Tetrafunctional template-assisted strategy to preciously construct co-doped Sb@C nanofiber with longitudinal tunnels for ultralong-life and high-rate sodium storage

Abstract

Antimony (Sb) is an attractive alloy-type anode material for sodium-ion batteries (SIBs) owing to its high theoretical capacity and the very appropriate reaction potential. However, it suffers from rapid capacity fading and poor rate performance caused by the huge volume changes (∼390%) and sluggish kinetics during sodiation and desodiation, severely hindering its practical application. Structural or component-based modulation strategies alone are usually not effective in solving all issues. Herein, we rationalized the facile construction of N, S co-doped Sb and carbon nanofibers (Sb@N,S-CNFs) with longitudinal tunnels through a tetrafunctional template-assisted strategy, taking into account the overall structural and compositional considerations. The pyrolysis of Sb2S3 nanorod template and the volatilization of Sb results in the formation of void space and Sb nanorods in longitudinal tunnels as well as the doping of Sb nanodots and sulfur in carbon fiber matrix. This well-designed multilevel structure optimized for favorable annealing time not only effectively mitigates large volume changes, but also greatly improves the diffusion kinetics of ions and electrons, thus resulting in much improved rate performance (219 mAh g−1 at 4 A g−1) and cycling stability (85.1% capacity retention after 1000 cycles at 2 A g−1) in half cells as well as a favorable rate capability and cycling performance in full cells matched with Na3V2(PO4)2O2F cathode. Additionally, the multifunctional template-assisted strategy provides precious guidance for the rational design and construction of high-performance electrode materials.