Phosphorus-Mediated Local Charge Distribution of N-Configuration Adsorption Sites with Enhanced Zincophilicity and Hydrophilicity for High-Energy-Density Zn-Ion Hybrid Supercapacitors

Tailor-made carbonaceous-based cathodes with zincophilicity and hydrophilicity are highly desirable for Zn-ion storage applications, but it remains a great challenge to achieve both advantages in the synthesis. In this work, a template electrospinning strategy is developed to synthesize nitrogen and phosphorous co-doped hollow porous carbon nanofibers (N, P-HPCNFs), which deliver a high capacity of 230.7 mAh g(-1) at 0.2 A g(-1), superior rate capability of 131.0 mAh g(-1) at 20 A g(-1), and a maximum energy density of 196.10 Wh kg(-1) at the power density of 155.53 W kg(-1). Density functional theory calculations (DFT) reveal that the introduced P dopants regulate the distribution of local charge density of carbon materials and therefore facilitate the adsorption of Zn ions due to the increased electronegativity of pyridinic-N. Ab initio molecular dynamics (AIMD) simulations indicate that the doped P species induce a series of polar sites and create a hydrophilic microenvironment, which decreases the impedance between the electrode and the electrolyte and therefore accelerates the reaction kinetics. The marriage of ex situ/in situ experimental analyses and theoretical simulations uncovers the origin of the enhanced zincophilicity and hydrophilicity of N, P-HPCNFs for energy storage, which accounts for the faster ion migration and electrochemical processes.

Automated summary

A new technique is developed to synthesize nitrogen and phosphorous co-doped hollow porous carbon nanofibers (N, P-HPCNFs) with zincophilicity and hydrophilicity for Zn-ion storage applications. These fibers exhibit high capacity, superior rate capability, and maximum energy density. Theoretical simulations show that the introduced P dopants regulate the distribution of local charge density and create a hydrophilic microenvironment, accelerating the reaction kinetics.