In-Situ Growth of MnO 2 Nanosheets on Biomass Waste for Long-Life Supercapacitors

In the face of global energy security, environmental pollution and climate change challenges, vigorously promoting the utilization of waste biomass is crucial for guard the green water and green mountains, digging “urban mines”, and realize the sustainable development of resources is the way to go. Durian shells represent an abundant lignocellulosic agricultural waste biomass, characterized by ready availability, an intrinsic porous structure, and significant fiber content. Utilizing DS as the carbon source, potassium hydroxide (KOH) and potassium permanganate (KMnO 4 ) were synergistically employed as composite modifiers. Through the hydrothermal synthesis method, Manganese dioxide (MnO 2 ) in-situ grown onto the DS carbon material, thereby preparing DS-based porous carbon, which has abundant pore structure. The findings reveal that when the mass ratio between KMnO 4 and active DS carbon reaches 0.03, the resulting DCK-MnO 2 -0.03 composite exhibited the optimal specific capacitance, achieving an amount of 334 F·g -1 at 0.5 A·g -1 . Symmetrical supercapacitors assembled with DCK-MnO 2 -0.03 exhibit energy densities of 15.56 Wh·kg -1 and 13.9 Wh·kg -1 at power densities of 622 W·kg -1 and 6250 W·kg -1 , respectively. Furthermore, the assembled supercapacitor demonstrates remarkable cycle stability, maintaining 95.3% of its initial energy density after enduring 10,000 cycles at a current density of 10 A·g -1 .