| 摘要 |
PURPOSE:To make it possible to obtain a separator for a lithium battery which is of low electric resistance, is thin but excellent in mechanical strength, and is easy for handling while a shut down phenomenon occurs at low temperature by making up the separator for a lithium battery out of a specified fine porous membrane. CONSTITUTION:A membrane to be used for a separator for a lithium battery is substantially made of polyethylene. The separator contains more than 1 % polyethylene by weight of ultra high molecular weight the weight average molecular weight of which is equal to or more than 7X10<5>, is composed of polyethylene composition the weight average molecular weight/number average molecular weight of which is 10 to 300, and is also composed of a fine porous membrane which is as thin as 0.1 to 25mum, is provided with a hole rate of 40 to 95%, is provided with an average through hole diameter of 0.001/0.1mum, and is provided with break strength per 10mm equal to or more than 0.5g. By this constitution, the separator for the lithium battery composed of the fine porous membrane can thereby be obtained wherein the memrane is of low electric resistance, is thin but excellent in mechanical strength, and is easy for handling while a shut-down phenomenon occurs at low temperature. |
