To afford a laminated body that is usable as a nonaqueous electrolyte secondary battery separator and that is not easily curled, a laminated body includes: a porous base material containing a polyolefin-based resin as a main component; and a porous layer containing a polyvinylidene fluoride-based resin, the porous base material having a parameter X of not more than 20, the parameter X being calculated in accordance with a particular formula, the polyvinylidene fluoride-based resin containing crystal form α in an amount of not less than 36 mol % with respect to 100 mol % of a total amount of the crystal form α and crystal form β contained in the polyvinylidene fluoride-based resin.

An alkaline electrochemical cell includes a cathode, an anode which includes an anode active material, and a non-conductive separator disposed between the cathode and the anode, wherein from about 20% to about 50% by weight of the anode active material relative to a total amount of anode active material has a particle size of less than about 75 μm, and wherein the separator includes a unitary, cylindrical configuration having an open end, a side wall, and integrally formed closed end disposed distally to the open end.

A nonaqueous electrolyte secondary battery separator that is not easily curled is provided by a laminated body including a porous base material containing a polyolefin-based resin and a porous layer on at least one surface of the porous base material. The difference between the white index of a surface of the porous base material after being irradiated with ultraviolet light with an intensity of 255 W/m.sup.2 for 75 hours and the white index of the surface of the porous base material before irradiation is not more than 2.5. The porous layer contains a polyvinylidene fluoride-based resin which contains crystal form α in an amount of not less than 36 mol % with respect to 100 mol % of a total amount of the crystal form α and crystal form β contained in the resin.

To afford a nonaqueous electrolyte secondary battery separator that is not easily curled, a laminated body of the present invention includes: a porous base material containing a polyolefin-based resin as a main component; and a porous layer on at least one surface of the porous base material, the porous layer containing a polyvinylidene fluoride-based resin, the porous film having a lightness (L*) of not less than 83 and not more than 95 and a white index (WI) of not less than 85 and not more than 98, the polyvinylidene fluoride-based resin containing crystal form α in an amount of not less than 34 mol % with respect to 100 mol % of a total amount of the crystal form α and crystal form β contained in the polyvinylidene fluoride-based resin.

A laminated body includes: a porous base material containing a polyolefin-based resin as a main component; and a porous layer which is disposed on at least one surface of the porous base material and which contains a polyvinylidene fluoride-based resin, the laminated body being arranged so that: a diminution rate of diethyl carbonate dropped on the porous base material is 15 sec/mg to 21 sec/mg; a spot diameter of the diethyl carbonate 10 seconds after the diethyl carbonate was dropped on the porous base material is not less than 20 mm; and the polyvinylidene fluoride-based resin containing crystal form α in an amount of not less than 36 mol % with respect to 100 mol % of a total amount of the crystal form α and crystal form β contained in the polyvinylidene fluoride-based resin. A nonaqueous electrolyte secondary battery separator made of the laminated body is not easily curled.

A separator with a heat-resistant insulation layer for an electric device includes a resin porous substrate and a heat-resistant insulation layer containing heat-resistant particles and a binder, the heat-resistant insulation layer being formed on at least one surface of the resin porous substrate. The heat-resistant particles contain alumina and a parameter X is 0.018 to 0.336. Parameter X is represented by X=C.sub.a×R.sub.zjis/D, wherein C.sub.α is a ratio of the alumina, which occupies the heat-resistant particles, R.sub.zjis is surface roughness of a surface of the heat-resistant insulation layer, the surface being opposite the resin porous substrate, and D is a thickness of the heat-resistant insulation layer.

A thin, freestanding, microporous polyolefin web with good heat resistance and dimensional stability includes an inorganic surface layer. A first preferred embodiment is a microporous polyolefin base membrane in which colloidal inorganic particles are present in its bulk structure. Each of second and third preferred embodiments is a thin, freestanding microporous polyolefin web that has an inorganic surface layer containing no organic hydrogen bonding component for the inorganic particles. The inorganic surface layer of the second embodiment is achieved by hydrogen bonding with use of an inorganic acid, and the inorganic surface layer of the third embodiment is achieved by one or both of hydrogen bonding and chemical reaction of the surface groups on the inorganic particles.

A non-aqueous electrolyte secondary battery allows gas generated when an aqueous binder is used as a binder of a negative electrode active material to be effectively discharged from the electrode, and has small decrease of the battery capacity despite use over a long period of time. The non-aqueous electrolyte secondary battery has a positive electrode active material layer, a negative electrode active material layer, and a separator. The density of the negative electrode active material layer is 1.4 to 1.6 g/cm.sup.3, an electrolyte solution layer is disposed between at least one layer of the negative electrode active material layer and the positive electrode active material layer, and the separator, and the ratio of total thickness of the positive electrode, the negative electrode and the separator to total thickness of the positive electrode, the negative electrode, the separator and the electrolyte solution layer, is 0.85 or more and less than 1.0.

Provided is a secondary battery capable of breaking an external electrical connection by way of a simpler configuration when an abnormality such as overcharge occurs. A secondary battery 1 comprises a battery element comprising a positive electrode 11, a negative electrode 12, a separator 13, and an electrolytic solution, and a casing sealing the battery element. The electrolytic solution comprises a gel component and an organic solvent having a boiling point of 125° C. or less. The separator 13 comprises a fiber assembly or a microporous structure composed of one or more resins selected from aramid, polyimide, and polyphenylenesulfide, and has an average void size of 0.1 μm or more.

An ion-permeable membrane is substantially free of holes and has excellent ion permeability, heat resistance, strength, and flexibility, and can form a battery electrolyte membrane that uses the ion-permeable membrane, and an electrode composite. The polymer-ion-permeable membrane has a per-unit-thickness puncture strength of 0.3-3.0 N/μm and a membrane resistance of 3.0-100.0 Ω.Math.cm.sup.2 at 25° C.