An improved bioinspired strategy to construct nitrogen and phosphorus dual-doped network porous carbon with boosted kinetics potassium ion capacitors

Abstract

Potassium-ion capacitors (PICs) have drawn appreciable attention because PICs can masterly integrate the virtues of the high energy density of battery-type anode and high power density of capacitor-type cathode. However, the sanguine scenario involves the incompatible capacity and sluggish kinetics in the PIC device. Herein, we report the synthesis of nitrogen and phosphorus-doped network porous carbon materials (NPMCs) via a self-sacrifice template strategy, which possesses a desired three-dimensional structure and prosperous electrochemical properties for K⁺ storage capacity. The obtained hierarchical porous carbon delivers a high reversible capacity of 420 mA h g⁻¹ at 0.05 A g⁻¹ and good cycling performance owing to its high concentration of reversible carbon defects and strong charge transfer kinetics. As expected, an advanced PIC device was assembled with a working voltage as high as 4.5 V, delivering an extraordinary energy density of 81.6 W h kg⁻¹ as well as a splendid long life. Systematic characterization analysis combined with density functional theory calculations indicates that the strategy for preparing PIC devices with outstanding performance in this work can provide new insights for the development of PICs for an extensive range of applications.