| abstract |
[PROBLEMS] Overcharged compared to conventional non-aqueous secondary batteries to enable the elimination of a protection circuit or simplification to a thermistor system such as a thermal switch or a thermal sensor while maintaining practical battery characteristics. Provided is a lithium ion secondary battery separator capable of providing a low-cost non-aqueous secondary battery with high safety at the time. SOLUTION: From sheet (A) having an average film thickness of 10 to 35 μm, a basis weight of 6 to 20 g / m 2 , an air permeability (JIS P8117) of 100 seconds or less, a Macmillan number of 10 or less, and a Macmillan number × average film thickness of 200 μm or less. Or a porous organic polymer film (B) that encloses the sheet (A) and swells and retains the electrolyte solution, and has an average film thickness of 10 to 35 μm and a basis weight of 10 to 25 g / m 2 . A separator for a lithium ion secondary battery comprising a porous film. [Selection figure] None |