Nonaqueous electrolyte secondary battery separator

Abstract

The present invention provides, as a separator having both a sufficient level of safety and sufficient strength, a nonaqueous electrolyte secondary battery separator including a polyolefin porous film, the nonaqueous electrolyte secondary battery separator being arranged such that in regard to a surface of the nonaqueous electrolyte secondary battery separator, a product obtained by multiplying (a) a difference between a surface roughness in a machine direction obtained by a contact measurement and a surface roughness in the machine direction obtained by a non-contact measurement by (b) a difference between a surface roughness in a transverse direction obtained by a contact measurement and a surface roughness in the transverse direction obtained by a non-contact measurement is not less than 0.0020 and not more than 0.0280.

1 . A nonaqueous electrolyte secondary battery separator comprising a polyolefin porous film, wherein:
 in regard to a surface of the nonaqueous electrolyte secondary battery separator, a product obtained by multiplying (a) a difference between a surface roughness in a machine direction obtained by a contact measurement and a surface roughness in the machine direction obtained by a non-contact measurement by (b) a difference between a surface roughness in a transverse direction obtained by a contact measurement and a surface roughness in the transverse direction obtained by a non-contact measurement is not less than 0.0020 and not more than 0.0280.   
     
     
         2 . The nonaqueous electrolyte secondary battery separator as set forth in  claim 1 , having a film thickness of not more than 19.5 μm. 
     
     
         3 . A nonaqueous electrolyte secondary battery laminated separator comprising:
 a nonaqueous electrolyte secondary battery separator as set forth in  claim 1 ; and   an insulating porous layer.   
     
     
         4 . A nonaqueous electrolyte secondary battery member comprising:
 a positive electrode;   a nonaqueous electrolyte secondary battery separator as set forth in  claim 1 ; and   a negative electrode,   the positive electrode, the nonaqueous electrolyte secondary battery separator, and the negative electrode being disposed in this order.   
     
     
         5 . A nonaqueous electrolyte secondary battery comprising:
 a nonaqueous electrolyte secondary battery separator as set forth in  claim 1 .   
     
     
         6 . A nonaqueous electrolyte secondary battery member comprising:
 a positive electrode;   a nonaqueous electrolyte secondary battery laminated separator as set forth in  claim 3 ; and   a negative electrode,   the positive electrode, the nonaqueous electrolyte secondary battery laminated separator, and the negative electrode being disposed in this order.   
     
     
         7 . A nonaqueous electrolyte secondary battery comprising:
 a nonaqueous electrolyte secondary battery laminated separator as set forth in  claim 3 .