Nanocellulose-Assisted Growth of Manganese Dioxide on Thin Graphite Papers for High-Performance Supercapacitor Electrodes

High volumetric energy density, based on the entire electrodes, is necessary for the miniaturization of supercapacitors. The growth of manganese dioxide (MnO₂) on graphite papers via chemical reactions was very limited, resulting in the inferior volumetric-specific capacitance. Cellulose nanofibers, coated on graphite papers, impressively enhanced the thickness of grown MnO₂ layers and, thus, volumetric-specific capacitance. The symmetric supercapacitors displayed an extremely high volumetric energy density of 10.6 mWh/cm³ at a power density of 0.11 W/cm³. The performance was superior to that of MnO₂-based symmetric and even asymmetric devices in the past studies. This research opens a new opportunity to fabricate high-performance supercapacitor electrodes by utilizing cellulose nanofibers detached from natural cellulose.