2D MoS2 as an efficient protective layer for lithium metal anodes in high-performance Li-S batteries

Among the candidates to replace Li-ion batteries, Li-S cells are an attractive option as their energy density is about five times higher (-2,600 Wh kg(-1) ). The success of Li-S cells depends in large part on the utilization of metallic Li as anode material. Metallic lithium, however, is prone to grow parasitic dendrites and is highly reactive to several electrolytes; moreover, Li-S cells with metallic Li are also susceptible to polysulfides dissolution. Here, we show that similar to 10-nm-thick two-dimensional (2D) MoS2 can act as a protective layer for Li-metal anodes, greatly improving the performances of Li-S batteries. In particular, we observe stable Li electrodeposition and the suppression of dendrite nucleation sites. The deposition and dissolution process of a symmetric MoS2 -coated Li-metal cell operates at a current density of 10 mA cm(-2) with low voltage hysteresis and a threefold improvement in cycle life compared with using bare Li-metal. In a Li-S full-cell configuration, using the MoS2 -coated Li as anode and a 3D carbon nanotube-sulfur cathode, we obtain a specific energy density of similar to 589 Wh kg(-1) and a Coulombic efficiency of similar to 98% for over 1,200 cycles at 0.5 C. Our approach could lead to the realization of high energy density and safe Li-metal-based batteries.