N/S codoping modification based on the metal organic framework-derived carbon to improve the electrochemical performance of different energy storage devices

Abstract

Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources, low cost, and environmental friendliness. However, the low capacity and poor high rate performance still constitute great challenges. Metal organic framework-derived carbon has been widely researched because of its high porosity, tunable structure, and good conductivity. In this work, N/S codoped hierarchical porous carbon microspheres were prepared by a high-temperature heat treatment and atomic doping process using a zinc-based organic framework as the precursor. When used as a potassium-ion battery anode, it has a high reversible specific capacity (435.7 mAh g−1), good rate performance (133.5 mAh g−1 at 10,000 mA g−1), and long-term cycling stability (73.2% capacity retention after the 2500th cycle). The potassium storage mechanism of the derived carbon was explained by various electrochemical analysis methods and microstructure characterization techniques, and the relationship between the structural characteristics and electrochemical properties was researched. In a supercapacitor, the porous carbon material exhibits a specific capacitance of 307.2 F g−1 at a current density of 0.2 A g−1 in a KOH aqueous solution and achieves a retention rate of 99.88% after 10,000 cycles. The assembled symmetric supercapacitor device delivers a high energy density of 6.69 Wh kg−1, with a corresponding power density of 2500 W kg−1. In addition, density functional theory calculations further confirmed that N/S codoping can improve the adsorption capacities of potassium and hydroxyl ions in the derived carbon.