Separators for electrochemical devices with reduced self-discharge rates and methods for producing same

Abstract

Disclosed is a separator for an electrochemical element, the separator comprising fibrillated fibers of regenerated cellulose, the fibrillated fibers of regenerated cellulose constituting at least 75% of the separator's mass. The separator has a weight per unit area of ​​at least 8 g / m² and a maximum of 17 g / m², and an average individual sheet thickness of the separator of at least 12 pm and a maximum of 40 pm. With respect to its thickness and fiber structure, the separator exhibits homogeneity characterized by the simultaneous realization of the following characteristics (i) and (ii): (i) the ratio of the average individual sheet thickness of the separator to the individual sheet thickness of the separator is at least 0.88 and a maximum of 1.04, and (ii) the contrast value C, determined by image analysis, is at least 1000 and a maximum of 1600.

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