Impact of carbon pores size on ionic liquid based-supercapacitor performance

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Supercapacitors are crucial energy storage devices.
• Carbon electrode pore structure significantly impacts supercapacitor performance.
• Ionic liquid electrolytes offer enhanced stability and operating voltage.

Purpose of the Study:

• To investigate the influence of carbon electrode pore size on supercapacitor performance.
• To compare microporous, mesoporous, and combined micro-mesoporous carbon networks.
• To evaluate the role of pore size in capacitance, rate capability, and volumetric performance.

Main Methods:

• Fabrication of symmetrical supercapacitors using carbon electrodes with varying pore structures.
• Electrochemical characterization using 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) in acetonitrile electrolyte.
• Analysis of capacitance, rate performance, and electrode density.

Main Results:

• Capacitance at low current density is primarily determined by surface area in pores > 0.8 nm, irrespective of pore size distribution.
• Larger pores do not necessarily enhance supercapacitor response rate.
• Wider porosity leads to increased electrolyte uptake, higher cell weight and cost, and reduced electrode density.

Conclusions:

• The presence of large pores in carbon electrodes does not guarantee improved supercapacitor performance.
• Reduced electrode density due to wider porosity negatively impacts volumetric performance, limiting practical applications.
• Optimizing pore structure, particularly avoiding excessive widening, is critical for efficient and cost-effective supercapacitor design.