Patent ID: 7112389

Claim:
A battery having a separator comprising a porous fine fiber layer of polymeric fibers having a mean diameter in the range from about 50 nm to about 3000 nm, wherein the porous fine fiber layer has a mean flow pore size of between about 0.01 μm and about 15 μm, a thickness of between about 0.1 mils (0.0025 mm) and about 12 mils (0.3 mm), a porosity of between about 20% and about 90%, a basis weight of between about 1 g/m 2 and about 90 g/m 2 , a Frazier air permeability of less than about 150 cfm/ft 2 (46 m 3 /min/m 2 ) and a MacMullin number of between about 2 and about 15.