Crosslinking polymer-supported porous film for battery separator and method for producing battery using the same

Abstract

A porous film having a crosslinking polymer supported thereon, which can preferably be used for producing a gel electrolyte battery having sufficient adhesion between the electrodes and the separator, low internal resistance and high rate performance, and which can function as a separator in a battery, and a method for producing a gel electrolyte battery using such a crosslinking polymer-supported porous film. The crosslinking polymer-supported porous film for battery separator comprises a porous film substrate having supported thereon a crosslinking polymer having plural cation-polymerizable functional groups in the molecule. The method for producing a battery, includes the steps of: laminating electrodes on the crosslinking polymer-supported porous film to prepare a laminate of crosslinking polymer-supported porous film/electrodes; placing the laminate in a battery container; and pouring an electrolyte solution containing a cation polymerization catalyst in the battery container to induce cation polymerization and crosslinking of the crosslinking polymer, thereby at least partially gelling the electrolyte solution to adhere the porous film and the electrodes.

What is claimed is:  
     
         1 . A crosslinking polymer-supported porous film for battery separator, comprising a porous film substrate having supported thereon a crosslinking polymer having plural cation-polymerizable functional groups in the molecule.  
     
     
         2 . The crosslinking polymer-supported porous film as claimed in  claim 1 , wherein the crosslinking polymer has a plurality of at least one cation polymerizable functional group selected from the group consisting of 3-oxetanyl group and epoxy group.  
     
     
         3 . The crosslinking polymer-supported porous film as claimed in  claim 1 , wherein the crosslinking polymer is a radical copolymer comprising at least one radical-polymerizable monomer selected from the group consisting of a radical-polymerizable monomer having 3-oxetanyl group and a radical-polymerizable monomer having epoxy group, and other radical-polymerizable monomer.  
     
     
         4 . The crosslinking polymer-supported porous film as claimed in  claim 1 , wherein the crosslinking polymer is a radical copolymer comprising 5-50% by weight of a radical-polymerizable monomer having 3-oxetanyl group and other radical-polymerizable monomer.  
     
     
         5 . The crosslinking polymer-supported porous film as claimed in  claim 1 , wherein the crosslinking polymer is a radical copolymer comprising 5-50% by weight of a radical-polymerizable monomer having epoxy group and other radical-polymerizable monomer.  
     
     
         6 . The crosslinking polymer-supported porous film as claimed in  claim 3 , wherein the radical-polymerizable monomer having 3-oxetanyl group is 3-oxetanyl group-containing (meth)acrylate represented by the following formula (I):  
       
         
           
           
               
               
           
         
       
       wherein R 1  represents hydrogen atom or methyl group; and R 2  represents hydrogen atom or an alkyl group having 1-6 carbon atoms.  
     
     
         7 . The crosslinking polymer-supported porous film as claimed in  claim 3 , wherein the radical-polymerizable monomer having epoxy group is epoxy group-containing (meth)acrylate represented by the following formula (II):  
       
         
           
           
               
               
           
         
       
       wherein R 3  represents hydrogen atom or methyl group; and R 4  represents an epoxy group-containing group represented by the following formula (1) or (2):  
       
         
           
           
               
               
           
         
       
     
     
         8 . The crosslinking polymer-supported porous film as claimed in  claim 3 , wherein the other radical-polymerizable monomer is at least one monomer selected from the group consisting of (meth)acrylate represented by the following formula (III):  
       
         
           
           
               
               
           
         
       
       wherein R 5  represents hydrogen atom or methyl group; A represents an oxyalkylene group having 2 or 3 carbon atoms; R 6  represents an alkyl group having 1-6 carbon atoms or a fluorinated alkyl group having 1-6 carbon atoms; and n is an integer of 0-3, and vinyl ester represented by the following formula (IV):  
       
         
           
           
               
               
           
         
       
       wherein R 7  represents methyl group or ethyl group; and R 8  represents hydrogen atom or methyl group.  
     
     
         9 . The crosslinking polymer-supported porous film as claimed in  claim 1 , wherein the porous film substrate has a thickness of 3-50 μm and a porosity of 20-95%.  
     
     
         10 . A method for producing a battery, comprising: 
 laminating electrodes on the crosslinking polymer-supported porous film as claimed in  claim 1  to prepare a laminate of crosslinking polymer-supported porous film/electrodes,    placing the laminate in a battery container, and    pouring an electrolyte solution containing a cation polymerization catalyst in the battery container to induce cation polymerization and crosslinking of the crosslinking polymer, thereby at least partially gelling the electrolyte solution to adhere the porous film and the electrodes.    
     
     
         11 . The method for producing battery as claimed  claim 10 , wherein the cation polymerization catalyst is an onium salt.  
     
     
         12 . The method for producing battery as claimed in  claim 10 , wherein the electrolyte solution contains at least one member selected from the group consisting of lithium hexafluorophosphate and lithium tetrafluoroborate, as an electrolyte salt further functioning as a cation polymerization catalyst.