| abstract |
The characteristics required for a separator for a non-aqueous electrolyte secondary battery that has high heat resistance and high ion permeability and requires high output at a high current rate, that is, high current discharge characteristics (rate characteristics). A porous film that provides a separator that can be further enhanced is provided. A heat resistance resin and two or more kinds of fillers, and the first largest value among the values obtained by measuring the average particle diameter of particles constituting each of the two or more kinds of fillers. when was a large value of 1, the second D and D 2, a porous film the value of D 2 / D 1 is 0.15 or less. D 1 is 0.1 μm or more and 1 μm or less, and D 2 is 0.01 μm or more and less than 0.1 μm. The porous film as described above, wherein all of the particles constituting the filler are alumina particles. [Selection figure] None |