Lithium (Li) metal electrodes are widely regarded as the promising anodes since their energy densities far exceed those of lithium-intercalated carbon anode materials. However, Li metal anodes are plagued with dendrite formation and electrolyte incompatibility that limits their lifespan and stability within any battery systems that employ them. A promising way to resolve those limitations involves the use of passivating layers to protect the surface of Li metal. This study will explore the mechanism behind the formation of Li dendrite and the passivation of the Li metal surface; it will also discover how coating Li metal with Li ion-conducting layers would effectively protect it from attacks by solvents, contamination, and active species in the electrolyte. Here, we demonstrate the facile method to protect the surface of Li metal with precise structural control. Utilizing symmetric Li-Li cell configuration, the protected Li exhibited stable cycling with minimal polarization at current density of 10 mA cm^-2; it also demonstrated over 300% longer cycle life than unprotected Li metal. In addition, a full-cell system using sulfur cathode confirmed an improved capacity retention with our protected Li metal over the cell with bare Li metal for over 300 cycles. The improvement in cycle life and the suppression of lithium dendrite growths through the passivation of Li metal electrodes reveal a new direction for the advancement of Li metal anode in rechargeable batteries.