BASE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, AND SEPARATOR FOR LITHIUM ION SECONDARY BATTERY

摘要

Disclosed is a base material for a lithium ion secondary battery, which is characterized by comprising a non-woven fabric of polyester short fibers and containing polyester ultra-short fibers having an average fiber diameter of 5.0 µm or less and a fiber length of 2 mm or less as an essential component. The base material is highly safe when over-charged and can be formed into a complex suitably. Also disclosed is a separator for a lithium ion secondary battery, which is produced using the base material.