Embedding tin disulfide nanoparticles in two-dimensional porous carbon nanosheet interlayers for fast-charging lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have attracted significant attention for their high specific capacity, non-toxic and harmless advantages. However, the shuttle effect limits their development. In this work, small-sized tin disulfide (SnS2) nanoparticles are embedded between interlayers of two-dimensional porous carbon nanosheets (PCNs), forming a multi-functional nanocomposite (PCN-SnS2) as a cathode carrier for Li-S batteries. The graphitized carbon nanosheets improve the overall conductivity of the electrode, and the abundant pores not only facilitate ion transfer and electrolyte permeation, but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material. More importantly, the physical confinement of PCN, as well as the strong chemical adsorption and catalytic reaction of small SnS2 nanoparticles, synergistically reduce the shuttle effect of polysulfides. The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS2-S electrode high electrochemical performance. Even at a high rate of 2 C, a discharge capacity of 650 mA h g−1 is maintained after 150 cycles, underscoring the positive results of SnS2 based materials for Li S batteries. The galvanostatic intermittent titration technique results further confirm that the PCN-SnS2-S electrode has a high Li+ transmission rate, which reduces the activation barrier and improves the electrochemical reaction kinetics. This work provides strong evidence that reducing the size of SnS2 nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.