Hierarchical carbon aerogels from DES-carboxylated cellulose nanofibers through multicomponent precursor engineering

Agricultural biomass-derived cellulose nanofibers (CNFs) are promising renewable building blocks for lightweight porous carbons; however, preserving network connectivity while regulating hierarchical porosity during their conversion into carbon aerogels remains challenging. Here, sugarcane-pulp-derived cellulose was treated with a hydrated choline chloride/citric acid deep eutectic solvent to prepare carboxylated cellulose nanofibers (C-CNFs), which were subsequently integrated with gelatin and zinc 1,3,5-benzenetricarboxylate (Zn-BTC) to form a multicomponent precursor. Following freeze-drying and carbonization, the assembled precursor was converted into an ultralight, interconnected carbon aerogel with hierarchical porosity, a Brunauer–Emmett–Teller specific surface area of 849.3 m 2 g −1 , a total pore volume of 1.27 cm 3 g −1 , and a density of approximately 0.01 g cm −3 . The optimized GZBTC 0.2 -900 electrode delivered a specific capacitance of 250 F g −1 at 0.5 A g −1 and retained 172 F g −1 at 20 A g −1 in a three-electrode configuration. The corresponding symmetric device achieved an energy density of 7.43 Wh kg −1 at a power density of 250 W kg −1 and retained 95.2% of its initial capacitance after 10,000 cycles at 2 A g −1 . These results establish a multicomponent precursor-engineering approach for converting functionalized cellulose nanofiber assemblies into ultralight carbon aerogels with interconnected frameworks and hierarchical porosity for electrochemical energy storage.