N-Doped Carbon Encapsulated FeV2S4/Fe Nanorods as Fast-Charging Anodes for All-Climate Sodium-Ion Storage

Abstract

FeV2S4 holds promise as an anode for sodium-ion batteries (SIBs) because of its large interlayer spacing, high storage capacity, and metallic conductivity. However, the significant volume expansion and polysulfides dissolution during cycling usually lead to material pulverization and performance degradation. Herein, the thin N-doped carbon (NC) layer encapsulated FeV2S4/Fe nanorods (FeV2S4/Fe@NC) have been constructed via the multi-step strategy. Under the synergistic effect of outer NC and inner FeV2S4/Fe, the optimized FeV2S4/Fe@NC anode prepared at 850 °C demonstrates fast-charging sodium storage capabilities (525 mAh g−1/2 A g−1/400 cycles and 281 mAh g−1/15 A g−1). Remarkably, except for 25 °C, such well-chosen anode can easily run at extreme temperatures, demonstrating excellent all-climate rate capabilities (135 mAh g−1/5 A g−1 at 0 °C and 289 mAh g−1/15 A g−1 at 40 °C) and cyclic stability (371 mAh g−1/0.5 A g−1/200 cycles at 0 °C and 529.2 mAh g−1/2 A g−1/300 cycles at 40 °C). Additionally, the components of SEI film, electrochemical kinetics, theoretical calculations, and various in-situ/ex-situ characterizations confirm the rapid charge transfer, highly efficient Na+ diffusion, and conversion-based reaction mechanism in FeV2S4/Fe@NC. Furthermore, the full cells consisted of FeV2S4/Fe@NC anodes and reduced graphene oxide modified Na3V2(PO4)3 (Na3V2(PO4)3@rGO) cathodes realize satisfied electrochemical performances (242 mAh g−1 over 140 cycles at 1 A g−1). This work offers a rational synthesis approach for designing high-performance dual-metal chalcogenide-based anodes for sodium-ion storage.