Enhanced electrochemical performance of SnS nanoparticles/CNTs composite as anode material for sodium-ion battery

Abstract SnS nanoparticles/CNTs composite (SnS/CNTs composite) is synthesized by a facile one-pot solvothermal reaction. The structural characterizations reveal pure SnS nanoparticles with the size of less than 10 nm distribute on the surface of CNTs with the diameter of less than 20 nm. The SnS/CNTs composite electrode performs high reversible capacity and good cyclability (365 mAh/g at 50 mA/g after 50 cycles), which is superior to that of pure SnS electrode synthesized without the adding of CNTs (115.9 mAh/g at 50 mA/g after 50 mA/g cycles). Even increasing the current density to 500 mA/g, the SnS/CNTs composite electrode still delivers a reversible capacity up to 210 mAh/g after 100 cycles, nearly two times higher than that of the pure SnS electrode (108 mAh/g after 100 cycles). The rate performance of the SnS/CNTs composite electrode is also better than that of pure SnS electrode at different current densities from 50 mA/g to 800 mA/g. The enhanced electrochemical performance of SnS/CNTs composite can be attributed to the adding of CNTs as a flexible and conductive structure supporter and the formation of SnS nanoparticles with small size. The SnS nanoparticles/CNTs composite structure not only benefits for buffering the volume change during charge and discharge process, but also increases the surface area for sufficient electrode-electrolyte contacting, and shortens Na+ diffusion length, which improves the conductivity and stability of active material and finally provides desirable electrochemical performance.