Developing a “Water‐Defendable” and “Dendrite‐Free” Lithium‐Metal Anode Using a Simple and Promising GeCl₄ Pretreatment Method

Lithium metal is an ultimate anode in “next‐generation” rechargeable batteries, such as Li–sulfur batteries and Li–air (Li–O 2 ) batteries. However, uncontrollable dendritic Li growth and water attack have prevented its practical applications, especially for open‐system Li–O 2 batteries. Here, it is reported that the issues can be addressed via the facile process of immersing the Li metal in organic GeCl 4 –THF steam for several minutes before battery assembly. This creates a 1.5 µm thick protection layer composed of Ge, GeO x , Li 2 CO 3 , LiOH, LiCl, and Li 2 O on Li surface that allows stable cycling of Li electrodes both in Li‐symmetrical cells and Li–O 2 cells, especially in “moist” electrolytes (with 1000–10 000 ppm H 2 O) and humid O 2 atmosphere (relative humidity (RH) of 45%). This work illustrates a simple and effective way for the unfettered development of Li‐metal‐based batteries.