Insight into the Use of Ionic Liquid-Based Polymer Electrolytes for Lithium-Ion Batteries
Abstract
The rapid evolution of energy storage technologies has intensified research into safer, higher-performance electrolyte systems for lithium-ion batteries (LIBs). Ionic liquid-based polymer electrolytes (ILPEs) have emerged as a transformative class of materials that combine the wide electrochemical stability windows and negligible volatility of ionic liquids (ILs) with the mechanical flexibility and processability of polymer matrices. This review critically examines the recent advances in ILPEs across ten thematic domains: the fundamental physicochemical properties of ionic liquids, the design and classification of polymer hosts, ion transport mechanisms, electrochemical stability, interfacial behavior with lithium metal and cathode materials, thermal and mechanical performance, fabrication strategies, gel polymer electrolyte formulations, composite and hybrid architectures, and practical device integration. Drawing on literature published predominantly between 2018 and 2025, the review highlights key structure–property relationships governing ionic conductivity, lithium transference number, and cycling stability. Persistent challenges including high viscosity, cost, and scalability are critically assessed alongside emerging solutions such as ternary composite designs, nanostructured fillers, and block copolymer engineering. The review concludes with a forward-looking perspective on the role of ILPEs in enabling next-generation solid-state and lithium-metal battery technologies.