Constructing a fluorinated interface layer enriched with Ge nanoparticles and Li-Ge alloy for stable lithium metal anodes

Lithium metal batteries (LMBs) based on metallic Li exhibit high energy density to be competent for advanced energy storage applications. However, the unstable solid electrolyte interphase (SEI) layer due to continuous decomposition of electrolytes, and the attendant problem of Li dendrite growth frustrate their commercialization process. Herein, a hybrid SEI comprising abundant LiF, lithiophilic Li-Ge alloy, and Ge nanoparticles is constructed via a simple brush coating method. This fluorinated interface layer with embedded Ge-containing components isolates the Li anode from the corrosive electrolyte and facilitates homogenous Li nucleation as well as uniform growth. Consequently, the modified Li anode exhibits remarkable stability without notorious Li dendrites, delivering stable cycling lives of more than 1000 h for symmetric Li∥Li cells and over 600 cycles for Li∥Cu cells at 1 mA·cm⁻². Moreover, the reinforced Li anodes endow multiple full-cell architectures with dramatically improved cyclability under different test conditions. This work provides rational guidance to design an artificial hybrid SEI layer and would stimulate more ideas to solve the dendrite issue and promote the further development of advanced LMBs.