Synthesis of Multiwalled Carbon Nanotubes That Are Both Filled and Coated by SnO₂ Nanoparticles and Their High Performance in Lithium-Ion Batteries

Multiwalled carbon nanotubes (MWCNTs) filled and coated with SnO 2 nanoparticles (NPs) have been prepared using a simple one-step chemical solution method at 50 °C. The SnO 2 /MWCNT hybrids were characterized by transmission electron microscopy and X-ray diffraction, and the formation mechanism has been discussed. The discharge capacities showed that MWCNTs coated and filled with SnO 2 had superior electrochemical performance. The first discharge capacities are 2127.4 and 1880.2 mAh/g at 70 and 200 mA/g and remain at 469 and 362 mAh/g after 40 cycles. Our results demonstrated that they had a better cycling performance at large discharge/charge current densities. The main reason is the huge volume expansion usually occurred in SnO 2 NPs during the Li + insertion/extraction process has been prevented when they were filled into the cavities of MWNTs who have a superior mechanical properties.