Ingeniously Designed Yolk–Shell-Structured FeSe<sub>2</sub>@NDC Nanoboxes as an Excellent Long-Life and High-Rate Anode for Half/Full Na-Ion Batteries
Jian Feng, Shaohua Luo, Zhan Yang, Shengxue Yan, Pengwei Li, Lin Zhang, Qing Wang, Yahui Zhang, Xin Liu
Abstract
Thanks to their high conductivity and theoretical capacity, transition metal selenides have demanded significant research attention as prospective anodes for sodium-ion batteries. Nevertheless, their practical applications are hindered by finite cycle life and inferior rate performance because of large volume expansion, polyselenide dissolution, and sluggish dynamics. Herein, the nitrogen-doped carbon (NC)-coated FeSe2 nanoparticles encapsulated in NC nanoboxes (termed FeSe2@NDC NBs) are fabricated through the facile thermal selenization of polydopamine-wrapped Prussian blue precursors. In this composite, the existing nitrogen-doped dual carbon layer improves the intrinsic conductivity and structural integrity, while the unique porous yolk–shell architecture significantly mitigates the volume swelling during the sodium/desodium process. Moreover, the derived Fe–N–C bonds can effectively capture polyselenide, as well as promote Na+ transportation and good reversible conversion reaction. As expected, the FeSe2@NDC NBs deliver remarkable rate performance (374.9 mA h g–1 at 10.0 A g–1) and long-cycling stability (403.3 mA h g–1 over 2000 loops at 5.0 A g–1). When further coupled with a self-made Na3V2(PO4)3@C cathode in sodium-ion full cells, FeSe2@NDC NBs also exhibit considerably high and stable sodium-storage performance.