LITHIUM METAL SECONDARY BATTERY HAVING IMPROVED LIFE CHARACTERISTICS

The present disclosure relates to a lithium metal secondary battery including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the lithium metal secondary battery further includes a protective layer interposed between the negative electrode and the separator, and the protective layer includes an additive, which is a mixture of hexagonal boron nitride (BN) flakes with an ionomer having a sulfur (S)-containing anionic group and fluorine (F), added thereto.