Typha orientalis leaves derived P-doped hierarchical porous carbon electrode and carbon/MnO2 composite electrode for high-performance asymmetric supercapacitor

Sustainable biomass-derived carbon used as electrode features the concept of green chemistry. Herein, Typha orientalis leaves, which show tunable porous structure with high phosphorus content, were used as precursor to prepare P-doped hierarchical porous carbon material and then acted as negative electrode for supercapacitor. Different with the traditional activation methods, the biomass was pretreated by ZnCl2 then activated with KOH (Zn-K-ATC). Owing to the hierarchical porous structure, large specific surface area (1975 m2 g-1) and pseudocapacitance provided by P self-doping, Zn-K-ATC had a high specific capacitance of 324 F g- 1 at 1 A g- 1 in 1 M KOH. Zn-K-ATC was further used as support to grow MnO2 (Zn-K-ATC/MnO2) as the positive electrode material with a specific capacitance of 384 F g- 1 at 1 A g-1 in 1 M Na2SO4. The assembled Zn-K-ATC/MnO2//Zn-K-ATC asymmetric supercapacitor device had a voltage window of 2 V with a high energy density of 46 Wh kg- 1 at 1000 W kg-1. This work gives a systematic research and complete inspection on the preparation of supercapacitor from biomass-derived materials, which expects to provide a valuable method for the preparation of green, low-cost, high-performance supercapacitor materials.