FeNb₂O₆ as a High-Performance Anode for Sodium-Ion Batteries Enabled by Structural Amorphization Coupled with NbO₆...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Transition metal oxides are explored as anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs).
• Challenges in SIBs include the larger sodium ion radius, limiting performance of current materials.
• Pseudocapacitance-type materials offer potential due to low volume change and safety.

Purpose of the Study:

• To report iron niobate (FeNb2O6) with a columbite structure as a novel anode for sodium storage.
• To investigate the structural and electrochemical properties of FeNb2O6 for sodium-ion intercalation.
• To demonstrate the potential of disordered transition metal oxides for high-performance SIB anodes.

Main Methods:

• Synthesis and structural characterization of iron niobate (FeNb2O6).
• Electrochemical testing of FeNb2O6 as an anode in sodium-ion batteries.
• Operando and ex situ characterizations to elucidate storage mechanisms.

Main Results:

• FeNb2O6 exhibits a disordered local structure in the FeO6 octahedra, enabling reversible sodium storage in an amorphous phase.
• Short-range ordered zigzag-chain structures in NbO6 planes act as a skeleton for pseudocapacitive storage and ion diffusion.
• Achieved a reversible capacity exceeding 300 mAh g-1 at a favorable average voltage of ~0.6 V.
• Demonstrated excellent rate capability with 180.4 mAh g-1 at 2 A g-1.

Conclusions:

• Iron niobate (FeNb2O6) is a highly effective intercalation host for sodium ions.
• The disordered structure and unique NbO6 framework contribute to high capacity and fast kinetics.
• This study offers insights into designing intrinsically active transition metal oxides for sodium-ion intercalation.