Performance, stability and operation voltage optimization of screen-printed aqueous supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Micropower energy harvesting necessitates efficient intermediate energy storage solutions.
• Printed aqueous supercapacitors present a cost-effective and environmentally benign option for such applications.

Purpose of the Study:

• To systematically investigate the impact of process variability and operating voltage on screen-printed aqueous supercapacitors.
• To determine the optimal operating voltage for maximizing performance and stability in energy harvesting contexts.

Main Methods:

• Fabrication of supercapacitors using screen-printed graphite current collectors and activated carbon electrodes with aqueous NaCl electrolyte.
• Characterization via galvanostatic discharge for capacitance and equivalent series resistance (ESR) determination.
• Impedance spectroscopy to analyze factors contributing to ESR.

Main Results:

• Capacitances ranged from 200–360 mF, with ESRs between 7.9–12.7 Ω, influenced by layer thicknesses.
• Equivalent series resistance was primarily governed by the graphite current collector resistance.
• An operating voltage of 1.0 V was identified as optimal for capacitance, leakage, and aging rate.

Conclusions:

• Screen-printed aqueous supercapacitors demonstrate performance compatible with low-power distributed electronics.
• The study provides critical insights into optimizing printed supercapacitors for reliable energy harvesting applications.
• 1.0 V is the recommended operating voltage for balancing performance and longevity in these devices.