Core–shell structured SnO2 hollow spheres–polyaniline composite as an anode for sodium-ion batteries

Abstract

A core–shell structured SnO₂ hollow spheres (designated SnO₂-HS)–polyaniline (PANI) composite (SnO₂@PANI) was synthesized by in situ polymerization of aniline monomers in the presence of SnO₂-HS, which were prepared by a two-step hydrothermal method and thermal treatment. When the SnO₂@PANI composite was used as an anode material for sodium-ion batteries (SIBs) it exhibited a long cycle life and good rate capability. The SnO₂@PANI composite is able to deliver a relatively high reversible capacity of 213.5 mA h g⁻¹ after 400 cycles at 300 mA g⁻¹, while a bare SnO₂ particle anode can only deliver a considerably lower capacity of 14.4 mA h g⁻¹ after 400 cycles at the same current density. The enhanced electrochemical performance could be ascribed to the unique hollow structure and the PANI buffer layer, which are found to be beneficial in decreasing the likelihood of the pulverization of SnO₂ and agglomeration of the generated Sn particles during the discharge and charge process.