Efficient Electron Injection into Graphullerene Enables Reversible NaC₂ Sodium Storage.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Sodium-ion (Na-ion) batteries are explored as alternatives to lithium-ion batteries for grid storage.
• Graphite anodes face limitations in Na-ion storage due to thermodynamics and structural instability.

Purpose of the Study:

• To computationally design and evaluate graphullerene as a novel anode material for reversible Na-ion storage.
• To investigate the electron injection capacity and Na-ion storage performance of graphullerene.

Main Methods:

• Computational design and exploration of graphullerene structure.
• Analysis of electron injection capacity and Na-ion stoichiometry.
• Evaluation of specific capacity, open circuit voltage, and ion diffusivity.

Main Results:

• Graphullerene exhibits a high electron injection capacity of 15 electrons per fullerene moiety.
• Achieved large-scale Na-ion storage up to NaC₂ stoichiometry with 551 mAhg⁻¹ specific capacity.
• Demonstrated rapid Na-ion insertion/extraction kinetics due to enhanced surface diffusivity.

Conclusions:

• Graphullerene is a promising anode material for high-capacity, reversible Na-ion storage.
• Increasing electron injection limit is a viable strategy for advanced carbon anodes.
• This approach avoids artificial defect introduction or doping for enhanced performance.