Tin quantum dots embedded in nitrogen-doped carbon nanofibers as excellent anode for lithium-ion batteries

Abstract

Sn/C composites with sub-10-nm-scale tin nanoparticles uniformly dispersed in a carbon matrices are believed to be excellent anode materials for high energy and power density lithium-ion batteries. However, it is difficult to incorporate high-capacity, active Sn into the carbon structures due to the hydrophobic nature of the carbon surface. Surfactants and/or templates are always required for uniform dispersion of active Sn, inevitably increasing the production cost and degrading the electronic conductivity. In this work, we reported a facile and scalable electrospinning technology to synthesize Sn quantum dots finely embedded in N-doped carbon nanofibers. The composite electrode exhibited a high reversible capacity of 887mAhg−1 at a current density of 0.1Ag−1 after 200 cycles, about 75% retention of the initial capacity. Moreover, it showed good rate capability even when cycled at 0.2Ag−1 about 685mAhg−1 after 500 cycles and 508mAhg−1 at 0.4Ag−1 after 200 cycles. The exceptional performance is supposed to benefit from the high electric conductivity of N-doped porous carbon nanofiber structures, which not only provides fast and versatile transport pathways for the electrolyte ions and electrons, but also simultaneously solves the major problems of pulverization, loss of electrical contact, and particle aggregation of Sn anode. Moreover, the short diffusion path for both electrons and ions provided by the ultrasmall Sn particles further improved the rate performance.