Enhancing Na+ transport in single atomic Fe-anchored hierarchical porous carbon anode in SIB: Implanting high energy azole

Abstract

Developing highly porous carbon materials with abundant active sites is a promising strategy for creating high-performance anodes in sodium-ion batteries (SIBs). However, achieving a balance between high porosity and uniform active site dispersion remains challenging. In this study, we implanted high-energy N4-tetrazole rings to construct Fe single atoms anchored within a hierarchical porous nitrogen-rich carbon sponge. As an anode in SIBs, this material demonstrated an impressive reversible capacity of 249.4 mAh g⁻¹ at 0.2 A g⁻¹ after 1000 cycles, with coulombic efficiency of 99.7 %, and exhibited excellent rate performance with a reversible capacity of 107.3 mAh g⁻1 at 1 A g⁻1. Density of states (DOS) calculations revealed that doping with Fe and N atoms significantly enhances the material’s electrical conductivity. Additionally, the abundant pores in Fe@N₄ enable rapid Na⁺ insertion/extraction and diffusion. The transport kinetics of the anode material at the battery interface were further elucidated using in situ electrochemical impedance spectroscopy (in situ EIS).