Abstract: An object of the invention is to provide a separator for an electrochemical element in which the occurrence of fluff on the sheet surface thereof is suppressed and an internal short-circuit defect rate is low, and the invention provides a separator for an electrochemical element, comprising: a fibrillated solvent spun cellulose fiber; and a synthetic fiber, wherein the separator for an electrochemical element contains, as the synthetic fiber, from 5 to 40% by weight of a core-sheath type composite fiber having a fiber diameter of 6.0 ?m or less which is composed of: a core component made of a resin having a melting point of 160° C. or more; and a sheath component made of polyethylene.

Abstract: A separator for electrochemical elements includes beaten solvent-spun cellulose fibers and rayon fibers having a fiber diameter of 9.5 ?m or less. More preferably, the separator for electrochemical elements has a content of the rayon fibers relative to all fibers of 10 to 25% by mass, and can be applied to electrochemical elements such as electric double layer capacitors, hybrid capacitors, redox capacitors, and lithium secondary batteries. The separator can provide low internal short circuit failure rates and high surface strength.

Abstract: An object of the invention is to provide a separator for an electrochemical element in which the occurrence of fluff on the sheet surface thereof is suppressed and an internal short-circuit defect rate is low, and the invention provides a separator for an electrochemical element, comprising: a fibrillated solvent spun cellulose fiber; and a synthetic fiber, wherein the separator for an electrochemical element contains, as the synthetic fiber, from 5 to 40% by weight of a core-sheath type composite fiber having a fiber diameter of 6.0 ?m or less which is composed of: a core component made of a resin having a melting point of 160° C. or more; and a sheath component made of polyethylene.

Abstract: A separator for electrochemical elements includes beaten solvent-spun cellulose fibers and rayon fibers having a fiber diameter of 9.5 ?m or less. More preferably, the separator for electrochemical elements has a content of the rayon fibers relative to all fibers of 10 to 25% by mass, and can be applied to electrochemical elements such as electric double layer capacitors, hybrid capacitors, redox capacitors, and lithium secondary batteries. The separator can provide low internal short circuit failure rates and high surface strength.