Activating graphite with defects and oxygenic functional groups to boost sodium-ion storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are a cost-effective alternative to lithium-ion batteries (LIBs) for large-scale energy storage.
• Graphite anodes in SIBs suffer from low reversible capacity due to weak sodium binding.

Purpose of the Study:

• To design and fabricate activated graphite (AG) with enhanced sodium-ion storage performance.
• To investigate the structural evolution and electrochemical properties of AG produced via ball-milling.

Main Methods:

• Fabrication of activated graphite (AG) using a facile and eco-friendly ball-milling method.
• Investigation of structural evolution through physical characterizations.
• Electrochemical performance testing of AG electrodes for sodium-ion storage.
• Density functional theory (DFT) calculations to understand storage mechanisms.

Main Results:

• The AG-50 electrode (50-hour ball-milling) achieved a stable reversible capacity of 139.1 mA h g⁻¹ at 1.0 A g⁻¹ after 4500 cycles.
• A remarkably low capacity decay ratio of 0.0034% per cycle was observed.
• Ball-milling introduced defects, enlarged interlayer spacing, and increased surface area, enhancing sodium-ion storage.

Conclusions:

• Activated graphite fabricated by ball-milling significantly improves specific capacity and cycling stability for sodium-ion storage.
• The enhanced performance is attributed to defect sites facilitating sodium adsorption/desorption.
• This work provides a valuable reference for developing modified graphite anodes for high-performance SIBs.