A negative electrode for an electrochemical cell of a secondary lithium metal battery may comprise a metal substrate, a lithium metal layer overlying a major surface of the metal substrate, and a protective interfacial layer formed on a major surface of the lithium metal layer over the metal substrate. The protective interfacial layer may comprise a stack of monomolecular layers including at least one aryl siloxane monomolecular layer overlying the major surface of the lithium metal layer. The protective interfacial layer may be formed on the major surface of the lithium metal layer by applying a mixture of monoaryl silanes to the major surface of the lithium metal layer.