The present invention relates to an electrochemical cell comprising an anode, a cathode, and a separator disposed between the anode and cathode. More particularly, the present invention relates to an electrochemical cell comprising, among other things, a separator impregnated with, and/or coated with a layer of, a clay and/or a metal sulfide additive. The present invention additionally or alternatively relates to an electrochemical cell which comprises, among other things, a self-supporting or free-standing thin film separator. The present invention additionally or alternatively relates to an electrochemical cell which comprises, among other things, a separator, wherein at least a portion thereof is covered by an adhesive material that is bonded to the container or a sealing assembly of the cell.