Built-In Electric Field Enhanced Sodium Storage in Fe₃O₄/Fe Homogeneous Heterojunction Confined by N-Doped Carbon...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Iron oxide (Fe3O4) is a promising anode material for sodium-ion batteries (SIBs) due to its abundance and high theoretical capacity.
• However, its practical use is hindered by low conductivity, poor ion diffusion, and volume changes during cycling.

Purpose of the Study:

• To address the limitations of Fe3O4 anodes in SIBs.
• To design and synthesize a novel Fe3O4/Fe@N-doped carbon (Fe3O4/Fe@CN) nanostructure with enhanced electrochemical properties.

Main Methods:

• Fabrication of a Fe3O4/Fe@CN nanostructure integrating Fe-Fe3O4 heterojunctions with a nitrogen-doped carbon shell.
• Electrochemical characterization of the anode material in SIBs.
• Assembly and testing of a full cell with a Na3V2(PO4)3 cathode.

Main Results:

• The Fe3O4/Fe@CN anode exhibited a high reversible capacity of 336.9 mAh g⁻¹ at 0.1 A g⁻¹.
• Excellent rate capability (244.7 mAh g⁻¹ at 2 A g⁻¹) and cycling stability (76.4% capacity retention after 500 cycles) were achieved.
• A full cell demonstrated a high energy density of 112.67 Wh·kg⁻¹ and outstanding cycling performance.

Conclusions:

• The synergistic Fe3O4/Fe@CN nanostructure effectively enhances electrical conductivity and buffers volume expansion, overcoming Fe3O4 limitations.
• This work presents a viable strategy for developing high-performance SIB anodes using iron oxide through heterojunction and interfacial engineering.