An example electrolyte includes a solvent, a lithium salt, and an additive selected from the group consisting of a silane with at least one Si—H group; a fluorinated methoxysilane; a fluorinated chlorosilane; and combinations thereof. The electrolyte may be used in a method for making a solid electrolyte interface (SEI) layer on a surface of a lithium electrode. A negative electrode structure may be formed from the method.