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

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journal contribution
posted on 2021-03-22, 19:05 authored by Chen-Jui Huang, Kuan-Yu Lin, Yi-Chen Hsieh, Wei-Nien Su, Chia-Hsin Wang, Gunther Brunklaus, Martin Winter, Jyh-Chiang Jiang, Bing Joe Hwang
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.