Slurry for forming insulating layer, separator for electrochemical device, method for producing the same, and electrochemical device

Abstract

A slurry for forming an insulating layer of the present invention includes heat-resistant insulating fine particles, a thickening agent, and a dispersion medium. The insulating fine particles are dispersed in the dispersion medium. The slurry for forming an insulating layer has a viscosity of 5 to 500 mPa·s. The proportion of particles with a particle size of 1 μm or less in the insulating fine particles is 30 vol % or more and the proportion of particles with a particles size of 3 μm or more in the insulating fine particles is 10 vol % or less. An electrochemical device of the present invention includes a separator for an electrochemical device of the present invention that is produced using the slurry for forming an electrochemical device of the present invention.

1 . A slurry for forming an insulating layer that is capable of being used to form an insulating layer of a separator for an electrochemical device, comprising:
 heat-resistant insulating fine particles;   a thickening agent; and   a dispersion medium,   wherein the insulating fine particles are dispersed in the dispersion medium,   the slurry for forming an insulating layer has a viscosity of 5 to 500 mPa·s, and   a proportion of particles with a particle size of 1 μm or less in the insulating fine particles is 30 vol % or more and a proportion of particles with a particle size of 3 μm or more in the insulating fine particles is 10 vol % or less.   
     
     
         2 . The slurry for forming an insulating layer according to  claim 1 , wherein a proportion of particles with a particle size of 2 μm or more in the insulating fine particles is 10 vol % or less. 
     
     
         3 . The slurry for forming an insulating layer according to  claim 1 , wherein the insulating fine particles are at least one selected from the group consisting of alumina fine particles, silica fine particles, and boehmite fine particles. 
     
     
         4 . The slurry for forming an insulating layer according to  claim 1 , wherein the insulating fine particles include plate-like particles. 
     
     
         5 . The slurry for forming an insulating layer according to  claim 1 , wherein the insulating fine particles include secondary particles formed by agglomeration of primary particles. 
     
     
         6 . The slurry for forming an insulating layer according to  claim 1 , wherein the thickening agent is a natural polysaccharide. 
     
     
         7 . The slurry for forming an insulating layer according to  claim 1 , further comprising a dispersing agent. 
     
     
         8 . The slurry for forming an insulating layer according to  claim 7 , wherein the dispersing agent includes a plurality of ion-dissociable acid groups or salt groups in molecules. 
     
     
         9 . The slurry for forming an insulating layer according to  claim 8 , wherein the dispersing agent is at least one selected from the group consisting of polycarboxylate, polyacrylate, and polymethacrylate. 
     
     
         10 . The slurry for forming an insulating layer according to  claim 1 , further comprising a binder. 
     
     
         11 . The slurry for forming an insulating layer according to  claim 10 , wherein the binder includes a self-crosslinking (meta) acrylic acid copolymer. 
     
     
         12 . The slurry for forming an insulating layer according to  claim 1 , further comprising at least one selected from the group consisting of a preservative and a germicide. 
     
     
         13 . The slurry for forming an insulating layer according to  claim 1 , further comprising an antifoaming agent. 
     
     
         14 . A separator for an electrochemical device comprising:
 a porous insulating layer,   wherein the insulating layer comprises heat-resistant insulating fine particles and a binder, and   a proportion of particles with a particle size of 1 μm or less in the insulating fine particles is 30 vol % or more and a proportion of particles with a particle size of 3 μm or more in the insulating fine particles is 10 vol % or less.   
     
     
         15 . The separator for an electrochemical device according to  claim 14 , further comprising a porous base. 
     
     
         16 . The separator for an electrochemical device according to  claim 15 , wherein the porous base is at least one selected from the group consisting of a woven fabric, a nonwoven fabric, and a microporous film. 
     
     
         17 . The separator for an electrochemical device according to  claim 16 , wherein the microporous film is made of a thermoplastic resin with a melting point of 80° C. to 150° C. 
     
     
         18 . The separator for an electrochemical device according to  claim 14 , wherein the insulating fine particles are integrated with a crosslinked body of a self-crosslinking (meta) acrylic acid copolymer. 
     
     
         19 . A method for producing a separator for an electrochemical device that comprises a porous insulating layer, comprising:
 applying the slurry for forming an insulating layer according to  claim 1  to at least one base selected from the group consisting of a positive electrode, a negative electrode, and a porous base material; and   drying the base to which the slurry for forming an insulating layer is applied.   
     
     
         20 . An electrochemical device comprising:
 a positive electrode;   a negative electrode; and   the separator for an electrochemical device according to  claim 14 .