Destructuring ionic liquids in ionogels: enhanced fragility for solid devices

Abstract

Confining ionic liquids (ILs) with added lithium salt within silica host networks enhances their fragility and improves their conductivity. Overall, conductivity measurements, Raman spectroscopy of the TFSI anion and NMR spectroscopy of the lithium cation show segregative interaction of lithium ions with the SiO2 host matrix. This implies at IL/SiO2 interfaces a breakdown of aggregated regions that are found systematically in bulk ILs. Such destructuration due to the interface effect determines the fragility and thus results locally at the interface in short relaxation times, low viscosity, and good ionic conductivity. The "destructuration" of ion pairs or domains makes ILs within ionogels a competitive alternative to existing solid ionic conductors in all-solid devices, such as lithium batteries and supercapacitors.

High Areal Energy 3D‐Interdigitated Micro‐Supercapacitors in Aqueous and Ionic Liquid Electrolytes

“…The areal capacitance (Figure B,C) of the 3D MnO 2 thin film electrode is evaluated in EMI TFSI at different scan rates from 5 up to 500 mV s −1 within the proposed electrochemical window (1.5 V). The CV shape is quite stable up to 500 mV s −1 demonstrating the excellent behavior of the 3D electrodes in EMI TFSI at high sweep rate; such performance could be assigned to the high surface‐to‐volume ratio of the device, resulting in decreased viscosity at the electrode/electrolyte interface, consistently with previous observations . In Figure D, the capacitance retention is reported at 10 mV s −1 in EMI TFSI within the used potential windows.…”

“…On the one hand, the use of ILs is a preliminary step toward solid‐state pseudocapacitive MSC with ionogel technology . It is here worth pointing out that interfaces between ILs and oxides were shown to enhance charge transport in ILs by reducing locally their viscosity . A high surface‐to‐volume ratio is advantageous for a better use of the electrochemical properties of ILs.…”

Ionic Liquids Confined in Silica Ionogels: Structural, Thermal, and Dynamical Behaviors

“…When increasing the temperature, these nanoscale domains or ion pairing disappear. There is a temperature at which the Coulomb vs. Van der Waals interactions clearly put a disadvantage in the overall attractive energy which tight any correlated domains or pairs [24][25][26]. Thus, breaking of these correlations possibly gives rise to the decreased activation energies which can be clearly seen around 340 K in the Arrhenius plot of the ionic conductivity [11,12].…”

Polymer-based hybrid battery electrolytes: theoretical insights, recent advances and challenges

“…10 À6 S cm À1 ) unless additional solvent is added. [112][113][114] Therefore, ionogels are typically used for applications above 60 C since they also show enhanced thermal properties. [115][116][117] As llers, SiO 2 , Al 2 O 3 , metal organic frameworks, and boron nitride particles have been employed.…”