Controllable Nitrogen-Doped Carbon Nano-Hollow Cage Structures as Supercapacitor Electrode Materials

Supercapacitors (SCs) have attracted much attention due to their high-power density and long cycle life, where carbon materials have become the focus of electrode material research due to their excellent conductivity, stability, and reproducibility. However, the low specific capacitance and specific surface area of carbon materials lead to poor electrochemical properties, which seriously hinder their practical applications. The work here presents a simple but effective strategy to construct hollow nanocage structures by tannic acid etching ZIF-8. In this process, tannic acid releases protons to etch the MOF structure, and the remaining relatively large molecules are attached to the surface of ZIF-8 to prevent its structure from collapsing, and after high-temperature heat treatment, novel hollow nitrogen-doped carbon nanocage structures (HNCs) are obtained. Electrochemical tests show that the material has a capacity of 349.3 F g-1 at a current density of 0.5 A g-1, and still has a coulombic efficiency of 97.61% as well as a capacity retention of 97.86% after cycling for 10, 000 cycles at a current density of 3 A g-1. Therefore, this study provides a novel idea to explore the application of carbon materials with excellent electrochemical performance for energy storage.