Cellulose as an Adhesive for the Synthesis of Carbon Aerogel with a 3D Hierarchical Network Structure for Capacitive Energy Storage

Abstract As an abundant biomaterial, lignin is often used as a low‐end material, because it has an inferior formability at normal temperature and a poor solubility in most solvents. In this study, an innovative lignin/cellulose carbon aerogel with a 3D hierarchical network structure composed of nanochains connecting nanospheres is successfully synthesized by dissolving cellulose and lignin in 1‐butyl‐3‐methylimidazolium chloride, regenerating in deionized water, freeze‐drying, and carbonizing. Cellulose, as the adhesive connects lignin by hydrogen bonds, increases the specific surface area and improves the graphitization degree. Consequently, the sample with 10 wt % cellulose (C‐10) has a high specific capacitance (166 F g −1 at 0.1 A g −1 ), low impedance ( τ =5.56 ms), and excellent capacitance retention (98.6 % after 1000 cycles). The C‐10‐based flexible supercapacitor exhibits a stable output capability (≥99 %) at different bending angles, long cycle life (≥1000 cycles), and high energy density (102 Wh kg −1 at 175 W kg −1 ).