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Author: search.filters.author.Pimanpang, SamukSubject: search.filters.subject.Activated carbon

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    Self-activation of carbons derived from bio-waste cabbage for a green supercapacitor based on seawater electrolyte
    (2024-12-01)
    Phakkhawan, Authit
    ;
    Sakulkalavek, Aparporn
    ;
    Chanlek, Narong
    ;
    Nijpanich, Supinya
    ;
    Ngernyen, Yuvarat
    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, CaCO<inf>3</inf>, Ca(ClO)<inf>2</inf>, K<inf>2</inf>SO<inf>4</inf>, and Ca<inf>5</inf>(PO<inf>4</inf>)<inf>3</inf>(OH), has the highest specific surface area (S<inf>BET</inf>, 130.04 m<sup>2</sup> g<sup>−1</sup>), a high specific capacitance (64.06 F g<sup>−1</sup>), 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), S<inf>BET</inf> values increased to 919.22 and 1146.51 m<sup>2</sup> g<sup>−1</sup>, respectively. KCl, Ca(ClO)<inf>2</inf>, and K<inf>2</inf>SO<inf>4</inf> are removed from the AC-DI, whereas all compounds are washed from the AC-HCl-DI. Removing these compounds enlarges S<inf>BET</inf> values, specific capacitance (114.47 F g<sup>−1</sup> at 0.5 A g<sup>−1</sup>), 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<sup>−1</sup> at 0.5 A g<sup>−1</sup>, respectively. Symmetric AC-HCl-DI/seawater/AC-HCl-DI cell gives a high energy density of 2.32 Wh kg<sup>−1</sup> at a large power density of 0.25 kW kg<sup>−1</sup>. The four serial AC-HCl-DI/seawater/AC-HCl-DI coin cells could light an LED over 60 s.
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    Item type:Publication,
    Electrochemical mechanisms of activated carbon, α-MnO2 and composited activated carbon-α-MnO2 films in supercapacitor applications
    (2021-12-30)
    Tagsin, Patin
    ;
    Suksangrat, Pitphichaya
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    Klangtakai, Pawinee
    ;
    Srepusharawoot, Pornjuk
    ;
    Ruttanapun, Chesta
    Pure α-MnO<inf>2</inf> and activated carbon-MnO<inf>2</inf> (AC-MnO<inf>2</inf>) films coated on Ni foam by electrophoretic deposition were applied as a supercapacitor electrode. The specific capacitance of AC-MnO<inf>2</inf> films (155.03 F g<sup>−1</sup>) surpasses those of the pure AC (110.62 F g<sup>−1</sup>) and pure MnO<inf>2</inf> film in the 1 M NaOH electrolyte. EDX and XPS detect an increase in the Na content and the reduction of Mn<sup>4+</sup> to Mn<sup>3+</sup> on the discharged MnO<inf>2</inf> electrode (at 0.0 V), whereas a decrease in the Na content and the oxidation of Mn<sup>3+</sup> to Mn<sup>4+</sup> were obtained on the charged MnO<inf>2</inf> electrode (at 0.45 V). Computational simulation of the Na inserted α-MnO<inf>2</inf> structure displays the connection of Na to O atoms and the increasing electron density on Mn atoms. EDX of the charged AC-MnO<inf>2</inf> (at −1.0 V) film detects a rise in the Na and a fall in the O contents, but the discharged AC-MnO<inf>2</inf> film (at 0.0 V) shows a decrease in Na and increase in O contents. The AC-MnO<inf>2</inf> film could retain 82.29% of the initial specific capacity after 10,000 cycles. Four series-supercapacitor coin cell assembled from the AC-MnO<inf>2</inf> anode and MnO<inf>2</inf> cathode delivers a power density of 2.79 kW kg<sup>−1</sup> and an energy density of 168.8 Wh kg<sup>−1</sup>.