Issue 7, 2023

Ultra-low cost supercapacitors from coal char: effect of electrolyte on double layer capacitance

Abstract

Electrochemical double-layer capacitors (EDLCs) provide high power density and long cycle life energy storage. This work examines the use of inexpensive, raw coal char as an electrode material for supercapacitors. The effect of electrolyte composition on the performance of coal char supercapacitors is explored for the first time to determine the relative contributions of double-layer capacitance vs. faradaic reactions on total charge storage. Six electrolytes are examined with coal char electrodes, including: four aqueous electrolytes (0.5 M H2SO4, 6 M KOH, 0.5 M Na2SO4, 4 M LiNO3); a water-in-salt electrolyte using 13 m NaClO4; and an ionic liquid electrolyte (1-butyl-3-methylimidazolium tetrafluoroborate in acetonitrile). Voltage range, specific capacitance, electrochemical impedance, and charge–discharge characteristics of the coal char in the different electrolytes are characterized. The results indicate that neutral aqueous, water-in-salt, and ionic liquid electrolytes present a charging/discharging process approaching ideal EDLC behavior. The study provides insight into the optimal electrolyte composition for use with coal char electrodes and contributes to the current understanding of electrode-electrolyte interactions in carbon supercapacitors.

Graphical abstract: Ultra-low cost supercapacitors from coal char: effect of electrolyte on double layer capacitance

Supplementary files

Article information

Article type
Paper
Submitted
07 fev 2023
Accepted
15 mai 2023
First published
23 mai 2023
This article is Open Access
Creative Commons BY-NC license

Energy Adv., 2023,2, 1036-1044

Ultra-low cost supercapacitors from coal char: effect of electrolyte on double layer capacitance

Z. Karimi, J. Moon, J. Malzahn, E. Eddings and R. Warren, Energy Adv., 2023, 2, 1036 DOI: 10.1039/D3YA00064H

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