A Review on Multifaceted Role of Ionic Liquids in Modern Energy Storage Systems: From Electrochemical Performance to Environmental Sustainability

Ionic liquids (ILs) have attracted considerable attention in energy storage due to their unique properties, including a wide electrochemical stability window that facilitates their use in high-voltage systems, enhancing the battery energy density. For instance, the electrolyte consisting of polyethylene glycol diacrylate (PEGDA), LiBF 4 salt, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF 4 ) ionic liquid, and SiO 2 nanoparticles exhibited the total conductivity with significant values, reaching approximately 10 –4 S cm –1 at −40 °C, 10 –3 S cm –1 at 25 °C, and 10 –2 S cm –1 at 100 °C for battery. Taking this into consideration, this Review highlights recent advancements in the development and utilization of ionic liquid electrolytes for various energy storage devices, including batteries and supercapacitors. Additionally, this review presents the bibliometric analysis of global research on ILs for energy storage devices from 2019 to 2024. By analyzing 2486 research articles from Web of Science (WOS) and Scopus databases, the study explores publication trends, citation patterns, and collaboration networks. Furthermore, the incorporation of additives, nanostructured materials, and polymer matrices has been explored to improve the mechanical and electrochemical stabilities of ionic liquid electrolytes. The study addresses the gap in understanding the practical implications of ILs in real-world energy storage systems, emphasizing the need for further research on their scalability and integration. The findings suggest that ILs hold promise for developing safer and more efficient energy storage solutions with potential applications across various industries. These insights aim to guide future research and development in the field and promote the adoption of ILs in next-generation energy technologies.