Preparation of in-situ N/O co-doped lily-derived porous carbon framework material and its application in supercapacitors

The choice of an activator and activation method is crucial to the preparation of high-quality activated carbon. Herein, inspired by a foaming strategy, we selected KMnO4 as activator, and hierarchical porous framework carbon material was prepared via lily powder being fully foamed and activated in the KMnO4 hot solution. The Lily-derived Porous Carbon Material (LPCM) possesses the characteristics of in-situ co-doping of N and O. The maximum specific surface area of the obtained sample was 1852.5 m2g-1, and the corresponding total pore volume was 1.11 cm3g-1. Due to the interconnected hierarchical pore network structure and rich O (13.16 at%) & N (3.31 at%) contents, at 600 °C, the specific capacitance of the LPCM was 352 F g−1 at 0.5 A g1 and the cycling reliability was 100% after 10,000 charges and discharges. In addition, the voltage window of All-solid-state Symmetric Flexible Supercapacitor (ASFS) fabricated with PVA-KOH gel electrolyte was 1.4 V. And the fabricated ASFS device had energy density of 23.82 Wh kg−1 at 700 W kg−1. At the same time, two ASFSs in series could light up a small red bulb and maintained for more than 6 min.