Non-aqueous secondary battery and separator used therefor

摘要

A non-aqueous secondary battery separator composed of a porous film made of an organic polymer, which includes a network-like support, swells in the electrolyte solution and retains the electrolyte solution, wherein the network-like support has a mean film thickness of 10-30 mum, a basis weight of 6-20 g/m², a Gurley value of no greater than 10 sec/100 cc, a McMullin number (25° C.) of no greater than 10 and a (McMullin numberxmean film thickness (mum)) product of no greater than 200 mum, and the separator has a mean film thickness of 10-35 mum, a basis weight of 10-25 g/m² and a Gurley value of no greater than 60 sec/100 cc, or exceeding 60 sec/100 cc and no greater than 500 sec/100 cc. Both battery characteristics and safety are achieved by establishing a specific electrochemical relationship between the effective active substance content of the battery system and the overcharge-preventing function characteristic values.