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Ionic-Liquid-Based Deep Eutectic Solvents as Novel Electrolytes for Supercapacitors: COSMO-SAC Predictions, Synthesis, and Characterization
journal contribution
posted on 2019-12-13, 19:15 authored by Upasana Mahanta, Sambita Choudhury, R. Prasanna Venkatesh, Sujatha SarojiniAmma, S. A. Ilangovan, Tamal BanerjeeThe current work investigated two ionic-liquid (IL)-based
deep
eutectic solvents (DESs) composed of ethylene glycol (EG) and N-methylacetamide (NMAc) as hydrogen bond donors (HBD) and
high-melting IL, namely, 1-butyl-3-methylimidazolium methanesulfonate
([BMIM][MeSO3]), as the hydrogen bond acceptor (HBA). Initially,
the COSMO-SAC model was employed for prediction of the eutectic points
of the DESs. The computed melting points of the formulated DESs were
found to be 70–100 °C lower than that of HBA. The viscosity
of the newly developed DESs (∼15 cp) was significantly lower
than that of neat room temperature IL electrolytes, and their ionic
conductivity was found to be comparable to that of ILs. TGA study
revealed no mass loss up to 90 °C, favoring the high temperature
application of supercapacitors. To assess electrolytic performance
in supercapacitors, electrochemical characterization was done using
linear scan voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic
charge–discharge (GCD) techniques. LSV provided electrochemical
stability up to 3.8 V against a glassy carbon electrode. [BMIM][MeSO3] + EG and [BMIM][MeSO3] + NMAc resulted in operating
potential windows (OPWs) of 2 and 3 V, respectively, with a carbon
electrode. Moderate values of specific capacitance (55–67 F
g–1) and power (0.56–1.3 kW kg–1) were observed due to higher internal resistance. However, [BMIM][MeSO3] + NMAc resulted in noteworthy specific energy (∼84
Wh kg–1) due to its wider OPW.