POROUS FILM AND ELECTRICITY STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a porous film which is uniformly in contact with an electrode surface when the porous film is used as a separator for a lithium ion battery and which exhibits excellent uniformity of ionic conductivity between the separator and an electrode interface.SOLUTION: The porous film has 9.5% or less of a variance of surface roughness Ra on both surfaces obtained by use of a laser microscope.