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

Abstract

Hollow-structured carbon nanofibers embedded with ultrafine SnO_x nanoparticles (SnO_x/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 SnO_x/H-CNFs possess a large specific surface area of 739 m² 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 SnO_x during the lithiation/delithiation processes. Consequently, the SnO_x/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).