FUNCTIONAL COATING FOR SEPARATOR

A coated separator including a microporous film and a coating on at least one side of the microporous film, wherein the coated separator shuts down at a temperature less than or equal to 140° C. In some embodiments, the coating causes the separator to shutdown at a temperature lower than the temperature at which the microporous film would shrink more than 15%, more than 12%, more than 10%, or preferably more than 5% without any coating. The microporous film of the separator by itself (uncoated) does not shut down or does not shutdown at a temperature less than or equal to 140° C. The microporous film may shut down at a temperature between 140° C. and 350° C. The coating of the coated separator may contain polyethylene, binder, and inorganic or heat resistant fine particles. Fine particles may have a particle size D50 less than or equal to 500 nm.