4. What is a battery separator?
The primary purpose of a separator in the battery is to act as an insulator between the two electrodes and prevent short circuiting. Although the separator is an insulator, it still needs to allow the transport of the ionic species between the electrodes. Ideally, a separator will be thermally, chemically, and mechanically stable. At the same time, it should have resistance to organic solvents, good wettability, and high puncture resistance, as well as being thin. Separators are typically microporous membranes (10-40µm) having a small pore size (<1µm) and low porosity (~40%). They are manufactured either by a dry or wet production process, including either an extrusion, or casting step, respectively.