## 1 Introduction  
Continuous progress and comprehensive knowledge of the development of functional materials are essential to meet the demands of the rapidly growing energy sectors. Polymeric gels are a type of soft material that is gaining increasing attention in the electrochemical energy storage, conversion, sensing, gas sorption, and biomedical sectors [1, 2, 3, 4, 5, 6]. Gels are three-dimensional networks of cross-linked polymeric units in liquid systems with variable pore sizes that exhibit exceptional structural derivability, including high water/solvent swellability, materials permeability, and tunable mechanical elasticity [7, 8]. Additionally, a superior ability to serve as biocompatible materials and for transporting ions makes them potential candidates to be utilized in a wide variety of fields. Among various types of gels, IL-based gels, which incorporate ILs either as a solvent or as a polymerizable unit, have garnered substantial attention owing to their attractive properties derived from IL and their tunable functionalities. ILs are a unique type of liquid; they are mainly organic salts composed solely of organic cations and organic or inorganic anions with melting temperatures of less than 100 \({}^{\circ}\)C and have been well utilized in developing a variety of gels [9, 10, 11]. They are often classified as a green category of solvents (and electrolytes) and are distinguished by distinctive qualities, including negligible vapor pressure, high thermal stability, wide electrochemical potential windows, high ionic conductivity, and so on. Due to the tunable physical features of IL-based gels, they have broader prospects in energy applications. There is a growing need for clean and sustainable energy, particularly for energy storage and conversion materials and systems. Lithium batteries, supercapacitors, and fuel cells are typical examples, with their commercial applications including hybrid/electric/fuel cell automobiles, as well as being utilized in large-scale power supply systems such as multistoried building, hospitals, housing apartments that are already underway. Extensive and ongoing research has contributed to the development of novel materials employed in these devices. Furthermore, IL-based materials are popular not only in Li-ion batteries, but also in Li-sulfur and Li-oxygen batteries, owing to being less prone to side reactions, degradation, and evaporation (solvent) compared to traditional carbonate-based electrolytes. Water-assisted proton conductivity of proton conducting membranes, primarily Nafion, impedes fuel cell use at temperatures above 100 \({}^{\circ}\)C due to the rapid evaporation of water and associated reduction in proton conductivity. These problems have sparked research into new electrolyte materials based on ILs. Meanwhile, because of their nonvolatility and high thermal stability, ILs have been employed as carbon material precursors in some cases. This innovative method uncovered functional and designable carbon molecules for energy applications [12].  
This manuscript compiles and examines the most recent scientific advances in the synthesis and application of IL-based gels. While IL liquid-based gels have a wide range of applications in energy storage and conversion, sensors, actuators, wearable devices, gas absorption, and biomedicine, this article will mainly focus on the latest developments and applications of IL-based gels in the energy storage and conversion sectors, and their future prospects will be discussed to guide researchers in choosing the most effective strategies for developing and enhancing research in pertinent domains.