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Author: search.filters.author.Chanlek, NarongSubject: search.filters.subject.Hydrothermal

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    Synthesis and electrochemical properties of activated lignite carbons-reduced graphene oxide nanocomposites symmetric supercapacitors
    (2024-08-15)
    Tuichai, Wattana
    ;
    Karaphun, Attaphol
    ;
    Phrompet, Chaiwat
    ;
    Chanlek, Narong
    ;
    Swatsitang, Ekaphan
    Ultra-fast chargeable or rechargeable symmetric carbon-based supercapacitors (SCSs) with high capacity, inexpensive, and non-flammability have attracted much attention for electronics and energy storage devices. However, improving both high redox reaction and ion transport/diffusion processes by enhancing high energy storage performance and rapid ion/electron transport SCSs electrode materials remains challenging. Herein, we presented a successful preparation of activated lignite carbons-reduced graphene oxide (ALC-rGO) nanocomposite (NCp) with the ALC:rGO ratio of 80:20 wt% by a one-pot hydrothermal for high electrochemical performance. Importantly, the matrix of ALC-rGO NCp was primary amorphous carbon with hexagonal graphitic layers and pore structures of plentiful micropores and mesopores. Remarkably, the ALC-rGO NCp electrode exhibited a maximum specific capacitance (C<inf>sc</inf>) of 152.12 F/g at 0.5 A/g. Interestingly, the SCSs-ACL-rGO device could illustrate a good performance at a potential voltage of 1.8 V with C<inf>sc</inf> of 50.90 F/g at 1 A/g and capacity retention of 96.0 % at 5 A/g after 2,000 cycles GCD test.
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    Hydrothermal transforming phase structure and chemical composition of V2O5 for elevating electrochemical property of zinc ion batteries
    (2024-05-01)
    Triosod, Sureerat
    ;
    Phakkhawan, Authit
    ;
    Phumuen, Phatcharin
    ;
    Wanabut, Wassana
    ;
    Chanlek, Narong
    V<inf>2</inf>O<inf>5</inf> was hydrothermally modified in NaOH or KOH solutions at 180 °C for 24 h. The NaOH-modified powders had a nanorod-like structure with a crystal structure matching Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O. The TG/DTA results of Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O powders show a mass reduction of 4.24 % at 300 °C, corresponding to n of 1.496. KOH-modified powders have large rods and irregular structures with a crystal structure matching KV<inf>3</inf>O<inf>8</inf>. Its TG/DTA spectrum shows a very small percentage change, just 0.37 % at 600 °C. Cyclic voltammetry (CV) curves of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O cathode in a 2 M ZnSO<inf>4</inf> electrolyte exhibit higher oxidation and reduction current densities than those of pure V<inf>2</inf>O<inf>5</inf> and KV<inf>3</inf>O<inf>8</inf> electrodes.The best capacity of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O electrode is 296.10 mAh g<sup>-1</sup> at a current density of 50 mA g<sup>−1</sup>, which is higher than those of pure V<inf>2</inf>O<inf>5</inf> (102.90 mAh g<sup>-1</sup>) and KV<inf>3</inf>O<inf>8</inf> (91.07 mAh g<sup>-1</sup>) electrodes. EDS and XPS results reveal that the charge and discharge states involve de-insertion and insertion of Zn<sup>2+</sup> ions out of/into the electrodes. Computational analysis of Zn intercalation into V<inf>2</inf>O<inf>5</inf>, Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O, and KV<inf>3</inf>O<inf>8</inf> structures displays increasing electron density on neighboring V atoms, which explains the increasing V<sup>4+</sup>/V<sup>5+</sup> ratio in the discharged state as evidenced by XPS spectra.