Interface Engineering of Fe(7)S(8)/FeS(2) Heterostructure in situ Encapsulated into Nitrogen-Doped Carbon Nanotubes for High Power Sodium-Ion Batteries

Heterostructure engineering combined with carbonaceous materials shows great promise toward promoting sluggish kinetics, improving electronic conductivity, and mitigating the huge expansion of transition metal sulfide electrodes for high-performance sodium storage. Herein, the iron sulfide-based heterostructures in situ hybridized with nitrogen-doped carbon nanotubes (Fe(7)S(8)/FeS(2)/NCNT) have been prepared through a successive pyrolysis and sulfidation approach. The Fe(7)S(8)/FeS(2)/NCNT heterostructure delivered a high reversible capacity of 403.2 mAh g(−1) up to 100 cycles at 1.0 A g(−1) and superior rate capability (273.4 mAh g(−1) at 20.0 A g(−1)) in ester-based electrolyte. Meanwhile, the electrodes also demonstrated long-term cycling stability (466.7 mAh g(−1) after 1,000 cycles at 5.0 A g(−1)) and outstanding rate capability (536.5 mAh g(−1) at 20.0 A g(−1)) in ether-based electrolyte. This outstanding performance could be mainly attributed to the fast sodium-ion diffusion kinetics, high capacitive contribution, and convenient interfacial dynamics in ether-based electrolyte. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40820-023-01082-w.