Designing Sphere-like FeSe₂-Carbon Composites with Rational Construction of Interfacial Traits towards Considerable...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are attractive due to low cost and high stability.
• Further development of SIBs is hindered by limited energy density, necessitating high-capacity anode materials.
• Iron selenide (FeSe2) offers high conductivity and capacity but faces challenges with sluggish kinetics and volume expansion.

Purpose of the Study:

• To synthesize novel FeSe2-carbon composites for enhanced SIB anode performance.
• To address the sluggish kinetics and volume expansion issues associated with FeSe2 anodes.
• To investigate the structure-property relationships for advanced sodium storage.

Main Methods:

• Sacrificial template methods were employed to create sphere-like FeSe2-carbon composites.
• Uniform carbon coatings and interfacial FeOC bonds were achieved.
• Precursor and acid treatments introduced structural voids to mitigate volume expansion.

Main Results:

• The optimized FeSe2-carbon composite anode achieved a capacity of 462.9 mAh g-1 at 1.0 A g-1 with 88.75% coulombic efficiency.
• A capacity of 318.8 mAh g-1 was maintained at a high current density of 5.0 A g-1.
• Stable cycling performance was demonstrated for over 200 cycles.
• Kinetic analysis revealed that interfacial FeOC bonds facilitate rapid ion transport and enhanced surface properties.

Conclusions:

• The developed FeSe2-carbon composites show significant potential as high-performance anodes for sodium-ion batteries.
• The structural design, including carbon coating and internal voids, effectively alleviates volume expansion and improves electrochemical kinetics.
• This research provides valuable insights for designing advanced metal-based anode materials for next-generation sodium-ion energy storage systems.