Phase-separation induced hollow/porous carbon nanofibers containing in situ generated ultrafine SnOx as anode materials for lithium-ion batteries

Hollow-structured carbon nanofibers embedded with ultrafine SnOx nanoparticles (SnOx/H-CNFs) have been prepared by a simple single-spinneret electrospinning technique assisted by phase separation between polyvinylpyrrolidone and tetraethyl orthosilicate. The nitrogen adsorption-desorption isothermal analysis shows that the SnOx/H-CNFs possess a large specific surface area of 739 m(2) g(-1) and large amounts of mesopores. The high specific surface area provides a large electrode/electrolyte contact interface for Li+ transport and storage, while the hollow structure shortens the Li+-diffusion pathway and thus favors the rate capability. Moreover, the hollow and porous carbon matrix can act as a buffer zone to accommodate the volume change of the highly active SnOx during the lithiation/delithiation processes. Consequently, the SnOx/H-CNF electrode delivers a high reversible capacity of 732 mA h g(-1) at the rate of 500 mA g(-1) upon the 100th cycle, good rate performance (254 mA h g(-1) at 4 A g(-1)), and long-term cycling stability (513 mA h g(-1) at 1 A g(-1) after 500 cycles).