Polyolefin and ceramic battery separator for non-aqueous battery applications

Abstract

A ceramic microporous polyolefin battery separator membrane, high in air permeability, low in shrinkage and improved temperature resistance addresses the safety requirements of lithium ion batteries. The separators made by the current invention consists of one or more polyolefin polymers and kaolin fillers comprised of aluminum oxide and silicon oxide. The membranes of current invention have a thickness of 5-200 microns, air permeability of 1-200 sec/10 cc (Gurley seconds), and average pore diameter of less than 1 micron.

1 - 14 . (canceled) 
     
     
         15 . A separator for a lithium-ion battery with resistance to thermal runaway and without shutdown, the separator comprising a combination of polyolefin and kaolin, wherein the combination is formed into a microporous membrane having no shutdown temperature. 
     
     
         16 . The separator of  claim 15  wherein the kaolin is a calcined kaolin. 
     
     
         17 . The separator of  claim 15  wherein the polyolefin includes an ultra high molecular weight polyethylene having an average molecular weight of 1×10 6  or more. 
     
     
         18 . The separator of  claim 17  wherein the polyolefin includes polypropylene with a melt index of 2 or less. 
     
     
         19 . The separator of  claim 15  wherein the polyolefin includes an ultra high molecular weight polyethylene having an average molecular weight of 1×10 6  or more and polypropylene with a melt index of 2 or less and the kaolin is a calcined kaolin. 
     
     
         20 . The separator of  claim 19  wherein a weight ratio of the ultra high molecular weight polyethylene to the polypropylene is about two to one. 
     
     
         21 . The separator of  claim 19  wherein a weight ratio of polyolefin to calcined kaolin is about three to two. 
     
     
         22 . The separator of  claim 15  wherein the microporous membrane has a porosity of at least 60% and an air permeability of between 1 and 200 sec/10 cc. 
     
     
         23 . The separator of  claim 15  wherein the separator has a melt integrity of at least 190° C., a puncture resistance of more than 550 grams and a tensile strength at 1000 psi of less than 2% offset. 
     
     
         24 . A lithium-ion battery with resistance to thermal runaway and without shutdown, the battery comprising a separator formed of a combination of polyolefin and kaolin, wherein the combination is formed into a microporous membrane having no shutdown temperature. 
     
     
         25 . The battery of  claim 24  wherein the kaolin is a calcined kaolin. 
     
     
         26 . The battery of  claim 24  wherein the polyolefin includes an ultra high molecular weight polyethylene having an average molecular weight of 1×10 6  or more. 
     
     
         27 . The battery of  claim 26  wherein the polyolefin includes polypropylene with a melt index of 2 or less. 
     
     
         28 . The battery of  claim 24  wherein the polyolefin includes an ultra high molecular weight polyethylene having an average molecular weight of 1×10 6  or more and polypropylene with a melt index of 2 or less and the kaolin is a calcined kaolin. 
     
     
         29 . The battery of  claim 28  wherein a weight ratio of the ultra high molecular weight polyethylene to the polypropylene is about two to one. 
     
     
         30 . The battery of  claim 28  wherein a weight ratio of polyolefin to calcined kaolin is about three to two. 
     
     
         31 . The battery of  claim 24  wherein the microporous membrane has a porosity of at least 60% and an air permeability of between 1 and 200 sec/10 cc. 
     
     
         32 . The battery of  claim 24  wherein the separator has a melt integrity of at least 190° C., a puncture resistance of more than 550 grams and a tensile strength at 1000 psi of less than 2% offset.