A lithium metal battery comprising: a positive electrode comprising a positive electrode active material; a negative electrode comprising lithium metal or lithium alloy; and an electrolyte, wherein the positive electrode active material comprises an elemental sulfur, and wherein the electrolyte comprises a lithium salt, an organic solvent and an additive, wherein the additive is represented by the following Formula 1: [Formula 1] A- m -B- n wherein A is an alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with fluorine; an alkenyl group having 2 to 20 carbon atoms which is substituted or unsubstituted with fluorine; an alkynyl group having 2 to 20 carbon atoms which is substituted or unsubstituted with fluorine; a cycloalkyl group having 3 to 20 carbon atoms which is substituted or unsubstituted with fluorine; or an aryl group having 6 to 40 carbon atoms which is substituted or unsubstituted with fluorine, B is a single bond; an alkanediyl group having 1 to 10 carbon atoms which is substituted or unsubstituted with fluorine; an alkenediyl group having 2 to 10 carbon atoms which is substituted or unsubstituted with fluorine; an unsubstituted alkynediyl group having 2 to 10 carbon atoms; a cycloalkyl group having 3 to 20 carbon atoms which is substituted or unsubstituted with fluorine; or an arylene group having 6 to 40 carbon atoms which is substituted or unsubstituted with fluorine, at least one of A and B is substituted with fluorine, O is oxygen, X is independently selected from a thiol group, an amine group or a hydroxy group, m is 0 or 1, and n is an integer of 1 to 3. a positive electrode comprising a positive electrode active material; a negative electrode comprising lithium metal or lithium alloy; and an electrolyte, wherein the positive electrode active material comprises an elemental sulfur, and wherein the electrolyte comprises a lithium salt, an organic solvent and an additive, wherein the additive is represented by the following Formula 1: [Formula 1] A- m -B- n wherein A is an alkyl group having 1 to 20 carbon atoms which is substituted or unsubstituted with fluorine; an alkenyl group having 2 to 20 carbon atoms which is substituted or unsubstituted with fluorine; an alkynyl group having 2 to 20 carbon atoms which is substituted or unsubstituted with fluorine; a cycloalkyl group having 3 to 20 carbon atoms which is substituted or unsubstituted with fluorine; or an aryl group having 6 to 40 carbon atoms which is substituted or unsubstituted with fluorine, B is a single bond; an alkanediyl group having 1 to 10 carbon atoms which is substituted or unsubstituted with fluorine; an alkenediyl group having 2 to 10 carbon atoms which is substituted or unsubstituted with fluorine; an unsubstituted alkynediyl group having 2 to 10 carbon atoms; a cycloalkyl group having 3 to 20 carbon atoms which is substituted or unsubstituted with fluorine; or an arylene group having 6 to 40 carbon atoms which is substituted or unsubstituted with fluorine, at least one of A and B is substituted with fluorine, O is oxygen, X is independently selected from a thiol group, an amine group or a hydroxy group, m is 0 or 1, and n is an integer of 1 to 3.