Dendrite‐Free Epitaxial Growth of Lithium Metal during Charging in Li–O2 Batteries

Abstract Lithium (Li) dendrite formation is one of the major hurdles limiting the development of Li‐metal batteries, including Li‐O 2 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 3 dual anion electrolyte under O 2 atmosphere. This phenomenon is due to the formation of an ultrathin and homogeneous Li 2 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 3 − 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.