Ultrathin and large-size nanosheets. The study presents the fabrication process of ultrathin, large-size C₂N nanosheets with a well-organized nanostructure by polymerizing precursor on sodium chloride templates via the chemical vapor deposition method. When used as anodes for sodium-ion batteries, C₂N nanosheets exhibit outstanding cyclic stability and rate performance.

Abstract

In this study, we have created and investigated ultrathin, large-size two-dimensional C₂N nanosheets, which serve as promising anode materials for sodium ion batteries. Those ultrathin C₂N nanosheets were produced through a chemical vapor deposition process, involving the polymerization of the precursor molecule HAT-CN on sodium chloride templates. Notably, these nanosheets inherit an abundance of nitrogen sites from the precursor molecules, which are highly advantageous for sodium ion storage. In addition, the ultrathin nature of these nanosheets leads to significantly shorter ion transport pathways, enhancing their capacity for rapid ion storage compared to C₂N particles. As a result, the anode constructed using C₂N nanosheets demonstrates a notably higher capacity of 335.1 mAh g⁻¹ at 0.5 A g⁻¹, outperforming the 211.5 mAh g⁻¹ of C₂N particles. Furthermore, it exhibits outstanding rate performance, achieving 255.4 mAh g⁻¹ at a current density of 2.0 A g⁻¹, along with excellent cycle stability, maintaining a reversible capacity retention of 92.9 % over 1500 cycles at 2.0 A g⁻¹. This research introduces a novel approach to developing high-capacity anode materials for sodium storage by utilizing carbon nitride materials.