Insights into the charge storage mechanism of binder-free electrochemical capacitors in ionic liquid electrolytes

Pal, Bhupender and Parameswaran, Abhilash Karuthedath and Wu, Bing and Děkanovský, Lukáš and Mazánek, Vlastimil and Sarkar, Kalyan Jyoti and Jose, Rajan and Sofer, Zdeněk (2023) Insights into the charge storage mechanism of binder-free electrochemical capacitors in ionic liquid electrolytes. Industrial and Engineering Chemistry Research, 62 (10). pp. 4388-4398. ISSN 0888-5885. (Published)

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Electrochemical capacitors (synonymously supercapacitors) working under an electrochemical double-layer charge storage mechanism (EDLC) are widely investigated because of their excellent power density and cycle life; however, their energy density is lower than those of lithium-ion batteries. Ionic liquids (ILs) are of great interest as electrolytes for EDLCs due to their wide operational voltage window. Here, we provide a systematic investigation on the influence of anions of ILs on the charge storage mechanism and electrochemical stability of EDLC electrodes. Two IL electrolytes, viz., [1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI)], having similar cations but different anions and carbon nanotube (CNT) electrodes are chosen for this study. The CNT//BF4:TFSI//CNT-based device showed superior electrochemical performance (∼69 F•g-1 gravimetric specific capacitance, ∼949 W•kg-1 power density, and ∼139 Wh•kg-1 energy density at 0.5 A•g-1) to CNT//EMIMBF4//CNT and CNT//EMIMTFSI//CNT devices. The device using a mixture of BF4:TFSI (1:0.5) electrolytes has an operating voltage of 0-3.8 V and specific capacitance retention of ∼45% at 0.5 A•g-1 after 500 cycles. In the case of the IL mixture (BF4:TFSI), the combined anion structure and their properties play very crucial part in the improvement of the electrochemical performance of the CNT//BF4:TFSI//CNT device. The assembled Teflon Swagelok-type cell could light up green (3.3 V) and red (2.1 V) light-emitting diodes for more than 5 min.

Item Type: Article
Additional Information: Indexed by Scopus
Uncontrolled Keywords: Charge storage; Double layers; Electrochemical capacitor; Electrochemical performance; Electrochemicals; Energy density; Ionic liquid electrolytes; Layer charge; Power densities; Storage mechanism
Subjects: H Social Sciences > HD Industries. Land use. Labor
Q Science > Q Science (General)
T Technology > T Technology (General)
T Technology > TA Engineering (General). Civil engineering (General)
Faculty/Division: Faculty of Industrial Sciences And Technology
Depositing User: Mr Muhamad Firdaus Janih@Jaini
Date Deposited: 29 Aug 2023 07:32
Last Modified: 29 Aug 2023 07:32
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