Cork-Derived Carbon Sheets for High-Performance Na-Ion Capacitors.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Developing advanced carbon materials for energy storage is crucial.
• Sustainable and cost-effective precursors are needed for large-scale applications.
• Sulfur doping can enhance the electrochemical performance of carbon materials.

Purpose of the Study:

• To prepare sulfur-doped carbon sheets from renewable biomass (cork).
• To investigate the sodium storage performance of these S-doped carbon sheets.
• To develop and test a sodium-ion capacitor using S-doped and porous carbon sheets.

Main Methods:

• Mild ball-milling of cork to deconstruct its 3D structure.
• Sulfur doping using an earth-abundant sulfur source (>14 wt% S).
• Chemical activation to produce highly porous carbon sheets (SBET > 2700 m²/g).

Main Results:

• S-doped carbon sheets exhibit high Na storage capacities (300-550 mAh/g at 0.1 A/g) and good volumetric capacities.
• Materials handle high current densities (55-140 mAh/g at 10 A/g).
• A sodium-ion capacitor achieved high energy/power (90 Wh/kg at 29 kW/kg) with robust cycling (>10,000 cycles, 0.0018% fade/cycle).

Conclusions:

• Sustainable S-doped carbon sheets from cork are promising anode materials for sodium-ion batteries.
• Porous carbon sheets enhance anion storage and capacitor performance.
• The developed sodium-ion capacitor demonstrates excellent energy density, power density, and cycling stability.