Ionic liquid-solvent mixture of propylene carbonate and 1,2-dimethoxyethane as electrolyte for electric double-layer capacitor

Electrochemical Double-Layer Capacitor Containing Mixtures of Ionic Liquid, Lithium Salt, and Organic Solvent as an Electrolyte

“…Moreover, a high energy density of 26.35 Wh kg −1 can still be sustained even the applied current is increased to 10 A g −1 , which is significantly higher than that measured in EMI-BF 4 /LiPF 6 /PC (22.03 Wh kg −1 ) and pure EMI-BF 4 (15.93 Wh kg −1 ). The EDLC performance based on the designed EMI-BF 4 /LiPF 6 /PC/DMC electrolyte is comparable and even superior to previous reports with other 3 V-class electrolytes or those adopting asymmetric design (Lu et al, 2019;Vijayakumar et al, 2019).…”

“…The rate capability of the EDLC in EMI-BF 4 /LiPF 6 /PC/DMC is also well demonstrated in the CV measurement at varied scan rates (Figure 6), where good rectangular shape can be maintained, and even the scan rate is up to 50 mV s −1 . The excellent rate performance profits from a less viscous and more conductive advantage when carbonate solvent and LiPF 6 were simultaneously introduced into the IL electrolyte: 1) highly dielectric PC can break the ion pair in IL, absorbing more ions on the surface of the porous electrode (Lu et al, 2019); 2) low viscous DMC (Marcinek et al, 2015) reduce ion movement resistance and benefit ion transport in the electrolyte and porous electrode; 3) dissociative Li salt also provides more mobile ions for conduction in the electrolyte. Besides, it is likely to involve the conversion of the double-layer structure (Yamagata et al, 2013); for example, Li + may occupy the electrode/electrolyte interface preferentially due to a strong interaction between Li + and the negatively polarized electrode at a high charge density, which decreases the thickness of the Helmholtz layer and leads to the increase in the electric double-layer capacitance.…”

Nanoporous carbon for electrochemical capacitive energy storage

“…346 A large amount of experimental and simulation works over the years have shown that with a mixture of different solvents and ionic liquids or ionic liquids with different viscosities, the general properties (viscosity, ionic conductivity, diffusion coefficient and so on) are improved; also the interaction of ionic liquids at an electrified surface can be modified. [347][348][349][350][351][352][353][354][355][356] As a kind of solvent in the salt approach, the wettability of ionic liquids with a small addition of solvent has been improved for porous materials. 357 Although this work did not yet result in a major breakthrough in terms of performance, it led to important advances in the scientific understanding of the ionic/carbon interaction in porous carbon electrodes.…”

New types of hybrid electrolytes for supercapacitors

“…The optimal combination of the EMIMBF 4 /acetonitrile/methyl acetate-based electrolyte enables the constructed SC with activated polyanilinederived carbon as the active material to work at a high potential window of 3.5 V, which delivers a maximum energy density of 80 W h kg À1 and a power density of 26 kW kg À1 at a very low temperature of À50°C. Lu et al [90] also employed a binary solvent that combines the EMIBF 4 with PC and 1,2-dimethoxyethane (DME) for EDLCs. The capacitor employing an AC electrode with such an electrolyte yields an energy density of 38.5 W h kg À1 at Fig.…”

“…The viscosity of ILs is higher at low temperatures, which greatly reduces the ion mobility. The hybrid method of mixing with other types of certain species can improve the conductivity at low temperatures [89][90][91]. Compared with aqueous and organic electrolytes, IL is a kind of molten salt at room temperature, which is non-flammable and non-volatile, and generally employed as a green electrolyte with a wide voltage range.…”