Yolk–shell SnSe2@NC nanocubes: synergistic interior void and spatial confinement for superior sodium-ion battery anodes

Abstract

Rationally designed nanostructured electrode materials, especially yolk–shell metal selenide@void@C architectures, are gaining prominence as potential anode candidates for sodium-ion batteries (SIBs) due to their exceptional sodium-ion storage capabilities. In this work, we propose a template-assisted carbon coating route to fabricate nitrogen-doped carbon nanocubes encapsulating SnSe₂ nanoparticles, forming a yolk–shell structure with an internal void space (SnSe₂@NC), resulting in a high-performance anode for SIBs. The yolk–shell architecture, with SnSe₂ nanoparticles embedded within a nitrogen-doped carbon shell, significantly boosts structural integrity and sodium storage performance. The SnSe₂@NC electrode delivers a high reversible capacity of 368.9 mA h g⁻¹ after 50 cycles at 0.5 A g⁻¹ and an impressive capacity retention of 324.2 mA h g⁻¹ at 5 A g⁻¹ after 1000 cycles. Electrochemical analyses reveal that the enhanced performance is attributed to the improved Na-ion diffusion kinetics, reduced charge-transfer resistance, and the structural stability conferred by the nitrogen-doped carbon shell and the internal void space. The yolk–shell SnSe₂@NC nanocubes demonstrate superior electrochemical properties, representing a potential strategy for the development of advanced SIB anode materials.