Phosphorus incorporation-induced adsorption behavior modulation for carbon cathodes enables ultrastable and high-energy aqueous Zn-ion hybrid capacitors

Abstract

The aqueous zinc ions hybrid capacitors (ZHCs) have great potential for future energy storage devices by their high safety and low cost merits, more importantly, it could combine the advantages of batteries and supercapacitors with high energy density and power output, respectively. However, the development of reliable cathodes is still a challenge with the unsatisfactory cycling stability and limited reaction kinetic, severely restricting its further commercial applications. Herein, we present phosphorus functionalized nitrogen-doped hierarchical porous carbon nanosheets (PN-HPCNS), where the P incorporation could effectively enhance the electronic transfer kinetics and ion adsorption capability to achieve superior zinc-ion storage properties. The as-prepared PN-HPCNS cathode-based ZHC exhibits a high energy and power density (169.1 Wh kg⁻¹/68 W kg⁻¹, 15,840 W kg⁻¹/30.8 Wh kg⁻¹) and long cycling lifespans more than 20,000 cycles with 92.0% capacity retention. Systematic characterizations coupled with kinetics studies indicate that phosphorus modification is crucial to superior zinc ion storage, enabling PN-HPCNS with favorable reaction kinetics, promoting ion adsorption by providing more active sites. Moreover, the theoretical calculation reveals that the phosphorus modification could enhance the adsorption ability, contributing to the superior ZHCs performance of PN-HPCNS.