In-situ fabrication of active interfaces towards FeSe as advanced performance anode for sodium-ion batteries

Transition metal selenides have gained enormous interest as anodes for sodium ion batteries (SIBs). Nonetheless, their large volume expansion causing poor rate and inferior cycle stability during Na. inser-tion/extraction process hinders their further applications in SIBs. Herein, a confined-regulated interfacial engineering strategy towards the synthesis of FeSe microparticles coated by ultrathin nitrogen-doped carbon (NC) is demonstrated (FeSe@NC). The strong interfacial interaction between FeSe and NC endows FeSe@NC with fast electron/Na. transport kinetics and outstanding structural stability, delivering unex-ceptionable rate capability (364 mAh/g at 10 A/g) and preeminent cycling durability (capacity retention of 100 % at 1 A/g over 1000 cycles). Furthermore, various ex situ characterization techniques and density functional theory (DFT) calculations have been applied to demonstrate the Na. storage mechanism of FeSe@NC. The assembled Na3V2(PO4)(2)F-3@rGO//FeSe@NC full cell also displays a high capacity of 241 mAh/g at 1 A/g with the capacity retention of nearly 100 % over 2000 cycles, and delivers a supreme energy density of 135 Wh kg(-1) and a topmost power density of 495 W kg(-1), manifesting the latent appli-cations of FeSe@NC in the fast charging SIBs. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study demonstrates a confined-regulated interfacial engineering strategy for the synthesis of FeSe@NC. The strong interfacial interaction between FeSe and NC endows FeSe@NC with excellent electron/sodium transport kinetics and structural stability, resulting in outstanding rate capability and cycling stability. The sodium storage mechanism of FeSe@NC is also revealed, and the potential applications of FeSe@NC in high-performance sodium ion batteries are demonstrated.