| abstract |
[Problem] To provide a multi-layered porous membrane having excellent ion conductivity, good withstand voltage characteristics, high strength and excellent heat resistance. A multilayer porous film comprising a porous film mainly composed of a polyolefin resin, and a porous layer including an inorganic filler and a resin binder laminated on at least one surface of the porous film, the porous film comprising: The average pore diameter d, the curvature τa and the number of holes B calculated by the gas-liquid method are 0.035 ≦ d ≦ 0.060 μm, 1.1 ≦ τa ≦ 1.7, 100 ≦ B ≦ 500 / A multilayer porous membrane having a thickness of μm 2 and a thickness L of the porous membrane of 5 ≦ L ≦ 22 μm. [Selection figure] None |