Spatially Confined Fe₇S₈ Nanoparticles Anchored on a Porous Nitrogen-Doped Carbon Nanosheet Skeleton for High-Rate and Durable Sodium Storage

Abstract

Iron sulfides are widely explored as anodes of sodium-ion batteries (SIBs) owing to high theoretical capacities and low cost, but their practical application is still impeded by poor rate capability and fast capacity decay. Herein, for the first time, we construct highly dispersed Fe7S8 nanoparticles anchored on a porous N-doped carbon nanosheet (CN) skeleton (denoted as Fe7S8/NC) with high conductivity and numerous active sites via facile ion adsorption and thermal evaporation combined procedures coupled with a gas sulfurization treatment. Nanoscale design coupled with a conductive carbon skeleton can simultaneously mitigate the above obstacles to obtain enhanced structural stability and faster electrode reaction kinetics. With the aid of density functional theory (DFT) calculations, the synergistic interaction between CNs and Fe7S8 can not only ensure enhanced Na+ adsorption ability but also promote the charge transfer kinetics of the Fe7S8/NC electrode. Accordingly, the designed Fe7S8/NC electrode exhibits remarkable electrochemical performance with superior high-rate capability (451.4 mAh g–1 at 6 A g–1) and excellent long-term cycling stability (508.5 mAh g–1 over 1000 cycles at 4 A g–1) due to effectively alleviated volumetric variation, accelerated charge transfer kinetics, and strengthened structural integrity. Our work provides a feasible and effective design strategy toward the low-cost and scalable production of high-performance metal sulfide anode materials for SIBs.

Prussian Blue Analogue Derived CoS2/FeS2 Confined in N, S Dual-Doped Carbon Nanofibers for Sodium Storage

“…Between 300 and 500 °C, the weight decreases sharply due to the combustion of carbon nanofibers to produce CO 2 . Then, from 500 to 700 °C, H-CoS 2 /FeS 2 in these composites is oxidized to from H-Co 3 O 4 /Fe 2 O 3 . According to the TG results, the carbon content of H-CoS 2 /FeS 2 @CNFs-2 is estimated to be 48.9 wt %.…”

Prussian Blue Analogues Derived Heterostructured CoS2/FeS2 Particles Anchored on Carbon Nanosheets as Anodes for Boosted Sodium Storage Properties

“…75-0039), [25] except for the diffraction peak at 26.1°arising from the carbon nanosheets. [26] Regarding the sample of the CoS 2 /FeS 2 /C hybrid composite, the characteristic peaks at 32.4°, 36.5°, 40.1°, 46.7°a nd 55.3°can be readily indexed to the cubic phased CoS 2 (JCPDS No. 41-1471), [27] while the other peaks appearing at 33.1°, 37.1°, 40.8°, 47.4°and 56.3°are also detected attributing to the cubic phased FeS 2 (JCPDS No.…”

“…It is worth noting that the high content of pyridinic N and pyrrolic N can provide more defects in the carbon materials acting as electrochemical active sites, and boost the adsorption of Na + during the repeated cycling process. [20,26,42,43] The N 2 adsorption-desorption isotherms and pore size distribution curves of the CoS 2 /FeS 2 /C and CoS 2 /FeS 2 hybrid composites are displayed in Figure S2. It is found that both samples present typical type IV isotherms with mesoporous features.…”

“…As shown in Figure 1E, all the distinct diffraction peaks located at 17.5°, 24.9° and 35.5° can be well attributed to the (200), (220) and (400) planes of bulk Co 2 Fe(CN) 6 phase (JCPDS No. 75–0039), [25] except for the diffraction peak at 26.1° arising from the carbon nanosheets [26] . Regarding the sample of the CoS 2 /FeS 2 /C hybrid composite, the characteristic peaks at 32.4°, 36.5°, 40.1°, 46.7° and 55.3° can be readily indexed to the cubic phased CoS 2 (JCPDS No.…”

“…In the case of N 1s spectrum in Figure 4F, three peaks located at 398.7, 400.0 and 401.2 eV can be attributed to pyridinic N, pyrrolic N and graphitic N, [41] which account for 63.3 atom%, 26.9 atom% and 9.8 atom%, respectively, demonstrating the successful incorporation of N atoms into the carbon layers. It is worth noting that the high content of pyridinic N and pyrrolic N can provide more defects in the carbon materials acting as electrochemical active sites, and boost the adsorption of Na + during the repeated cycling process [20,26,42,43] . The N 2 adsorption‐desorption isotherms and pore size distribution curves of the CoS 2 /FeS 2 /C and CoS 2 /FeS 2 hybrid composites are displayed in Figure S2.…”