SEPARATOR FOR ELECTROCHEMICAL ELEMENT AND ELECTROCHEMICAL ELEMENT

Provided is a separator for an electrochemical element， the separator having improved tensile strength and short-circuit resistance while maintaining the impedance characteristics and denseness expected of a separator comprising highly beaten regenerated cellulose fibers. The separator for an electrochemical element is interposed between a pair of electrodes and capable of holding an electrolytic solution containing an electrolyte， the separator for an electrochemical element comprising: 20 to 80 mass% of natural cellulose fibers A in which the length weighted average fiber length is 0.30 to 1.19 mm and the CSF is 500 to 50 ml; 10 to 50 mass% of natural cellulose fibers B in which the length weighted average fiber length and the maximum distribution fiber length are 1.20 to 1.99 mm and the CSF is 500 to 50 ml; and 10 to 50 mass% of beaten regenerated cellulose fibers.

本发明提供一种电化学元件用隔膜，该隔膜在保留由高度打浆再生纤维素纤维构成的隔膜所应具备的阻抗特性与致密性的同时，提升了拉伸强度与耐短路性能。该电化学元件用隔膜设置于一对电极之间，可容纳含电解质的电解液，其组成如下：20~80质量%的天然纤维素纤维A，其长度加权平均纤维长度为0.30~1.19mm，打浆度（CSF，Canadian Standard Freeness）为500~50ml；10~50质量%的天然纤维素纤维B，其长度加权平均纤维长度与最大分布纤维长度均为1.20~1.99mm，打浆度（CSF）为500~50ml；以及10~50质量%的打浆再生纤维素纤维。