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Concentrated Ionic‐Liquid‐Based Electrolytes for High‐Voltage Lithium Batteries with Improved Performance at Room Temperature
Author(s) -
Gao Xinpei,
Wu Fanglin,
Mariani Alessandro,
Passerini Stefano
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201901739
Subject(s) - electrolyte , ionic liquid , electrochemistry , faraday efficiency , lithium (medication) , inorganic chemistry , imide , chemical engineering , materials science , chemistry , battery (electricity) , electrode , organic chemistry , thermodynamics , medicine , power (physics) , physics , engineering , endocrinology , catalysis
Ionic liquids (ILs) have been widely explored as alternative electrolytes to combat the safety issues associated with conventional organic electrolytes. However, hindered by their relatively high viscosity, the electrochemical performances of IL‐based cells are generally assessed at medium‐to‐high temperature and limited cycling rate. A suitable combination of alkoxy‐functionalized cations with asymmetric imide anions can effectively lower the lattice energy and improve the fluidity of the IL material. The Li/Li 1.2 Ni 0.2 Mn 0.6 O 2 cell employing N ‐ N ‐diethyl‐ N ‐methyl‐ N ‐(2‐methoxyethyl)ammonium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (DEMEFTFSI)‐based electrolyte delivered an initial capacity of 153 mAh g −1 within the voltage range of 2.5–4.6 V, with a capacity retention of 65.5 % after 500 cycles and stable coulombic efficiencies exceeding 99.5 %. Moreover, preliminary battery tests demonstrated that the drawbacks in terms of rate capability could be improved by using Li‐concentrated IL‐based electrolytes. The improved room‐temperature rate performance of these electrolytes was likely owing to the formation of Li + ‐containing aggregate species, changing the concentration‐dependent Li‐ion transport mechanism.