Mo2C quantum dots@graphene functionalized separator toward high-current-density lithium metal anodes for ultrastable Li-S batteries

Lithium-sulfur battery is one of the most promising next-generation energy storage devices due to its low cost and ultrahigh energy density. However, the uncontrolled formation of Li dendrites and shuttle effect seriously hinder its practical applications. To simultaneously address both fatal issues, herein, for the first time, we present a novel Mo2C quantum dots (MQDs) anchored N-doped graphene functionalized interlayers (MQD@NG). The DFT calculations show that lithiophilic feature of Mo2C QDs, which can construct a fast electrolyte diffusion pathway for Li+ transportation and achieve uniform Li deposition. Moreover, the polar Mo2C QDs possess strong chemical adsorption of polysulfides. As a result, the lithium symmetric cells with MQD@NG interlayers achieve a dendrite-free lithium deposition over 1600 h at a high current density of 10 mA cm(-2). The Li-S cells exhibit a high capacity of 1230 mAh g(-1) at 0.2 C and a highly stable cycling performance over 400 cycles without obvious capacity fading. This work provides a new insight to design and fabricate high-energy and safe Li-metal-based batteries.