128 research outputs found
Cycling stability of a hybrid activated carbon//poly(3- methylthiophene) supercapacitor with N-butyl-Nmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid as electrolyte
A long cycle-life, high-voltage supercapacitor featuring an activated carbon//poly(3-methylthiophene) hybrid configuration with N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid, a solvent-free green electrolyte, was developed. The cyclability of a laboratory scale cell with electrode mass loading sized for practical uses was tested at 60 °C over 16,000 galvanostatic charge–discharge cycles at 10 mA cm−2 in the 1.5 and 3.6 V voltage range. The reported average and maximum specific energy and power, specific capacitance and capacity, equivalent series resistance and
coulombic efficiency over cycling demonstrate the long-term viability of this ionic liquid as
green electrolyte for high-voltage hybrid supercapacitors
High temperature carbon–carbon supercapacitor using ionic liquid as electrolyte
This paper presents results about the electrochemical and cycling characterizations of a supercapacitor cell using a microporous activated carbon as the active material and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) ionic liquid as the electrolyte. The microporous activated carbon exhibited a specific capacitance of 60 F g−1 measured from the three-electrode cyclic voltammetry experiments at 20mVs−1 scan rate, with a maximum operating potential range of 4.5V at 60 ◦C. A coin cell assembled with this microporous activated carbon and PYR14TFSI as the electrolyte was cycled for 40,000 cycles without any change of cell resistance (9cm2), at a voltage up to 3.5V at 60 ◦C, demonstrating a high cycling stability as well as a high stable specific capacitance in this ionic liquid electrolyte. These high performances make now this type of supercapacitor suitable for high temperature applications (≥60 ◦C)
Tuning Solid-State Photoluminescence Frequencies and Efficiencies of Oligomers Containing One Central Thiophene-S,S-dioxide Unit
We have synthesized thienylene- and phenylene-based oligomers displaying solid-state photoluminescence efficiencies up to 70% and photoluminescence frequencies which cover the entire visible range. All compounds contain one central nonaromatic thienyl-1,1-dioxide moiety in the main chain. The tuning of the light-emission frequency was achieved by progressively varying the degree of π−π electron delocalization between the nonaromatic moiety and the α-linked aromatic rings. All compounds displayed greater electron affinities than thienylene or phenylene oligomers of comparable lengths, as deduced from the reduction potentials measured by cyclic voltammetry
Chemically and thermally stable photo- and electroluminescent thiophene-based materials
We present a new class of thiophene-based oligomers and polymers with widely tunable photo and electroluminescence properties and which offer great potential for many different areas of application. We were able to synthesize materials displaying high solid-state fluorescence efficiency across the entire visible range. Electroactive polymers emitting light in the near IR were obtained by chemical and/or electrochemical polymerization of oligomers of different length. The polymers also displayed electrochromism, i.e. color change when electric current flowed through the material. All compounds were characterized by great thermo and photooxidative stability. With some of these materials efficient electroluminescent devices were fabricated and characterized
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