Atomistic study of the physical properties of sulfonium-based ionic liquids as electrolyte for supercapacitors

Sampaio, Abner Massari; Fileti, Eudes Eterno; Siqueira, Leonardo José Amaral de

doi:10.1016/j.molliq.2019.112065

Cited by 23 publications

(11 citation statements)

References 67 publications

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“…ILs confined in between charged planar surfaces are organized in alternated layers of ions that extend up to 30 Å toward the bulk region of the slab. ,,− This is also the case for [P 222,2O1 ][NTf 2 ] confined to planar GO electrodes, as depicted in Figure . Figure shows the ion density profile close to Gra and GO electrodes.…”

Section: Resultsmentioning

confidence: 80%

Comparing Graphite and Graphene Oxide Supercapacitors with a Constant Potential Model

2021

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Electric double-layer capacitors store energy because of the adsorption of ions on the surface of electrodes. A realistic model to describe the electrolyte–electrode interface is based on the constant potential method that allows the electrode charges to fluctuate in order to try to mimic the polarization of metallic electrodes [J. Phys. Chem. Lett. 2013, 4, 264–268]. We performed molecular dynamics simulations of graphene oxide (GO) electrodes using the constant potential model comparing carefully the interface structure, polarization, and charging processes of an ionic liquid with the respective properties calculated for graphite electrodes. The layered structure of the ions at the electrode–electrolyte interface is less organized in comparison with that observed for graphite electrodes, which reduces overscreening. With regard to performance in terms of energy storage, graphite performs better than GO in a wide range of applied voltages. The charging dynamics of GO is slower at low applied voltages. At high voltages, the stronger electrostatic interactions between the charged electrode and electrolyte prevail, allowing for similar charging times for both supercapacitors.

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Section: Resultsmentioning

confidence: 80%

Comparing Graphite and Graphene Oxide Supercapacitors with a Constant Potential Model

2021

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“…68,69 The NTf 2 anions and ACN were simulated with model used in previous simulations. 13,24,49,55,70,71 All the parameters used in the simulations, the number of ionic pairs and acetonitrile molecules used in each system are available in Tables S1 to S7 of the supporting information. The x ACN = 0.5 and 0.88 correspond to a 3.0M and a 1.5M solution of ionic liquid and acetonitrile.…”

Section: Bulk Simulationsmentioning

confidence: 99%

Ether-Functionalized Sulfonium Ionic Liquid and Its Binary Mixtures with Acetonitrile as Electrolyte for Electrochemical Double Layer Capacitors: A Molecular Dynamics Study

Sampaio

Siqueira

2020

J. Phys. Chem. B

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Ether-functionalized sulfonium ionic liquids have been investigated as promising electrolytes in electrochemical storage energy devices due to their wide electrochemical window, high ionic conductivity and low viscosity. In spite of that, the viscosity of neat ionic liquids is still high for supercapacitor applications. Here we have used atomistic molecular dynamics simulations to describe transport properties, structure and supercapacitor performance of (2-methoxy-ethyl)-ethyl-methylsulfonium bis(trifluoromethanesulfonyl)imide [S 12G1 ][NTf 2 ] and its mixtures with acetonitrile (ACN). The viscosity and ionic conductivity of neat ionic liquid are in quite good agreement with the experimental results in a wide range of temperature. The addition of ACN decreases viscosity and, consequently, increases ionic conductivity and diffusion coefficients. Typical alternated layers of ions close to the electrodes surfaces are observed in supercapacitor built with [S 12G1 ][NTf 2 ] when is applied high voltage, DY = 3.0 V. Sharp layers of solvent adsorbed on the surface of electrodes are observed in the mixtures containing ACN. The charge accumulated on the electrodes is barely affected by the amount of ACN, which imply in similar performance in terms of ca-pacitance. However, the charging times follow the viscosities of the electrolytes, that is, the electrolytes with high content of ACN have higher power performance. At low voltage, the rearrangements of ions close to electrodes responsible to the charge accumulation is very low in neat [S 12G1 ][NTf 2 ]. The sharp layer of ACN makes this rearrangement easier, but it acts as a barrier to ion exchange at higher voltages, which increase the charging time. Charging of the supercapacitors is dependent of ion exchange and counter-ion adsorption at DY = 3.0 V.

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“…Sampaio and co-workers also (Sampaio et al, 2019) It was observed that both viscosity and ionic conductivity of these ILs varied according to cation size. However, the differences in the properties had a negligible effect on the performance of the SC, especially on the specific capacitance value, which is contradictory to the earlier reports (Li S. et al, 2016) and our previously highlighted relationships.…”

Section: Sulfonium Based Ionic Liquids Electrolytementioning

confidence: 91%

Prospects and Design Insights of Neat Ionic Liquids as Supercapacitor Electrolytes

2021

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Ionic liquids present an opportunity to design efficient electrolytes for supercapacitors, which are among the most extensively studied electrochemical energy storage systems. Ionic liquids are promising candidates for supercapacitor electrolytes because they can eliminate issues associated with aqueous and organic solvent-based electrolytes, such as narrow operating potential windows, safety, and performance. The full potential of ionic liquids as electrolytes in supercapacitors need to be further explored due to promising previous efforts invested in ionic liquid-based electrolyte systems for supercapacitor. This review aims to provide an outlook on neat (pure) ionic liquids applied as supercapacitor electrolytes to isolate the prospects and influences of ionic liquids in supercapacitor electrolyte systems. This work primarily focuses on ionic liquid chemistry links to their performance in supercapacitor electrolytes. Deduced features of importance to supercapacitor performance include the presence of functional groups in the ionic liquids, the ionic liquids physicochemical and electrochemical properties. With the different classes of ionic liquids evaluated, ion size-pore size matching of ionic liquid electrolytes and electrode materials, respectively, affect resulting capacitances and energy densities. Several design strategies to enhance supercapacitor performance by improving ionic liquid transport and electrochemical properties are proposed. The proposed strategies and obtained insights consequently informed further discussions on challenges associated with the commercialization of ionic liquids electrolytes.

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Atomistic study of the physical properties of sulfonium-based ionic liquids as electrolyte for supercapacitors

Cited by 23 publications

References 67 publications

Comparing Graphite and Graphene Oxide Supercapacitors with a Constant Potential Model

Comparing Graphite and Graphene Oxide Supercapacitors with a Constant Potential Model

Ether-Functionalized Sulfonium Ionic Liquid and Its Binary Mixtures with Acetonitrile as Electrolyte for Electrochemical Double Layer Capacitors: A Molecular Dynamics Study

Prospects and Design Insights of Neat Ionic Liquids as Supercapacitor Electrolytes

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