Separators in lithium-ion batteries must offer the ability to shut down at a temperature slightly lower than that at which thermal runaway occurs, while retaining its mechanical properties. A separator is a permeable placed between a and. The main function of a separator is to keep the two electrodes apart to prevent electrical while also allowing the transport of. Materials include nonwoven fibers (,,, ), polymer films (,, poly (), ), and naturally occurring substances (,, ). Some separators employ. The separator is always placed between the anode and the cathode. The pores of the separator are filled with the electrolyte and packaged for use. Many structural defects can form in polymer separators due to temperature changes. These structural defects can result in a thicker separators. Furthermore, there can be intrinsic defects in the polymers themselves, such as polyethylene often. Unlike many forms of technology, polymer separators were not developed specifically for batteries. They were instead spin-offs of existing technologies, which is why most are not optimized for the systems they are used in. Even though this may seem unfavorable, most. Polymer separators generally are made from microporous polymer membranes. Such membranes are typically fabricated from a variety of inorganic, organic and naturally occurring materials. Pore sizes are typically larger than 50-100 Å. Dry and wet processes. Chemical stability The separator material must be chemically stable against the electrolyte and electrode materials under the strongly reactive environments when the battery is fully charged. The separator should not degrade. Stability is assessed by use testing.
