2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

Wippermann, Klaus; Wackerl, Jürgen; Lehnert, Werner; Huber, Benedikt; Korte, Carsten

doi:10.1149/2.0141602jes

Cited by 43 publications

(62 citation statements)

References 97 publications

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“…When the ionic liquid is in contact with a solid, the interface structure is also affected by the topography, atomic arrangement, reactivity, local charge, and polarizability of the solid surface [11]. This interface structure becomes additionally distorted when electrical potential is applied to the solid, as is the case in electrochemical cells such as PEMFCs that employ ionic liquids as an electrolyte [48]. In consequence, a complex layered structure is formed in the ionic liquid that determines the kinetics of ion transport and reactions at the interface.…”

Section: Appl Sci 2019 9 X For Peer Review 4 Of 28mentioning

confidence: 99%

Atomic Force Spectroscopy on Ionic Liquids

2019

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Ionic liquids have become of significant relevance in chemistry, as they can serve as environmentally-friendly solvents, electrolytes, and lubricants with bespoke properties. In particular for electrochemical applications, an understanding of the interface structure between the ionic liquid and an electrified interface is needed to model and optimize the reactions taking place on the solid surface. As with ionic liquids, the interplay between electrostatic forces and steric effects leads to an intrinsic heterogeneity, as the structure of the ionic liquid above an electrified interface cannot be described by the classical electrical double layer model. Instead, a layered solvation layer is present with a structure that depends on the material combination of the ionic liquid and substrate. In order to experimentally monitor this structure, atomic force spectroscopy (AFS) has become the method of choice. By measuring the force acting on a sharp microfabricated tip while approaching the surface in an ionic liquid, it has become possible to map the solvation layers with sub-nanometer resolution. In this review, we provide an overview of the AFS studies on ionic liquids published in recent years that illustrate how the interface is formed and how it can be modified by applying electrical potential or by adding impurities and solvents.

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Section: Appl Sci 2019 9 X For Peer Review 4 Of 28mentioning

confidence: 99%

Atomic Force Spectroscopy on Ionic Liquids

2019

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“…Despite the high operation temperature of 160°C, the presence of H 3 PO 4 causes a slow cathodic oxygen reduction reaction kinetics (ORR). This is primarily caused by an inhibition effect due to a poisoning by adsorption of H 3 PO 4 species onto active catalyst sites [4]. Also discussed is a low solubility of O 2 and a slow diffusion of O 2 through the H 3 PO 4 film which covers the platinum catalyst [5].…”

Section: Introductionmentioning

confidence: 99%

PBI‐type Polymers and Acidic Proton Conducting Ionic Liquids – Conductivity and Molecular Interactions

Lin

Korte

2020

Fuel Cells

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Proton conducting ionic liquids (PILs) are discussed as new electrolytes for the use as non‐aqueous electrolytes at operation temperatures above 100 °C. During fuel cell operation the presence of significant amounts of residual water is unavoidable. The highly Brønsted‐acidic PIL 2‐Sulfoethylmethylammonum triflate [2‐Sema][TfO] is able to perform fast proton exchange processes with H2O, resulting from 1H‐NMR and pulsed field gradient (PFG)/diffusion ordered spectroscopy (DOSY) self‐diffusion measurements. Proton conduction takes place by a vehicle mechanism via PIL cations or H3O+, but also by a cooperative mechanism involving both species. Thus, highly Brønsted‐acidic PILs are promising candidates for the use as non‐aqueous electrolytes. To use [2‐Sema][TfO] as electrolyte in a proton electrolyte fuel cell (PEFC) it has to be immobilized in a host polymer. There is a (slow) uptake of the PIL by polybenzimidazole (PBI) up to a weight increase of ∼130%, due to a swelling process. A protonation of the basic imidazole moieties takes place. NMR analysis was applied to elucidate the molecular interactions between PBI, PIL, and residual water. Proton exchange, respectively an interaction between the polar groups and water can be observed in spectra, indicating a network of H‐bonds in doped PBI. Therefore, highly acidic PILs are promising candidates for the use as non‐aqueous electrolytes.

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“…Electrochemical applications, which demand practically anhydrous electrolytes include, for instance, lithium batteries, 1,2 electrochemical supercapacitors, 3,4 solar cells, 5,6 field-effect double-layer transistors 7,8 and electrochemical synthesis. 9,10 For other applications, the presence of water is either unavoidable (e.g., fuel cells [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] ) or even desirable (humidity sensors 28 or drying agents [29][30][31][32] ).…”

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confidence: 99%

In Situ Determination of the Water Content of Ionic Liquids

Wippermann

Giffin

Korte

2018

J. Electrochem. Soc.

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This study examines the applicability of electrochemical methods to the in situ determination of the water content in proton-conducting ionic liquids (PILs). Two proton-conducting ionic liquids with different acidities and hygroscopicities of the cations, sulfoethylmethylammonium trifluoromethanesulfonate, [2-Sema][TfO] and N,N-diethylmethylammonium trifluoromethanesulfonate, [Dema][TfO], were used. At first, PIL water electrolytes with known water concentrations ([2-Sema][TfO]: 0.64-6.1 wt%, [Dema][TfO]: 0.18-99.5 wt%) were prepared. Then, the influence of the water content on the electrochemical properties, namely the electrical conductivity, charge of hydrogen oxidation, charge of Pt oxide reduction and onset potential of Pt oxidation, were investigated. The four parameters were plotted as a function of the water concentration and fitted by exponential, linear or asymptotic functions. These fits serve as calibration curves that can be used to determine the actual water concentration by measuring one or more of the four parameters investigated. It was found that the measurement of specific ion conductivity is a fast and simple method across a wide range of water concentrations. The evaluation of the Pt oxide reduction charge from cyclic voltammograms is more time-consuming, but provides higher accuracy at low water concentrations, although the accuracy also depends on the nature of the ionic liquid.

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2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

Cited by 43 publications

References 97 publications

Atomic Force Spectroscopy on Ionic Liquids

Atomic Force Spectroscopy on Ionic Liquids

PBI‐type Polymers and Acidic Proton Conducting Ionic Liquids – Conductivity and Molecular Interactions

In Situ Determination of the Water Content of Ionic Liquids

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