A Nonpresodiate Sodium-Ion Capacitor with High Performance.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion capacitors (SICs) offer high energy/power density and long cycle life.
• Challenges include anode material limitations and complex presodiation processes.

Purpose of the Study:

• To develop a high-performance SIC using a novel anode material and electrolyte.
• To eliminate the need for a tedious presodiation step in SIC fabrication.

Main Methods:

• Fabrication of a SIC utilizing a Fe_1-xS anode and an ether-based electrolyte.
• Electrochemical characterization of the Fe_1-xS electrode and the complete SIC device.
• Evaluation of cycling performance, energy density, and power density.

Main Results:

• The Fe_1-xS anode exhibits reversible intercalation and high capacity (340 mAh g^-1 at 0.05 A g^-1).
• The SIC demonstrates high energy density (88 Wh kg^-1) and power density (11,500 W kg^-1).
• The device achieves an ultralong cycle life with 93% capacity retention after 9000 cycles.

Conclusions:

• A simple and effective strategy for fabricating high-performance SICs without presodiation is presented.
• Fe_1-xS is a promising anode material for advanced sodium-ion capacitors.
• This approach enables efficient energy storage with enhanced energy and power densities.