High-Performance Supercapacitor Device with Ultrathick Electrodes Fabricated from All-Cellulose-Based Carbon Aerogel

A thick electrode with a high mass loading is one of the promising structural designs to improve the energy density of supercapacitors. However, the slow ion transport and sluggish charge kinetics caused by the increased electrode thickness are still major challenges toward high-performance energy storage devices. Herein, an all-cellulose-based carbon aerogel asymmetric supercapacitor (ACAS) device is successfully assembled by using a thin cellulose aerogel as a separator and cellulose carbon aerogel and RuO2/cellulose carbon aerogel as the ultrathick anode and cathode, respectively. Benefiting from the 3D hierarchical porous percolation network structure, both cellulose aerogel and carbon aerogel provide continuous pathways that are beneficial to the electrolyte penetration, thereby facilitating the rapid transport of ions and electrons. As a result, the assembled ACAS device achieves an ultrathickness (up to ∼2.3 mm), including the anode (up to 1.2 mm) and the cathode (up to 1.0 mm). Consequently, the ACAS device possesses a high volumetric capacitance of 6.18 F cm–3 and a high energy density (3.4 Wh L–1) with a maximum power density of 23 W L–1, which surpass values for the most-reported cellulose-based asymmetric supercapacitor. This work presents a design concept using renewable cellulose materials for the separator and thick electrodes in supercapacitors, which further facilitates the future application of sustainable and high-density energy storage devices.