| abstract |
A porous film (A) to be treated is placed in a coating treatment apparatus, a specific raw material is present in a gaseous state in the apparatus, and a coating treatment is carried out while the additive gas is coexisted, And a porous film (A ') obtained by forming a film containing constituent elements of the additive gas. A porous membrane having excellent heat shrinkability, shutdown characteristics, anti-meltdown characteristics, wettability with an electrolytic solution, and electrochemical stability without deteriorating the ion permeability and mechanical properties required for a battery separator, and a battery separator using the same do. |