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

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.