Dendrite-Free Epitaxial Growth of Lithium Metal during Charging in Li-O Batteries.

Lithium (Li) dendrite formation is one of the major hurdles limiting the development of Li-metal batteries, including Li-O batteries. Herein, we report the first observation of the dendrite-free epitaxial growth of a Li metal up to 10-μm thick during charging (plating) in the LiBr-LiNO dual anion electrolyte under O atmosphere. This phenomenon is due to the formation of an ultrathin and homogeneous Li O-rich solid-electrolyte interphase (SEI) layer in the preceding discharge (stripping) process, where the corrosive nature of Br seems to give rise to remove the original incompact passivation layer and NO oxidizes (passivates) the freshly formed Li surface to prevent further reactions with the electrolyte. Such reactions keep the SEI thin (<100 nm) and facilitates the electropolishing effect and gets ready for the epitaxial electroplating of Li in the following charge process.