In situ growth of MnO2 on graphitized cellulose nanocrystal: A novel coaxial heterostructures with unblocked conductive networks as advanced electrode materials for supercapacitor

Manganese dioxide (MnO 2 ) with high theoretical capacitance and natural abundance has attracted great attention but is still challenging for use in supercapacitors, due to the limited conductivity and lower electron and ion migration. Here, a facile in situ growth strategy is developed to prepare heterostructural graphitized cellulose nanocrystal (GCNC)/MnO 2 with unblocked conductive networks through a hydrothermal reaction. The GCNC with highly ordered graphitic carbon layers as conductive support framework solves the agglomeration problem of MnO 2 and increases effective specific surface areas in contact with electrolyte ions. Meanwhile, the stable connection of Mn O C covalent bonds enhances the interface bonding, which effectively reduces the contact resistance at the interface of heterostructural GCNC/MnO 2 and enhances the interface firmness. The resulting GCNC/MnO 2 electrode shows a remarkable specific capacitance of 528.2 F g −1 at 0.5 A g −1 . Furthermore, the symmetric supercapacitor based on GCNC/MnO 2 -15 mM exhibits high rate capability and excellent cycle stability of 100 % capacitance retention after 3000 cycles. This work provides a new path to designing high performance electrode material for sustainable energy technologies.