Effect of Different Nitrogen Configurations on Sodium Storage Properties of Carbon Anodes for Sodium Ion Batteries

Nitrogen doping carbon materials are considered to be promising candidates for Na+ storage anodes. However, hitherto, the effects and mechanism of specific single N configuration (among pyrrolic N, quaternary N, and pyridinic N), on the sodium storage behaviors of carbon materials, are still puzzling, owing to the difficulties in accurately synthesizing a certain type of single N configuration dominated carbon materials (NCDCMs). Here, various NCDCMs have been successfully controlled and synthesized by small molecule polymerization methods, and their synthesis process has been also verified by NMR, MOLDI-TOF, TG-MS, etc. When serving as sodium ion battery anodes, the NCDCMs dominated by a high concentration of pyrrolic N (>80.3%) exhibits a satisfactory reversible capacity (434.5 mA h g-1 at 50 mA g-1 and 146.7 mA h g-1 at 2000 mA g-1, respectively). It is revealed that pyrrolic N has more suitable adsorption energy and larger interlayer spacing, by density functional theory calculations and electron orbital theory, respectively, which synergistically makes the material obtain excellent electrochemical performance. This research exhibits a more efficient way to reveal the differences in the sodium ions storage behavior of different nitrogen configurations doped carbon, and provides new insight for the precise design and synthesis of a certain type of heteroatom doping to achieve satisfactory electrochemical performance.