A novel composite of SnOx nanoparticles and SiO2@N-doped carbon nanofibers with durable lifespan for diffusion-controlled lithium storage

Abstract

Carbon group materials, such as Si, SiO2, Sn and SnO2, with high theoretical capacity as anodes for lithium ion batteries (LIBs), suffer from the poor cycling stability resulting from the huge volume variation. To overcome the defects, a novel composite of hydrothermally synthesized ultrafine SnOx nanoparticles and SiO2@one-dimensional (1D) N-doped carbon nanofibers (SnOx/SiO2@N-CNF) is fabricated by electrospinning technique. Benefiting from the unique structure design that the SnOx and SiO2 nanoparticles are firmly encapsulated in the N-doped carbon nanofibers (N-CNFs), the SnOx/SiO2@N-CNF electrode exhibits not only excellent rate performance (434 mAh/g at 2 A/g), but also remarkable long-term cycling performance (754 mAh/g at 1 A/g after 1000 cycles) as the anode of LIBs. The N-CNFs can efficiently prevent the volume expansion and the direct contact with electrolyte of SnOx and SiO2, as well as shorten the diffusion path of lithium ions to improve the electrical conductivity. Interestingly, owing to the synergistic effect of SnOx and SiO2, the diffusion-controlled redox reaction dominates the charge transfer during charge-discharge process. As a consequence, the SnOx/SiO2@N-CNF could be a promising anode material with the extraordinary long-term cycling performance at high current densities, and provide a novel alternative anode material for LIBs quick-acting charging technology.