The Si3N4/MoS2 hetero-structure as an effective polysulfide regulator for high-performance lithium-sulfur battery

Though Lithium-Sulfur battery possesses several advantages such as ultrahigh energy density and abundant resources; the insulating nature of sulfur (S), sluggish electrode kinetics, polysulfide shuttle, and poor capacity retention are the major concerns for their practical applications. Here, we develop cathode composite architecture containing silicon nitride (Si3N4)-molybdenum disulfide (MoS2) hetero-structure over the multi-walled carbon nanotube (MWCNT) that can resolve the above issues to a great extent. The freestanding sulfur cathode S@Si3N4/MoS2-MWCNT delivers an initial discharge capacity of 1123 mAh g(-1) at a 0.2 degrees C rate. At 1C rate the cell exhibits capacity retention of 80.7% by the end of 500 cycles with small capacity fade of 0.03% per cycle. Even at 3C rate the cell exhibits reversible capacity of 677 mAh g(-1). The excellent stability and capacity retention of the cell is attributed to (i) the highly polar Si3N4/MoS2 hetero-structure that improves electrode wettability and would efficiently trap the polysulfides through dipole-dipole interactions, and (ii) the structural advantage of Si3N4/MoS2 -MWCNT which improves both Li+ transport and charge transfer kinetics. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Lithium-Sulfur batteries have high energy density but face challenges such as insulating sulfur, slow electrode kinetics, polysulfide shuttle, and poor capacity retention. A new cathode composite system has been developed to address these issues effectively, achieving high capacity retention.