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–O₂) batteries. However, uncontrollable dendritic Li growth and water attack have prevented its practical applications, especially for open-system Li–O₂ batteries. Here, it is reported that the issues can be addressed via the facile process of immersing the Li metal in organic GeCl₄–THF steam for several minutes before battery assembly. This creates a 1.5 µm thick protection layer composed of Ge, GeO_x, Li₂CO₃, LiOH, LiCl, and Li₂O on Li surface that allows stable cycling of Li electrodes both in Li-symmetrical cells and Li–O₂ cells, especially in “moist” electrolytes (with 1000–10 000 ppm H₂O) and humid O₂ atmosphere (relative humidity (RH) of 45%). This work illustrates a simple and effective way for the unfettered development of Li-metal-based batteries.