Ultrafine SnO2 Nanoparticles Encapsulated in High-Conductivity Graphited Carbon Nanotubes As Anodes for High Electrochemistry Performance Lithium-Ion Batteries

Efficient use of tin-based composites plays an active role in energy-storage systems due to their high theoretical capacity and environmental benignity. But, large volume expansion during Li-ion insertion/extraction and undesirable aggregation of tin particles greatly limit the commercial application of Sn-based anodes. In this work, the SnO2 nanoparticles encapsulated in high-conductivity graphited carbon nanotubes (gCNTs) had been designed and synthesized by a facile wet chemical method, in which SnO2 nanoparticles with a diameter of 3-6 nm were protected by gCNT nano-containers. With the increase of graphiting temperature from 2400 degrees C to 2800 degrees C, more SnO2 nanoparticles were encapsulated in the gCNT containers instead of being attached to the outer surface. The SnO2/gCNT composites showed an excellent Li-ion storage capability and long cycling stability. The initial discharge capacities of the SnO2-gCNT composites were 1455 mAh g(-1), and kept final capacity of 383 mAh g(-1) after 620 cycles at 4 A g(-1). Furthermore, this work provides a simple and effective strategy to prepare the ultrafine nanoparticles encapsulated in high-conductivity gCNTs for Li-ion batteries.