Abstract
In this study, four novel eutectogel electrolytes were developed by confining four hydrophobic natural deep eutectic solvents (NADESs) within a solid titania (TiO2) matrix using a non-aqueous sol-gel method and further mediating them with the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The NADESs were carefully formulated by mixing decanoic acid, lauric acid, myristic acid, and palmitic acid with DL-Menthol in optimized molar ratios. The electrochemical properties of these eutectogels were comprehensively investigated utilizing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with porous reduced graphene oxide (rGO) electrodes. The findings reveal that the eutectogels exhibit a distinct double-layer capacitive behavior, featuring an impressively broad operating potential window (OPW) of approximately 4 V with decent values of specific capacitance (16.23 – 47.72 F g−1). High room-temperature ionic conductivities (14.53 – 16.28 mS cm−1) were also obtained. While we observed moderate values of specific power (1.7 – 3.5 kW kg−1) due to relatively higher internal resistance, the gels demonstrated specific energy as high as 106 W h kg−1. These results underscore the considerable practical potential of these eutectogels in various electrochemical applications, specifically as electrolytes in high-performance electrochemical supercapacitors.