posted on 2021-03-22, 19:05authored byChen-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.