A freestanding metallic tin-modified and nitrogen-doped carbon skeleton as interlayer for lithium-sulfur battery

Lithium-sulfur (Li-S) batteries are considered as a promising next generation battery system because of their theoretical high capacity and large energy density. However, such battery still faces many obstacles, mainly including the shuttle effect of polysulfides and sluggish reaction kinetics of the electrode actions. Herein, a freestanding metallic tin-modified and nitrogen-doped carbon-skeleton (TCS) was designed and used as the interlayer for Li-S batteries to efficiently mitigate the above issues and sustain a long lifespan. Here, the carbon skeleton builds a high-effective conductive network for the whole interface, while the uniformly distributed metallic tin nanoparticles act as an absorbent of polysulfides and a catalyst to promote the conversion of sulfur species. As a result, both the specific capacity and cycle stability of Li-S battery are significantly improved with the assistance of the TCS interlayer. With a high sulfur content of 72.6 wt%, Li-S battery used TCS as interlayer shows an ultrahigh initial capacity of 1123.1 mA h g(-1) at 0.2C and a high capacity retention of 92.8% after 100 cycles. Besides, when the sulfur areal loading increased to 3.67 mg cm(-2), it still keeps a high areal capacity of 3.15 mA h cm(-2) under a current density of 0.2C, and the decay rate in the first 50 cycles is only 0.0043%. As such, this work will provide a facile and practical strategy to the development of a long cycling Li-S battery.