Geminal Dicationic Ionic Liquid-Based Freestanding Ion Membrane for High-Safety Lithium Batteries

Abstract

A freestanding ion membrane with high ionic conductivity, electrochemical compatibility, satisfactory strength, and safety is a goal pursued for advanced energy storage. Geminal dicationic ionic liquids (GDILs) are expected to be designed and synthesized as a basic building block for the target ionic conductors. Herein, we fabricated a GDIL-based flexible ion conductive material, which appears and behaves as a freestanding film, an ion membrane actually, denoted as iMembrane. The iMembrane presented high thermal stability, broad electrochemical stability, and capable ionic conductivity. Stable lithium-ion intercalation/de-intercalation can be achieved at the iMembrane/graphite interface without co-intercalation of imidazole rings, which is attributed to the specific anion-derived solid electrolyte interphase. Moreover, iMembrane is well compatible with the lithium metal anode and LiFePO4 cathode. The soft-packed batteries assembled with iMembrane were punctured with a nail without any fire or smoke. Hence, as an ionic membrane in nonprotonic, iMembrane is promising to enhance safety and energy density of lithium batteries.

Effect of Lithium-Ion on the Structural Organization of Monocationic and Dicationic Ionic Liquids

“…In this context, geminal dicationic ionic liquids (GDILs) are thought to be a good candidate due to their higher thermal and chemical stability than many MILs. − In fact, it has also been shown that the properties of GDILs are superior than the MILs in terms of the higher glass transition temperature, higher surface tension, and larger electrochemical window . We note that, due to the large electrochemical window (4.3 V to 4.7 V) of the GDILs, an electrolytic system comprising of GDILs and lithium-ion is expected to be beneficial in improving the electrochemical stability of the electrolytic medium at higher voltages. − All these properties make GDILs as an attractive electrolytic medium for high-temperature batteries and dye sensitized solar cells despite the fact that they have high density . Since the above discussions depict many of the previous works that have been carried in understanding the behavior of MILs in the absence and presence of lithium-ion, studies on this aspect by employing GDILs are expected to be interesting.…”

“…38−40 All these properties make GDILs as an attractive electrolytic medium for hightemperature batteries and dye sensitized solar cells despite the fact that they have high density. 41 Since the above discussions depict many of the previous works that have been carried in understanding the behavior of MILs in the absence and presence of lithium-ion, studies on this aspect by employing GDILs are expected to be interesting. Moreover, as reported earlier introduction of lithium-ion to the IL medium can cause significant changes in the structure and dynamics of the concerned media and all these matters are all intricately related to the performance of a suitable electrolytic medium in the lithium-ion battery.…”

A highly conductive and stable hybrid solid electrolyte for high voltage lithium metal batteries

“…6a). 52 Fig. S13 † presents the CV measurement of the NCM622kLi cell, which demonstrated that the battery has a stable redox potential.…”

Phosphonate-Functionalized Ionic Liquid Gel Polymer Electrolyte with High Safety for Dendrite-Free Lithium Metal Batteries

“…PPL-IL obtains a lower ion barrier, which is proved by the lower Ea. The improving electrochemical performance is attributed to PFIL, which decreases crystallinity and enhances the mobility of Li + . , Ionic conductivity, activation energy, and Li + transference numbers are shown in Table S3.…”