Enhanced cycle stability of polypyrrole-derived nitrogen-doped carbon-coated tin oxide hollow nanofibers for lithium battery anodes

SnO₂ hollow nanofibers (SnO₂ hNFs) are prepared through electrospinning and annealing processes. The polypyrrole layers coated onto the surface of the SnO₂ hNFs are annealed in a nitrogen atmosphere. The nitrogen-doped carbon-coated SnO₂ hNFs (SnO₂/NC hNFs) are composed of SnO₂ hNFs with a wall thickness of 60–80 nm and a nitrogen-doped carbon layer ∼10 nm thick. The nitrogen content in the carbon layer is approximately 7.95%. Owing to the nitrogen-doped carbon shell layers, the specific reversible capacity of SnO₂/NC hNFs at a current density of 0.2 A g⁻¹ after 100 cycles is 1648 mAh g⁻¹, which is 427% higher than that of (386  mAh g⁻¹) SnO₂ hNFs. This strategy may open new avenues for the design of other composite architectures as electrode materials in order to achieve high-performance lithium ion batteries.