Multi-heteroatoms doped hierarchical porous carbons from rice husk for zinc ion hybrid capacitors

As a big agricultural country, china produces more than 40 million tons renewable rice husk (RH) per year. Accordingly, it is still a monstrous difficulty to realize its high value-added utilization. Herein, a simple strategy was reported to prepare the N, P, S doped hierarchical porous carbon (NPS-HPC) by potassium hydrogen carbonate activation combined with in-situ doping technique from RH. The as-obtained NPS-HPC owns superb surface area of 1976.8 m 2 g −1 , thin sheet-like structures and suitable content of heteroatoms, which supplies abundant active sites, enables electron fast transfer and boosts the redox reaction between C=O/P-O and Zn 2+ . Owing to the structural advantages, the NPS-HPC-based zinc ion hybrid capacitor (ZIC) obtains high discharge capacity of 198.56 mAh g −1 at 0.1 A g −1 , superb energy density of 167.69 Wh kg −1 and power density of 19.64 kW kg −1 . Moreover, the NPS-HPC-based ZIC also demonstrates long-term life with no decay over 23,000 cycles. This work furnishes an efficient strategy for the preparation of multi-heteroatoms doped hierarchical porous carbon from biomass waste for ZICs.