MULTILAYER POROUS MEMBRANE AND SEPARATOR FOR ELECTRICITY STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide: a multilayer porous membrane having excellent lithium ion permeability while satisfying both of handling ability and adhesiveness during battery winding; a separator for an electricity storage device comprising the multilayer porous membrane; and an electricity storage device using the separator for an electricity storage device.SOLUTION: The multilayer porous membrane comprises a polyolefin microporous membrane and a thermoplastic polymer coating layer which coats at least a part of at least one outermost surface of the polyolefin microporous membrane. In the thermoplastic polymer coating layer, there exist particulate thermoplastic polymer having an average particle diameter of 500 nm or more and 2000 nm or less. On the outermost surface, there is formed a sea-island structure comprising a portion containing the particulate thermoplastic polymer and a portion not containing the particulate thermoplastic polymer.SELECTED DRAWING: Figure 1