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Self-activation of carbons derived from bio-waste cabbage for a green supercapacitor based on seawater electrolyte
Author(s)
Phakkhawan, Authit
Chanlek, Narong
Nijpanich, Supinya
Ngernyen, Yuvarat
Buranurak, Siritorn
Pimanpang, Samuk
Klangtakai, Pawinee
Date Issued
December 1, 2024
Type
Article
Abstract
Carbonized carbons (CC) derived from cabbage were self-activated via a carbonization process at 500–900 °C in Ar. CC synthesized at 800 °C (CC-800), containing KCl, CaCO3, Ca(ClO)2, K2SO4, and Ca5(PO4)3(OH), has the highest specific surface area (SBET, 130.04 m2 g−1), a high specific capacitance (64.06 F g−1), and an excellent rate capability (65.12 %). After washing the CC-800 powder in either deionized (DI) water (AC-DI) or hydrochloric acid (HCl) followed by DI water (AC-HCl-DI), SBET values increased to 919.22 and 1146.51 m2 g−1, respectively. KCl, Ca(ClO)2, and K2SO4 are removed from the AC-DI, whereas all compounds are washed from the AC-HCl-DI. Removing these compounds enlarges SBET values, specific capacitance (114.47 F g−1 at 0.5 A g−1), and rate capability (68.95 %). A high capacitance retention of 97.56 % after 20,000 cycles was achieved from the AC-HCl-DI electrode with 6 M KOH. 0.6 M NaCl and seawater were applied as green electrolytes with the AC-HCl-DI electrode, resulting in the promising specific capacitance of 116.89 and 102.21 F g−1 at 0.5 A g−1, respectively. Symmetric AC-HCl-DI/seawater/AC-HCl-DI cell gives a high energy density of 2.32 Wh kg−1 at a large power density of 0.25 kW kg−1. The four serial AC-HCl-DI/seawater/AC-HCl-DI coin cells could light an LED over 60 s.
Citation
Sustainable Materials and Technologies, 42, 2024