Functionalized graphene for high performance lithium ion capacitors.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium ion capacitors (LICs) combine supercapacitor power and lithium-ion battery energy.
• Conventional LICs with activated carbon cathodes have limited energy density.
• Graphene oxide is explored as an alternative electrode material.

Purpose of the Study:

• To enhance the energy density of lithium ion capacitors.
• To investigate urea-reduced graphene oxide as a cathode material.
• To improve lithium ion binding and specific capacity.

Main Methods:

• Synthesis of urea-reduced graphene oxide.
• Fabrication of LICs using urea-reduced graphene oxide cathodes.
• Electrochemical characterization including specific capacity, energy density, and power density measurements.
• Cycling stability tests up to 1000 cycles.

Main Results:

• Urea reduction generated amide functional groups, facilitating reversible Li binding.
• Specific capacity increased by 37% compared to activated carbon and hydrazine-reduced graphene oxide.
• LICs achieved an energy density of ~106 Wh/kg and power density of ~4200 W/kg.
• Perfect capacity retention was observed over 1000 cycles.

Conclusions:

• Urea-reduced graphene oxide significantly enhances LIC performance.
• The material offers a promising alternative for high-performance energy storage.
• Appropriately treated graphene is a viable electrode material for advanced LICs.