Dendrite-free lithium plating enabled by yolk shell structured ZnO/C sphere coated polyethylene separator for stable lithium metal anodes

Abstract Lithium metal has great attraction as an ultimate anode material due to its extremely high capacity of 3860 mAh g−1 and the lowest electrochemical potential (−3.04 V vs SHE). However, Li dendrite growth and corresponding poor cyclability still obstruct the practical use of Li metal anodes. Here, we report the yolk shell structured zinc oxide/carbon sphere coated polyethylene separator (ZnO/C@SE) to suppress Li dendrite growth and improve the cycle life of Li metal anodes. Initially ZnO could be lithiated first to form LiZn and Li2O. The lithiated ZnO and carbon layer on a polyethylene separator not only enables uniform surface current flows at an interface between a Li metal anode and an electrolyte, but also efficiently utilizes electrochemically inactive “dead” Li. With those synergistic advantages, Li could be deposited with dendrite-free morphology with the areal capacity up to 5 mAh cm–2. The Li || Cu cell with ZnO/C@SE shows outstanding performance even at a high current density of 2 mA cm–2 with a high capacity of 2 mAh cm–2 over 100 cycles. Furthermore, the Li–S battery with the ZnO/C@SE exhibits significant improvement in cycle performance at 0.2 C over 300 cycles.