Direct pyrolysis fabrication of N/O/S self-doping hierarchical porous carbon from Platycladus Orientali leaves for supercapacitor

Abstract

To meet the growing market requirement for low-cost supercapacitor electrode materials, N/O/S self-doping hierarchical porous carbon is successfully fabricated by direct pyrolysis of platycladus orientalLeaves (POL). The obtained carbon material exhibits wide application prospects, because of simple and green-environmental technology, low-cost and satisfactory electrochemical properties, which avoided complex preparation routes and consumption of expensive chemical reagents in the traditional activation process. Under the optimum pyrolysis temperature (850 °C), the obtained POL-derived carbon (POL-850) possesses a high specific surface area (1140.2 m2g−1), sheet-like hierarchical porous microstructure, and uniform ternary heteroatoms co-doping (O: 6.79 at.%; N: 3.45 at.% and S: 2.20 at.%). As an electrode material for supercapacitor, the specific capacitance of the POL-850 reaches 224.4 Fg−1 of 0.5 Ag−1and 156.0 Fg−1 at 30 Ag−1, revealing excellent rate performance. The capacitance retention maintains 96.3 % after 10,000 consecutive charge-discharge cycles at 20 Ag−1, demonstrating superior cycling stability. Additionally, the assembled carbon-based symmetric supercapacitor device delivers a satisfied energy density of 11.0 Wh kg−1 with the power density of 65 W kg−1 and ultralong cycle-lifetime with 95.65 % capacitance retention after 10,000 charge/discharge cycles, while the Coulombic efficiency is retaining up to approximately 100 %. This work provides an easy and cost-effective way to rapidly prepare N/O/S co-doping hierarchical porous carbon for supercapacitors, which is very suitable for large-scale production.