Abstract: A multi-layer composite functional separator for lithium ion battery includes four layers. Layer A is a base separator. Layer B is a porous structural layer composed of insulating inorganic compounds or high temperature resistant polymers. Layer C is a porous layer composed of polymer microspheres with temperature-induced expansion characteristics. Layer D is a thermoplastic resin with a melting point of 80-110° C. and a crystallinity of <50%. Layer B, Layer C and Layer D are sequentially attached on either or both sides of Layer A. Compared with the existing lithium-ion battery separator, the multi-Layer Composite functional separator has excellent heat resistance. The thermal shrinkage rate is less than 1% when heated for less than one hour at 200° C. Inclusion of organic polymer microspheres produces thermal closure of the batteries, which improves the safety of the batteries.

Abstract: A multi-layer composite functional separator for lithium ion battery includes four layers. Layer A is a base separator. Layer B is a porous structural layer composed of insulating inorganic compounds or high temperature resistant polymers. Layer C is a porous layer composed of polymer microspheres with temperature-induced expansion characteristics. Layer D is a thermoplastic resin with a melting point of 80-110° C. and a crystallinity of <50%. Layer B, Layer C and Layer D are sequentially attached on either or both sides of Layer A. Compared with the existing lithium-ion battery separator, the multi-Layer Composite functional separator has excellent heat resistance. The thermal shrinkage rate is less than 1% when heated for less than one hour at 200° C. Inclusion of organic polymer microspheres produces thermal closure of the batteries, which improves the safety of the batteries.