%0 Journal Article
%A Ximei Gao
%A Guobin Zhu
%A Qunting Qu
%A Gao Liu
%A Vincent S Battaglia
%A Honghe Zheng
%B Journal of The Electrochemical Society
%D 2018
%G eng
%N 16
%P A3844 - A3853
%R 10.1149/2.0491916jes
%T Effects of Room Ionic Liquid as Solute on the Electrolyte Solution Structure and Electrochemical Performances in Ethylene Carbonate-Based Electrolyte
%V 165
%8 12/2018
%! J. Electrochem. Soc.
%X <p>Room ionic liquid N-allyl-N-methylpiperidinium bis(trifuoromethansulfonyl)imide (PP<sub>13</sub>∗ TFSI) was adopted as a solute to partly substitute LiPF6 in concentrated ethylene carbonate (EC) based electrolyte (1.8 mol L−1 LiPF6 /EC). Raman and FTIR spectroscopic studies revealed that the electrolyte solution structure was adjusted in the presence of&nbsp;<span>PP</span><sub>13</sub><span>∗ TFSI</span> ionic liquid. Solvation number of Li+ cation could be effectively regulated by the competitive coordination of PP<sub>13</sub>∗+ and Li+ with EC molecules. More importantly, the appearance of TFSI− anion brings about a different coordinating environment of PF<sub>6</sub>− anion in virtue of the stronger association capability of the TFSI− than that of PF<sub>6</sub>−, which resulted in a content regulation of the SEI components between Li<sub>2</sub> CO<sub>3</sub> and LiF, finally contributing to a remarkable cycle life of graphite/Li cell comprising electrolyte with <span>PP</span><sub>13</sub><span>∗ TFSI</span>. The optimized molar ratio between LiPF<sub>6</sub> salt and&nbsp;<span>PP</span><sub>13</sub><span>∗ TFSI</span> ionic liquid was obtained to be 3:1. Differential scanning calorimetry (DSC) confirmed significantly widened liquid range in the EC-based electrolytes with&nbsp;<span>PP</span><sub>13</sub><span>∗ TFSI</span> substitution. This work will provide a new insight and thinking on the application of room ionic liquid.</p>