A comparative study of alkylimidazolium room temperature ionic liquids with FSI and TFSI anions near charged electrodes

Hu, Zongzhi; Vatamanu, Jenel; Borodin, Oleg; Bedrov, Dmitry

doi:10.1016/j.electacta.2014.08.072

Cited by 57 publications

(76 citation statements)

References 107 publications

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“…3 [37], the adsorption of coordinated Li + (either with two anions or partially dissociated with one TFSI anion) causes an increase in TFSI anion concentration at the electrode surface that may facilitate its breakdown (reduction). In the case of a pure ionic liquid, the adjacent layer is composed almost solely of large cations [38] which block access to the electrode for the TFSI anions. The reduction process is thus suppressed and no reduction peak is visible.…”

Section: Resultsmentioning

confidence: 99%

Catalytic reduction of TFSI-containing ionic liquid in the presence of lithium cations

Tułodziecki

Tarascon

Taberna

et al. 2017

Electrochemistry Communications

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. a b s t r a c tThe influence of the electrochemical double layer (EDL) structure on the electrochemical processes in ionic liquids is an intriguing subject. The complex layered structure of the EDL and its restructuring have been shown to strongly affect metal deposit morphology and electrochemical reaction kinetics. In this work, we demonstrate that the breakdown of an ionic liquid containing TFSI anions can be catalyzed through the addition of Li + cations.We ascribe this catalytic effect to the change in the EDL structure: the Li + cations preferentially adsorb on the electrode surface and drag the TFSI anions with them, facilitating their reduction. The decomposition of the ionic liquid leads to the formation of an SEI layer, which is studied using an electrochemical quartz crystal microbalance.

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Section: Resultsmentioning

confidence: 99%

Catalytic reduction of TFSI-containing ionic liquid in the presence of lithium cations

Tułodziecki

Tarascon

Taberna

et al. 2017

Electrochemistry Communications

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“…Rough edges provide dual beneficial effect. On the one hand, they enhance the EDL capacitance via the classical effect of surface roughness when their roughness dimensions are similar to the ions' sizes, as shown in references [7,12,93], and on the other hand, the electronic structure of the zigzag rough edges allows them to behave essentially as conductors. Furthermore, the rough edges have an advantage of increasing (almost doubling) the capacitance in the subnanometer pores as compared to smooth surface pores of similar widths [102].…”

Section: Discussionmentioning

confidence: 99%

Tailoring graphene-based electrodes from semiconducting to metallic to increase the energy density in supercapacitors

Vatamanu

Liu

et al. 2015

Nanotechnology

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The semiconducting character of graphene and some carbon-based electrodes can lead to noticeably lower total capacitances and stored energy densities in electric double layer (EDL)capacitors. This paper discusses the chemical and electronic structure modifications that enhance the available energy bands, density of states and quantum capacitance of graphene substrates near the Fermi level, therefore restoring the conducting character of these materials. The doping of graphene with p or n dopants, such as boron and nitrogen atoms, or the introduction of vacancy defects that introduce zigzag edges, can significantly increase the quantum capacitance within the potential range of interest for the energy storage applications by either shifting the Dirac point away from the Fermi level or by eliminating the Dirac point. We show that a combination of doping and vacancies at realistic concentrations is sufficient to increase the capacitance of a graphene-based electrode to within 1 μF cm(−2) from that of a metallic surface.Using a combination of ab initio calculations and classical molecular dynamics simulations we estimate how the changes in the quantum capacitance of these electrode materials affect the total capacitance stored by the open structure EDL capacitors containing room temperature ionic liquid electrolytes.

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“…The C d measured by EIS was confirmed to be equal to the zero-frequency (static) C d for the Hg|aqueous solution interface, 14 where the zero-frequency C d can be evaluated from electrocapillarity, i.e., potential dependence of interfacial tension. Theoretical and simulation studies such as mean field theory 3,33-35 and molecular dynamics (MD) simulations [36][37][38][39][40][41][42][43][44] always predict zero-frequency C d (capacitance in equilibrium) and the predicted and experimental zero-frequency C d could directly be compared and discussed if the latter is available. The ultraslow relaxation leads to deviation of the C d values obtained by EIS from the zero-frequency C d .…”

Section: Introductionmentioning

confidence: 99%

Electrocapillarity and zero-frequency differential capacitance at the interface between mercury and ionic liquids measured using the pendant drop method

Nishi

Hashimoto

Minami

et al. 2015

Phys. Chem. Chem. Phys.

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The structure of ionic liquids (ILs) at the electrochemical IL|Hg interface has been studied using the pendant drop method. From the electrocapillarity (potential dependence of interfacial tension) differential capacitance (Cd) at zero frequency (in other words, static differential capacitance or differential capacitance in equilibrium) has been evaluated. The potential dependence of zero-frequency Cd at the IL|Hg interface exhibits one or two local maxima near the potential of zero charge (Epzc), depending on the cation of the ILs. For 1-ethyl-3-methylimidazolium tetrafluoroborate, an IL with the cation having a short alkyl chain, the Cdvs. potential curve has one local maximum whereas another IL, 1-octyl-3-methylimidazolium tetrafluoroborate, with the cation having a long alkyl chain, shows two maxima. These behaviors of zero-frequency Cd agree with prediction by recent theoretical and simulation studies for the electrical double layer in ILs. At negative and positive potentials far from Epzc, the zero-frequency Cd increases for both the ILs studied. The increase in zero-frequency Cd is attributable to the densification of ionic layers in the electrical double layer.

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A comparative study of alkylimidazolium room temperature ionic liquids with FSI and TFSI anions near charged electrodes

Cited by 57 publications

References 107 publications

Catalytic reduction of TFSI-containing ionic liquid in the presence of lithium cations

Catalytic reduction of TFSI-containing ionic liquid in the presence of lithium cations

Tailoring graphene-based electrodes from semiconducting to metallic to increase the energy density in supercapacitors

Electrocapillarity and zero-frequency differential capacitance at the interface between mercury and ionic liquids measured using the pendant drop method

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