Phytic acid assisted preparation of N, P Co-doped hierarchical porous carbon for high-rate Zn-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSCs) not only combines the advantages of batteries and supercapacitors, but also features low cost and environmental friendliness. However, the poor active site density and sluggish diffusion kinetics of carbon cathode brings about low capacity and terrible rate capability of ZHSCs. In this work, an activation assisted template procedure is proposed to synthesize nitrogen and phosphorous dual-doped hierarchical porous carbon (NP-HPC), where phytic acid acts as both doing precursor and activation medium. Benefitting from the synergetic modulation in porosities and surface functionalities, the optimized NP-HPC-2 delivers high capacity (394.51 F g −1 at 0.2 A g −1 ), superior rate capability (200.21 F g −1 at 50 A g −1 ) and excellent durability (95.7 % retention over 10,000 cycles). Consequently, the assembled ZHSC exhibits a remarkable energy density of 140 Wh kg −1 and an impressive power density of 40 kW kg −1 . Density functional theory (DFT) calculations revealed that the introduction of P doping adjust the distribution of local charge density of edged N with a lowered adsorption energy barrier for Zn 2+ storage. This work not only sheds light on the integrative effect of structure modulation and functionality regulation but also provide a feasible solution for the preparation of carbon cathodes towards high energy and power density ZHSCs.