LITHIUM-ION SECONDARY BATTERY SEPARATOR

摘要

The present invention provides a lithium-ion secondary battery separator which resolves the defects of a non-woven fabric separator which is not suitable for use in a lithium-ion secondary battery, and is thin but does not short-circuit and has excellent electrolyte retainability and rate characteristics. The lithium-ion secondary battery separator comprises a composite of a non-woven fabric having a basis weight of 2 to 20 g/m 2 formed from fibers of a thermoplastic material having an average fiber diameter of 5 to 40 µm and ultra-microfibers having an average fiber diameter of 1 µm or less in an amount of 1/5 to 3 times the mass of the non-woven fabric, the composite having a thickness of 10 to 40 µm after being subjected to a heat-pressing treatment carried out under such conditions that the non-woven fabric has a glossiness measured at 60º in accordance with JIS standard (JIS Z 8741) in the range of 3 to 30 and a thickness of 10 to 40 µm if only the non-woven fabric is subjected to the heat-pressing treatment.