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Electrolytes based on N‐Butyl‐N‐Methyl‐Pyrrolidinium 4,5‐Dicyano‐2‐(Trifluoromethyl) Imidazole for High Voltage Electrochemical Double Layer Capacitors
Author(s) -
Scalia Alberto,
Varzi Alberto,
Moretti Arianna,
Ruschhaupt Peter,
Lamberti Andrea,
Tresso Elena,
Passerini Stefano
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201801172
Subject(s) - electrolyte , propylene carbonate , electrochemistry , ionic liquid , supercapacitor , conductivity , inorganic chemistry , electrochemical window , ionic conductivity , melting point , solvent , chemistry , materials science , electrode , organic chemistry , catalysis
Owing to their exceptional electrochemical stability, ionic liquids (ILs) are highly promising electrolytes for high voltage electrochemical double layer capacitors (EDLCs). However, these molten salts often suffer from high viscosity and low conductivity, strongly affecting their application at room temperature. In this work the potential role of N‐butyl‐N‐methyl‐pyrrolidinium 4,5‐dicyano‐2‐(trifluoromethyl) imidazole (Pyr 14 TDI) as electrolyte component is evaluated for the first time. Although it is classified as an IL, its melting point at 48 °C hinders the use of the pure IL as solvent‐free electrolyte at medium‐to‐low temperatures. For this reason, mixtures with propylene carbonate (PC) are investigated to widen its temperature operation range (−30 to 60 °C). Different Pyr 14 TDI:PC ratios are investigated, from diluted solution (1 : 3 w/w) to solvent‐in‐salt (3 : 1 w/w). The properties of such electrolytes are determined in terms of viscosity, density, flash point, ionic conductivity, and electrochemical performance in EDLC. By proper electrode balancing, a maximum cell voltage of 3.3 V is achieved in case of PC:Pyr 14 TDI (1 : 3). However, despite the voltage limitation to 3 V, the highest specific energy and power values are obtained with the most diluted solution (3 : 1).