Lithium metal battery

A lithium metal battery comprising:

• a lithium metal anode;
• a protective layer disposed on the lithium metal anode, the protective layer comprising:
• i) a polymer and ii) a metal salt comprising a Group 1 or a Group 2 element and a nitrogen-containing additive;
• a cathode comprising lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, or a combination thereof;
• and
• a liquid electrolyte disposed between the protective layer and the cathode, the liquid electrolyte comprising an organic solvent,
• wherein the metal salt and a nitrogen-containing additive comprising a Group 1 element or Group 2 element are insoluble in the organic solvent of the liquid electrolyte,
• wherein the metal salt comprises
• at least one selected from a Group 1 element or Group 2 element selected from Cs, Rb, K, Ba, Sr, Ca, and Mg,
• NaNO3, or
• a combination thereof;
• and
• wherein the nitrogen-containing additive is at least one selected from an inorganic nitrate, an organic nitrate, an inorganic nitrite, an organic nitrite, an organic nitro compound, an organic nitroso compound, an N—O compound, and lithium nitride, and
• wherein the metal salt has a solubility of less than 100 parts per million per liter of the organic solvent.