Synergistic Ion Transport and Spatial Confinement in Sb-Embedded Hollow Carbon Nanofibers for Stable Na Metal Anodes.

Sodium metal anodes (SMAs) are pivotal for developing high-energy-density sodium metal batteries (SMBs) but are plagued by uncontrollable dendrite growth and unstable solid-electrolyte interphases (SEI). While 3D core-shell hosts can mitigate these issues, these conventional designs often lack active control over ion transport and involve complex syntheses. Herein, we develop an sodiophilic 3D Sb-embedded hollow carbon nanofiber (Sb@HCF) host via electrospinning and wet etching approach. Combining in situ characterizations and theoretical simulations, it was clearly verified that the in situ formed Na-Sb alloy not only guides uniform Na deposition but also serves as Na+ transport highways, thereby significantly suppressing Na dendrite and promoting the formation of a robust NaF-rich SEI. As a result, the Na||Sb@HCF delivers an exceptional Coulombic efficiency of 99.88% over 1400 cycles at 4 mA cm-2/4 mAh cm-2, and the symmetric cells simultaneously operate steadily over 1200 h at 10 mA cm-2/2 mAh cm-2, achieving a superior cumulative plating capacity of 6 Ah cm-2. Moreover, the Na@HCF||Na3V2(PO4)3@C full cell retains a capacity of 84.10 mAh g-1 with a Coulombic efficiency of 98.05% even after 1000 cycles. Our strategy paves a promising way for for stabilizing SMA and developing high-energy-density SMBs.