Laminable, dimensionally-stable microporous webs

Abstract

Laminable microporous polymer webs wish good dimensional stability are disclosed herein. Methods of making and using laminable microporous polymer webs with good dimensional stability are also disclosed herein.

1 - 37 . (canceled) 
     
     
         38 . A battery separator comprising:
 a free-standing multi-layer structure with first and second major surfaces, the structure comprising:
 a microporous polymer web characterized by a melting point and having two major surfaces; and 
 an inorganic material including one or more of nanoparticles or microparticles deposited from an aqueous dispersion as a first porous layer on one or both of the major surfaces of the microporous polymer web, the first porous layer providing in-plane high-temperature dimensional stability above the melting point of the microporous polymer web; 
 a gel-forming material disposed as a second porous layer on the first porous layer, the gel-forming material being laminable to an electrode. 
   
     
     
         39 . The battery separator of  claim 38 , wherein the microporous polymer web comprises polyethylene. 
     
     
         40 . The battery separator of  claim 38 , wherein the inorganic material is deposited on both major surfaces of the microporous polymer web. 
     
     
         41 . The battery separator of  claim 38 , wherein the second porous layer comprises polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene) copolymers, poly(vinylidene fluoride-acrylic acid) copolymers, polyacrylate copolymers, polymethacrylate copolymers, or mixtures thereof. 
     
     
         42 . The battery separator of  claim 38 , wherein the first porous layer exhibits a coating ratio and a concentration of microparticles to nanoparticles that causes the structure to exhibit a thermal shrinkage below 5% at 180° C., wherein the coating ratio is a weight-to-weight basis of the first porous layer to the microporous polyolefin web. 
     
     
         43 . The battery separator of  claim 42 , wherein the first porous layer exhibits a nanoparticle concentration of 0% to 22% and the coating ratio is greater than 1.4-0.0036*N, wherein N is the nanoparticle concentration in percent form. 
     
     
         44 . The battery separator of  claim 42 , wherein the first porous layer exhibits a nanoparticle concentration of 22% to 33% and the coating ratio is greater than 1.32-0.0291*(N-22), wherein N is the nanoparticle concentration in percent form. 
     
     
         45 . The battery separator of  claim 42 , wherein the first porous layer exhibits a nanoparticle concentration of 33% to 48% and the coating ratio is greater than 1-0.0107*(N-33), wherein N is the nanoparticle concentration in percent form. 
     
     
         46 . The battery separator of  claim 42 , wherein the first porous layer exhibits a nanoparticle concentration of 48% to 67% and the coating ratio is greater than 0.84-0.0095*(N-48), wherein N is the nanoparticle concentration in percent form. 
     
     
         47 . The battery separator of  claim 42 , wherein the first porous layer exhibits a nanoparticle concentration of 67% to 100% and the coating ratio is greater than 0.66-0.0.0048*(N-67), wherein N is the nanoparticle concentration in percent form. 
     
     
         48 . The battery separator of  claim 38 , wherein the inorganic material comprises an inorganic oxide, carbonate, hydroxide, or mixtures thereof. 
     
     
         49 . The battery separator of  claim 48 , wherein the inorganic material comprises alumina, silica, zirconia, titania, mica, boehmite, magnesium hydroxide, calcium carbonate, or mixtures thereof. 
     
     
         50 . The battery separator of  claim 38 , wherein the first porous layer further comprises an organic hydrogen bonding component. 
     
     
         51 . The battery separator of  claim 50 , wherein the first porous layer further comprises a cross-linking agent reacted with the organic hydrogen bonding component. 
     
     
         52 . The battery separator of  claim 50 , wherein the microporous polymer web exhibits in-plane high temperature dimensional stability at greater than 150 C above the melting point of the microporous polymer web. 
     
     
         53 . The battery separator of  claim 38 , wherein the inorganic material comprises particles with a sufficient ratio of nanoparticles to microparticles to minimize water content at or above a threshold coating ratio that minimizes thickness of the first porous layer. 
     
     
         54 . A battery comprising:
 a secondary cell having at least two electrodes contained in a package filled with electrolyte and separated by the battery separator of  claim 38 .   
     
     
         55 . An electric motor vehicle power train, comprising:
 a battery pack providing direct current power to an inverter to produce alternating current power, the battery pack including multiple electrically connected secondary cells, each of the multiple secondary cells having multiple electrodes contained in a package filled with electrolyte and separated by the battery separator of  claim 38 ;   speed reduction gears operatively connected to a set of vehicle wheels; and   an electric motor operatively connected to the speed reduction gears and responding to the alternating current power produced by the inverter to impart motive force to the speed reduction gears and thereby turn the set of vehicle wheels.   
     
     
         56 . A battery separator comprising:
 a free-standing multi-layer structure with first and second major surfaces, the structure comprising a microporous polymer web characterized by a melting point and having two major surfaces, an inorganic material including one or more of nanoparticles or microparticles deposited from an aqueous dispersion as a first porous layer on both of the major surfaces of the microporous polymer web;   wherein the nanoparticles include individual particles or multi-particle aggregates with a mean size less than or equal to 100 nanometers, and microparticles include individual particles, multi-particle aggregates, or multi-aggregate agglomerates with a mean size of 100 nanometers to 1 micrometer, the first porous layer providing high-temperature dimensional stability above the melting point of the microporous polymer web even as fluid permeability of the unitary multi-layer structure is decreased at elevated temperature; and   wherein the first porous layer exhibits a coating ratio and a concentration of microparticles to nanoparticles that causes the structure to exhibit a thermal shrinkage below 5% at 180° C., wherein the coating ratio is a weight-to-weight basis of the first porous layer to the microporous polyolefin web, and wherein the coating ratio is greater than about 0.5.   
     
     
         57 . A method of making a laminable battery separator, comprising:
 providing a first aqueous-based dispersion comprising inorganic particles;   providing a microporous polymer web having first and second major surfaces, and characterized by a melting point;   wetting the first major surface of the microporous polymer web with the first aqueous-based dispersion;   drying the wetted microporous polymer web to form a first porous layer on the first major surface of the microporous polymer web, the first porous layer comprising inorganic particles;   providing a second aqueous-based dispersion containing a gel-forming polymer material;   wetting the first porous layer on the first major surface of the microporous polymer web with the second aqueous-based dispersion; and   drying the gel-forming polymer material to form, on the first porous layer, a second porous layer in which are formed passageways that extend from an outer surface of the second porous layer to an outer surface of the first porous layer.