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, GeOx , Li2 CO3 , LiOH, LiCl, and Li2 O 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 H2 O) 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.