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.
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