In situ three-dimensional cross-linked carbon nanotube-interspersed SnSb@CNF as freestanding anode for long-term cycling sodium-ion batteries

Alloying-based material has achieved tremendous appealing being anode used in sodium‑ion batteries (SIBs) by virtue of its relatively giant sodium storage specific capacity along with low discharge platforms. Nevertheless, the sluggish ion transmission dynamics and the huge volume change during cycling induced irreparable particle pulverization and agglomeration result in collapse of electrode structure and deterioration of cycling properties. In this work, three-dimensional cross-linked carbon nanotube-interspersed SnSb@CNF integrated structure (SnSb@CNF/CNT) is designed and synthesized. In this ingenious nanostructure, CNTs interspersed between CNF frames play the role of electron transport and diffusion "bridges" for enhancing the electrical conductivity of anode materials and relieve aggregation of SnSb alloy particles, the N doped-CNFs serve as external frame could efficiently mitigate dramatic volume effect to maintain system integrity. Based on these constructive advantages, the elastic conductive system can be directly available as anode for SIBs, showing ultralong cycling performance of 210 mAh g−1 over 700 sodiation/desodiation processes with a current density of 0.5 A g−1, even 161 mAh g−1 following 1000 cycling under a high current density of 1 A g−1 accompanied by an almost 100% superb capacity retention ratio, as well as distinguished high rate performance (470 mAh g−1 with a returned current density of 0.05 A g−1). This work shed distinctive insight to construct in situ three-dimensional cross-linked freestanding alloying-based anode materials used in alternative electrochemical grid-scale application.