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 SnO2 nanoparticles (NPs) have been prepared using a simple one-step chemical solution method at 50 degrees C. The SnO2/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 SnO2 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 SnO2 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.