Highly reversible lithium-sulfur batteries with nitrogen-doped carbon encapsulated sulfur cathode and nitrogen-doped carbon-coated ZnS anode

Practical application of Lithium-sulfur batteries (LSBs) has been suffered from challenging issues like polysulfide dissolutions of the sulfur cathode and lithium dendrite growths of the lithium anode. In this paper, nitrogen doped carbon encapsulated sulfur (S@NC) composite cathode material and NC-coated ZnS (ZnS@NC) anode material derived from the same ZnS precursors were prepared for full Lithium-sulfur batteries (LSBs). For the purpose to investigate the relations between the carbon shell thickness and electrochemical behaviors, the S@NC hybrids with three different sulfur contents of 52.0, 66.5 and 79.2 wt% were prepared. When an as-prepared S@NC hybrid with a sulfur content of 66.5 wt% (S67@NC) was applied to a cathode in LSBs, it delivered a high discharge capacity (1092.8 mAh g(-1)), long-term cycling life and excellent rate property. Moreover, the ZnS@NC anode showed a high specific capacity (1062.8 mAh g(-1)), excellent stability, and better rate performance, as compared to ZnS without NC coating layers. Consequently, when the full LSB consists with nano structured S67@NC cathode and ZnS@NC anode, it delivered the high initial discharge capacity above 921.9 mAh g(-1) in a voltage window between 0.1 and 2.5 V. This enhanced electrochemical performance suggests that this full-cell system with S@NC and ZnS@NC composites could be a promising next-generation rechargeable battery platform.