| abstract |
According to the present invention, there are provided: a polyolefin microporous membrane suitable for providing a uniform thickness of the porous layer; and a battery suitable for increasing the capacity of a battery in which the thickness of the porous layer is uniformly provided on the polyolefin microporous membrane Use a diaphragm. A battery separator provided with a polyolefin microporous membrane whose F25 value in the longitudinal direction varies by 1 MPa or less, and a fluorine-based resin and an inorganic membrane on at least one side of the polyolefin microporous membrane. Particles and a porous layer having an average thickness T(ave) of 1 to 5 μm. Here, the F25 value is a value obtained by dividing the load value when the test piece is extended by 25% with a tensile tester by the cross-sectional area of the test piece. |