Since the last decade, the need for deformable electronics exponentially increased, requiring adaptive energy storage systems, especially batteries and supercapacitors. Thus, the conception and elaboration of new deformable electrolytes becomes more crucial than ever. Among diverse materials, gel polymer electrolytes (hydrogels, organogels, and ionogels) remain the most studied thanks to the ability to tune the physicochemical and mechanical properties by changing the nature of the precursors, the type of interactions, and the formulation. Nevertheless, the exploitation of this category of electrolyte as a possible commercial product is still restrained, due to different issues related to the nature of the gels (ionic conductivity, evaporation of filling solvent, toxicity, etc.). Therefore, this review aims to resume different strategies to tailor the properties of the gel polymer electrolytes as well as to provide recent advancements in the field toward the elaboration of deformable batteries and supercapacitors.

TEM micrographs of the epoxy–IL cured systems with 30 wt% of phosphonium ionic liquid.