MULTI-FUNCTIONAL SEPARATOR FOR A LITHIUM SECONDARY BATTERY AND MANUFACTURING METHOD

A lithium secondary battery comprising a cathode, an anode, an elastic and flame retardant composite separator disposed between the cathode and the anode, and a working electrolyte. The elastic flame retardant composite separator comprises a high-elasticity polymer and from 1% to 99% by weight of a flame retardant additive dissolved in, dispersed in, or bonded to the high-elasticity polymer. The composite separator has a thickness from 50 nm to 100 μm and a lithium ion conductivity from 10S/cm to 5×10S/cm at room temperature and the high elasticity polymer has a fully recoverable tensile strain from 2% to 1,000% when measured without any additive dispersed therein. The polymer composite may further comprise particles of an optional inorganic solid electrolyte dispersed therein.