Carboxymethyl Cellulose-Derived Ionogels for Energy Storage: An Efficient Approach for Polysaccharide-Ionic Liquid Integration

Abstract We report carboxymethyl cellulose (CMC) based ion-conductive ionogel membranes as solid electrolytes for solid-state energy storage applications. First, CMC was functionalized with imidazolium groups by grafting 1-glycidyl-3-vinylimidazolium chloride ([GVIm] Cl) and/or 1-glycidyl-3-methylimidazolium chloride ([GMIm] Cl) to produce imidazolium-modified biomaterials. In a second step, these polymers were crosslinked with polyethylene glycol diacrylate (PEGDA) in the presence of [BMIM] TFSI to form flexible ionogel membranes. The resulting materials were extensively characterized by FT-IR, NMR, SEM, TGA, and contact angle measurements. Electrical conductivity was systematically evaluated by dielectric measurements, revealing ionic conductivity of 6.38 × 10−4 S cm−1 at 100 °C. Ionic functionalization of CMC is crucial to confer compatibility and efficient IL entrapment properties to the biopolymer matrix, providing a scalable pathway toward high-performance, sustainable ionogel electrolytes for energy storage devices such as supercapacitors and batteries. By ionic functionalization of the CMC matrix, the amount of entrapped IL can be increased by a factor of 4. We also demonstrate that ionic grafting with imidazolium groups enhances membrane robustness and surface hydrophobicity. This work establishes a generalizable strategy to overcome biopolymer−ionic liquid incompatibility, opening pathways toward biosourced ionogels as sustainable solid electrolytes for next-generation energy storage devices.