A Mixed Lithium-Ion Conductive Li2S/Li2Se Protection Layer for Stable Lithium Metal Anode

Constructing artificial solid-electrolyte interphase (SEI) on the surface of Li metal is an effective approach to improve ionic conductivity of surface SEI and buffer Li dendrite growth of Li metal anode. However, constructing of homogenous ideal artificial SEI is still a great challenge. Here, a mixed lithium-ion conductive Li2S/Li2Se (denoted as LSSe) protection layer, fabricated by a facile and inexpensive gas-solid reaction, is employed to construct stable surface SEI with high ionic conductivity. The Li2S/Li2Se-protected Li metal (denoted as LSSe@Li) exhibits a stable dendrite-free cycling behavior over 900 h with a high lithium stripping/plating capacity of 3 mAh cm(-2) at 1.5 mA cm(-2) in the symmetrical cell. Compared to bare Li anode, full batteries paired with LiFePO4, sulfur/carbon, and LiNi0.6Co0.2Mn0.2O2 cathodes all present better battery cycling and rate performance when LSSe@Li anode is used. Moreover, Li2Se exhibits a lower lithium-ion migration energy barrier in comparison with Li2S which is proved by density functional theory calculation.