Research Progresses on Gel Polymer Separators for Lithium-Ion Batteries

An important component in lithium-ion batteries, the separator consists of porous polyolefin polymeric materials; the corresponding electrolyte is a liquid one composed of organic carbonate solvents and lithium hexafluorophosphate. Although the liquid electrolyte shows high lithium ion conductivity, its flammability poses a risk to the lithium-ion battery. A gel polymer separator prepared from a polymer that can gel the liquid electrolyte combines the advantages of high conductivity of the liquid electrolyte system and the safety of the solid electrolyte. Examples include the simple microporous gel polymer separator, the gel polymer separator doped with a small amount of nano-inorganic particles, and the gel ceramic separator with a large amount of nanoparticles. In this review, the physical and chemical properties of these gel polymer separators and development trends of gel polymer separators are discussed in detail.