Novel Ternary Composite Electrolytes: Li Ion Conducting Ionic Liquids in Silica Glass

Abstract

In this contribution, we report on a novel composite solid electrolyte material, SiO2/[BMIM]BF4/LiTf ([BMIM]BF4 = 1-butyl-3-methylimidazolium tetrafluoroborate, LiTf = lithium trifluoromethanesulfonate), prepared via a one-pot sol−gel synthesis route, in which the amorphous SiO2 glass network provides the mechanical stability and the ionic liquid/Li salt part the high ionic conductivity (0.5 × 10−2 S cm−1 at 298 K). The mobility of the ionic liquid and Li salt confined within the pores of the fully condensed SiO2 network is found to increase with the [BMIM]BF4/LiTf ratio, exhibiting an almost liquidlike mobility, as evidenced by multinuclear solid-state NMR, pulsed-field-gradient solid-state NMR, and impedance spectroscopy.

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

“…Subsequently, results on novel hybrid electrolytes, in which a mixture of an ionic liquid and Li salt is confined within the pore system of a SiO 2 glass will be presented [96]. The section will conclude with a report on the analysis of the mechanism of Li transport in the crystalline electrolyte Li 5 La 3 Nb 2 O 12 [97,98].…”

“…13 C NMR, data not shown)) and anions (Tf or TFSI, BF 4 − ) within the pore system of the fully condensed SiO 2 network. This very high ionic mobility is continued down to subambient temperatures, extending to temperatures as low as 240 K (data not shown) [96].…”

“…the amount of connectivity among the phosphate units. In our approach, we employed an in situ synthesis of the hosting SiO 2 glass matrix using a non-aqueous sol-gel process with the ionic liquid [BMIM]BF 4 (1-butyl-3-methylimidazolium tetrafluoroborate) and the Li salt (LiTf or LiTFSI) being present in the starting mixture [96,105]. Confining ionic liquids into a SiO 2 matrix via a sol-gel process has been shown to produce stable solid membranes [106][107][108][109][110][111]; the resulting materials have been considered as materials for dye-sensitized solar cells [112,113], electrolytes for fuel cells etc..…”

Properties of Ionic Liquid Confined in Porous Silica Matrix

“…Porous silica xerogel obtained by incorporating ILs in porous solid matrixes (material is often referred to as "ionogel"), have recently been subject of interest of many studies particularly monitoring the change in the dynamic properties of the confined ILs. [24,38] Many applications of such materials like optical solvents, catalysis, biocatalysis, sensors and biosensors, have been reported (see review by A. Vioux et al [39] and references cited therein). Recently, Devenport et al [40] have applied such materials to obtain rectifying diodes. ])…”

Ionogel Fiber Mats: Functional Materials via Electrospinning of PMMA and the Ionic Liquid Bis(1-butyl-3-methyl-imidazolium) Tetrachloridocuprate(II), [Bmim]2[CuCl4]

“…Ionogels are IL/inorganic or IL/polymer hybrid materials combining the properties of the matrix such as mechanical robustness and the properties of the IL [35,36]. Nowadays luminescent [37 -39], photochemically active [40], magnetic [41,42], proton- [43] and other ionconductive [44,45], along with mechanically robust ionogels with adjustable mechanical properties [46] are known. Most ionogels so far are bulk materials with low surface areas [35,36].…”