| abstract |
(57) Abstract: To further develop an efficient method for producing a relatively thin battery separator having improved puncture strength. A microporous battery separator having a first co-extruded multilayer portion and a second co-extruded multilayer portion. These two parts are joined together. In a preferred embodiment, the battery separator of the present invention has two substantially identical multilayer portions that are joined opposite each other. Each of these two multilayer parts It has at least one strength layer and at least one barrier layer. A method for manufacturing a battery separator is also provided. Preferably, the multilayer blown film is extruded and folded itself to form a multilayer battery separator precursor. Next, the precursor is bonded, annealed, and then stretched to form a microporous multilayer battery separator. |