NOVELTY - The battery has an electrode assembly provided with an anode, an electrolyte and a cathode. A separation film is interposed between the anode and the cathode. The separation film is made of porous foam. Diameter of a pore of the porous foam is from 1000 sub-micrometer to 0.1 micrometer. The porous foam is formed with a non-woven fabric by using a foaming agent or porous polymer sheet.    USE - Secondary battery e.g. lithium ion battery, lithium ion polymer battery and lithium polymer battery, for a battery module of a battery pack of a power storage device, an electric vehicle, a hybrid electric vehicle and a plug-in hybrid electric vehicle (all claimed).    ADVANTAGE - The separation film is interposed between the anode and the cathode so as to increase content of the electrolyte, ensure high porosity, prevent the electrolyte by avoiding repeated rechargeable cycle and avoid performance degradation of the battery.    DETAILED DESCRIPTION - The porous polymer sheet or nonwoven fabric is made of polyolefin, polyester, polyamide, polyacetal, polycarbonate, polyimide, polyether ketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, polyethylenenaphthalete, PTFE, polyvinylidene fluoride, PVC, polyacrylo nitrile, cellulose, nylon, polyparaphenylenebenzobisoxazole, polya reel rat, polyurethane or glass. The foaming agent is made of azo series compound, carbonate series compound, hydrazide series compound, nitrile series compound, amine group compound, amide system compound or carbazide crab thermal compound. The anode is made of lithium transition-metal oxide that comprises aluminum, magnesium, nickel, carbon monoxide, iron, chromium, vanadium, titanium, copper, boron, calcium, zinc, zirconium, niobium, molybdenum, strontium, antimony, tungsten, bismuth, dual-cycle transition metals, nitrate, phosphate, borate and carbon trioxide. The cathode is made of carbon-based material or silicon. INDEPENDENT CLAIMS are also included for the following:    (1) a secondary battery manufacturing method    (2) a battery module    (3) a battery pack    (4) a power storage device.