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

Abstract

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 nanostructured 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.