Wood-based hierarchical porous nitrogen-doped carbon/manganese dioxide composite electrode materials for high-rate supercapacitor

Supercapacitor is an important energy storage device with rapid charge/discharge, long cycle life, and high-power density. The macron vertical channel structure in wood can provide an effective buffer space for the transport and storage of electrolyte ions. The transport kinetics of the electrolyte with wood-derived carbon electrode has an important effect on its capacitance performance. Herein, the wood branch of cedar is employed to construct supercapacitor electrode with high-rate performance by facile carbonization and KOH activation. The cedar demonstrates arranged pore structure and high specific surface area. The special pore structure is retained after carbonization. Furthermore, the carbonization temperature and carbonization process are explored. As the optimized, the wood-derived porous carbon electrode displays high specific capacitance of 108 F/g at a higher current rate of 15 A/g, implying its good rate capability. Moreover, after compounding MnO₂, the specific capacitance of composite electrode delivers 162.4 F/g at 0.5 A/g. The assembled symmetric supercapacitor shows high energy density of 3.01 Wh/kg at the power density of 250 W/kg. This work offers an idea for developing clean and efficient new energy technologies with high-rate performance.