Novel hybrid of amorphous Sb/N-doped layered carbon for high-performance sodium-ion batteries

Antimony (Sb) based materials, which have been proved to be promising anodes to fabricate high-performance sodium-ion batteries (SIBs), have attracted considerable interest owing to its large theoretical capacity (660 mAh g⁻¹), appropriate inserting potential of sodium (0.5–0.8 V vs Na⁺/Na), and moderate electrode polarization (~0.35 V). Unfortunately, fast capacity decay and serious structure pulverization resulting from large volume variation upon cycling are often observed for Sb-based anodes, and further structure design is needed. In this work, a novel hybrid of amorphous Sb/N-doped layered carbon (a-Sb/NC) was fabricated through a facile bottom-up method, where ultrafine amorphous Sb nanoparticles are uniformly anchored on layered N-doped carbon (NC). When applied as anode material for SIBs, this hybrid exhibits a large reversible capacity (479.6 mAh g⁻¹ at 0.1 A g⁻¹ up to 100 cycles), robust rate capability (298.7 mAh g⁻¹ at current density of 2 A g⁻¹), and remarkable stability upon long-term cycling (280.5 mAh g⁻¹ at 1.0 A g⁻¹ up to 500 cycles), outperforming most of the reported amorphous anodes for SIBs. In principle, such impressive sodium storage properties of a-Sb/NC should be mainly ascribed to the amorphous feature of Sb nanoparticles as well as the synergistic effect between amorphous Sb and layered NC, thereby endowing the composite with improved electron/ion dynamics and efficient self-buffering ability.