Ultrasmall Sn Nanoparticles Embedded in Carbon as High-Performance Anode for Sodium-Ion Batteries

Designed as a high-capacity, high-rate, and long-cycle life anode for sodium-ion batteries, ultrasmall Sn nanoparticles (approximate to 8 nm) homogeneously embedded in spherical carbon network (denoted as 8-Sn@C) is prepared using an aerosol spray pyrolysis method. Instrumental analyses show that 8-Sn@C nanocomposite with 46 wt% Sn and a BET surface area of 150.43 m(2) g(-1) delivers an initial reversible capacity of approximate to 493.6 mA h g(-1) at the current density of 200 mA g(-1), a high-rate capacity of 349 mA h g(-1) even at 4000 mA g(-1), and a stable capacity of approximate to 415 mA h g(-1) after 500 cycles at 1000 mA g(-1). The remarkable electrochemical performance of 8-Sn@C is owing to the synergetic effects between the well-dispersed ultrasmall Sn nanoparticles and the conductive carbon network. This unique structure of very-fine Sn nanoparticles embedded in the porous carbon network can effectively suppress the volume fluctuation and particle aggregation of tin during prolonged sodiation/desodiation process, thus solving the major problems of pulverization, loss of electrical contact and low utilization rate facing Sn anode.