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Microwave-activated reduced graphene oxide composite with hydrothermally treated corn husk activated carbon as an active electrode for high electrochemical performance in symmetrical carbon-based supercapacitor devices
(2026-07-01)
Srakaew, Khattiya
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Ratchayotee, Pornthip
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Janorat, Phattharawadee
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Phrompet, Chaiwat
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Kitiwan, Mettaya
This work applies microwaves for synthesizing reduced graphene oxide (rGO) and waste material corn husk activated carbon composites as active electrode materials for symmetric supercapacitors. The rGO is activated by microwave treatment and corn husk carbon by KOH in processed hydrothermal activation, followed by compositing at various weight ratios. Among all compositions, rGO:H_Corn_C (90:10) is reported with the best properties, with a specific surface area of 314.2 m2/g and a high specific capacitance of 1152 F/g at 0.1 A/g. The optimized composite also delivered increasing energy and power densities of up to 160 Wh/kg and 9.68 × 102 W/kg, respectively, within a 1 V operating window. In an experiment by assembling a symmetric coil cell supercapacitor, the device showed a specific capacitance of 142.23 F/g at 0.1 A/g, cycling stability with 98.8% capacitance retention after 1000 cycles of charge-discharge, and peak energy and power densities of 40.68 Wh/kg and 5.74 × 102 W/kg. Overall, the composite material with a high content of rGO and corn husk-derived activated carbon prepared by the hydrothermal method exhibits high-performance for the material in supercapacitor applications.
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Multi-phase structure electrospun CNF@Ag/Mn/Bi/Fe composite nanofiber enhanced supercapacitor behavior
(2025-02-15)
Sinprachim, Tanayt
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Klompong, Narit
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Chanlek, Narong
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Kidkhunthod, Pinit
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Maensiri, Santi
This study presents the development of carbon-based multiphase metal oxide nanocomposites (CNF@MO<inf>x</inf>; M = Ag, Mn, Bi, and Fe) incorporating silver, manganese, bismuth, and iron nanoparticles within polyacrylonitrile (PAN)-derived carbon nanofibers. These nanocomposites were fabricated via the electrospinning technique with metal oxide concentrations of 10, 20, and 40 %w. This was followed by annealing in an argon atmosphere. The resulting nanofibers exhibited diameters ranging from 559 to 830 nm, with embedded nanoparticles measuring from 9 to 21 nm. Comprehensive characterization revealed that the nanofibers possessed uniform morphology, high porosity, and robust thermal stability. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) confirmed the valence states of the metal oxides (Ag⁰, Bi³⁺, Mn²⁺, Mn³⁺, Fe²⁺, and Fe³⁺), which are integral to redox reactions and charge storage mechanisms. Among the fabricated composites, CNF@Ag/Mn/Bi/Fe-20 demonstrated the best electrochemical performance, achieving a specific capacitance of 156 F g−1 at a scan rate of 2 mV s−1 and outstanding cycling stability with a capacity retention of over 96 % after 1400 charge-discharge cycles. The synergistic combination of double-layer capacitance and pseudocapacitance mechanisms in these nanofibers represents a significant improvement over conventional electrode material. This study highlights CNF@Ag/Mn/Bi/Fe nanocomposites as highly promising candidates for advanced energy storage applications, particularly in supercapacitor technologies.
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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
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Sakulkalavek, Aparporn
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Chanlek, Narong
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Nijpanich, Supinya
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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 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), S<inf>BET</inf> values increased to 919.22 and 1146.51 m2 g−1, 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−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.
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Electrochemical mechanisms of activated carbon, α-MnO2 and composited activated carbon-α-MnO2 films in supercapacitor applications
(2021-12-30)
Tagsin, Patin
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Suksangrat, Pitphichaya
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Klangtakai, Pawinee
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Srepusharawoot, Pornjuk
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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−1) surpasses those of the pure AC (110.62 F g−1) 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 Mn4+ to Mn3+ on the discharged MnO<inf>2</inf> electrode (at 0.0 V), whereas a decrease in the Na content and the oxidation of Mn3+ to Mn4+ 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−1 and an energy density of 168.8 Wh kg−1.
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Nitrogen-doped graphene nanosheet-double-walled carbon nanotube hybrid nanostructures for high-performance supercapacitors
(2021-09-01)
Muangrat, Worawut
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Obata, Michiko
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Htay, Myo Than
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Fujishige, Masatsugu
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Dulyaseree, Paweena
A hybrid nitrogen-doped graphene nanosheet-grafted double-walled carbon nanotube (NG-DWCNT) was synthesized by chemical vapor deposition (CVD). Double-walled carbon nanotube (DWCNT) was synthesized by floating catalytic CVD using ferrocene and thiophene dissolved in ethanol. NG was directly grafted onto the DWCNT bundles by thermal CVD using mixed ethanol-urea solution. The NG possess sharp-edged petal-like structure on one-dimensional DWCNT bundle. The NG-DWCNT showed the nitrogen content of approximately 1.93 at%. The NG-DWCNT hybrid nanostructures exhibited a higher specific capacitance of 563 F g−1 than that of the DWCNT and un-doped G-DWCNT. The improvement of capacitance value is attributed to the synergic effect of the nitrogen doping together with the sharp-edged petal-like structure of the NG. The facile technique by CVD method provides a promising approach for simple and low-cost technique to synthesize the NG-DWCNT hybrid nanostructures. A hybrid carbon nanostructure of NG-DWCNT has a potential application in electrochemical conversion and energy storage devices.
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Preparation of activated carbon via acidic dehydration of durian husk for supercapacitor applications
(2020-08-01)
Ukkakimapan, Pundita
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Sattayarut, Vichuda
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Wanchaem, Thanthamrong
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Yordsri, Visittapong
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Phonyiem, Mayuree
In this study, the preparation of activated carbons (ACs) via acidic dehydration of durian husk (DH) for supercapacitor application was investigated. The DH was dehydrated using sulfuric acid and subsequently activated by using sodium hydroxide as chemical reagent at 720 °C to obtain activated carbon (hereinafter referred to as DA). Surpassing the commercial ACs and the ACs derived from the conventional carbonization and activation (hereinafter referred to as CA), the DA exhibited superior properties in high surface area (2578 m2/g) and total pore volume (1.27 cm3/g). Moreover, besides carbon and oxygen, the DA contained sulfur and nitrogen in the carbon network. The DA can act as a suitable material for supercapacitor electrode with the specific gravimetric and volumetric capacitances of 145 F/g and 70 F/cm3 in an organic electrolyte. The device also showed a promising performance with an energy density of 32 Wh/kg and a power density of 316 W/kg. These results demonstrate that the preparation of ACs via acidic dehydration of DH offers the advantages in terms of simplicity, low cost, and short-time processing to achieve heteroatom self-doped ACs with a high surface area for high-performance supercapacitors.
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Investigation on electrochemical properties of sugarcane leaves-derived activated carbon by steam activation
(2020-01-01)
Ukkakimapan, Pundita
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Ukakimaparn, Prapart
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Wanchaem, Thanthamrong
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Yordsri, Visittapong
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Sattayarut, Vichuda
Sugarcane leaves (SLs) are a bio-waste from sugar production industry. To explore the value-added SLs, the SLs were used raw materials of activated carbons (ACs) by steam activation and their electrochemial properties were investigated for supercapacitor applications. The synthesis of ACs from the SLs consisted of two steps; carbonization at 500ºC and steam activation. The synthesis condition was optimized by varying activation temperature (800 and 850ºC) The porous structures were thoroughly formed on the surface after steam activation and the surface areas were reached to 630 and 639 m2 g-1 at the activation temperature of 800 and 850ºC, respectively. The SLs-derived ACs activated at 800ºC assembled in coin cell using organic electrolyte showed the highest specific capacitance of approximately 16 F g-1 with a capacitance retention of 62% when the current density increased to 1.5 A g-1. Even though there is a room to improve the electrochemical properties such as optimization of porosity and removal of inorganic component, the SLs show a potential use as raw materials of ACs for supercapacitor applications.

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