| 摘要 |
PROBLEM TO BE SOLVED: To prepare a porous film capable of preventing the temperature increase of a lithium battery owing to the reaction of metallic lithium, which deposits on a negative pole when the lithium battery becomes an overcharge state, with the electrolyte, and suitable as a separator. SOLUTION: This porous film contains polyethylene and polypropylene as essential components, and it has a multilayered structure consisting of a low- content layer, whose polyethylene content is 0-20 wt.%, and a high-content layer, whose polyethylene content is 61-100 wt.%, and which contains >=0.5 wt.% a polyethylene having a melt index of >=3. When the porous film is used in a lithium battery, the polyethylene which forms the high-content layer covers the surface of metallic lithium which has molten and deposited on a negative pole to prevent the contact of the metallic lithium with the electrolyte, and thus the temperature elevation of the battery is prevented. |
