Abstract
Lithium metal has long been considered one of the most promising anode materials for advanced lithium batteries (for example, Li-S and Li-O2), which could offer significantly improved energy density compared to state-of-the-art lithium ion batteries. Despite decades of intense research efforts, its commercialization remains limited by poor cyclability and safety concerns of lithium metal anodes. One root cause is the parasitic reaction between metallic lithium and the organic liquid electrolyte, resulting in continuous formation of an unstable solid electrolyte interphase, which consumes both active lithium and electrolyte. Until now, it has been challenging to completely shut down the parasitic reaction. We find that a thin-layer coating applied through atomic layer deposition on a hollow carbon host guides lithium deposition inside the hollow carbon sphere and simultaneously prevents electrolyte infiltration by sealing pinholes on the shell of the hollow carbon sphere. By encapsulating lithium inside the stable host, parasitic reactions are prevented, resulting in impressive cycling behavior. We report more than 500 cycles at a high coulombic efficiency of 99% in an ether-based electrolyte at a cycling rate of 0.5 mA/cm2 and a cycling capacity of 1 mAh/cm2, which is among the most stable Li anodes reported so far.