Quinone/ester-based oxygen functional group-incorporated full carbon Li-ion capacitor for enhanced performance

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium ion capacitors (LICs) offer a promising bridge between lithium ion batteries and supercapacitors.
• Key challenges include electrode mismatches impacting energy density, high-rate performance, and cycling stability.
• Addressing these limitations is crucial for advancing LIC technology.

Purpose of the Study:

• To develop novel oxygen-modified carbon materials for improved LIC performance.
• To investigate the role of oxygen functional groups in enhancing electrode kinetics and capacity.
• To demonstrate the potential of these materials in high-performance full carbon LIC devices.

Main Methods:

• Chemical activation with alkali to synthesize quinone and ester-type oxygen-modified carbon.
• Electrochemical characterization of electrode performance in LIC devices.
• Density Functional Theory (DFT) calculations to elucidate the mechanism of lithium storage.

Main Results:

• Synthesized oxygen-modified carbon effectively absorbs PF6- and lithium ions, improving electrode kinetics.
• Cathode capacity significantly increased with higher oxygen functional group content.
• Achieved an energy density of 144 Wh kg-1 at 200 W kg-1 and 70.8% capacity retention after 10,000 cycles at 20,000 W kg-1.
• DFT calculations confirmed enhanced electrochemical activity for lithium storage via surface-induced redox reactions.

Conclusions:

• Oxygen functional groups on carbon materials are critical for enhancing LIC cathode capacity and overall device performance.
• The developed materials offer a viable solution to electrode mismatches in LICs, leading to high energy and power density with excellent cycling stability.
• This study provides insights into surface engineering strategies for advanced energy storage materials.