MnO₂/SWCNT buckypaper for high performance supercapacitors

We report the supercapacitive performance of manganese oxide (MnO₂)/single-walled carbon nanotube (SWCNT) buckypaper electrodes enabled via electrochemical deposition of MnO₂ onto SWCNT buckypaper for the first time. The entangled SWCNT network provides electro-conductive pathways for the charge transfer. We demonstrate that the MnO₂/SWCNT buckypaper supercapacitor exhibits a specific capacitance of 605 Fg⁻¹ and gravimetric energy density of ∼120 Whkg⁻¹. Furthermore, our MnO₂/SWCNT buckypaper electrode shows excellent rate capability (85% capacity retention at 20 Ag⁻¹) and long cycle life (1% capacity loss after 10,000 charge/discharge cycles). The excellent performance of MnO₂/SWCNT buckypaper supercapacitor is attributed to the flower-like unique hierarchical porous architecture of MnO₂ around SWCNTs arranged in “pearl necklace” formation, enabling large electrode/electrolyte interface and charge storage surface, better electrolyte penetration, and rapid charge transfer. The results suggest that the MnO₂/SWCNT buckypaper electrode can provide excellent supercapacitive performance suitable for future generation electric vehicles.