A Dual Ionic Liquid-Based Low-Temperature Electrolyte System
By Xu, Yifei; Lin, Wendy J.; Gliege, Marisa; Gunckel, Ryan; Zhao, Zuofeng; Yu, Hongyu; Dai, Lenore L.
Published in The Journal of Physical Chemistry B
Abstract
Ionic liquids (ILs) show a promising future as electrolytes in electrochemical devices. In particular, IL-based electrolytes bring operations at extreme temperatures to realization that conventional electrolytes fail to accomplish. Although IL electrolytes demonstrate considerable progress in high-temperature applications, their breakthroughs in devices operating at low temperatures are still very limited due to undesirable phase transitions and unsatisfying transport properties. In this study, we present an approach where, by tuning molecular interactions in the system, the designed electrolyte of an IL-based mixture can reach a lower operating temperature with improved transport properties. We have discovered that the incorporation of the IL, ethylammonium nitrate ([EA][N]), can contribute to reforming the molecular interactions within the system, which effectively resolve the crystallization accompanied with the excess of water and retain a low glass transition temperature. The reported liquid electrolyte systems based on a mixture of 1-butyl-3-methylimidazolium iodide ([BMIM][I]), [EA][N], water, and lithium iodide exhibit a glass transition temperature below ?105