Microstructure Evolution and Its Correlation with Performance in Nitrogen-Containing Porous Carbon Prepared by...

Area of Science:

• Materials Science
• Computational Chemistry
• Electrochemistry

Background:

• Nitrogen-containing porous carbon (NCPC) materials are crucial for electrochemical energy storage and conversion due to their high surface area and conductivity.
• Controlling the microstructure of amorphous porous carbon during synthesis remains challenging due to poorly understood carbonization mechanisms.
• Establishing clear relationships between microstructure and performance is difficult without precise control over material synthesis.

Purpose of the Study:

• To elucidate the atomic-level carbonization mechanism of polypyrrole (PPy).
• To identify key structural factors governing the conductivity and pore size of the resulting NCPC materials.
• To develop predictive models for structure-property relationships in NCPC materials.

Main Methods:

• Reactive molecular dynamics (ReaxFF-MD) simulations to model the carbonization process at the atomic scale.
• First-principles calculations to investigate electronic and structural properties.
• Machine learning techniques to build interpretable models correlating structure and performance.

Main Results:

• Detailed atomic-level ring expressions for polypyrrole thermal conversion were constructed.
• The study identified specific structural factors that dictate the conductivity and pore size of carbonized products.
• Physically interpretable machine learning models were developed to quantitatively link structure to performance.
• Preferential deprotonation via dihydrogen atom desorption from nitrogen atoms during carbonization was confirmed.

Conclusions:

• This work provides unprecedented atomic-scale insight into the microstructure evolution of polypyrrole during carbonization.
• The findings facilitate a deeper understanding of structure-property relationships in NCPC materials.
• This theoretical approach offers a new pathway for designing and developing NCPC materials with tailored morphology and enhanced performance for energy applications.