Fabrication of superior-performance SnO2@C composites for lithium-ion anodes using tubular mesoporous carbon with thin carbon walls and high pore volume

Abstract

A tubular composite, including ultrafine SnO₂ particles encapsulated in ordered tubular mesoporous carbon with thin walls and high pore volume, is fabricated through the in situ hydrolysis method. It is observed that up to 80 wt% of SnO₂ particles with size between 4–5 nm are highly dispersed and homogeneously encapsulated in the mesopore channels and no bulky aggregates are visible. The tubular composite exhibits a considerably high reversible capacity of 978 mA h g⁻¹ and a high initial efficiency of 71% at a current density of 200 mA g⁻¹ between 0.005–3 V. Its reversible capacity even increases up to 1039 mA h g⁻¹ after 100 cycles, which is much higher than the conventional theoretical capacity of SnO₂ (782 mA h g⁻¹), meanwhile, it also displays fast discharge/charge kinetics at a high current density of 1500 mA g⁻¹. The excellent electrochemical performance is ascribed to its unique mesostructure by recruiting tubular mesoporous carbon with thin carbon walls (∼2 nm) and high pore volume (2.16 cm³ g⁻¹). This tubular nanostructure provides confined nanospace for hosting immobilized ultrafine SnO₂ with high loading, compensates volume expansion of SnO₂, warrants efficient contact between nanoparticles and carbon matrix before and after Li⁺ insertion. We believe this special structure model might be extended for the fabrication of other cathode and anode electrode materials, to achieve high performance LIBs.