Nitrogen-Rich Pitch-Derived Carbon Nanosheets as Anode Materials for Sodium-Ion Batteries

Abstract

This study focuses on the preparation of nitrogen-rich pitches using nitrogen-containing aromatics and simulates the synthesis process using molecular dynamics. Nitrogen-rich pitch-based carbon nanosheets are synthesized using the template method. Negative electrode materials for nitrogen-rich pitch sodium-ion batteries are fabricated via high-temperature carbonization. Additionally, the sodium-storage capabilities of carbon nanosheets derived from various nitrogen-rich pitches are investigated. The forms of nitrogen in nitrogen-rich pitches synthesized from different N-containing aromatic hydrocarbons are examined as well. The valence alterations of nitrogen in the carbon nanosheets subjected to high-temperature conditions are examined. The findings confirmed that the escape of nitrogen elements, which results in intrinsic defects, can enhance the sodium-storage capacity. Additionally, the results suggest that during high-temperature carbonization, the escape of nitrogen increases the disorder of carbon nanosheets, thus improving the sodium-storage capacity of the material. Notably, the PPD-800/1300 sample maintains a stable sodium-storage capacity of 330.2 mAh g-1 after 200 cycles at a current density of 50 mA g-1. This study introduces a technique to modulate intrinsic defects in the carbon layer via in-situ nitrogen escape, thereby increasing the sodium-storage sites and enhancing the electrochemical performance. Additionally, a viable strategy for utilizing nitrogen-rich pitches in the fabrication of sodium-ion anode materials is proposed.

Keywords: nitrogen-rich pitch, Carbon nanosheets, Porous carbon, Electrochemical performance, sodium battery