Examining the Electrochemical Nature of an Ionogel Based on the Ionic Liquid [P₆₆₆₁₄][TFSI] and TiO₂: Synthesis, Characterization, and Quantum Chemical Calculations

With countries and regions setting strict targets for adopting renewable and sustainable technologies, worldwide demand for energy storage has surged dramatically. Novel materials and new storage chemistry solutions are being explored to realize storage technologies for the next generation. This step-change includes fundamental research in the design of new electrolytes. Ionogels are gaining popularity in electrochemical applications because of their ability to overcome the drawbacks of their liquid counterparts while retaining certain beneficial qualities of the latter. The present study reports the preparation of a novel quasi-solid ionogel through the confinement of the ionic liquid (IL) trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P₆₆₆₁₄][TFSI]) into a matrix of titania (TiO₂) by a simple one-pot sol–gel process. The properties of the ionogel have been studied via field emission scanning electron microscopy (FESEM), rheology, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and cyclic voltammetry (CV). The ionogel manifests shear-thinning viscoelastic behavior. The integrity of the IL remains unaffected after its confinement in TiO₂. Thermal stability analysis shows little mass loss of the ionogel up to a temperature of ∼93 °C, favoring its utilization in high-temperature applications. The ionogel demonstrates a double-layer capacitive behavior with an impressive operating potential window (OPW) of 4 V (−4 to +4 V), substantiating its applicability and excellent stability in the electrochemical domain. The formation of the weakly coordinating ionogel is analyzed using density functional theory (DFT). The electronic structures of the precursors and the ionogel are elucidated at the B3LYP/LANL2DZ level of theory. The quantum chemical (QC) calculations reveal that the interaction of the IL with the cross-linker results in some dimensional changes due to alterations in the vibrational frequencies of the respective groups present in the ionogel system.