Electronically modified hierarchical porous carbon by N, P heteroatoms for zinc ion hybrid capacitor

Abstract

Due to the low cost and steady physicochemical properties of carbon materials, zinc-ion hybrid capacitors (ZICs) composed of carbon cathode and Zn anode have aroused considerable attracts in recent years. However, the unsatisfactory capacity and electrochemical kinetics of carbonaceous cathode hinder its application in ZICs. Herein, a facile self-template thermal treatment method was proposed to prepare N, P co-doped hierarchical porous carbons (NP-HPCs). The electronically modified NP-HPC3 has an ultrahigh ratio of active N species and abundant micropores, which is favorable for zinc ions adsorption. In addition, the three-dimensional cross-linked network with abundant mesoporous cavities synchronously boosts electrons/ions transfer kinetics. Ex-situ characterization shows that the introduction of N, P heteroatoms is helpful to improve the adsorption of zinc ions. Thanks to these favorable structural characteristics, the NP-HPC3 displays an exceptional specific capacitance (275.0 F g−1 at 0.1 A g−1) and rate capability (182.0 F g−1 at 20 A g−1). More significantly, the NP-HPC3-based ZIC delivers a prominent energy density of 107.8 Wh kg−1 at a power density of 90.7 W kg−1, a long cycle life (96.9 % capacitance retention after 10,000 cycles) together with an outstanding anti-self-discharge performance (0.001145 V h−1@200 h). This study not only affords a feasible and environmental route to construct advanced heteroatom doped carbonaceous materials, but also explores the interrelation between zinc ions storage behavior and structural characteristics of carbon materials.