Browsing by Author "Winie, Tan"

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Effect of ionic liquid concentration on the photovoltaic performance of dye-sensitized solar cell
(2019-01-01)
Saaid, F., I
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Tseng, Tseung-Yuen
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Winie, Tan
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Quasi-solid-state electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdf-HFP), propylene carbonate (PC), 1,2-dimethoxyethane (DME) and different concentrations of 1-methyl-3-propylimidazolium iodide (MPII) salt were prepared. The highest room temperature conductivity of 4.6 x 10(-3) S cm(-1) was achieved with 1.0M MPII. The effect of MPII on the conductivity was discussed on the basis of number free ions. The number of free ions were estimated by impedance spectroscopy method. DSSC at 1.0M MPII shows the conversion efficiency, eta of 3.70% with short-circuit current density, J(sc) of 8.65 mA cm(-2), open circuit voltage, V-oc of 641 mV and a fill factor, FF of 66%. (C) 2019 Elsevier Ltd. All rights reserved.
Flexible solid-like electrolytes with ultrahigh conductivity and their applications in all-solid-state supercapacitors
(2018-01-01)
Yang, Chih-Chieh
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Lin, Hao-Yang
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Kumar, Amit
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Pattanayak, Bhaskar
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Tsai, Hung-Yi
All-solid-state supercapacitors (ASSS) with solid-state electrolytes (SSEs) can be used to overcome the liquid leakage problem in devices. However, ionic conduction in solid electrolytes is one of the barriers to further improvements in ASSS. This paper describes the fabrication of a flexible SSE composed of poly(vinylidene fluoride-co-hexafluoropropylene), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and ethylene carbonate, which demonstrates an ultrahigh conductivity of 8.52 mS cm(-1) and a wide 5 V operation voltage window of -2 to +3 V. Electrodes composed of active carbon, multiwall carbon nanotubes, and polyvinylidene fluoride were used as both anode and cathode to assemble a symmetrical supercapacitor. The resultant supercapacitor exhibits a maximum power density of 3747 W kg(-1) at an energy density of 7.71 W h kg(-1) and a maximum energy density 17.1 W h kg(-1) at a power density of 630 W kg(-1). It displays excellent cycling stability with 91.3% of the initial specific capacitance after 3000 charging/discharging cycles. This flexible SSE in this study demonstrates a high potential for use in energy storage, conversion, and wearable device applications.
Hexanoyl chitosan/ENR25 blend polymer electrolyte system for electrical double layer capacitor
(2019-03-01)
Winie, Tan
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Jamal, Asheila
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Saaid, Farish Irfal
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
Single salt polymer electrolytes based on hexanoyl chitosan-ENR25 were prepared by employing LiN (CF3SO2)(2) or LiCF3SO3 as the doping salt. Elastic property of hexanoyl chitosan was enhanced with the incorporation of ENR25. DSC studies revealed immiscibility of hexanoyl chitosan and ENR25, and dissolution of salt was favored in ENR25 phase. Conductivity enhancement was observed in the blends as compared with the neat hexanoyl chitosan. The maximum conductivities achieved for LiCF3SO3- and LiN (CF3SO2)(2)-comprising electrolyte systems were 1.6 x 10(-8) and 5.0 x 10(-7) S cm(-1), respectively. Deconvolution of spectra bands in the v(as) (SO2-) mode of LiN (CF3SO2)(2) and v(s) (SO3-) mode of LiCF3SO3 has been carried out to estimate the relative percentage of free ions and associated ions. The findings were in good agreement with conductivity results. Electrical double layer capacitor (EDLC) was fabricated with hexanoyl chitosan/ENR25 (90:10)-LiN (CF3SO2)(2)-EmImTFSI electrolyte and activated carbon-based electrodes. The conductivity and electrochemical stability window of hexanoyl chitosan/ENR25-LiN (CF3SO2)(2)-EmImTFSI were similar to 10(-6) S cm(-1) and 2.7 V, respectively. The performance of the EDLC was analyzed by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). From GCD, the specific capacitance of EDLC was 58.0 F g(-1) at 0.6 mA cm(-2). The specific capacitance was found to decrease with increasing current density.
The synergistic effect of iron cobaltite compare to its single oxides as cathode in supercapacitor
(1970-01-01)
Saaid, Farish Irfal
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Arsyad, Akmal
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Azman, N. S. H.
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Kumar, Amit
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Yang, Chih-Chieh
Mixed transition metal oxides have attracted great attention in supercapacitors applications due to their better electrochemical performance than their single oxides. In this work, iron cobaltite (FeCo2O4) and its single metal oxides i.e. iron oxide (Fe2O3) and cobalt oxide (Co3O4) were synthesized by a simple hydrothermal process. The structural, spectroscopic and morphological properties were studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field-emission scanning electron microscope (FESEM). XRD and FTIR results show the composition of the products. The obtained iron oxide was alpha-Fe2O3. FESEM images show that FeCo2O4 and its single metal oxides exhibit different morphology even though they were synthesized via similar method. The electrochemical properties of the alpha-Fe2O3, Co3O4 and FeCo2O4 electrodes were examined by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) in a 6 M KOH electrolyte solution. At comparable current density, the FeCo2O4 electrode has the highest specific capacitance (C-sp), followed by Co3O4 and alpha-Fe2O3. An asymmetric FeCo2O4/KOH/GO supercapacitor was fabricated. The supercapacitor exhibits maximum energy density of 14.5 Wh kg(-1) and maximum power density of 2177 W kg(-1). It demonstrates 60% rate capability after 1000 continuous charge-discharge cycles at 1 A g(-1).