Defect-rich SnS2-xSex nanodots embedded in N-doped carbon nanofibers facilitating fast and stable sodium-ion storage

Abstract

Sodium-ion batteries (SIBs) show promising potential in the field of electrochemical energy storage due to their cost-effectiveness and similar operational mechanisms to lithium-ion batteries (LIBs). However, the dramatic volume expansion of electrode materials and the slow reaction kinetics caused by the large sodium ion (Na⁺) radius hinder the practical application of SIBs. Here, we successfully prepared SnS_2−xSe_x nanodots embedded within N-doped carbon nanofibers (CNF) for use as electrode materials of SIBs. The introduction Se provided abundant anionic defect sites for Na⁺ storage and enlarged the interlayer spacing of SnS₂. In addition, the ultrafine nanodot structure reduces the volume expansion of SnS_2−xSe_x and shortens the ion transport path. As an anode of SIBs, SnS_2−xSe_x/CNF demonstrates remarkable reversible capacity (719 mAh g⁻¹ at 0.5 A g⁻¹), along with rapid charging ability (completing a charge in just 127 s). Meanwhile, the assembled full-cell battery manifested exceptional energy density of 165.8 Wh kg⁻¹ at a high-power output of 5526 W kg⁻¹. This study presents an effective strategy for fabricating high-performance sulphide-based anode materials for SIBs, offering broad prospects for application.