Polyaniline-coated nanoporous antimony with improved performance for sodium-ion battery anodes

Antimony (Sb), a typical anode material in sodium-ion batteries (SIBs), undergoes sharp capacity fading due to large volume changes during electrochemical cycling. To solve this issue, recent research has focused on designing Sb with special morphologies or introducing another component as a buffer to generate Sb-based composites. In this study, the above two strategies were combined, focusing on a nanoporous Sb/polyaniline (NP-Sb/PANI) anode where PANI was directly coated on the surface of NP-Sb by in situ oxidative polymerization. This composite anode demonstrated enhanced performance, delivering an initial reversible capacity of 510 mAh g⁻¹ and showed capacity retention of up to 82.4% after 250 cycles at a C-rate of C/2. The improved electrochemical performance is attributed to the synergetic effect of NP-Sb and conductive PANI. Specifically, the porosity in NP-Sb can accommodate the volume variation and facilitate electrolyte penetration into the electrodes, while the PANI coating can further buffer the volume expansion and improve the diffusion rate of sodium ions in the electrode.