AUSTRALIAN PATENT OFFICE(54) Title Electric separator comprising a shut-down mechanism, method for the production thereof and itsuse in lithium batteries(51)G International Patent Classification(s) H01M 002/16(21) Application No: 2003250909 (22) Application Date: 2003 .07.08(87) WIPO No: WO04/021469(30) Priority Data (31) Number (32) Date 102 38 945.4 2002 .08.24 (33) Country DE 200511037(43)Publication Date : 2004.03.19(43)Publication Journal Date : 2004 .05.06(71) Applicant(s) CREAVIS GESELLSCHAFT FUR TECHNOLOGIE UND INNOVATION MBH(72) Inventor(s) Horpel, Gerhard; Henniqe, Volker;Hying, Christian-1- Electrical separators for batteries, especially lithium batteries, having a shutdown mechanism. A process for their production. An electrical separator is used in batteries and other systems in which electrodes have to be separated from each other while maintaining ion conductivity. Safety is very important in lithium batteries, since in contrast to other types of battery (Pb, NiCd, NiMeH) the solvent for the electrolyte is not water but a combustible solvent. A separator for lithium cells must possess a shutdown mechanism while not being able to melt down. This is achieved by an electrical separator having a shutdown layer which comprises particles which melt at a desired temperature, close the pores of the separator, and so stop ion flow. Since the separator also comprises a porous inorganic (ceramic) layer on a carrier, the cells cannot melt down as a result of a completely melted separator. Lithium battery separator having a shutdown function and comprising a porous carrier having a porous inorganic nonelectroconductive coating layer on and in said carrier, wherein a shutdown layer of shutdown particles which melt at a predetermined temperature and close the pores of said inorganic layer is present on said inorganic layer and bonded thereto, characterized in that said porous inorganic layer is produced by using a polymeric sol comprising a silane adhesion promoter for said shutdown particles to be applied later. Separator according to Claim 1, characterized in that said carrier is flexible and less than 50 µm in thickness. Separator according to Claim 1 or 2, characterized in that said carrier comprises woven or non-woven polymeric or glass fibres. Separator according to Claim 3, characterized in that said carrier is a polymeric nonwoven. Separator according to Claim 3 or 4, characterized in that said polymeric fibres are selected from fibres of polyacrylonitrile, polyester and/or polyolefin. Separator according to at least one of Claims 1 to 5, characterized in that said carrier is less than 30 µm in thickness. Separator according to any one of Claims 1 to 6, characterized in that said porous inorganic coating layer present on said carrier comprises oxide particles of the elements Al, Si and/or Zr from 0.5 to 10 µm in size on average. Separator according to at least one of Claims 1 to 7, characterized in that said shutdown particles have an average size (Dw) which is greater than the average pore size (d) of said pores of said porous inorganic layer. Separator according to at least one of Claims 1 to 8, characterized in that the layer of shutdown particles has a thickness (zw) which is approximately in the range from said average size of said shutdown particles (Dw) up to 10 times said particle size Dw. Separator according to at least one of Claims 1 to 9, characterized in that said shutdown particles are selected from polymers, polymer blends, natural waxes or artificial waxes. Process for producing a separator having a shutdown function according to any one of Claims 1 to 10, characterized in that it comprises particles having a defined, desired melting temperature being applied to and fixed on a porous inorganic layer of a separator. Process according to Claim 11, characterized in that a separator according to at least one of Claims 1 to 10. Process according to Claim 11 or 12, characterized in that said porous inorganic layer is hydrophobicized before said shutdown particles are applied to it. Process according to any one of Claims 11 to 13, characterized in that said porous inorganic layer is treated with an adhesion promoter before said shutdown particles are applied to it. Process according to one of Claims 11 to 14, characterized in that said layer of shutdown particles is generated by applying a suspension of shutdown particles having an average size larger than the average pore size of the separator layer in a suspension medium selected from a sol, water or alcohols. Process according to Claim 15, characterized in that said suspension comprises an adhesion promoter. Process according to Claim 16, characterized in that it comprises selecting said adhesion promoter from hydrolyzed or nonhydrolyzed functionalized alkyltrialkoxysilanes. Process according to any one of Claims 15 to 17, characterized in that said suspension is applied to said porous inorganic layer by printing on, pressing, pressing in, rolling on, knifecoating on, brushing on, dipping, squirting, spraying or pouring on. Process according to at least one of Claims 15 to 18, characterized in that said layer is obtained by said applied suspension being dried at a temperature in the range from room temperature to 100°C. Process according to at least one of Claims 11 to 19, characterized in that following application to said porous inorganic layer the particles are fixed by single heating to a temperature above the glass transition temperature to fuse on said particles without changing the actual shape. Process according to at least one of Claims 11 to 20, characterized in that said shutdown particles are selected from particles composed of polymers, polymer blends, natural waxes and/or artificial waxes. Process according to Claim 21, characterized in that said shutdown particles are particles composed of polyethylene wax. Use of a separator according to at least one of Claims 1 to 10 as a separator in lithium batteries. Battery comprising a separator according to at least one of Claims 1 to 10.