New Insights into the N–S Bond Formation of a Sulfurized-Polyacrylonitrile Cathode Material for Lithium–Sulfur Batteries

• Published in: ACS applied materials & interfaces 2021-03, Vol.13 (12), p.14230-14238
• Main Authors: Huang, Chen-Jui, Lin, Kuan-Yu, Hsieh, Yi-Chen, Su, Wei-Nien, Wang, Chia-Hsin, Brunklaus, Gunther, Winter, Martin, Jiang, Jyh-Chiang, Hwang, Bing Joe
• Format: Article
• Language: English
• Subjects: Energy, Environmental, and Catalysis Applications
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.0c22811

Sulfurized polyacrylonitrile (S-cPAN) has been recognized as a particularly promising cathode material for lithium–sulfur (Li–S) batteries due to its ultra-stable cycling performance and high degree of sulfur utilization. Though the synthetic conditions and routes for modification of S-cPAN have been extensively studied, details of the molecular structure of S-cPAN remain yet unclear. Herein, a more reasonable molecular structure consisting of pyridinic/pyrrolic nitrogen (NPD/NPL) is proposed, based on the analysis of combined X-ray photoelectron spectroscopy, 13C/15N solid-state nuclear magnetic resonance, and density functional theory data. The coexistence of vicinal NPD/NPL entities plays a vital role in attracting S2 molecules and facilitating N–S bond formation apart from the generally accepted C–S bond in S-cPAN, which could explain the extraordinary electrochemical features of S-cPAN among various nitrogen-containing sulfurized polymers. This study provides new insights and a better understanding of structural details and relevant bond formation mechanisms in S-cPAN, providing a foundation for the design of new types of sulfurized cathode materials suitable for application in next-generation high-performance Li–S batteries.