Physically Cross-Linked Titania-Supported Novel Eutectogels as Solid-State Electrolytes: An Experimental and Quantum Chemical Investigation

Abstract

Four novel eutectogel (Egel) electrolytes are prepared from the confinement of four hydrophobic deep eutectic solvents (DESs) within a solid matrix of titania (TiO 2 ) by a nonaqueous sol−gel method. The DESs are composed of decanoic acid, lauric acid, myristic acid, and palmitic acid, each mixed with DL-Menthol in optimal molar ratios. The characteristics of the Egels have been analyzed with the help of field emission scanning electron microscopy, field emission transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, electrochemical impedance spectroscopy, and cyclic voltammetry characterization techniques. The structural properties of the DESs remain unaffected after their confinement into TiO 2 . Thermal stability analyses show almost no mass loss for all the Egels up to a temperature of ∼ 42 °C, with an average initial decomposition temperature of ∼ 150 °C. The gels demonstrate a double-layer capacitive behavior with an operating potential window of about 4 V (−4 to + 4 V) each, proving their potential practicality in electrochemical applications. The nonbonded interactive network facilitated by various noncovalent interactions (H-bonding and van der Waals dispersion) and charge transfer phenomena among the different components of the Egel systems are particularly responsible for their stable and sustainable electrochemical properties suitable for the development of potential electrolytes.