Porous membrane and process for preparing the same

摘要

The present invention relates to a porous membrane containing cellulose fibers, wherein the cellulose fibers contain 5% by weight or more of cellulose fibers with a diameter of 1 μm or more, relative to the total weight of the cellulose fibers, the mode diameter (maximal frequency) of the pore distribution determined by the mercury penetration method is less than 0.3 μm, the air resistance per thickness of 10 μm is from 20 to 600 seconds, and the porous membrane has a volume resistivity of 1500 Ω·cm or less determined by alternate current with a frequency of 20 kHz in which the porous membrane is impregnated with 1 mol/LiPF6/propylene carbonate solution. The porous membrane according to the present invention can provide a separator for electrochemical devices with superior properties at a reasonable cost.

主权项

1. A porous membrane comprising cellulose fibers, wherein
said cellulose fibers comprise cellulose fibers with a diameter of 1 μm or more in an amount of 5% by weight or more based on the total weight of said cellulose fibers, a mode diameter (maximal frequency) of a pore distribution determined by a mercury penetration method is less than 0.3 μm, an air resistance per thickness of 10 μm ranges from 20 to 600 seconds, and said porous membrane has a volume resistivity of 1500 Ω·cm or less determined by alternate current with a frequency of 20 kHz in which said porous membrane is impregnated with a 1 mol/LiPF6/propylene carbonate solution.