Separator is one of core components of lithium-ion secondary battery. It allows electric current to go back and forth between negative and positive nodes while preventing overheat and ignition caused by short-circuit.
Four core components of lithium-ion secondary battery are positive and negative electrodes material, electrolyte and separator. In addition, there are between 20 and 30 materials such as metal foil, binder and additive agents. Performance and material cost of lithium-ion secondary battery are mostly determined by those 4 core components.
Separator is generally made of microporous membrane, which enables lithium-ion to efficiently flow while separating positive and negative electrodes at the same time. When battery is abnormally overheated, polyolefin will melt to close micropores on membrane and shut down flow of lithium ion so that battery can safely stop. It also plays crucial role in warranting safety of battery.