LITHIUM-ION SECONDARY BATTERY SEPARATOR

摘要

Provided is a lithium-ion secondary battery separator which resolves the weaknesses of a non-woven fabric separator which is not suited for use in a lithium-ion secondary battery, does not have short-circuits despite being thin, and has superior electrolyte retention and rate characteristics. The lithium-ion secondary battery separator is formed from a composite formed from a non-woven fabric with a basis weight of 2-20g/m2 configured from fiber formed from a thermoplastic material with an average fiber diameter of 5-40µm, and ultra-fine fibers with an average fiber diameter of 1µm or less and 1/5-3 times non-woven fabric mass. The composite has a thickness of 10-40µm after a heat pressing process is performed under conditions in which the gloss of the non-woven fabric measured at 60° according to JIS Z 8741 would be in the range of 3-30 if the heat pressing process had been carried out on the non-woven fabric alone and in which the thickness would become 10-40µm.