Fe0.6Co0.3Ni0.1S2@NC core-shell nanoboxes as anodes for ultrafast sodium-ion batteries

Developing sodium storage anode materials with high capacity and high rate capability is the primary challenge for high-performance sodium-ion batteries. This study presents sulfide nanoboxes with nitrogen-doped carbon encapsulation, specifically Fe0.6Co0.3Ni0.1S2@NC, as a promising anode material for sodium-ion batteries due to its high electrical conductivity. The Fe0.6Co0.3Ni0.1S2@NC is manufactured using polydopamine-coated Prussian blue analogues as the precursor in a sulfidation-in-nanobox strategy. Experimental analysis suggests that the Fe0.6Co0.3Ni0.1S2 nanoparticles with conformal carbon layers are uniformly embedded in a three-dimensional, high-conductivity carbon shell to form Fe0.6Co0.3Ni0.1S2@NC. The anode material demonstrates a high capacity of up to 1000 mAh g-1 at 0.1 A g-1 and delivers 390 mAh g-1 even at a high rate of 10 A g-1.