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New Insights to Self‐Aggregation in Ionic Liquid Electrolytes for High‐Energy Electrochemical Devices
Author(s) -
Kunze Miriam,
Jeong Sangsik,
Paillard Elie,
Schönhoff Monika,
Winter Martin,
Passerini Stefano
Publication year - 2011
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201000052
Subject(s) - ionic liquid , electrochemistry , electrolyte , materials science , imide , ion , alkyl , lithium (medication) , ionic conductivity , raman spectroscopy , inorganic chemistry , supercapacitor , ionic bonding , chemical physics , chemical engineering , chemistry , organic chemistry , polymer chemistry , electrode , medicine , physics , optics , endocrinology , catalysis , engineering
Some cations of ionic liquids (ILs) of interest for high‐energy electrochemical storage devices, such as lithium batteries and supercapacitors, have a structure similar to that of surfactants. For such, it is very important to understand if these IL cations tend to aggregate like surfactants since this would affect the ion mobility and thus the ionic conductivity. The aggregation behaviour of ILs consisting of the bis(trifluoromethanesulfonyl)imide anion and different N ‐alkyl‐ N ‐methyl‐pyrrolidinium cations, with the alkyl chain varied from C 3 H 7 to C 8 H 17 , was extensively studied with NMR and Raman methods, also in the presence of Li + cations. 2 H NMR spin‐lattice and spin‐spin relaxation rates were analyzed by applying the “two step” model of surfactant dynamics. Here we show that, indeed, the cations in these ILs tend to form aggregates surrounded by the anions. The effect is even more pronounced in the presence of dissolved lithium cations.