申请人:Wakizaka Yasuhiro
公开号:US20120189897A1
公开(公告)日:2012-07-26
Disclosed is a porous membrane for a secondary battery, which has further improved output characteristics and long-term cycle characteristics when compared with conventional porous membranes. The porous membrane for a secondary battery is used for a lithium ion secondary battery or the like. Specifically disclosed is a porous membrane for a secondary battery, which contains polymer particles A that have a number average particle diameter of 0.4 μm or more but less than 10 μm and a glass transition temperature of 65° C. or more and polymer particles B that have a number average particle diameter of 0.04 μm or more but less than 0.3 μm and a glass transition temperature of 15° C. or less. It is preferable that the polymer particles B have a crystallization degree of 40% or less and a main chain structure that is composed of a saturated structure.