Abstract: The present invention relates to a process for preparing a separator for an electrochemical device, including the steps of: applying a slurry including at least cellulose fibers and a hydrophilic pore former with a boiling point of 180° C. or more onto a substrate; drying the slurry to form a sheet on the substrate; and separating the sheet from the substrate to obtain a separator, wherein the separator has a volume resistivity of 1500 ?·cm or less determined by alternate current with a frequency of 20 kHz in which the separator is impregnated with a 1 mol/LiPF6/propylene carbonate solution. The present invention can provide a separator for electrochemical devices which has superior separator properties such as low inner resistivity for electrochemical devices, has high lithium shielding properties that cannot be exerted by non-woven fabrics, paper or the like, and can be prepared at a reasonable cost.

Abstract: 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 ?m 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 ?m, the air resistance per thickness of 10 ?m is from 20 to 600 seconds, and the porous membrane has a volume resistivity of 1500 ?·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.

Abstract: The present invention relates to a process for preparing a separator for an electrochemical device, including the steps of: applying a slurry including at least cellulose fibers and a hydrophilic pore former with a boiling point of 180° C. or more onto a substrate; drying the slurry to form a sheet on the substrate; and separating the sheet from the substrate to obtain a separator, wherein the separator has a volume resistivity of 1500 ?·cm or less determined by alternate current with a frequency of 20 kHz in which the separator is impregnated with a 1 mol/LiPF6/propylene carbonate solution. The present invention can provide a separator for electrochemical devices which has superior separator properties such as low inner resistivity for electrochemical devices, has high lithium shielding properties that cannot be exerted by non-woven fabrics, paper or the like, and can be prepared at a reasonable cost.

Abstract: 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 ?m 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 ?m, the air resistance per thickness of 10 ?m is from 20 to 600 seconds, and the porous membrane has a volume resistivity of 1500 ?·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.