| 摘要 |
PROBLEM TO BE SOLVED: To provide a battery separator capable of achieving both excellent adhesion property of a heat-resistant resin layer and a small increase width of an air permeability resistance degree even assuming that the battery separator will be further thinned in the future, and to provide a battery separator suitable for increase in capacity of the battery, excellent ion permeability, and high-speed processability at a battery assembling processing step, especially suitable for a separator for a lithium ion secondary battery.SOLUTION: In a battery separator obtained by laminating a heat-resistant resin, and a porous film B consisting of inorganic particles or cross-linked high polymer particles on a porous film A consisting of a polyethylene-based resin, the porous film A satisfies expressions (a) to (c), and the whole of the battery separator satisfies expressions (d) to (f). |
