LAUSR

This work reports an amorphization and partial desulfurization method to improve the performance of sulfide-based materials for Na+ storage. Specifically, the polypyrrole derived carbon coated amorphous substoichiometric tin sulfide supported on aminated carbon nanotubes (PPY-C@SnSx /ACNTs) with amorphized and substoichiometric tin sulfide (SnSx ) is synthesized by simply thermal annealing the PPY-C@SnS2 /ACNTs. The PPY-C@SnSx /ACNTs shows stable reversible capacities of 410.2 mAh g-1 for Na+ storage at 0.1 A g-1 and excellent rate capacities of 270.2, 235.5, 217.4, and 210.0 mAh g-1 at 5.0, 10.0, 20.0, and 30.0 A g-1 , respectively. Nearly zero drops on the reversible capacities can be observed when it is sodiated/desodiated at 2.0, 5.0, and 10.0 A g-1 for up to 1000, 6500, 8000 cycles, respectively. Its outstanding rate capacities and degradation-free cycling stabilities mainly arise from the amorphized and substoichiometric structure of SnSx , which improve the reversible capacities and Na+ diffusivities of the PPY-C@SnSx /ACNTs. The density functional theory (DFT) calculations indicate that the partial desulfurization can improve the electric conductivity and promote the sodiation/desodiation of SnSx . It explains why the PPY-C@SnSx /ACNTs can exhibit high performance for Na+ storage well.