Sn nanocrystals embedded in porous TiO2/C with improved capacity for sodium-ion batteries

Abstract

Sn-Based materials are attracting increasing attention for application in sodium-ion batteries (SIBs), due to the ultra-high theoretical capacity of pure Sn. However, low structural stability and poor rate capability restrict their further development. Herein, a facile method is reported to embed Sn nanocrystals into a TiO₂/porous carbon (TiO₂/C) composite by direct carbonization of a mixture of tetraphenyltin and a Ti-based metal–organic framework. The obtained cylinder-like Sn/TiO₂/porous carbon (Sn/TiO₂/C) composite is uniformly built from TiO₂ nanoparticles, Sn nanocrystals and N-doped carbon. Importantly, pores, formed by the accumulation of nanoparticles, can effectively restrict the huge volume change of Sn during cycling. When evaluated as an anode in SIBs, the Sn/TiO₂/C composite not only possessed amazing cycling stability (159.6 mA h g⁻¹ at 1.0 A g⁻¹ after 3000 cycles), but also exhibited excellent rate performance (172.3 mA h g⁻¹ at 1.0 A g⁻¹ and 114.0 mA h g⁻¹ at 10.0 A g⁻¹). These superior properties can be attributed to Sn nanocrystals which enhanced specific capacity and electrical conductivity, and the TiO₂/C substrate which improved structural stability, facilitating charge transfer kinetics.